Acamptonectes

Acamptonectes is a genus of ophthalmosaurid ichthyosaur, a type of dolphin-like marine reptile that lived during the Early Cretaceous around 130 million years ago. The first specimen—a partial adult skeleton—was discovered in Speeton, England, in 1958, but it was not formally described until 2012 by Valentin Fischer and colleagues. They also recognised a partial subadult skeleton belonging to the genus from Cremlingen, Germany, and specimens from other localities in England. The genus contains the single species Acamptonectes densus; the generic name means "rigid swimmer" and the specific name means "compact" or "tightly packed".
The scientific name of the genus refers to unusual adaptations in the body of "Acamptonectes" that made its trunk rigid, including tightly-fitting bones in the occiput (back and lower part of the skull) and interlocking vertebral centra ("bodies" of the vertebrae), which were likely adaptations that enabled it to swim at high speeds with a tuna-like form of locomotion. Other distinguishing characteristics include an extremely slender snout and unique ridges on the basioccipital bone of the braincase. As an ichthyosaur, "Acamptonectes" had large eye sockets and a tail fluke. "Acamptonectes" was similar in morphology to the related but earlier ophthalmosaurines "Ophthalmosaurus" and "Mollesaurus".
The discovery of "Acamptonectes" had significant implications for the evolutionary history of ichthyosaurs. It was long believed the generalised platypterygiine ophthalmosaurids were the only lineage of ichthyosaurs that survived into the Early Cretaceous following a mass extinction of ichthyosaurs across the Jurassic–Cretaceous boundary. As one of the first-known ophthalmosaurine ophthalmosaurids from the Early Cretaceous, the discovery of "Acamptonectes" provided evidence against such a mass extinction. Although the larger eyes of "Acamptonectes" would have made it better adapted than platypterygiines to depth diving, it was probably a generalist predator. Its teeth, which were slender and textured with longitudinal ridges, were adapted for impaling prey, which suggests it likely fed on soft, fleshy prey such as fish and squid.
History of discovery.
Over a series of weekends in 1958, four students and a technician from Hull University's geology department collected a fossil specimen from the Speeton Clay Formation at Speeton in northern England. The fossil belonged to an ichthyosaur or "fish lizard", a Mesozoic group of marine reptiles; it consists of a partial adult skeleton that includes a fragmentary skull roof, a mandible, vertebrae, ribs, and the scapular girdle (the shoulder area). In 1991, it was transferred to the Hunterian Museum of the University of Glasgow (GLAHM) when the geology department of Hull University was closed. It was catalogued under the specimen number GLAHM 132855, and was also known as the "Speeton Clay ichthyosaur". Palaeontologist Robert M. Appleby described the specimen and assigned it to the genus "Platypterygius" as the species "P. speetoni" (which he considered primitive within that genus), in a monograph that remained unpublished at the time of his death in 2003. A second specimen of this ichthyosaur was found in 1985, also in the Speeton Clay, and is catalogued as NHMUK R11185 at the Natural History Museum, London (NHMUK). This specimen consists of a partial rostrum (snout) and mandible, fragmentary ribs, and a complete right humerus (upper-arm bone).
Palaeontologist Jeff Liston recognised the significance of the Speeton Clay icthyosaur while working at the Hunterian Museum, and Appleby's widow Valerie asked him to help finish Appleby's unpublished monograph. Liston approached ichthyosaur specialist Valentin Fischer about writing a description of the animal. Fischer examined the specimen in 2011 and realised it represented the same ichthyosaur as a specimen from Cremlingen in northern Germany about which he had recently written a draft paper with several colleagues. This German specimen was discovered in 2005 when private fossil collector Hans-Dieter Macht found some vertebrae in a construction area. Macht notified the director of the State Natural History Museum of Braunschweig (SNHM), whereafter excavation began; the specimen was collected within three days because construction work had to continue. It was prepared and mounted in 2005 at the museum, where it is catalogued as SNHM1284-R. It consists of a partial skeleton of a subadult and includes a fragmentary skull roof, a complete mandible, a partial axial skeleton, and a partial scapular girdle. It was assigned to the genus "Platypterygius" in a 2008 article.
Historically, the genus "Platypterygius" has been treated as a catch-all wastebasket taxon for Cretaceous ichthyosaurs which contained multiple distantly-related species. Liston and Fischer recognised the specimens were distinct from other species referred to "Platypterygius" and belonged to a new species and genus. After determining the Speeton Clay specimen is much larger than the Cremlingen specimen and thus likely more mature, Liston and Fischer decided to make it the holotype of the new species because juvenile specimens often have characteristics absent in adults. The Cremlingen specimen and the other Speeton Clay specimen became paratypes (additional specimens in the series of type specimens). In 2012, a team of palaeontologists led by Fischer formally named the new genus and species "Acamptonectes densus". The generic name is derived from the Greek words "akamptos" and "nektes", which together mean "rigid swimmer"; the specific name means "compact" or "tightly packed". In full, the scientific name refers to the robust, tightly fitting bones of the occiput (back and lower part of the skull) and the tightly interlocking centra ("bodies") of the cervical (neck) and dorsal (back) vertebrae. The holotype, GLAHM 132855, was listed under the incorrect specimen number GLAHM 132588 in the original version of the description.
