Lariosaurus

Lariosaurus is an extinct genus of nothosaurid from the Middle Triassic (late Anisian to late Ladinian stage) of central and western Europe and China. With a length of just , it was one of the smallest known nothosaurs. First discovered at Perledo on the Lake Como in 1830, it was named in 1847 by Curioni, its name meaning "Lizard from Larius", the ancient name of the lake. This makes it one of the earliest studied reptiles from the Alps. It is known from an almost complete skeleton holotype and several other fairly complete fossils.
The nothosaur "Eupodosaurus", initially classified as a stegosaurian dinosaur, is now considered synonymous with "Lariosaurus". In 1998 Rieppel synonymised "Lariosaurus, Silvestrosaurus" and "Ceresiosaurus," but this is disputed by many authors and they are usually considered close relatives.
Features.
For a nothosaur, "Lariosaurus" was primitive, possessing a short neck and small flippers in comparison to its relatives. This would have made it a relatively poor swimmer, and it is presumed to have spent much time on dry land, or hunting in shallows. It had a large postorbital region of the skull with the temporal fossae noticeably larger than the orbits. The premaxillary and anterior dentary teeth are strongly elongated, like fangs, and could have acted as a 'fish trap'. The parietal and squamosal bones are elongated into a small occipital crest for the attachment of jaw muscles. The vertebrae are pachyostotic and have a low neural spine. Ribs are present from the neck all the way down to the sacrum, which has a cluster of four or five pairs. There are caudal ribs, but they are very small and not present beyond the 15th caudal vertebra. The gastral ribs are made up of multiple elements and form a sturdy kind of armour. The humerus has a weakly developed deltapectoral crest, and increases gradually in width towards the distal end. There is a distinct space between the radius and the more slender ulna. The fingers have more bones than the toes and clearly show how "Lariosaurus" was unique among nothosaurs because its front legs were adapted into paddles, while the back legs remained five-toed. The femur is more lightly built than the humerus but longer. There is less difference between tibia and fibula than between radius and ulna. Further, based on skeletal findings of immature lariosaurs inside the adults, "Lariosaurus" is believed by many to be viviparous, or able to bear live young. Another "Lariosaurus" skeleton was found with two juvenile placodonts of the genus "Cyamodus" in its stomach, giving an indication of its diet.
In 2014 a skull was found in the Winterswijk Muschekalk quarry, of what appeared to be a new species, that was named "Lariosaurus vosseveldensis". In 2015 it was added to the collection of Museum TwentseWelle in Enschede. It was registered TW.480000504.
Also found was an isolated, fused parietal, that was registered TW.4800000505.
In popular culture.
Loch Ness mocking Lariosaurus sightings are often reported on the newspapers of the Lake Como area. The myth has been cited in various books, songs and TV programmes.


Bertie Formation

The Bertie Group or Bertie Limestone, also referred to as the Bertie Dolomite and the Bertie Formation, is an upper Silurian (Pridoli, or Cayugan and Ulsterian age in the local chronologies) geologic group and Lagerstätte in southern Ontario, Canada, and western New York State, United States. Details of the type locality and of stratigraphic nomenclature for this unit as used by the U.S. Geological Survey are available on-line at the National Geologic Map Database. The formation comprises dolomites, limestones and shales and reaches a thickness of in the subsurface, while in outcrop the group can be thick.
The group represents the uppermost unit of the Cayugan Series and the youngest Silurian unit in Ontario. The group overlies the Salina Group and is conformably overlain by the Devonian Bois Blanc Formation in Ontario and Onondaga Limestone in New York.
Two formations within the Bertie Group, the Fiddler's Green and Williamsville, are considered Konservat-Lagerstätten; geologic units that contain a unique and typically soft-bodied fauna. These formations have produced thousands of Silurian eurypterids (sea scorpions) as well as "Proscorpius osborni", the oldest known scorpion, xiphosurans, primitive fossil flora, and the fish "Nerepisacanthus denisoni". The excellent preservation of the many eurypterids and other taxa was the possibly result of periodic hypersaline and anoxic conditions owing to the groups position within a shallow inland sea (the Appalachian basin).
Description.
The type locality for the Bertie Group is Ridgemount Quarry, located west of Fort Erie on the Niagara Peninsula of Bertie, Ontario, west of Buffalo, New York, after which the group is named. The first author who recognized the group as a separate stratigraphic unit was Chapman in 1884. In more recent years, the unit has been elevated to group status.
Geographic extent.
The Bertie Group forms the bedrock in a narrow band extending from Fort Erie, west of Buffalo, New York, through Hagersville, New Hamburg, Harriston, and Walkerton to Southampton on Lake Huron. The group consists of medium- to massive-bedded aphanitic brown to grey, laminated, bituminous and burrowed dolomites, with minor thin-bedded shaly dolomites.
Along the outcrop area between Fort Erie and Hagersville, the thickness varies from . It thickens to in the subsurface. Sanford (1969) used the term Bertie Groupfrom Fort Erie to the vicinity of Hagersville and the term Bass Islands Formation north and west of Hagersville. The group is correlated with the Bass Islands Formation of Michigan. Bertie Group dolomite is quarried for crushed stone at Fort Erie, Port Colborne, Dunnville, Cayuga, and Hagersville.
Stratigraphy.
The Bertie Group is the uppermost unit in the Cayugan Series and forms part of the Tippecanoe II sequence. At its type locality, the group is subdivided into several formations. In central New York, the Group is subdivided into the Fiddlers Green Dolomite, Forge Hollow Shale, and Oxbow Dolomite members, from oldest to youngest. Here, the Bertie Group is overlain by the Honeoye and Chrysler formations. In New York, the Onondaga Limestone overlies the Bertie Group. The group is in Ontario conformably overlain by the Middle Devonian Bois Blanc Formation.
Laterally, the group is equivalent to the Bass Islands Formation and is mapped as a combined stratigraphic unit. Haynes and Parkins (1992) reported that the
Bertie Group is progressively cut by the Bass Islands Formation from Dunnville to Hagersville. In Pennsylvania, the Bertie Group is time-equivalent with the Keyser Formation.
Fossils.
The Bertie Group Fiddler's Green and Williamsville formations are considered Konservat-Lagerstätten; units characterized by rare and typically soft-bodied fauna. These formations have produced thousands of fossil eurypterids (sea scorpions) since collecting began in earnest in the mid-20th century. Other fossils from the unit include "Proscorpius osborni", the oldest known scorpion, early flora, and a fossil fish; "Nerepisacanthus denisoni". The excellent preservation of the many eurypterids possibly was the result of periodic hypersaline and anoxic conditions.
Age.
The Bertie Formation is late Silurian (Pridoli, or Cayugan and Ulsterian in the local chronologies).
Interpretations of depositional environments.
The Appalachian Foreland basin was formed during the Alleghanian orogeny in the Early to Middle Ordovician. The period of mountain building led to the closure of the Iapetus and Rheic Oceans. Due to tectonic loading, the foreland basin developed in the present-day area north of the Appalachian Mountains. The late Silurian climate was arid and warm; this, and the restricted and shallow nature of the inland basin, resulted in the deposition of evaporites in the Salina Group, ranging in thickness from . Zones of stromatolites and thrombolites (non-laminated algal
mounds) occur in several formations in the Bertie Group, along with numerous desiccation cracks. During the Hercynian orogeny in the Devonian, many of the Silurian sediments were eroded to the south in the Appalachians, while north of the mountains the Silurian units were preserved.
The sediments of the Bertie Group were deposited on the paleosouthern side of the subsiding Algonquin Arch, flanking the northern rim of the Appalachian foreland basin of Laurentia.
The Bertie Group was deposited in a hypersaline marine environment. The stratigraphic sections and the fossil content suggest that the group was deposited in a near-shore marine to lagoonal setting, and the evaporites and casts of halite pseudomorphs, with sides of up to , suggest the environment was far from normal marine; hypersalinity must have prevailed throughout most of the depositional history of the group. Alternating hypersaline and brackish estuarine conditions have been recorded in the group. The dolomitization of the group most probably was not primary.


Cerro Miscanti

Cerro Miscanti is a mountain located in the Antofagasta Region of Chile, immediately south of Chiliques and north of Miñiques. It towers over Laguna Miscanti. Rock samples from Cerro Miscanti are of andesitic composition, but andesite-containing dacites have also been found.


Acotango

Acotango is the central and highest of a group of stratovolcanoes straddling the border of Bolivia and Chile. It is high. The group is known as Kimsa Chata and consists of three mountains: Acotango, Umurata () north of it and Capurata () south of it.
The group lies along a north–south alignment. The Acotango volcano is heavily eroded, but a lava flow on its northern flank is morphologically young, suggesting Acotango was active in the Holocene. Later research has suggested that lava flow may be of Pleistocene age. Glacial activity has exposed parts of the inner volcano, which is hydrothermally altered. Glacial moraines lie at an altitude of but a present ice cap is only found past of altitude.
The volcano is a popular hiking route in the Sajama National Park and Lauca National Park. To climb the summit from the Chilean side is dangerous due to land mines, however it is relatively safe to climb the summit from the Bolivian side. The southern ascent starts over a glacier and passes an abandoned copper mine.
It is believed that Pedro Rosende, a Chilean explorer, found the remains of firewood at the summit of Acotango. Because of this, it is thought that the mountain might have been one of the high Incan Andean sanctuaries. However, more exploration is needed to verify this information.


Rhadinosaurus

Rhadinosaurus (meaning "slender lizard") is a genus of nodosaurid ankylosaur first described in 1881 by Harry Govier Seeley, based on remains uncovered in Austria. It was a herbivore that lived around 84.9 to 70.6 million years ago (during the Late Cretaceous period). The type species is "R. alcimus".
Fossils.
The "Rhadinosaurus" hypodigm (holotype) consists of one tibia fragment, one limb fragment, two fibulae, and two dorsal vertebrae. The fibulae (PIUW 2349/34), which are clearly ankylosaurian, were originally identified as femora in the original description, but were eventually re-identified in a 2001 review of ankylosaur specimens from the Grünbach Formation. Sachs and Hornung (2006) re-identified one of the putative humeral bones (PIUW 2348/35) as a tibial fragment of an rhabdodontid ornithopod dinosaur, referring it to "Zalmoxes" sp.
Taxonomy.
"Rhadinosaurus" was initially classified as a dinosaur of uncertain position, and later considered an ornithosuchid as well as possible synonym of "Doratodon", until Franz Baron introduced the now popular theory that classifies it as a probable synonym of "Struthiosaurus".


Syberg

The Syberg is a hill in the Ruhr, 244.63 m above sea level (NN), which is part of the Ardey Hills. The Syberg is home to the Hohensyburg, the Vincke Tower, a monument to Emperor William I and other points of interest.
The family name of the House of Syberg is derived from the Syberg.


Kuehneosaurus

Kuehneosaurus is an extinct genus of Late Triassic kuehneosaurid reptile known from the Late Triassic (Norian stage) of Luxembourg. It was named by P. L. Robinson in 1962 and the type and only species is Kuehneosaurus latus. Measuring 72 centimetres long (2.3 feet), it had "wings" formed from ribs which jutted out from its body by as much as 14.3 cm, connected by a membrane which allowed it to slow its descent when jumping from trees. It is a member of a family of gliding reptiles, the Kuehneosauridae, within the larger group Lepidosauromorpha, which also contains modern lizards and tuatara.
Unlike its longer "winged" relative "Kuehneosuchus" (which may be a species of the same genus or represent a different sexual morph), aerodynamic studies have shown that "Kuehneosaurus" was probably not a glider, but instead used its elongated ribs to parachute from the trees. A study by Stein "et al." in 2008 found that its parachuting speed, descending at a 45-degree angle, would be between 10 and 12 metres per second. Pitch was controlled by lappets (wattle-like flaps of skin) on the hyoid apparatus, as in the modern gliding lizard "Draco".


Sumidero Canyon

Sumidero Canyon () is a deep natural canyon located just north of the city of Chiapa de Corzo in the state of Chiapas, in southern Mexico. The canyon's creation began around the same time as the Grand Canyon in the U.S. state of Arizona, by a crack in the area's crust and subsequent erosion by the Grijalva River, which still runs through it. Sumidero Canyon has vertical walls which reach as high as , with the river turning up to 90 degrees during the length of the narrow passage.
The canyon is surrounded by the Sumidero Canyon National Park, a federally protected natural area of Mexico which extends for over four municipalities of the state of Chiapas. This park is administered by the National Commission of Protected Natural Areas (CONANP). Most of the vegetation in the park is low- to medium-height deciduous rainforest, with small areas of mixed pine-oak forest and grassland. At the north end of the canyon is the Chicoasén Dam and its artificial reservoir, one of several on the Grijalva River, which is important for water storage and the generation of hydroelectric power in the region.
The canyon and national park is the second most important tourist site in Chiapas, drawing mostly Mexican visitors who see the canyon from boats which embark on the river from Chiapa de Corzo. The park borders Tuxtla Gutiérrez, the state's largest city, which has caused problems with human encroachment and settlement on park land. More importantly, the urban areas and logging industries upstream from the canyon have caused serious pollution problems, with up to 5000 tons of solid waste extracted from the Grijalva River each year. This waste tends to build up in the canyon because of its narrowness, the convergence of water flows and the presence of the Chicoasén Dam.
Description.
Geology.
The Sumidero Canyon was formed by cracks in the earth's crust along with erosion by the Grijalva River, which still flows through it. The process of its formation began about 35 million years ago, making the Sumidero contemporary with the Grand Canyon on the Colorado River. The Grijalva is the main water system in the area, beginning in the Cuchumatanes in neighboring Guatemala. The river then flows through Chiapas, including the 13-km length of the canyon, from south to north, then on to Tabasco before it empties into the Usumacinta River. This river basin is one of the two most important in Chiapas, and one of the most important in Mexico with a total river length of approximately , draining an area of , with an average flow of about forty million cubic meters.
In addition to the Grijalva, there are other flows of water in the area in and around the canyon, many of which are seasonal. These consist of streams, some of which form waterfalls on the canyon's sides, and underground movements which have created caves and karst formations. The last important water formation in the area is the manmade reservoir of the Chicoasén Dam.
The canyon proper is deep and narrow, characterized by vertical walls. As the gap changes direction as much as 90 degrees in places, it separates the Meseta de las Animas mesa in the west from the Meseta de Ixtapa mesa in the east. The width of the canyon varies from . Most of the canyon's walls are between high, reaching at their highest point. These walls expose a long process of disturbance in the Earth's crust with layers of limestone from the Upper Mesozoic, which contain fossils of marine creatures. During the Mesocretac Period, there was an elevation of ocean floor which formed much of the mountains of the area.
Notable features.
The interior of the canyon has thirty rapids, five waterfalls, three beaches, two freshwater springs and a cofferdam three meters wide. The canyon contains endangered and threatened species such as the Central American river turtle and the American crocodile, which can be seen on the riverbanks. The walls of the canyon contain numerous small caves, rock formations and other notable features. The best known of the area's caves is the "Cueva de Colores" ("Cave of Colors"). This cave gets its name from the filtration of magnesium, potassium and other minerals which form colors on the walls, especially shades of pink. It contains an image of the Virgin of Guadalupe inside usually surrounded by fresh flowers and burning candles left by visitors. The "Cueva de Silencio" ("Cave of Silence") is so named because of a lack of echo or any other kind of resonance in its interior. In another small cave, there is a stalactite called the "Caballito de Mar" or "Seahorse" after its shape. Of the various seasonal waterfalls, the best known is the "Árbol de Navidad" ("Christmas Tree"). The “branches” of the Árbol are made by deposits from the waterfall which have been covered in moss. During the rainy season, when the waterfall is active, the water and the light change the colors of the “branches” and make the formation stand out. The park was a candidate in 2009 as one of the Seven New Natural Wonders of the World.
Climate.
Despite its biological, ecological and cultural diversity, there have been few studies performed in the park area. For this reason, there is a lack of information about species, habitats and water flow. There is also relatively little information about how human activities affect the park.
As the park is located in the Central Valley of Chiapas and borders the Northern Mountains region, altitudes vary from approximately above sea level in the municipality of Chiapa de Corzo to above sea level at the El Roblar lookout point. This geography produces a channel for air flow from northwest to southeast as well as three main climates based on the Köeppen system as modified for Mexico. These are hot and dry (where airflow is blocked), semi-hot and humid, and hot and humid. The average rainfall for the park is about 1,000 mm during the rainy season from May to October and 200 mm during the dry season from November to April. Average annual temperature is 26 °C. The rugged terrain also forms a number of microclimates.
Vegetation.
Most of the park's vegetation, especially around the canyon, is dense tropical rainforest. Most species found in the park are members of the family Fabaceae with 59 species and the family Asteraceae with 25 species, which reflect the abundance of these families statewide. Other important families include the Orchidaceae and Euphorbiaceae, each with 22 species, the family Convolvulaceae with 17 species, and the Cactaceae with 11 species. 122 species are considered valuable as ornamental plants with 46 having medicinal uses and 31 species valuable for logging. These mostly come from the rainforest areas. The rainforest vegetation is mostly deciduous, shedding leaves in the dry season. However, there are perennial rainforests, forests of pine and oak, grasslands (mostly induced) and areas with secondary vegetation.
The three main vegetation classifications are low-height rainforest, medium-height rainforest (as per the size of the trees), pine-oak forest and meadows. Medium-height deciduous rainforest is mostly located on either side of the canyon, in the north and east of the part towards San Fernando and in the Cañada Muñiz at altitudes of between 150 and 1250 masl. It is mostly found in areas with basalt or granite rock and where there are lime deposits, covering an area of in total. While many plants here loose leaves in the dry season, there are some that retain them year-round. Maximum height of trees varies between 25 and 30 meters. The density of the tree cover in these areas is enough to lower temperatures on the ground in the summer rainy season due to the maximum foliage which occurs at this time. The tree cover is composed of the following species: breadnut ("Brosimum alicastrum"), guanacaste ("Enterolobium cyclocarpum"), totoposte ("Licania arbórea"), jocotillo ("Astronium graveolens"), cedar ("Cedrela odorata"), cuaulote blanco ("Luehea candida"), hormiguillo ("Platymiscium dimorphandrum"), chicozapote ("Manilkara zapota"), tempisque ("Mastichodendron capiri") and various types of amate fig trees ("Ficus" spp.). Under the tree cover, there is significant plant diversity, including palms and araceas. Epiphytes (air plants) are abundant as well, along with orchids, Bromeliaceae and cactus. Cactus are primarily found on the vertical walls of the canyon and belong to the Acanthocereus family. In the 1970s, tree area in a good state of conservation amounted to , or 17.72% of the total land area. From 1988 to 1993, this amount was reduced to , or 5.35%. From 1990 to 2000, it is estimated that eight percent of the remaining forests and 38% of the rainforests were damaged. Many of the areas in good condition are broken up by disturbed areas. Most of the damage is due to illegal logging and the clearing of land for pasture or agriculture. Medium-height perennial rainforest (also known as evergreen cloud forest) exists only in small dispersed patches, mostly on the sides of the canyon in contact with the Grijalva River. Many of these patches are less than one hectare in size, as they are located on small areas of flat land at altitudes between 1000 and 2,500 masl. The soils are rich in undecomposed plant matter which holds in moisture.
Low-height deciduous rainforest is mostly found around the La Ceiba and La Coyota lookout points in the south and southeast sections of the park, with some in the east towards the La Chacona Cañada. These occupy a territory of in the park. Tree heights extend from four to ten meters with some as high as 15 meters. Non-tree species are not as common and mostly consist of succulent species such as "Agave", "Opuntia", "Stenocereus" and "Cephalocereus". Other important species include "Alvaradoa amorphoides", "Bursera simaruba", "Ceiba acuminate", "Bursera bipinnata", "Bursera excels", "Cochlospermum vitifolium", "Haematoxylon brasiletto", "Piscidia piscipula", "Swietenia humilis", "Acacia collinsii" and "Pseudobombax ellipticum".
Pine-oak forests exist in the northwest of the park in the highest altitudes, covering about . They are part of the same type of forest found in the Soyaló region it is adjacent to. They are found at an altitude of 1,200 masl and above in areas that receive precipitation of about 1500 mm annually. The most common species is the oak "Quercus conspersa", often found mixed with the two kinds of rainforest found in the park. Air plants are common here as well as bromeliads, orchids and plants from the "Maxillaria", "Lycaste", "Cattleya" and "Laelia" groups.
Grassland is not naturally occurring but rather exists due to human activities such as farming and livestock raising. It is seen on the north and south sides of the canyon and is usually associated with secondary vegetation such as "Tecoma stans", "Gliricidia sepium", "Plumeria rubra" and "Acacia collinsii", occupying an area of in the park.
Wildlife.
Throughout the history of the area, especially since it was definitively explored in the 1960s, the area's wildlife diversity has been severely negatively impacted by human encroachment in the form of settlements, agriculture and hunting. However, since the federal park was established in the 1980s, wildlife diversity has increased. In 1986, the federal "Secretaría de Agricultura y Recursos Hidráulicos" (SARH) reported a total of ninety species of vertebrates divided into four species of fish, one amphibian, 14 reptiles, 26 birds and 40 mammals. A 2005 study indicates 308 species with four species of fish, 15 amphibians, 195 birds, and 53 mammals. Between these two, there have been a number of other studies which also show the growth of the number of wildlife species in the park.
Information about fish species is scarce but at least four protected species have been detected. According to a CONANP study in 2007, there are 12 species of reptile here under protection, including the river crocodile ("Crocodylus acutus"), and one threatened species, the Yucatán banded gecko ("Coleonyx elegans"). Birds are the most common type of animal in the park, with about 195 species documented. Six of these species are threatened and 17 are subject to special protection. One threatened bird species in the park is the great curassow ("Crax rubra"). Relatively abundant species include "Actitus macularia", "Dendrocygna autumnalis", "Egretta caerulea", "Egretta thula", "Tachybaptus dominicus" and "Coragyps atratus", all of which are associated with bodies of water. There have been 53 species of mammals detected recently in the park, of which two are considered threatened, two in danger and two subject to special protection. Endangered and threatened species include the spider monkey ("Ateles geoffroyi"), jaguarundi, ocelot, lowland paca, white-tailed deer, anteater ("Tamandua tetradactyla") and buzzard ("Sarcoramphus papa"). The most abundant species include the bat "Artibeus jamaicensis" and the rat "Peromyscus mexicanus".
National park.
Establishment of the park.
The Sumidero Canyon National Park has its origins in a Chiapas state decree issued in 1972, which made the area around the canyon an ecological reserve to preserve its geology, history and wildlife and to allow for scientific study. For similar reasons, the park was taken over and enlarged to 21,789 hectares by the federal government in 1980. Most private landholders in the area were compensated for their lands, but not all resident persons or businesses were evicted. Since that time, the park has been under the administration of various agencies such as SAHOP, SEDUE and SEMARNAP, with the current managers being the "Comisión Nacional de Áreas Naturales Protegidas" and the "Secretaría de Educación Pública". In 2004, the park came under the protection of the Ramsar Convention due to the importance of its ecology and water systems. It was also named a "Región Prioritaria Terrestre" and an "Área de Importancia para la Conservación de las Aves" by the "Comisión Nacional para el Conocimiento y Uso de la Biodiversidad" (CONABIO) in 2000. In 2005 and 2006, this agency enlarged the park again with the expropriation of lands in the municipalities of San Fernando and Tuxtla Gutiérrez, adding a total of . It remains, however, smaller than most other national parks in Mexico.
The center of the park is the Sumidero Canyon and the Grijalva River that runs from south to north through it. The park's borders on this river are marked by the Belisario Domínguez Bridge, over which the Pan-American Highway runs, in the south and the Chicoasén Dam, to the north. The rest of the park's borders extend into the municipalities of Tuxtla Gutiérrez, Chiapa de Corzo, Osumacinta and San Fernando. This territory is mostly located in the Central Valley region of the state. The park is open 365 days a year. The park is divided into four sections by direction: the northwest includes medium-height, somewhat deciduous rainforest as well as some lowland rainforest and grassland, found in the municipalities of Osumacinta and San Fernando; the western section has similar vegetation, and is located entirely in San Fernando; the eastern section has forests of pine as well as medium-height semi-deciduous rainforest and grasslands, and is found in Chiapa de Corzo; and the southeast has most of the sides of the canyon itself and a navigable section of the Grijalva River, but only remnants of medium-height rainforest and pachycaulous vegetation. The main land access into the park is from Tuxtla Gutiérrez north through Osumacinta then past the Chicoasén Dam. Another access point is from Chiapa de Corzo by boat from the Cahuaré Docks. As the main attraction of the park is the canyon, several lookout points have been constructed on various parts of the rim. La Ceiba is closest to the city of Tuxtla Gutiérrez, only away. The Los Chiapas point is near where the canyon's walls rise highest from the river below, where according to legend, a number of Chiapa people preferred to commit suicide by jumping rather than submit to Spanish domination. This lookout also has a restaurant.