Multiple basioccipitals (a bone at the lower part of the occiput), stapes (one of the ear bones), and a basisphenoid (a bone within the lower part of the braincase) from the Cambridge Greensand Formation of Cambridge, England, were also assigned to "Acamptonectes" sp. (i.e., an uncertain species within the genus "Acamptonectes") by Fischer and colleagues in 2012. This was based on the assumption that "Acamptonectes" was the only Cretaceous ichthyosaur of the subfamily Ophthalmosaurinae from Eurasia. Some of the specimens are housed at the Sedgwick Museum of Earth Sciences, University of Cambridge (CAMSM), and several others are housed at the Hunterian Museum and the Natural History Museum. Several of the bones are essentially identical to those of "A. densus", while others differ in some details. The bones are generally small so their differences from "A. densus" were considered to be related to either the ages of the animals or evolutionary changes. In 2014, Fischer and colleagues identified a basoccipital and humerus belonging to "Ophthalmosaurus" (or a closely-related ichthyosaur) from Berriasian-aged rocks (dating to between 145 and 139.8 million years old) near Nettleton, Lincolnshire. Therefore, since their prior assumption no longer held, Fischer and colleagues re-listed the Cambridge Greensand specimens as belonging to indeterminate ophthalmosaurines that are not identifiable below the subfamily level.
Additional "Acamptonectes" remains known may also include an ichthyosaur specimen from Hannover, Germany. In 1909, German palaeontologist Ferdinand Broili named it as a new species of the genus "Ichthyosaurus", "Ichthyosaurus brunsvicensis", but considered its assignment to the genus tentative. Broili's specimen consisted of an incomplete basicranium (skull base) and an incomplete interclavicle (a bone between the clavicles, or collar bones); however, the specimen was destroyed during World War II. Palaeontologist Christopher McGowan regarded it as a member of "Platypterygius" in 1972 and 2003 but Fischer and colleagues assigned it to cf. "Acamptonectes" (i.e., possibly "Acamptonectes" or a related animal). They found it similar in several features to "Acamptonectes" but also different in others; they suggested the specimen was a juvenile because of the size and shape of its basicranium. Due to its fragmentary and inaccessible nature, they considered "I. brunsvicensis" a "nomen dubium" (dubious name).
Description.
"Acamptonectes", like other ichthyosaurs, had a long, thin snout, large eye sockets, and a tail fluke that was supported by vertebrae in the lower half. Ichthyosaurs were superficially similar to dolphins and had flippers rather than legs, and most (except for early species) had dorsal fins. Although the colour of "Acamptonectes" is unknown, at least some ichthyosaurs may have been uniformly dark-coloured in life, which is evidenced by the discovery of high concentrations of eumelanin pigments in the preserved skin of an early ichthyosaur fossil. "Acamptonectes" was similar in morphology to the related but earlier ophthalmosaurines "Ophthalmosaurus" and "Mollesaurus". Features of the humerus in specimen SNHM1284-R are indicative of its immaturity; however, the humerus lacks the sandpaper-like texture of the humeral shafts (shafts of the upper arm bones) of juvenile ichthyosaurs and is thus thought to represent a subadult. The holotype and specimen NHMUK R11185 are large compared to other members of the wider family Ophthalmosauridae; the holotype is thought to have been an adult because of the extensive fusion of its bones, including within the occiput, and the smooth texture of the humerus.
Skull.
The snout of "Acamptonectes" was elongated and extremely slender; in the holotype, it is only wide in front of the bony nostrils. The snout was also only 0.044 times as deep as it was long, one of the lowest ratios among ophthalmosaurids. Much of the snout was formed by the premaxillae, which formed the front portion of the upper jaw. The fossa praemaxillaris, a groove that ran parallel to the tooth row of the upper jaw, was deep and continuous, and ended in a series of aligned foramina (depressions). Behind and above the premaxillae were the nasals, which the holotype preserves in three dimensions, documenting the shape of the upper side of the snout. The back part of the nasal had a downward-extending bulge that was similar to that of related genera such as "Ophthalmosaurus". This bulge gave rise to a short, robust, wing-like extension that formed an overhang over the rear of the bony nostril; this feature was also present in "Ophthalmosaurus" and "Platypterygius australis". The edge of this overhang was roughened, indicating this was probably the attachment site for a soft tissue structure. The back part of the skull roof is incompletely known from the hind part of the lacrimal bone (in front of the eye opening), the postfrontal (above and behind the eye opening), the parietal (at the rear of the skull roof), and parts of a supratemporal that formed the rear corners of the skull roof. A forward-directed extension of the supratemporal formed the internal rear edge of the supratemporal fenestra, an opening in the skull roof situated behind the eyes. The parietal, which would have formed the inner margin of the supratemporal fenestra, had a convex front margin that would have interdigitated (interlocked) with either the frontal or postfrontal bones, which are not preserved in the known specimens.
When viewed from the side, the quadrate bone, which connected to the lower jaw to form the jaw joint, was C-shaped. Two probable hyoid bones (tongue bones) are preserved in specimen SNHM1284-R; these bones were rod-like with one spatula-shaped end. The stapes had a shaft that was more slender than in any other ichthyosaur, and its head was large and square; these features are regarded as an autapomorphy—a characteristic that distinguishes the genus from related genera. The basisphenoid had a well-developed crest on its upper surface; this is considered another autapomorphy because this surface was a wide, flat plateau in other ichthyosaur species. At its front end, the basisphenoid was fused to the parasphenoid (another bone within the lower part of the braincase) and no suture (border between the two bones) can be seen.
The supraoccipital at the upper rear of the braincase (part of the skull which encloses the brain) was only weakly arched; it thus differed from those of "Platypterygius" and "Baptanodon", which were U-shaped. Below the supraoccipital were the two exoccipitals, which formed the sides of the foramen magnum (the canal for the spinal cord). Located further below was the basioccipital, which formed the floor of the foramen magnum. The midline canal that formed this floor was bordered by ridges, giving a bilobed appearance when seen from above; this is also regarded as an autapomorphy of the genus. Below the foramen magnum, the basioccipital formed the occipital condyle, which connected with the first vertebra of the neck to form the head joint. The occipital condyle was well-demarcated from the remainder of the bone by a constricted band, unlike most other ophthalmosaurids. The condyle was rounded and had visible growth rings, as in related genera. The opisthotics, which are on either side of the basioccipital, possessed extensions called the paroccipital processes which pointed backwards and upwards. These processes were elongated and slender in "Acamptonectes" and "Ophthalmosaurus", but short and stout in other ophthalmosaurids.
The dentary (the tooth-bearing bone at the front of the lower jaw) was elongated, straight, and had a blunt front tip; this contrasts with the down-turned and beak-like tips of some ichthyosaurs in the subfamily Platypterygiinae. The splenial bones expanded in depth at their rear, forming the lower margin of the mandible and much of its midline surface. A groove similar in morphology to the fossa premaxilliaris of the upper jaw, termed the fossa dentalis, ran parallel to the dentary. Two "Acamptonectes" specimens lack the "3"-shaped upper surface of the angular bones that are otherwise typical of ophthalmosaurids; instead, the surface in these specimens consists of a simple, flat groove bordered by two walls. Because the "3" shape is present in the holotype specimen, however, this feature may have varied between individuals or growth stages. The articular bone in one specimen was stouter than those in other ophthalmosaurids, which were nearly as thick as it was long. The teeth of "Acamptonectes" had striated bases and quadrangular roots, as in numerous ophthalmosaurids, but they were not square like those of "Platypterygius". Some of the roots of SNHM1284-R had resorption pits, indicating its teeth were still growing. The only-known complete tooth crown was small compared to those of other ophthalmosaurids; it was also slender and sharply pointed, and similar to the teeth from the rear of the jaw in "Baptanodon". The bottom two-thirds of the crown had subtle, longitudinal ridges and was covered in a coarse texture that was nevertheless finer than those in "Aegirosaurus" and some "Platypterygius" specimens. The base of the crown was slightly bulbous and almost smooth, unlike those in other ophthalmosaurids.
Postcranial skeleton.
As was typical for ichthyosaurs, the vertebral centra of "Acamptonectes" were disc-shaped and deeply concave on both ends. The processes (bony projections that serve as muscle and rib attachments) projecting from the centra were greatly reduced as an adaptation for its fully aquatic lifestyle. In "Acamptonectes", the front-most cervical (neck) centra were high and short, and the following cervical and dorsal (trunk) centra become progressively longer. In the rear dorsal vertebral column, the centra became shorter and higher; this trend peaked at the first caudal (tail) vertebra, which was 3.12 times as high as it was long. The remaining caudals became longer and lower again; the caudals, which comprised the fin, were as long as they were high, a feature that was previously identified only in "P. platydactylus". The first two cervicals—the atlas and axis—were fused into a single complex that was wide when viewed from the rear. The front dorsal vertebrae have diapophyses (sideways-protruding processes to which ribs attach) fused to the centra; this feature was shared with several other ophthalmosaurids. The centra of the dorsal vertebrae were autapomorphic, being tightly interlocking and having extensive posterolateral lamellae (ridges lining the rear surfaces of the centra). This interlocking stiffened the front section of the vertebral column in conjunction with the strong occiput of the skull. Such stiffening can be observed in other ichthyosaurs belonging to the wider group Thunnosauria, though not to the degree as seen in "Acamptonectes".
The neural arches of the vertebrae had narrow pre- and postzygapophyses (articular processes projecting forward and backward from the centra) that were unpaired (fused into a single element) in all vertebrae. In contrast, in "P. hercynicus" and "Sveltonectes", these processes were paired in the front of the vertebral column. The neural spines (large upward-projecting processes) were of variable height within each specimen; they were markedly longer in some dorsals than others, reaching 1.25 times the height of the largest centrum. These long spines may be bony extensions that are analogous to the extraneural processes, a row of bones located above the tops of the neural spines that are preserved in two juvenile "Stenopterygius" specimens. The top surfaces of the neural spines were often pitted, indicating they had a cartilage covering. The ribs were distinct in being robust with a round cross-section; this contrasted with the "8"-shaped cross-section that is seen in other thunnosaurian ichthyosaurs.