Conservation issues.
The most important conservation issue in the park is the contamination of the Grijalva River, which passes through the Sumidero Canyon proper. However, other threats to the park include human encroachment and other human activities. An estimated 1500 to 2000 hectares, or about six percent of the park total, have been encroached upon, mostly by illegal human settlements next to the city of Tuxtla Gutiérrez since the park was established. It is estimated that about 15,000 people live within the park's borders. Most of these illegal constructions belong to the very poor who have migrated to the city from elsewhere. The demand for living space has created an industry of illegal subdivisions which are then sold without the proper title to victims. Three of the main neighborhoods to develop in this way are the Patria Nueva Alta, Arroyo Blanco, La Esperanza and Las Granjas. The encroachment is a result of the fast population growth of Tuxtla Gutiérrez and Chiapa de Corzo. The growth of these areas has led to land ownership disputes, loss of wild habitat and deforestation. In 2002, the federal and state government signed an accord to remove illegal human settlements and work to prevent further encroachment. Operations to evict illegal settlers have been carried out such as a 2005 operation which evicted about one hundred people and others that have prevented new settlements from getting established. However, the encroachment of human settlements into the park from the city of Tuxtla Gutiérrez has been so damaging that a 2007 report states that there is no other alternative than to deregulate this section of the park and work to prevent further incursion. However, the situation has not been helped by the fact that there are disputes over the boundaries of the park as decreed in 1980. Since 2009, there have been further efforts by park management to stop the advancement of these illegal settlements as well. Despite this, a number of areas in the park are well-conserved, mostly due to the very rugged terrain.
In addition to the illegal settlements, there are legal settlements and operations which affect the park. There are eight ejidos which border the parks and whose activities directly affect it: San Antonio Zaragoza, Venustiano Carranza, Francisco Sarabia, Gabriel Esquinca, Benito Juárez, Osumacinta, El Palmar, 16 de Septiembre and Nuevo Bochil. Established before the park, there are still five ejidos and three human settlements established within, Libertad Campesina (population 495), Nueva Esperanza (139), La Unión (329), El Paraíso (134), Tierra Colorada (199), La Candelaria / Triunfo Agrarista (631). As of 2005, the total population within the park's borders was 1927. Because of human activity, this park is one of the most susceptible to wildfires, and the most damaged by such in Mexico from 2009 to 2011. Many of these were started by human activity in or near the park such as one fire set on a nearby farm in May 2011.
In addition to this, there are lime and other extraction operations within the park's borders. They exist legally because they had been there well before the park was established. However, these operations have destroyed about 2,600 hectares. These operations produce noise, smoke, dust and small tremblers from explosions used to extract the minerals. Much of the environment damage come from runoff from mining waste which winds up in the Grijalva River. However the dust and smoke have produced a distinct white coating on surrounding flora.
Pollution problems.
Via the Grijalva River, the wastewater of about 552,000 people in seventeen municipalities finds its way through the canyon according to park director Edda González del Castilla, with most coming from Tuxtla Gutiérrez, Chiapa de Corzo, Berriozábal and Chicoasén . Much of the sewage comes into the Grijalva via the Sabinal River, which carries most of the waste water of the city of Tuxtla Gutiérrez. In addition, trash and raw sewage makes its way into the river from the various tributary streams. Agricultural waste comes from the farms that line the river and its tributaries.
The most obvious pollution is garbage, especially plastic containers, which mostly comes from area homes and businesses tossed onto the ground or in streams, especially from Chiapa de Corzo and Tuxtla Gutiérrez due to the lack of environmental awareness according to Conanp. The quantity of this trash reaches its height during the rainy season, when runoff and swollen streams can carry more of it into the Grijalva. While bottles and other plastic are what the casual visitor generally notices, other indicators include the overgrowth of water lilies (due to high levels of fecal matter) and dead animals. However, this accounts for only about five percent of the total tonnage of waste that comes into the river each year. Somewhere between 80 and 90% of the waste solids found in the river is branches, wood, rocks, sediment and other debris from legal and illegal logging, which cause deforestation . These mostly come into the river during the rainy season, especially from the Villa Flores and Villa Corzo municipalities. Only a small part of the solid waste is visible on the surface of the water, most is hidden underneath.
As the solids flow along the Grijalva, they are constricted by the narrow channel of the canyon and then by the presence of the Chicoasén Dam. This is particularly true at a point called “El Tapón” (The Plug), where two currents of water meet just before the reservoir back up of water from the Dam.
It is estimated that about 5000 tons of trash accumulate each year, and the river is considered to be one of the five most polluted in Mexico. 3700 tons of solids were extracted from the canyon area in 2010 alone. Many fish have died off or have developed abnormally due to contamination by fertilizers, pesticides and other chemicals. This threatens the native American crocodiles as the agrochemicals kill off and poison the fish they need to eat. In May 2011, the Fédération Internationale de Natation decided cancel its annual swim marathon in the canyon as they claimed that pollution levels in the river posed a risk to swimmers’ health. The Comisión Nacional del Agua and the government of Chiapas disputed this, presenting their own test results stating that levels were below such levels.
There are year-round and seasonal efforts to clean the river within the canyon and the area just upstream from it. Much of the daily effort is undertaken by workers with the "Comisión Nacional de Áreas Naturales Protegidas" (CONANP) and the Secretariat of Tourism in Chiapas, which extract twelve tons of garbage from the Grijalva river each day. Most of the season cleanup coincides with the rainy season, especially in September and October, when rains are heaviest. This seasonal effort has included local police, civil protections agencies, social organization, the army and individual volunteers. Efforts can involve up to 600 people at a time using 32 boats from four of the tourist cooperatives. During the annual campaign to clean the canyon in 2005 more than 60,000 tons of trash was removed. Generally, about forty tons of garbage is collected each day during these campaigns.
While the cleanup efforts have improved the situation in the canyon, the garbage reaccumulates especially during the rainy season. Part of the price that tourists pay for boat rides into the canyon pays for cleanup efforts, but the boat operators state that the canyon remains filled with trash. Conanp also states that cleanup efforts are insufficient. Mexico's federal environmental agency, the Secretaría de Medio Ambiente y Recursos Naturales (Semarnat) states that it cannot get involved in the situation as it is the municipalities that have the responsibility for disposing of trash appropriately. However, many of these local governments do not have landfills or the separation of recyclables.
Tourism.
The scenery of the canyon has become a major tourist attraction for the state, with developments for eco tourism and extreme sports. The navigable part of the Grijalva River is mostly used to ferry visitors into the canyon area. The park has six lookout points accessible by land called La Ceiba, La Coyota, El Roblar, Tepehuaje, Los Chiapas and Manos. In the rainy season, tourism is enhanced by the activity of waterfalls such as the Árbol de Navidad, Cueva del Hombre, Cueva del Silencio, Cueva de Colón, Cueva de Colores and Cueva del Suspiro. A lesser known attraction is the archeological site called the Ruins of Berlin. The most important economic activity in the canyon is ecotourism. Most of the visitors are Mexicans. Weekends are busiest with local and regional visitors to bike, swim, hike, camp and picnic.
The canyon is the second most visited site in Chiapas, after Palenque. The park is visited annually by 300,000 people, about 80% of whom are from Mexico and the rest from abroad. During vacation times, the park may be visited by anywhere from 1,000 to 7,000 people per day, who either enter by car to go to the lookout points or by boat from Chiapa de Corzo. Entrance and boating fees can generate about 70,000 pesos per day for clean-up efforts. The number of visitors to the park hit a peak in 2003 with about 196,500.
Commercial activity in the park is limited to those which serve tourists, sales of food and Mexican handcrafts and folk art. Tour operators are organized into cooperatives, with food and craft vendors working independently. These merchants must receive an annual permit in order to operate within the park's borders. The most important of these businesses are the boats which ferry people through the canyon along the Grijalva River. Most of these boat tours operate out of Chiapa de Corzo and run along the river to the Chicoasén Dam for a distance of about . Chiapa de Corzo has two main docks for this activity. The largest and oldest is called Cahuare, with paved areas and a restaurant; the second smaller one also has restaurants and a swimming area as well. These two docks host six tour cooperatives, with about 120 boats that can hold between ten and forty passengers each. As they take visitors from Chiapa de Corzo or Tuxtla Gutiérrez through the canyon and to the dam, they provide environmental, historical and cultural information. These are the most organized tourist activities in the park.
A spate of accidents involving these boats occurred from late 2009 to early 2010, claiming the lives of six tourists and hurt sixty two others. The accidents occurred on decrepit boats, many of which were operating without permission with underage or unlicensed crew members. There were no ambulance boats and no first aid services on shore. Two of the cooperatives, Ángel Albino Corzo and Nandiume were suspended and fined for the accidents, taking about sixty boats out of operation. These boating accidents caused significant problems for the tourism industry.
For those who choose to see the canyon from the lookout points above, there are restaurants and other food service places as well as camping and picnicking facilities.
The other two attractions of the park are general ecotourism and extreme sports. The park has hiking paths and sports fishing is allowed sporadically by permit. There are some locations that rent kayaks and other boats. The Amikúu Ecological Park is located within the canyon area, which is accessible by boat from Chiapa de Corzo. The park is divided into three parts; Discover the Canyon, Colors of Chiapas, and Area of Adventure. The first is located in the dock area, with a demonstration of the history of the canyon and a video of its geological formation. There is also a souvenir shop here. The interior of the park contains a 300 meter long zip line. Colors of Chiapas is a small museum which exhibits the traditional dress and native musical instruments of the state's indigenous peoples. The Area of Adventure takes visitors on a tour of the rainforest area, which include a suspension bridge. It also has a herpetarium, an aviary and enclosure for jaguars and one for crocodiles. The park was opened in 2009 at an initial cost of 120 million pesos.
Extreme sports include mountain biking, rappelling, spelunking and more. Rappelling allows for access to many of the canyon's small caves which are not accessible any other way. The dam area has recreational fishing with an annual tournament. One major annual event is the Copa Mundo Fino swimming marathon. An Australian base jumper plunged to his death in 2006 after jumping off an 800-meter cliff in the canyon. The accident occurred during a sanctioned event sponsored by an energy drink maker with jumpers from Australia, the U.S., Europe and Mexico.
Chicoasén Dam.
At the northern end of the Sumidero Canyon is the Chicoasén Dam, formally called the Manuel M. Torres Dam, is one of a number of dams which have been built along the Grijalva River for water storage and the generation of hydroelectric power. This dam and its reservoir is considered to be part of the Sumidero Canyon system. The Sumidero Canyon National Park is defined on the north end of the river by this dam and the Belisario Domínguez Bridge on the south. The dam was constructed between 1974 and 1980. The reservoir covers an average of 2,193 hectares, and the complex employs about 600 workers.
The Chicoasén Dam produces electricity and manages the flow of the Grijalva river along with the Hondo River and the Muñiz, El Jardín and El Cacao streams, which converge to form the Osumacinta River. This reservoir is one of the most important in the country. The hydroelectric station is also one of the most important in the country with thirty generators with installed capacity of 3,928.48 megawatts. This is just over thirty percent of all hydroelectric energy produced in Mexico.
History and archaeology of the area.
The history of the area is connected to the Chiapa people, who occupied the Central Valley area before the arrival of the Spanish. The origin of these people is not known, but theories have them migrating north from Nicaragua or even Paraguay. Their main settlement was in Chiapa de Corzo near the canyon, with a fortified area in the higher areas in the canyon for protection from invasions. The Chiapa fiercely resisted Spanish conquest and were not subdued until the arrival of Diego de Mazariegos in 1528. Their last refuge was in the fortified area, now known as the archeological site of the Ruins of Berlin. Here the last of the Chiapa held out from 1528 to 1535 after the Spanish took over the main city. Legend states that when this last fortification fell, the remaining Chiapa committed collective suicide by jumping into the canyon. Since then, the canyon has served as a boundary marker between the Zoque and Tzotzil peoples.
Until the 20th century, the canyon area was relatively unexplored. In 1895, three Frenchmen attempted to explore the canyon but were drowned in the river. An American came in 1932 but also perished. This gave rise to legends about witchcraft in the areas as well as the ferocity of the area's crocodiles. In 1960, an expedition of soldiers from the Mexican army, nicknamed the “red handkerchiefs” succeeded into crossing through the canyon by boat over twenty km. This opened up the canyon to local exploration and exploitation, including rudimentary tourism and the hunting of crocodiles and other native fauna.
There has been little archaeological work done in the area. The main site is called the Ruins of Berlin, named after German explorer Heinrich Berlin, who visited the area in 1946 and named the area “Sumidero". This site is located seven km from the Belisario Domínguez Bridge in Tuxtla on the edge of the river. It covers an area of 467 by 60 meters, bounded by small mounds surrounding patios. The original description of the site was undertaken in 1923 and 1932 by Becerra, who called it Chiapa Viejo, and stated it was the capital of the Chiapa people. However, Remesal in 1966 determined it was a secondary site. The last major survey was done in 1976 by Alejandro Martínez, discovering that there are 24 individual sites of which nine are mounds and fifteen are in caves. One of these contains cave paintings which indicate that the area has been occupied since at least the very early Pre Classic period.