The coracoid (a paired bone in the scapular girdle) was roughly hexagonal, contrasting with the rounded shape in "Platypterygius", and had outer and midline edges that were straight and parallel. The upper and lower surfaces were slightly paddle-shaped, and the mid-line surface was eye-shaped as in "Ophthalmosaurus", although it was not as thick as those in "Sveltonectes" and "P. australis". The mid-line surface was unfinished and had deep pits, indicating the presence of a thick layer of cartilage. At the front, the mid-line margin was strongly deflected outward, forming the rugose (roughened and wrinkled) edge of a wide, sheet-like process similar to that in "Ophthalmosaurus". The process was separated from the scapular facet (articulation with the scapula) by a deep, wide notch, as in many "Ophthalmosaurus" specimens. The scapular facet of the coracoid was small, deeply pitted, and triangular while the glenoid facet (articulation with the humerus) was large and eye-shaped. These facets were not markedly separated, unlike those in "Sveltonectes", where they were set at an angle of 100°. The hind margin of the coracoid was sheet-like and lacked a notch.
As with its coracoid, the scapula (shoulder blade) of "Acamptonectes" was similar to that of "Ophthalmosaurus". It was strongly compressed from side to side, unlike that in "P. hercynicus", in which the shaft was thick and rod-like. The lower part of the scapula was expanded from front to back, forming a wide, rugose, articular, tear-drop-shaped surface that articulated with the coracoid and glenoid facets. It had a large, flat, fan-like acromial process at the front (which connected with the clavicle), like those in "Ophthalmosaurus" and "P. americanus". The coracoid facet of the scapula was triangular and continuous with the larger glenoid facet, as in "Ophthalmosaurus" but unlike "P. australis". The side and mid-line surfaces of the acromial process were slightly concave.
The deltopectoral crest (to where the deltoid muscle attached) on the upper-front part of the humerus was more prominent in "Acamptonectes" than in "Ophthalmosaurus" and "Arthropterygius", but less so than in "Sveltonectes" and "Platypterygius". On the opposite side of the upper humerus, the trochanter dorsalis (a tubercle or protrusion where muscles attached) was tall and narrow, as in "Sveltonectes" and many species of "Platypterygius". The humerus had three facets on its lower side, including a facet for a bone at the front and a backward-deflected facet for the ulna, which was also similar to that of "Ophthalmosaurus", and had five articular processes. The expanded upper surface that articulated with the humerus was slightly concave and pitted, unlike that of "Arthropterygius", in which the ulna's humerus facet formed a pyramidal-shaped process. The facet for the radius was straight and trapezoidal, and merged with facets for two wrist bones, the intermedium and the ulnare. The facet for the pisiform, another wrist bone, was small and triangular, and was located at the back of the ulna's lower side. The ulna had a concave and edge-like hind margin. The phalanx bones (finger bones within the flipper) were oval as in "Ophthalmosaurus", "Arthropterygius", and some species of "Brachypterygius"; they tapered away from the body, and the edges of the peripheral phalanx bones were irregular and slightly concave.
Classification.
In 2012, a phylogenetic analysis conducted by Fischer and colleagues found "Acamptonectes" to be a member of the family Ophthalmosauridae based on several characteristics. These include: the reduced extracondylar area (a band of bone surrounding the occipital condyle), the plate-like dorsal trochanter of the humerus, the presence of a facet at the front of the humerus' bottom end for a paddle bone, and the lack of notching in the paddle bones that was considered to be homoplastic (independently acquired). It was also found to be more closely related to other ophthalmosaurids than "Arthropterygius" based on the large processes of the basipterygoids (bones at the base of the braincase), the lack of a peg on the basioccipital, and the large trochanters of the femur.
Relationships within Ophthalmosauridae have historically been unstable in analyses due to the fragmentary nature of many ophthalmosaurid specimens; furthermore, many ophthalmosaurid genera are known from a single specimen. Removal of these fragmentary genera, however, has degraded the resolution of analyses even further. The phylogenetic analysis conducted by Fischer and colleagues in 2012 recovered two novel clades (groups) within Ophthalmosauridae; the Ophthalmosaurinae and Platypterygiinae, the existence of which had long been suspected by ichthyosaur researchers—Maxim Arkhangelsky had named the clades as subfamilies as early as 2001—but had not yet been supported robustly by the results of phylogenetic analyses. Fischer and colleagues placed "Acamptonectes" was placed in the former clade, although its placement there represented a secondary reversal of the group's only uniting characteristic; a notch on the bottom of the basioccipital.