Lyell Cave

The Lyell Cave, formerly called Grande caverne d'Engihoul, is located near the "ancienne commune" of Éhein, municipality of Engis, Liège Province, Belgium. It is one of many caves investigated or discovered by Philippe-Charles Schmerling, in 1831; the cave is named for a later researcher, Sir Charles Lyell, who visited the cave in 1860.
Together with the Rosée Cave, it was classified as an in July 1988, making it accessible only to scientific researchers. The cave's troglofauna includes Belgium's only cave-inhabiting beetle, "".
Location.
The Lyell Cave is located in Éhein on the edge of the valley of Engihoul, where the stream named Engihoul runs by the "route des 36 tournants", in a syncline formed during the Viséan, near the "Lion's quarry".
Name.
Philippe-Charles Schmerling wrote of his searches in the "caves of Engihoul" in his book "Recherches sur les ossemens fossiles découverts dans les cavernes de la province de Liège", which was published two years after his exploration of the place.
In 1833 he met geologist Charles Lyell, who was passing through Liège, and told him of his theories about prehistoric humans. Lyell was interested enough to mention them in his "Principes de géologie" the following year, but without giving it the importance he would assign it later.
In 1860 Lyell returned to Liège and decided to examine the "caverne d'Engihoul" with the help of the Belgian professor Constantin Malaise, from the "Institut agricole de l'État" who got him to explore a cave different from Schmerling's.
In honor of that visit, the cave was renamed "Lyell Cave" in the 20th century, from "Grande Caverne d’Engihoul" as it was called in "Les Cavernes et les rivières souterraines de la Belgique" by E. Van den Broeck, É.-A. Martel and Ed. Rahir.
Description.
According to the 1910 description, there are two entrances: the one west, marked B on the map, consists of two couloirs, one of which is closed because the quarry's explosives were stored there. The other, marked A, is in the east, at the bottom of the rocky wall of the ravine of Engihoul, 13m from the Meuse. Very narrow and difficult to enter, this passage has been widened and leveled.
From west to east, there are five halls, connected via narrow passages:
Subsequent research.
Professor Joseph Antoine Spring, of the University of Liège, visited the cave in 1853, before Charles Lyell and Constantin Malaise did in 1860. Malaise exhumed fragments of human skulls that were later studied by E.-T. Hamy. De Puygt and Lohest, members of the Anthropological Society of Brussels, found Neolithic engravings made with silex. In 1894, paleontology professor Julien Fraipont of the University of Liège found animal bones and tools made of silex. The site has also been pilfered by private individuals for their personal collections.
In the 1890s, Ernest Doudou found new cavities containing human and animal remains, sharpened tools of silex, pottery fragments, bones that had been worked on, bronze and iron objects, traces of ancient fires, from different eras. He concluded that the cave was occupied from the Paleolithic to the Middle Ages; most of these objects were deposited at the University of Liège.
Exceptional patrimony classification.
With the Rosée Cave, with which it forms a single system, it is classified as an since 8 July 1988. It is accessible only to scientific researchers, since access by tourists and amateur speleologists risks upsetting the biotope's natural balance with changes to temperature and light, walking through the clay, and the import of nutritional elements that favor certain organisms. The entrance was closed after the cave was filmed.
The cave was owned in the past by the Carmeuse company, which transferred its ownership in 1999 to the non-profit "Les Chercheurs de la Wallonie".
Biological importance.
The Lyell Cave is relatively uninteresting from the point of view of paleontology, but has interesting biodiversity, as evidenced by 20th-c biospeleologists including Robert Leruth. They have verified many invertebrates some of which were considered endemic to this cave:
The Diplura "", discovered in June 1999, was thought to be endemic until June 2000.
Also found were:


Wellenkalk Formation

The Wellenkalk Formation is a geologic formation in Germany, and Poland.
Geological Period.
It preserves fossils dating back to the Triassic period.


Limagne

The Limagne () is large plain in the Auvergne region of France in the valley of the Allier river, on the edge of the Massif Central. It lies entirely within the "département" of Puy de Dôme. The term is sometimes used to include this, and three other less extensive plains, that lie along the valley of the Allier, in which case the first is known as "Grande Limagne" to distinguish it from the others. The name is derived from the Latin "Lacus Magnus", or large lake.
Geology.
The Limagne plain is a graben, downthrown from the Massif Central by a series of normal faults that border the western edge of the plain. It contains about 2 km of sediments, and the amount of stretching of the crust is estimated as 1.2–1.3. The rifting started in the Late Eocene and the main phase of subsidence continued into the Late Oligocene. The Limagne Graben forms part of a system of linked rifts, including the Rhine Graben, known as the European Cenozoic Rift System, that formed in response to compressional deformation of the Alpine foreland.
Volcanism accompanied the rifting and continued into the Pleistocene. The sediments deposited in the basin are affected by numerous intrusions. The area was the first where peperites were described, from a basaltic intrusion into lacustrine limestone.
Economy.
The Limagne is a very fertile plain and is mainly an area of cereal production, with some tobacco and sugar beet. Vineyards are found along the borders of the plain on the edge of the Massif Central, particularly at Corent and Châteaugay.


Metopacanthus

Metopacanthus is an extinct genus of cartilaginous fish from the Early Jurassic epoch in Europe. It is known from the Toarcian of the Posidonia Shale of Germany. It is unusual due to being an extrange aberrant Chimaera, with a jaw-like structure over the skull.


Diemel

The Diemel is a river in Hesse and North Rhine-Westphalia, Germany. It is a left tributary of the Weser.
Route.
The source of the Diemel is near Willingen, in Sauerland. The Diemel flows generally northeast through the towns Marsberg, Warburg, and Trendelburg. It flows into the Weser in Bad Karlshafen.


Shihual (Peru)

Shihual cave is located to the north of La Jalca, Peru, and has several caverns. In the interior of these, numerous stalactites and stalagmites have formed that serve as refuge to the different species of night birds of the zone.


Cerro Tapado

Cerro Tapado is a mountain in the Andes of Chile. It has a height of 5536 metres.


Los Tuxtlas Biosphere Reserve

The Los Tuxtlas Biosphere Reserve or Biósfera Los Tuxtlas, is a biosphere reserve located in the coastal and higher elevations of the Sierra de los Tuxtlas, in Los Tuxtlas of Veracruz state, in south eastern Mexico.
Ecoregion.
The area is notable for its diversity of plants and animals. It contains the neotropical Sierra de los Tuxtlas tropical rainforest ecoregion, of the tropical and subtropical moist broadleaf forests biome.
Other Tropical and subtropical moist broadleaf forests in the region include:


High Eifel

The High Eifel ( or "Hohe Eifel") forms part of the Eifel Mountains in the German state of Rhineland-Palatinate.
The landscape here between Adenau, Mendig and Daun rises to a height of 747 m. The region is not to be confused with the western "Hocheifel", better known as the Schnee Eifel.
Nürburg Castle and the famous Nürburgring racing track are located in the northwest of the area.
Climate.
Despite being between 600 m and 700 m high the High Eifel lies in the rain shadow of the Schneifel to the west. Its annual precipitation lies between 800 mm and 1000 mm.


Orthosuchus

Orthosuchus is an extinct genus of protosuchian crocodyliform that lived during the Early Jurassic, about 196 million years ago. It was first discovered in 1963 in the Red Beds Formation in the Qacha's Nek Province of Lesotho, southern Africa. The characteristics showed on its postcranial skeleton and the skull indicated that it is a Crocodyliform. The finding is significant since some of the characteristics found on this specimen were believed to be absent until Jurassic.
Description.
"Orthosuchus" has a body proportion similar to lizards, with a body length about 0.6 meters, and a flattened skull, a typical skull of crocodilian.
The external skull surface is covered randomly with small pits. The orbits are huge, with a complete dorsal roof made by the paired supraorbitals. The maxilla has sharp edge, which extends forward and covers some part of the lateral notch. The ears are protected by earflaps, which prevent water inflow to the otic recess when this animal is in water. The fossil resembles some features of a primitive crocodilian, one of them is the reduced antorbital fenestra. The quadratojugal is the backbone of the skull, which connects to the jugal and quadrate. The flattened head shape of "Orthosuchus" is made by the posterior quadrate contact, which is below the rear end of the squamosal. This form is a typical archosaurian characteristic that had lost in modern crocodiles, and also absent in teleosaurs. It developed a short secondary bony palate, with crocodilian featuring pterygoids. The elongated choana is located behind the secondary palate, which is made by the premaxilla and maxilla. In modern crocodiles, the choana is between the vomers and the anterior processes of pterygoids. The dentary forms the largest part of the lower jaw with some shallow pits, which indicated that the animal probably has 15-18 teeth, fewer teeth in the far back. The teeth are equal in size and similar in shape.
"Orthosuchus" has 24 vertebrae, and 8 of them are believed to be in the cervical region. All vertebrae appear to be amphicoelous. It does not have tall neural spine but the height of them decrease from head to tail. The vertebrae in the neck region are tightly bonded together. The ribs start at the twelfth vertebra, which supports the ilium. The tail consists of 8 vertebrae of different size and shape. The first one is in contact with the sacral ribs, three vertebrae at the far end of the tail are tiny in size, and the other four vertebrae form the middle of the tail. The ribs form antero-ventral and postero-dorsal flanges, which are for the muscle attachments.
"Orthosuchus" has similar pectoral girdles and pelvic girdles compare to living crocodiles, with a long scapula and a shorter coracoid. The interclavicle is hypothesized to be cartilaginous. As for the forelimb, the fossil records showed that "Orthosuchus" has similar humerus, but the distal and proximal expansions does not lay on the same plane as the modern crocodiles. Also, not like the living crocodiles, the ulna and radius of "Orthosuchus", or other typical archosaurs, are around 88% of the length of the humerus, while the radius and ulna in modern crocodiles are the shortest elements in the forelimb. It has two non-elongated carpals, with one of the elliptical shape. "Orthosuchus" appeared to have 5 digits. The first digit is the shortest and the fifth digit is the weakest. Although some of the phalanges are missing, it is believed that the phalanges formula is 2, 3, 4, 5, 3, 3. The femur is thought to be the longest bone. The tibia is more developed than the fibula, and they are 94% of the length of the femur. Taking all the bones into account, the forelimb is 91% the length of the hind limb. "Orthosuchus" has similar astragalus and calcaneum. Compared to the astragalus, the rectangular shaped calcaneum is small in size and forms a prominent tuber.
Discovery.
The first fossil materials were collected by an expedition of South African Museum in April 1963 led by Alfred W. Crompton. The materials were collected from the Lower Jurassic Red Bed Formation (= Upper Elliot Formation) of the Stormberg, so that as soon as they found out that the fossils belongs to a new crocodilian species, they named the species "Orthosuchus Stormbergi" in a paper published by Nash 1968. They also found a smaller skull that also belongs to "Orthosuchus Stormbergi" at the same horizon but in a different place at the same site. The main part of the skull and the law jaw was well preserved, but some of the phalanges, ribs, and one side of the pelvic girdle with its hind limb were missing. Since the specimens had some distortions, major issues were fix at the site before it was X-rayed.
In 1931, a new primitive form of crocodilian was found in the Dinosaur Canyon Beds of northern Arizona, United States. The beds are at the top of the Upper Triassic Formation and below the Lower Jurassic sediments. The crocodilian found is about 1 meter long, with flattened head and large frontals. Its more advanced transverse process indicates that it is a new crocodilian species. In 1933 Barnum Brown named it "Archaeosuchus", and then changed it to "Protosuchus" in 1934 and form the family of "Protosuchidae". The classification of "Protosuchidae" is debatable, however, since "Orthosuchus" resemble some of the characteristics of "Protosuchidae", it is believed to be in the part of this family.
Classification.
Modern crocodiles are considered within the group archosaurs, which also include birds, dinosaurs, and crocodilians. However, from appearance, archosaurs resemble more of crocodiles than of birds. "Orthosuchus" resembles a primitive form of crocodilian by some of its traits: the fusion midline together at the parietal, the form of the secondary palate, the fusion of pterygoid and quadrate, the extension of coracoid, radius, and ulna, and the form of tuber on the calcaneum. "Orthosuchus" is closely related to "Protosuchus, Notochampsa, Erythochampsa", and probably other crocodilian families. Although "Orthosuchus" could be grouped into "Notochampsa", more people want to keep the family "Protosuchidae" because it is widely accepted.
Paleobiology.
The existing specimens of "Orthosuchus" were found in the Lower Jurassic Red Bed Formation in South Africa in 1963. It was hypothesized that "Orthosuchus" lived main on terrestrial land, but some key factors contribute to the fact that it is spent the time mostly in water. The first notable evident is on the palate, which was covered by soft tissues, not bone. The choanae are on the back of the palate and a valve was used to help close the glottis. These features help "Orthosuchus" keep breathing when submerging in the aquatic system. The ears are protected by earflaps, which prevent water inflow to the otic recess when this animal is in water. Modern crocodiles also have earflaps to decreasing water entry. The shape of the skull, especially the snout, is similar to an Indian gharial, "Gavialis gangeticus", who prey on small fish. It is possible that "Orthosuchus" has the same predation, by slowly move toward schools of small fish and swallow from the side. The aquatic environment provides plenty of food for the animal, besides small fish, the animal could also feed on lake invertebrates. "Orthosuchus" has a small salt-secreting gland, which indicates that it is not a marine animal. And because the pubis articulates with the front region of the ischium, it is believed to be a basal animal that lived in swamps and lakes. The animal is probably quadrupedal because the fore limbs are approximately 91% the length of the hind limb, which also makes the walking on land easier. Unlike modern crocodiles, "Orthosuchus" does not creep on its belly; it probably walks at a high position with its femur vertical to the ground. According to Parrish, primitive crocodylomorph did not have a crawling stance because it was more used to the terrestrial environment. However, "Orthosuchus" may not be a good swimmer, since it has amphicoelous vertebrae, whereas modern crocodiles have procoelous vertebrae, which increase the mobility of the tail.


Cha-Kjeri Formation

The Cha-Kjeri Formation is an Eifelian geologic formation of central Bolivia. The formation comprises red sandstones deposited in a marine environment.
Fossil content.
The formation has provided fossils of "Globithyris aff. diana".


Linton-Kelly Lake Channels


Daguinaspis

Daguinaspis is an early Cambrian trilobite genus found in Morocco. Like the closely related "Choubertella" and "Wolynaspis", but unlike any other Fallotaspidoidea, it lacks genal spines.
Distribution.
Cambrian of the Anti-Atlas, Morocco, 30.4° N, 8.8° W (Daguinaspis trilobite zone, Tazemmourt Section and Tiout Section. Amouslek Formation, Middle Atdabanian (520.0 - 516.0 Ma) )
Ecology.
"Daguinaspis" occurs together with the trilobites "Marsaisia robauxi" and "Resserops bourgini", and the brachiopod "Brevipelta chouberti " (Tazemmourt), and also with the problematic "Microschedia amphitrite" (Tiout).