Within the Ophthalmosaurinae, various positions have been recovered for "Acamptonectes" due to the same issues. In 2012, Fischer and colleagues found that it grouped closest with ""Ophthalmosaurus" natans", with "Ophthalmosaurus icenicus" and "Mollesaurus" being successively less-closely related. The relationship with ""O." natans" was formed on account of the reduced presence of striations on the teeth, although Fischer and colleagues indicated this characteristic was homoplastic so they did not consider it sufficient to resurrect the previously-used genus name "Baptanodon" for ""O." natans". In 2013, they recovered the same arrangement in a derivative analysis for the description of "Malawania", as did Nikolay Zverkov and colleagues in a 2015 analysis focusing on "Grendelius"—albeit with a clade consisting of "Cryopterygius", "Undorosaurus", and "Paraophthalmosaurus" being closer to "Acamptonectes" than "Mollesaurus". Arkhangelsky and Zverkov previously recovered all of these species with the exception of "Mollesaurus" in a polytomy (unresolved clade) in 2014. A 2019 analysis by Zverkov and Vladimir Efimov found an otherwise identical arrangement, in which the positions of "Mollesaurus" and "Acamptonectes" were exchanged, which was also found in another 2019 analysis by Zverkov and Natalya Prilepskaya, and in the 2020 description of a new specimen of "Muiscasaurus" by María Páramo-Fonseca and colleagues, in which "Muiscasaurus" was the next-closest relative of these species. In their description of "Acuetzpalin", a 2020 analysis by Jair Barrientos-Laraa and Jesús Alvarado-Ortega found ""O." natans" and "O. icenicus" to form a clade with the exclusion of "Mollesaurus" and then "Acamptonectes", which was also recovered by Megan Jacobs and David Martill in their 2020 description of "Thalassodraco".
A 2014 analysis of the description of "Janusaurus" conducted by Aubrey Roberts and colleagues found "Acamptonectes" to be the sister group to a clade consisting of "O. icenicus" and "Leninia", which collectively constituted one branch of the Ophthalmosaurinae. The same arrangement was recovered by a 2017 analysis of the description of "Keilhauia" conducted by Lene Delsett and colleagues. In 2019, another analysis by the same authors found "Acamptonectes" closer to "Janusaurus", "Keilhauia", and "Palvennia" than to "Paraophthalmosaurus", ""O." natans" (as "Baptanodon"), "O. icenicus", or "Gengasaurus" in successive order of closeness to the base of the Ophthalmosaurinae. In each case, however, the Bremer support—a measure of the likelihood of a phylogenetic tree's arrangement over alternatives—of the groupings was low.
Other analyses also found "Acamptonectes" within unresolved polytomies. For the 2016 description of "Muiscasaurus", Erin Maxwell and colleagues found "O. icenicus", ""O." natans", "Undorosaurus", and "Acamptonectes" in a polytomy at the base of the Ophthalmosauridae. Contrary to most analyses, they did not recover a distinct Ophthalmosaurinae. Also in 2016, Fischer and colleagues found Ophthalmosaurinae to consist of "Mollesaurus" as the sister group to a polytomy including "O. icenicus", ""O." natans", "Leninia", "Acamptonectes", and a group containing "Cryopterygius", "Janusaurus", and "Palvennia". In 2019, Maxwell, Dirley Cortés, Pedro Patarroyo, and Parra Ruge recovered a poorly-resolved Ophthalmosauridae containing "Acamptonectes" in a large polytomy. In their 2020 description of "Arthropterygius thalassonotus", Lisandro Campos and colleagues placed "Acamptonectes" in a polytomy with "O. icenicus", "Leninia", and "Athabascasaurus", which formed the sister group to a clade of "Keilhauia" and "Undorosaurus"; the base of the Ophthalmosaurinae was formed by a polytomy of those species, and "Baptanodon" and "Gengasaurus".
The phylogenetic tree from the analysis of Páramo-Fonseca and colleagues in 2020 is reproduced below.
Palaeobiogeography.
Ichthyosaurs were traditionally thought to have been affected by three extinction events; one at the Triassic–Jurassic boundary, one at the Jurassic–Cretaceous boundary, and a final extinction in the Cretaceous at the boundary of the Cenomanian and Turonian ages that left no survivors. Some researchers suggested their species diversity declined after the mid-Jurassic, with the ichthyosaurs continuing until they disappeared at the end of the Cenomanian. This decline was thought to have been associated with a transition in the dominant ichthyosaur lineage; the large-eyed, thunniform (tuna-like) ophthalmosaurines, which were successful and widespread notwithstanding their hyper-specialisation, would have been replaced by the more generalised platypterygiines, which had smaller eyes and longer bodies.
"Acamptonectes" is a significant find because it is an ophthalmosaurine from the Early Cretaceous, demonstrating the ophthalmosaurines were not entirely wiped out at the Jurassic–Cretaceous boundary. Fischer and colleagues also found evidence of other ophthalmosaurines in the Early Cretaceous by reanalyzing known material, including the Nettleton "Ophthalmosaurus" specimens. They also cited reports of the Late Jurassic-aged platypterygiines "Brachypterygius", "Aegirosaurus", "Caypullisaurus", and "Yasykovia"—which has been synonymised with "Nannopterygius"—from the Early Cretaceous.
By tabulating the number of genera that disappeared in each age, Fischer and colleagues found no clear boundary between individual ages from the Late Jurassic (Oxfordian) to Early Cretaceous (Aptian) that could be considered an extinction event for ophthalmosaurids. The Jurassic–Cretaceous boundary had a net extinction rate of 0 and even the highest survival rates. By counting the number of new clades that emerged, however, they computed the cladogenesis (clade formation) rate to have been lower in the Cretaceous. They concluded—contrary to traditional thinking—the Jurassic-Cretaceous extinction event had a negligible impact on ichthyosaurs compared to its impact on other marine reptiles, and that ophthalmosaurids remained diverse until their final extinction.
Palaeobiology.
With their dolphin-like bodies, ichthyosaurs were better adapted to their aquatic environment than any other group of marine reptiles. They were viviparous that gave birth to live young and were likely incapable of leaving the water. As homeotherms ("warm-blooded") with high metabolic rates, ichthyosaurs would have been active swimmers. Jurassic and Cretaceous ichthyosaurs, including "Acamptonectes", had evolved a thunniform method of swimming rather than the anguilliform (undulating or eel-like) methods of earlier species. Thunniform ichthyosaurs were able to swim faster and more efficiently than other marine reptiles of similar sizes, and were better adapted to a pelagic (open-ocean) lifestyle. Their swimming was aided by their compact bodies and crescent-shaped tail fins.
Most of the skeleton of "Acamptonectes" appears to have been unusually rigid, which would have severely limited the extent of side-to-side motion in the front part of the skeleton. Its snout was also shallower than those in related species, and its ribs were more rounded in cross-section. According to palaeontologist Darren Naish, one of the describers of the genus, these may have been further adaptations to increase the stiffness of the animal's body by making these body parts more resistant to bending. The tightly packed occipital bones and cervical vertebrae would have allowed limited movement in the neck, suggesting "Acamptonectes" must have "shot through the water like a dart", according to fellow describer Ulrich Joger.
Diet and feeding.
As an ophthalmosaurine, "Acamptonectes" would likely have been an opportunistic generalist predator that fed on fish and squid. Adaptations for speed suggest that "Acamptonectes" and other ophthalmosaurines were likely also pursuit predators. In 1987, paleontologist Judy A. Massare proposed "feeding guilds" as a way to group marine reptiles; some ichthyosaur species were thought to have "pierced" small prey using needle-like teeth, and others to have "crunched" hard-shelled prey using robust teeth. In 2012, palaeontologist Maria Zammit suggested that the slender tooth crowns with longitudinal ridges seen in "Acamptonectes" (which placed it in the "pierce II/generalist" guild) were likely used to impale rather than grasp prey, and its diet may thus have consisted of fleshy prey that did not have a hard exterior. Nevertheless, she noted that its shallow snout and unique tooth morphology may indicate a different diet and lifestyle from other known Cretaceous ichthyosaurs.
Ichthyosaurs had the largest eyes of any known vertebrate group, which can be inferred from bones in the eye sockets known as sclerotic rings, and would therefore have possessed sensitive low-light vision that would have aided prey capture at great depths. In the related genus "Ophthalmosaurus", the maximum diameter of the eyeball would have been , allowing movement to be detected at depths of in the mesopelagic zone. "Ophthalmosaurus" could likely dive for around 20 minutes and reach depths of at least . In addition to good eyesight, the enlarged olfactory region of the brain indicates ichthyosaurs had a sensitive sense of smell.
Palaeoecology.
Speeton Clay.
"Acamptonectes" is known from rocks dating to the Hauterivian stage of the Lower Cretaceous (approximately 133 to 129 million years old) in the Speeton Clay Formation of England, which is composed of claystone and mudrock, and is generally about thick. The "Acamptonectes" holotype came from the D2D beds and the specimen NHUMK R11185 came from the slightly older D2C beds. Material preserved in these sediments is sometimes reworked from the underlying older Valanginian rocks rather than actually originating from the Hauterivian. The holotype of "Acamptonectes" is partially articulated, as were some nearby crinoid fossils, indicating the specimen was not reworked and genuinely came from the Hauterivian. Carbon-13 concentration (δ13C levels in the Speeton Clay Formation increased during the Valanginian and the early Hauterivian. This may have occurred when land submerged by rising sea levels released carbon-13 into the oceans. Concentrations of oxygen 18 (δ18O), however, increased during this time, indicating an episode of cooling; specifically, δ18O levels in belemnite fossils indicate the temperature of the Speeton Clay was about at the beginning of the Hauterivian, rose to during the middle part of this stage, and reverted to by its end. Evidence of photosynthetic organisms indicate the Speeton Clay environment was at least partially located in the photic zone (the layer in the ocean that light reaches).
Numerous other organisms have been recovered from the Speeton Clay Formation; many of these were borers, including foraminiferans, fungi, chlorophyte algae, and various animals such as sponges, polychaetes, brachiopods, barnacles, bivalves, and echinoids. In addition to the crinoids, other invertebrates in the Speeton Clay Formation are represented by a wide variety of ammonites and belemnites. While both bony fish and cartilaginous fish—the latter group represented by sharks and rays of various types—are known from the Speeton Clay, they are poorly preserved and not very abundant. Marine reptiles are uncommon in this formation; other than "Acamptonectes", they are represented by some fragmentary plesiosaur remains.
Lower Saxony Basin.
SNHM1284-R, the German specimen of "Acamptonectes", comes from late Hauterivian rocks of the Lower Saxony Basin near Cremlingen in eastern Lower Saxony. The Lower Cretaceous sediments of this basin are rich in siliclastic rocks that were deposited in the southern region of the proto-North Sea, an epicontinental sea covering much of Northwest Germany during the Lower Cretaceous. Since this region linked the warmer Tethys Sea and the colder Boreal Sea, its environment was very susceptible to change. The late Hauterivian rocks of the region were deposited in the neritic zone (shallow seas) during a time of alternating marine transgression and regression (rising and falling sea levels). The surface waters were generally cool, although they sometimes warmed when warmer water from the Tethys Sea entered the region. Sedimentation rates were high and the bottom waters were somewhat anoxic (oxygen deprived). Organisms that inhabited this sea include dinoflagellates, ammonites, and belemnites.