Aulostomoides

Aulostomoides is an extinct genus of prehistoric bony fish that lived from the early to middle Eocene.


Nundasuchus

Nundasuchus is an extinct genus of crurotarsan, possibly a suchian archosaur related to Paracrocodylomorpha. Remains of this genus are known from the Middle Triassic Manda beds of southwestern Tanzania. It contains a single species, Nundasuchus songeaensis, known from a single partially complete skeleton, including vertebrae, limb elements, osteoderms, and skull fragments.
"Nundasuchus" lived in what is now Tanzania, Africa around 240 million years ago. Members of this genus were likely carnivores, around 2.7 to 3 meters (9 feet) long, with ziphodont (steak knife-like) teeth and rows of bony plates (osteoderms) along their back. Phylogenetic analyses consistently place this genus within the group Crurotarsi based on features of the ankle. Most studies also consider it a pseudosuchian, meaning that it was more closely related to modern crocodilians than it was to dinosaurs. However, "Nundasuchus" had an upright stance, with legs situated directly underneath the body, as with various other early pseudosuchians (such as "rauisuchians" and aetosaurs) but unlike modern crocodilians.
The classification of "Nundasuchus" relative to other pseudosuchians is somewhat controversial. Some phylogenetic analyses place it near or at the base of the group, sometimes along with phytosaurs, based on certain plesiomorphic (primitive) features such as teeth on the palate, a short pubis, and characteristics of the calcaneum (heel bone). Another hypothesis, supported by its original 2014 description, considers it to be somewhat more "advanced" than those groups, instead being closer to "Ticinosuchus" and paracrocodylomorphs (the group containing "rauisuchians" and the ancestors of modern crocodilians). This classification scheme is justified by the presence of "staggered" osteoderms, heart-shaped "spine tables", and a groove on the femoral head. Regardless of these hypotheses, it is clear that "Nundasuchus" represents a previously unknown group of reptiles with a mixture of features both plesiomorphic and derived with respect to suchian archosaurs.
Discovery.
"Nundasuchus" is known solely from the holotype NMT RB48, a partially complete disassociated and mostly disarticulated individual housed at the National Museum of Tanzania, Dar es Salaam of Tanzania. The holotype consists of a partial right pterygoid, nearly complete right dentary, the right splenial, the right surangular, and isolated teeth, as well as the following postcranial bones: a partial atlas, two articulated mid-neck vertebrae, two articulated mid-back vertebrae, the last back vertebrae, the sacrum with sacral ribs, front-most tail vertebrae, dorsal ribs, gastralia, articulated and isolated paramedian osteoderms, partial shoulder girdle including interclavicle, parts of both clavicles, complete left and right scapulae, and the right coracoid, the left humerus, both pubes, both femora, the left fibula, inner and outer ends of the left tibia, as well as the left astragalus, left calcaneum, left fourth tarsal and all but fourth metatarsals, and outer ends of right third-to-fifth metatarsals, numerous isolated phalanges, a partial ungual and many other fragments.
NMT RB48 was discovered by Dr. Sterling Nesbitt in 2007 at an isolated outcrop approximately 100 square meters in area known as locality Z41, along with remains of other archosaurs and rhynchosaurs. Another locality (Z42) occurs in the immediate vicinity, and yielded four cynodonts including two unnamed forms, "Scalenodon attridgei" and "Mandagomphodon hirschsoni", four dicynodonts including "Tetragonias njalilus", "Sangusaurus parringtonii", "Angonisaurus cruickshanki", and "Rechnisaurus cristarhynchus", and the archosauromorphs "Stenaulorhynchus stockleyi" and "Asilisaurus kongwe". These localities, located between the Ndatira and Njalila rivers, belong to the fluviolacustrine mudstone-sandstone sequence in the middle of the Lifua Member of the Manda beds of Ruhuhu Basin in Tanzania. Based on comparison with the better studied tetrapod fauna of Subzone C of the "Cynognathus" Assemblage Zone of South Africa, this member is considered to date to the Anisian stage of the early Middle Triassic.
Description.
Skull.
Skull material is very limited for "Nundasuchus"; only a right lower jaw and a right pterygoid bone (which formed part of the roof of the mouth) were preserved in the holotype. However, even these fragments are informative. The pterygoid is convex when seen from above and concave from below. This ventral (lower) concavity manifests in the form of a deep depression bounded by posterior (rear) and medial (inner) ridges. The portion of the pterygoid which would have been positioned along the midline of the palate is unusual compared to other archosaurs due to possessing teeth. These teeth were small and rounded, placed in three rows parallel to the midline of the mouth. Pterygoid teeth are typically absent in archosaurs, although a few avemetatarsalians ("Eudimorphodon", "Eoraptor, Eodromaeus") and another likely pseudosuchian ("Turfanosuchus") are known to have possessed them.
The jaw is typical compared to that of most carnivorous archosaurs, being low and long, with serrated, knife-like teeth set in deep sockets. At least 14 teeth were present, with the teeth at the middle of the jaw (around tooth nine) being smaller than those at the front and rear of the jaw. The lower edge of the lateral (outer) side of the jaw was covered in small longitudinal grooves, a feature seemingly unique to "Nundasuchus" among early archosaurs. Less unusual is the presence of several rows of pits on the lateral surface and large grooves on the medial surface. The surangular bone at the back of the jaw forms a deeply concave jaw joint preceded by a longitudinal ridge (unique to the genus) and followed by a large, vertically-oriented plate of bone.
Vertebrae and osteoderms.
The two incompletely preserved cervical (neck) vertebrae were amphicoelous (concave from both the front and the rear), with a large lateral pit near the base of the neural arch. The concave pleurapophyses (lower rib facets) were near the lower front edge of the vertebrae, while the convex diapophyses (upper rib facets) were positioned higher up. The lower edge of each vertebra possessed a large keel which was deepest towards the rear. Isolated cervical neural spines were similar to those of "Batrachotomus," being expanded towards their upper front tips into heart-shaped structures when seen from above.
Most of the dorsal (back) vertebrae were tall and amphicoelous, and possessed a pair of ventral keels adjacent to the midline, separated by a shallow groove. These ventral keels are similar to those of the unusual aquatic archosauriform "Vancleavea", although not as pronounced. Considering that "Nundasuchus" is not closely related to "Vancleavea", its ventral keels were probably an example of convergent evolution, and they can be considered a unique trait compared to other archosaurs. The rib facets were short, positioned high on the vertebrae at the base of the neural arches. Three ridges radiate outwards from each diapophysis; one connects to the parapophysis, another connects to the main body of the vertebra, and the last one reaches the postzygapophyses (rear vertebral joints). One notable feature of the vertebrae of "Nundasuchus" is the possible presence of hyposphene-hypantrum articulations, as reported by the original description. However, a 2018 study doubted this interpretation, arguing that the supposed articulations were actually misidentified components of the zygapophyses. As with the cervicals, the neural spines of the dorsal vertebrae expand outwards into flat structures sometimes called "spine tables". Some dorsals near the hip lose the characteristic ventral keel, instead acquiring additional pits near the rib facets.
The sacrum was probably formed by two unfused vertebrae, connected to massive sacral ribs. The rib facets are huge in conjunction with the sacral ribs, but not large enough to annihilate the pits at the base of the neural arch. Each rib facet of the first sacral vertebra had a distinct upper and lower connection to the trumpet-shaped first sacral rib. The second sacral rib is flatter, and tilts diagonally so that its tapering rear edge is positioned higher than its front edge. A groove is present along the outer edge of this rib, roughly where it would connect to the ilium. The sacrum in general is similar to that of the rauisuchid "Stagonosuchus," except for having thinner neural spines.
The caudals (tail vertebrae) near the hip were tall and generally similar to the dorsals, except that their zygapophyses were inclined upwards at a higher angle. Further down the tail, they acquire chevrons and fuse to the caudal ribs, as well as becoming smaller and simpler in general. The dorsal ribs were two-headed, with concave and convex joints corresponding to the convex and concave rib facets of the vertebrae. They were flattened near the vertebrae, and at their tips they had small facets for attachment to the densely packed gastralia (belly ribs).
Several groups of osteoderms (plate-like bony scutes) were also preserved in "Nundasuchus". Individual osteoderms were lightly ornamented and heart- or leaf-shaped, with rounded edges and tapering front tips. They are similar to those of most other pseudosuchians as well as archosaur relatives such as "Euparkeria", but are less elongated than those of some of these taxa, instead being about as wide as they are long. Most of the osteoderms referred to "Nundasuchus" are thin bones, with sharply pointed front tips, a thin longitudinal ridge, and a fair amount of overlap. A rare "thick" morphotype is also present, with less overlap, a small and mound-like ridge, and more rounded front tips. At least the "thin"-type osteoderms formed several longitudinal rows stretching along the backbone of the animal. When seen from above, these rows would not have been symmetrical on each side of the animal. Instead, they were "staggered", with the left and right rows slightly offset from each other. An estimated five osteoderms were present per every two vertebrae.
Pectoral girdle and forelimbs.
The scapula (shoulder blade) was paddle-like and somewhat small. The lower portion of the scapula is where the glenoid (shoulder socket) is located, pointing backwards from the rear edge of the bone. This general area is the widest part of the bone when seen head-on, and underlies the thinnest part when seen from the side. Directly above the glenoid lies a small pit, likely the origin point of the triceps muscle. Meanwhile, the front edge of the scapula has a distinct ridge, probably the acromion process. The scapula of "Nundasuchus" differs from advanced pseudosuchians due to its small triceps pit, but also from phytosaurs due to its distinct acromion. The lower edge of the scapula connects to the semicircular coracoid bone. The rear portion of the coracoid extends back and curves upwards to form the lower half of the glenoid, but is not offset from the socket by a distinct notch. However, a wide groove is present below the glenoid when seen from the side, similar to the case in aetosaurs and "Postosuchus". In front of the glenoid, a hole known as the coracoid foramen pierces the coracoid, and, in a feature unique to "Nundasuchus", this hole is surrounded by several knob-like structures. Other fragments of the pectoral girdle, such as an interclavicle and clavicles, are also preserved. They are covered in grooves, with thin, blade-like edges. The interclavicle is spoon-shaped, concave from above and convex from below, although its true shape is unknown due to the rear portion being broken off. Overall it is more similar to those of paracrocodylomorphs rather than phytosaurs.
The only portion of the forelimb known for this genus was the humerus (upper arm bone). Its medial edge was concave while the lateral edge was almost straight as in phytosaurs. In conjunction with this, the deltopectoral crest (a large flattened structure near the humeral head) is oriented more anteriorly than laterally. Both the humeral head and the tip of the lower extremity of the bone were covered with deep grooves. Just above the lower extremity was a depression, and just lateral to this depression was a distinct ectepicondylar groove.
Pelvic girdle and hindlimbs.