Cerro Colorado (volcano)

Cerro Colorado is a stratovolcano that lies in northern Chile about west of the border with Bolivia and approximately the same distance southwest of the Putana Volcano.
Cerro Colorado is located immediately west of Cerro Curiquinca and northwest of volcán Escalante (El Apagado); all three mountains are considered to be part of the Sairecabur volcanic group.


Choerolophodontidae

Choerolophodontidae is an extinct family of large herbivorous mammals that were closely related to elephants. Two genera are known, "Afrochoerodon" and "Choerolophodon".
Taxonomy.
Although usually classified as part of Gomphotheriidae, recent cladistic analysis recovers choerolophodont gomphotheres as basal to trilophodont gomphotheres and therefore a distinct family.
Distribution.
Fossils of choerolophodontids have been found in Africa, China, Anatolia, and the Balkans.


Milos Island National Airport

Milos Island National Airport is an airport in Milos, Greece . Milos is an island in the Cyclades. The airport is located 5 kilometers southeast of the harbour of the island. The airport was opened on January 17, 1973. On October 1995, a new terminal was taken into use.
Infrastructure.
As the airport has a small apron (7,800 square meters) and a short runway, only Dash 8, ATR 42 or smaller aircraft are able to use the airport. Plans exist for a 2000 by 45 meter runway at a new location and the expansion of the apron space to 26,000 square meters. However, due to the economical difficulties, these plans have been suspended. The current apron can handle only one Dash 8 sized aircraft or 2 light aircraft at one given time.
Statistics.
Annual passenger throughput
Ground transport.
Other than by car, the airport is linked to the rest of the island by taxi. There are bus connections linking to the airport.


Harpides

Harpides is an extinct genus of harpetid trilobite of the family Harpididae.


Natascha Heintz

Natascha Heintz (born 25 February 1930) is a Norwegian paleontologist. She was born in New York City, and grew up in Bærum, a daughter of Anatol Heintz and Mary Solnørdal. Her scientific research specialized on fossile fish. She worked for the Paleontologisk Museum in Oslo from 1967 to 2000. She has been editor of the journal "Norsk Geologisk Tidsskrift", was a member of several governmental committees, and is an honorary member of "Norges Museumsforbund".


Garnish Formation

The Garnish Formation is a formation cropping out in Newfoundland.


Ctenaspis

Ctenaspis is an extinct genus of heterostracan cyathaspid agnathans from the early Devonian of Canada.
species