The only preserved part of the pelvic girdle (hip), not counting the sacrum, was the left pubis bone. This bone was characteristically small in "Nundasuchus", only about 30% the length of the femur. This is comparable to phytosaurs, aetosaurs, and early avemetatarsalians, but in contrast to the condition in other archosaurs. The areas where the pubis would have contacted other bones of the hip are broken, but evidently the pubis did possess features such as an inset obturator foramen and an insertion for the muscle under the acetabulum (hip socket). The main shaft of the pubis is not strongly expanded in most directions, but the medial edge has a plate-like inner extension known as a pubic apron, which would have contacted the corresponding extension on the right pubis. This pubic apron is convex when seen from the front.
The femur (thigh bone) is sigmoidal (S-shaped), with the femoral head being twisted slightly inwards and the distal condyles being twisted slightly outwards. This creates an angle of 45 degrees between these two extremities of the bone, as with most eucrocopodans apart from dinosaurs. As with other eucrocopodans, the femoral head has several distinct tubera (bumps), one on the anterolateral surface of the bone and another on the posteromedial surface. "Nundasuchus" also may have had a third tuber on the medial surface of the head as in archosaurs, but this portion of the bone is damaged so it cannot be assessed with certainty. The femoral head also has a groove on its upper surface, similar to paracrocodylomorphs. Further down the posteromedial face of the shaft is a long, sharp ridge known as the fourth trochanter. About 40% down the front part of the shaft is a tuber covered with grooves. This bump was likely an attachment point for the "iliofemoralis" muscle which helped to stabilize the hip. The distal part of the femur has a large crista tibiofibularis, an upper extension of the lateral condyle. Both the crista and the medial condyle are large, and taper into rounded apices. In addition, the lateral and medial condyles each have a small depression at their extemities, with that of the medial condyle likely corresponding to the "femorotibialis" muscle.
The proximal part of the tibia (inner shin bone) is roughly diamond-shaped in cross section, with rounded lateral and medial tubera as well as a low and indistinct forward-pointing ridge known as a cnemial crest. The lateral tuber is larger and more concave, like that of ornithosuchids. Apart from these tubera, the proximal part of the tibia is mostly convex. However, a distinct notch is present behind the lateral tuber. This is probably an attachment point for "flexor tibialis internus" muscle. The distal part is smooth and oval-shaped in cross section and 'flexed' when seen from behind. The fibula (outer shin bone) is sigmoidal, with a flattened medial surface, a large crest for the "iliofibularis" muscle on the lateral surface, and a distal face which tilts forwards.
The foot consisted of five metatarsals attached to phalanges (toe bones). The smallest metatarsal was the innermost one (I), with metatarsal II being longer and III being longer than either. Although metatarsal IV is incomplete, it has been estimated to be longer than III. This would be highly unusual among Triassic reptiles, of which only "Proterosuchus" shares this characteristic. Metatarsal I is somewhat squashed diagonally, with the edge facing the rest of the foot being positioned higher than the inner edge. A crest is also present on the inner edge. The articulation with the ankle is convex and expanded towards the rest of the foot. Metatarsal II is parallelogram-shaped in cross section, with a 'lip' on its upper edge that accepts the first metatarsal. Metatarsal III has the largest distal joint while IV has the smallest, indicating that the third toe was more massive than the fourth. Metatarsal V is hook-shaped, with two distinct proximal articulations for the fibula and the fourth distal tarsal of the ankle. The phalanges are generally robust, but those of the fifth toe were longer and hourglass-shaped, attached to a rough-textured ungual (claw). In general, the foot bones resemble those of "Prestosuchus" and phytosaurs.
Ankle.
The ankle was primarily formed by two bones, the calcaneum on the outer side and the astragalus on the inner side. These bones and their joints clearly show distinguishing features of the group Crurotarsi, which includes suchians, phytosaurs, and probably avemetatarsalians. For example, the calcaneum's attachment with the astragalus is concave, and the calcaneum also has a cylindrical extension with flared edges, known as a calcaneal tuber. The calcaneal tuber is directed about 45 degrees between sideways and backwards, similar to phytosaurs and non-archosaurian eucrocopodans, but in contrast to most other suchians, which have calcaneal tubera oriented more backwards. On the other hand, the length of the calcaneal tuber is moderate, similar to that of typical pseudosuchians rather than the much more elongated structure of phytosaurs. The lateral side of the tuber has a noticeable 'pad', which is seemingly unique to "Nundasuchus". The upper surface for the calcaneum connects to the fibula with a convex, barrel-shaped joint. This is also similar to phytosaurs and suchians but in contrast to ornithosuchids, where this joint is more dome-like. Both the fibular and astragalar facets of the calcaneum are a continuous surface, a condition unlike suchians.
The upper surface of the astragalus has a triangular facet for the fibula as well as a larger, oval-shaped facet for the tibia. The tibial facet is divided into two basins by a low convexity, although this flexion is somewhat indistinct compared to that of suchians and avemetatarsalians. The calcaneal facet comes in the form of a flat surface overlying a convex 'peg', a feature characteristic of crurotarsal joints. The peg is poorly developed, more similar to that of phytosaurs rather than other suchians. The front edge of the astragalus has a large concave surface (astragalar hollow) overlying a small convexity (astragalar ball). The astragalar ball is approximately as well developed as that of the aetosaur "Longosuchus".
Etymology.
"Nundasuchus" was first described and named by Sterling J. Nesbitt, Christian A. Sidor, Kenneth D. Angielczyk, Roger M. H. Smith and Linda A. Tsuji in 2014 and the type species is "Nundasuchus songeaensis". The generic name is derived from Swahili Language "nunda" meaning "predator", plus "suchus" from Greek "soukhos", an Egyptian crocodile god. The new specific name refers to the provincial capital of Songea, located near to the collection locality of the remains, as indicated by the Greek suffix "-ensis", meaning "from".
Classification.
The original description of "Nundasuchus," Nesbitt "et al." (2014), tested its phylogenetic position using the two most comprehensive early archosaur phylogenetic datasets available. The first dataset used was a version of Brusatte "et al.'s" 2010 archosaur phylogeny which had been updated by Butler "et al." (2011) during a study on the anatomy of "Ctenosauriscus". The second dataset was a more comprehensive and widely accepted study on archosaur relationships created by Nesbitt in 2011. Both analyses found that "Nundasuchus" was a pseudosuchian, meaning that it was an archosaur more closely related to crocodilians than it was to dinosaurs. This identification was primarily based on traits of the ankle which were shared between "Nundasuchus" and pseudosuchians. The Brusatte "et al."(2010) dataset placed it as the most basal pseudosuchian (although the name "Crurotarsi" was used for the group), less crownward (further from crocodilians) than even the phytosaurs.
Nesbitt "et al." (2014)'s application of the Nesbitt (2011) dataset placed "Nundasuchus" more crownward, compared to its position in Brusatte "et al."'s results. Nesbitt (2011) considered crocodylomorphs (crocodilian ancestors) to have been descended from taxa traditionally identified as "rauisuchians". Since Rauisuchia typically omits crocodylomorphs and would therefore be paraphyletic with his results, Nesbitt decided to scrap the name, replacing it with the monophyletic clade Paracrocodylomorpha. This clade itself is allied with the Swiss suchian "Ticinosuchus" based primarily on similarities of the ischium. When "Nundasuchus" was added into the dataset, it was placed as the sister taxon to the "Ticinosuchus" + Paracrocodylomorpha clade. This was justified by three traits: heart-shaped "spine tables", a groove on the proximal side of the femoral head, and "staggered" osteoderms.
Nesbitt "et al." (2014) questioned these results due to the fact that "Nundasuchus" possesses many plesiomorphic archosaurian traits (i.e. typical for very basal archosaurs) that appear to be autapomorphies (unique features), if it is truly a member of Pseudosuchia. These include palatal teeth, a short pubis, and a calcaneal tuber which is not as strongly deflected backwards. Thus, they performed further analyses under certain relationship constraints, such as forcing "Nundasuchus" to be outside Archosauria or closer to Phytosauria. These analyses revealed little change in the relationships (apart from the constraints themselves), but major chances to the traits associated with these relationships, changing the traits that were considered to diagnosed Pseudosuchia, Archosauria, and other clades. Therefore, it is not clear whether "Nundasuchus" is a suchian that has convergences with far more basal archosaurs as the two phylogenetic analyses suggest, or an archosauriform closely related to Archosauria, with features convergent to the morphology of the more advanced paracrocodylomorphs. However, support for the placement of "Nundasuchus" does weaken the further away it is placed from Paracrocodylomorpha. The results of the unconstrained analysis of Nesbitt "et al." (2014) using the Nesbitt (2011) dataset are simplified below (the relations within bolded clades are not shown).
In 2016, "Nundasuchus" was featured in Martin Ezcurra's study of archosauromorphs, and was placed into a phylogenetic analysis similar is size and scope to Nesbitt (2011). Contrary to the results of Nesbitt "et al." (2014), Ezcurra (2016) placed "Nundasuchus" as a basal pseudosuchian, although not quite as basal as Phytosauria. He also discussed the three features which those authors used to justify placement of "Nundasuchus" near Paracrocodylomorpha. Heart-shaped spine tables, for example, were considered to have had an erratic distribution within Pseudosuchia, with some taxa (such as gracilisuchids) lacking them and others (i.e. phytosaurs and "Batrachotomus") having them in only certain vertebrae. Likewise, staggered dorsal osteoderms were only found to be present in "Nundasuchus" and "Gracilisuchus", with none of the sampled paracrocodylomorphs sharing the trait. He did concede that a groove on the femoral head is consistent with the hypothesis of "Nundasuchus" being close to paracrocoylomorphs, as the trait is also found in "Prestosuchus" and "Batrachotomus".
However, Ezcurra also admitted that his analysis was more focused on basal archosauromorphs and archosauriforms rather than true archosaurs, and therefore it may not be completely accurate for crownward groups such as pseudosuchians. He noted that certain taxa crucial to Nesbitt (2011)'s results, such as "Ticinosuchus" and "Saurosuchus", were omitted from his study. These genera were paracrocodyomorphs which possessed staggered osteoderms, heart-shaped spine tables, and a groove on the femoral head, therefore justifying a close relationship to "Nundasuchus". In 2018, another early paracrocodylomorph, "Mandasuchus", received a long-awaited formal description. This genus also had these three features identified by Nesbitt "et al." (2014). A phylogenetic analysis was included in the description, based primarily on Nesbitt (2011) but also including new data from the "Nundasuchus" description as well as a recent study on gracilisuchids. The results found that either "Nundasuchus" or gracilisuchids were the sister taxa to Paracrocodylomorpha+"Ticinosuchus", although it could not precisely determine which one was closer.
An updated version of the Nesbitt (2011) dataset published by Da-Silva "et al". (2018) placed "Nundasuchus" at the base of Pseudosuchia. This study incorporated many recent revisions and additions to Nesbitt's methodology, though its results more closely resembled those of Ezcurra (2016) rather than Nesbitt (2014).


Cerro Piergiorgio

Cerro Piergiorgio is a mountain in Los Glaciares National Park in province of Santa Cruz in Patagonia, near the village of El Chaltén, at the border between Argentina and Chile. Its altitude is 2719 m.


Keilir (mountain)

Keilir (; 378 m asl) is a Pleistocene subglacial mound or perhaps a conical tuya on Reykjanes Peninsula in Iceland. Basal area is 0.773 km2, summit area 0.004 km2, basal width 0.99 km, summit width 0.07 km, volume 0.0362 km3.
It is located within the area of Krýsuvík volcanic system and Reykjanesfólkvangur. It is about 17 miles southwest of the capital city Reykjavík,
In March 2021 the mountain began to emit earthquakes followed by a fissure lava eruption further southwest at Fagradalsfjall.
2021 Keilir volcanic eruption.
On 3 March 2021 scientists in Iceland reported several days of seismic activity from the mountain. They said this was a "strong sign" that a volcanic eruption may be imminent. This would be the first in the area since the 12th century.
After weeks of tremors a small lava eruption began flowing from a fissure on 19 March 2021.
The eruption is in a valley bottom is mostly lava and sulphur dioxide gas and it is not expected to impact on air traffic or population centres.
Scientists studying the area have said that past eruptions from the volcano have been prolonged with intermittent eruptions expected to follow for around 100 years.
The Reykjanes Peninsula is a portion of the continuously spreading Mid-Atlantic Ridge that is permanently above sea level. The location is easily reached and the eruption is expected to be intensively studied by volcanologists.
Formation.
Keilir was formed during a subglacial fissure eruption which concentrated in the end at one vent. Except the cone, also some small subglacially formed hills to the north are results of this eruption.
Eruptions under the Weichselian glaciers on Reykjanes Peninsula.
When stratigraphy is considered in detail, it tells about the different parts of this eruption: The eruption thawed the glacier ice and formed a subglacial lake in which the volcano continued to develop. The water very soon touched the magma within the vent and caused explosive activity. Tephra set down in layers into the subglacial lake. With time, the tephra built up a hill and small elongated mountain over the vent(s). When such an eruption is continued over a longer time span, the water in the end does not reach the vent(s) any more and lava begins to flow.
In the top region of Keilir, there is a small cap of lava (area of lava cap 0,020 km2) which could mean that the volcanic mountain is a tuya (the lava being from subaerial eruptions at the end of the eruption series) or perhaps just represents a volcanic plug (the lava cooled and plugged up the vent).
Ice thickness and more exact time of eruption in the case of Keilir are not known, just that it took place during the Pleistocene (Weichselian).
Comparison to an Antarctic subglacial tuff cone.
"Smellie" and other scientists newly discovered a similar monogenetic subglacial tuff cone within the ice of Antarctica and could determine the thickness of ice which covered the vent during eruption. The Antarctic cone did lie under a polar ice sheet and not a temperate glacier as was the case with Keilir. Additionally, the Antarctic cone is much older (around 640 000 years), whereas Keilir is up to 100 000 years old. And the tuff cone from Victoria Land, Antarctica, is placed next to known granitic plutonic complexes and seems to be a parasitic cone of a stratovolcano, whereas Keilir is located adjacent to presently active volcanic systems and looks as if it were placed on top of the shield volcano Þráinskjöldur, though the last one is younger than the subglacial formation. Interestingly, similar tectonics, rift zones, are behind both expressions of volcanism: the West Antarctic Rift System on the one hand, and in the case of Keilir the Reykjanes Rift as part of the rift zones crossing Iceland. Also similar are their rocks – mafic lapilli tuff (in Icelandic: móberg).
Landmark.
As the mountain is easily recognized from afar, eg. from Reykjavík, but also from sea, it was used as a landmark by fishermen and seamen for many centuries.
Hiking.
There is a hiking trail leading up on the mountain from ENE. At the top, a guestbook can be found within a box.
An excellent view over a big part of Reykjanes Peninsula and Faxaflói is to be expected from the top in good weather.


Laguna Amarga

Laguna Amarga is a caldera and associated ignimbrite in the Andes of northwestern Argentina.
Laguna Amarga is part of the southern Central Volcanic Zone and one among several Miocene-Pliocene-Pleistocene volcanic centres of this volcanic region. The formation of magma chambers and thus of large volcanic systems has apparently been influenced by tectonic changes. The Laguna Amarga caldera is associated with the Cordillera Claudio Gay faults together with the Laguna Escondida and Wheelwright calderas, all of which are between 6.5 and 4 mya old. Laguna Amarga and Laguna Verde are sometimes associated with the Vallecito ignimbrite instead. The formation of the Laguna Amarga volcanic centre was probably influenced by orogenic changes in the Andes which triggered the formation of fractures in the crust.
The Laguna Amarga caldera has a diameter of and is linked to the Laguna Escondida caldera. It is the largest caldera in the area.
The Laguna Verde ignimbrite was erupted 4-3 mya ago and is associated with these two calderas. Other dates are 4.5 ± 0.5 to 3.0 ± 0.2 mya. The ignimbrite covers an area of , cropping out southwest of the Laguna Amarga ignimbrite. The Laguna Verde ignimbrite ranges from dacite to rhyolite in composition, containing biotite, pumice, quartz and sanidine.
The Laguna Amarga ignimbrite was erupted 5.1 mya ago, or 3.7-4.1 mya, and it has a volume of over . It extends north-northwest from Peinado volcano. The ignimbrite is somewhat welded and contains vesicular pumice, and bears some similarity with the Cyclops ignimbrite away. Further, the Laguna Amarga ignimbrites like the Cerro Blanco and Galan ignimbrites are rich in sodium. It covers a surface area of , cropping out around the Laguna Amarga. Another ignimbrite, Los Colorados, is located at the edge of the Amarga caldera but its eruptive centre is unknown. After its formation, lava flows from Cerro El Condor overran the floor of the caldera and monogenetic volcanos developed both on the caldera floor and on its ignimbrite.


Rancho Berlin Sandstone

The Rancho Berlin Sandstone is a geologic formation in Mexico. It preserves fossils dating back to the Paleogene period.


Rauna angusta

Rauna is an extinct genus of prawn, containing the single species Rauna angusta, described from the Solnhofen limestones of southern Germany.


Takaka Terrane

The Takaka Terrane is a Paleozoic terrane that outcrops in the South Island of New Zealand. It is most extensively exposed within the Kahurangi National Park in the Tasman District. The terrane is mostly made up of marble and volcanic rocks but is highly variable in composition. It ranges in age from mid-Cambrian to Devonian time (510–400 Ma), including New Zealand's oldest rocks, which are found in the Cobb Valley in north-west Nelson. The Cobb Valley is also the location of "Trilobite Rock" a glacial dropstone made from the moulted exoskeletons of trilobites. Asbestos was mined in the Cobb Valley from the Takaka Terrene between the late 1880s and 1917. The Takaka Terrane is highly deformed and has been intruded by many batholiths.
Description.
The Takaka Terrane has two main igneous units, the arc-related Devil River Volcanics Group (Middle to Late Cambrian) and the rift‐related Gendarme Dolerite (latest Cambrian to Early Ordovician age). The Devil River Volcanics Group sediments contain trilobites, brachiopods and conodonts. Sedimentary units in the Takaka Terrane (Haupiri Group and Junction Formation rocks) likely formed in a back-arc basin. The distinctive Arthur Marble from Takaka Hill and Mount Arthur is of Ordovician age. It has been speculated that the Takaka Terrane is equivalent to rocks in Tasmania, Australia and was separated from them with the opening of the Tasman Sea.
The Arthur Marble has been chemically weathered by rain and groundwater due to its high calcium carbonate content forming a karst geomorphology. This has led to the formation of extensive cave systems like Harwood Hole and the Riuwaka Resurgence.


Evie Member


Erythrovenator

Erythrovenator is a genus of basal theropod dinosaurs from the Late Triassic of Rio Grande so Sul, Brazil. It contains a single species, Erythrovenator jacuiensis. The genus name translates to "red hunter", in reference to the red color of its fossil, while the specific name references a nearby river, Rio Jacuí. "Erythrovenator" is one of the earliest known theropods, hailing from the early Norian (or possible late Carnian) Niemeyer Site of the Candelária Sequence in the Santa Maria Supersequence. No other dinosauromorphs are known from this site, which is dominated by the traversodontid cynodont "Siriusgnathus". The site probably corresponds to the "Riograndia" Assemblage Zone based on the presence of "Siriusgnathus".
The holotype, CAPPA/UFSM 1057, is an isolated proximal portion of the left femur, which had an estimated total length of about 190 millimeters (7.5 inches). The femoral head has a strongly concave lower edge, a rounded inner edge, and a distinct anterolateral tuber, all characteristics of dinosaur femora. It also had small anteromedial and posteromedial tubers, with the former structure quite different from the folded anteromedial tuber of other theropods. The rear surface of the femoral head has a thin vertical ridge in its medial portion and a raised scar in its lateral portion, similar to "Buriolestes". There is no evidence for a dorsolateral trochanter, unlike all other known Triassic dinosaurs. On the other hand, the anterior trochanter is a prominent pyramidal structure offset from the shaft by a cleft. This is most similar to neotheropods among early dinosaurs, and is also observed in some silesaurids. Although there is no distinct trochanteric shelf, the anterior trochanter does have a plate-like medial extension.
A phylogenetic analysis placed "Erythrovenator" as the most basal theropod, supported by the structure of its anterior trochanter. This would make it one of the oldest verifiable theropod known, and one of the few theropods known from the Triassic of Brazil. Other potentially older theropods include "Eodromaeus" (from Argentina), "Nhandumirim" and "Guaibasaurus" (from Brazil), and various herrerasaurids, but these taxa are not universally considered theropods. "Lepidus" and "Camposaurus" (from the United States) are theropods which may have a similar age to "Erythrovenator".


Moon-Airel Formation

The Moon-Airel Formation is a geological formation in France. It dates back to the late Rhaetian and early Hettangian.