Flims rockslide

The Flims rockslide happened about 10,000 years ago (8000 BC) in eastern Switzerland. It is the biggest known landslide incident in the Alps, and the biggest worldwide whose effects are still visible, moving some of rock, about 300 times that of the historic Swiss Goldau landslide. The town of Flims can be found at the line where the slip surface disappears under the debris. North of Flims the rock face of "Flimserstein" stands high whereas more westerly the slide surface is clearly visible. South of Flims is a huge hilly debris area that has been forest ever since, as this area is not suitable for farming, firstly for its shape and, even more for its lack of water. The river Rhine crosses this debris in a gorge called Ruinaulta. The Rhine still runs in debris, which shows that it has not yet reached its level as before the incident. The highest hill in the debris area is almost higher than Flims at the end of the sliding surface.
Landscape.
The top of the slide surface can be found at above sea north of Flims at Fil de Cassons; the end of the slide surface is at about 1100. The pre-slide valley would have been at . The rock is Mesozoic limestone, including Mergel; the angle of slide is (only) 20° to 25°. Debris covers . Pressure baked the debris together to a somewhat stable rock. Given the river Rhine as a base of the valley, the debris is as high as . This debris dammed the Vorderrhein and created a lake in the Ilanz area. The level of the lake was found to have been at a maximum of above sea level, which results in a lake some long.
Dating.
Clemens Augenstein from "Geologisches Institut der ETH Zürich" explored with Professor Flavio Anselmetti the sediments at a small lake called Dachlisee at near Obersaxen. The lake with no river flowing into it lies opposite Flims, some away. They were looking for dust, as an incident of this size would have produced a giant dust cloud. Drilling five times into the sediment they found embedded limestone dust. Using carbon dating the limestone dust was found to be 10055 years old (plus/minus 195 years).
A second source is wood, that was found inside the debris in the region, some upstream of the mouth of river Rabiusa, which was covered by massive rock identified from the Fil de Cassons area, hence reaching this point at the event; too old for the Dendrochronology line but confirming the above carbon dating.
Flow System.
After the slide most of the water escaped through the upper section of the debris. There are several examples of rivers disappearing in the Alps and also in Scotland. The lakes in the debris area still behave in this way such as Caumasee.
The Ilanz lake existed some 1000 to 2000 years before the water cut through the debris, creating the Gorge.


Necturus krausei

Necturus krausei is an extinct species of mudpuppy salamanders from the Paleocene of Saskatchewan in Canada. It is known from a set of vertebrae found in the Ravenscrag Formation.


Hedbergella

Hedbergella is an extinct genus of planktonic foraminifera from the Cretaceous, described by Loeblich and Tappan, 1961, as: Test free, trochospiral, biconvex, umbilicate, periphery rounded with no indication of keel or poreless margin; chambers globular to ovate; sutures depressed, radial, straight or curved; wall calcareous, finely perforate, radial in structure, surface smooth to hispid or rugose; aperture an interiomarginal, extraumbilical-umbilical arch commonly bordered above by a narrow lip or spatulate flap, ... Includes species otherwise similar to "Praeglobotruncana" but which lack a keel or poreless margin, hence is regarded as a separate genus rather than as a subgenus of "Praeglobotruncana" as by Banner and Blow (1959).
"Hedbergella" was named by Brönnimann and Brown in 1958, and is included in the family Hedbergellidae and the suborder Globigerinina. "Hedbergella" ranges through most of the Cretaceous, from the Hauterivian to the Maastrichtian at the end.
Related genera.
Genera possibly related closely to "Hedbergella" are "Asterohedbergella", "Costellagerina", and "Whiteinella", which are included with "Hedbergella" in the Hedbergellinae, but which have shorter ranges.
"Asterohedbergella", which has a stellate outline, is from the Upper Cretaceous (M. to U. Cenomanian) of Israel. "Costellagerina", which has a lobate outline, is from the Upper Cretaceous (Cenomanian to Campanian) and is cosmopolitan. "Whiteinella", which has a pustulate surface, is from the U. Cretaceous (M. Cenomanian to M. Turonian), and is also cosmopolitan.
The species "Muricohedbergella delrioensis", originally described as "Globigerina cretacea var. delrioensis", was formerly accepted as "Hedbergella delrioensis".
Species.
Species in "Hedbergella" include:


Cerro Bonete

Cerro Bonete is a mountain in the north of the province of La Rioja, Argentina, near the provincial border with Catamarca. Its summit is 6,759 m above mean sea level, making it the fifth-highest separate mountain in the Americas (after Aconcagua, Ojos del Salado, Monte Pissis, and Huascaran). SRTM data disproves the frequently-made claim that its summit is 6,872 m above sea level.
Within the last 3.5 million years, volcanic activity at Cerro Bonete has formed lava domes of dacite and rhyodacite.


Tata Sabaya

Tata Sabaya is a high volcano in Bolivia. It is part of the Central Volcanic Zone, one of several volcanic belts in the Andes which are separated by gaps without volcanic activity. This section of the Andes was volcanically active since the Jurassic, with an episode of strong ignimbritic volcanism occurring during the Miocene. Tata Sabaya lies in a thinly populated region north of the Salar de Coipasa salt pan.
Volcanic activity at Tata Sabaya and elsewhere in the Central Volcanic Zone is the consequence of the subduction of the Nazca Plate beneath the South America Plate. The volcano has developed along a lineament that separates older crust north of the lineament from younger crust in the south, and the edifice has been formed by andesitic rocks.
The southern flank of Tata Sabaya failed during the latest Pleistocene about 12,000 - 12,360 years before present. Debris from the collapse entered a lake that covered the Salar de Coipasa at that time and formed a deposit with a volume of . Subsequently, the collapse scar was partly filled in with more recent lava flows and lava domes; one eruption occurred about 6,000 years before present.
Geography and geomorphology.
Tata Sabaya lies just north of the Salar de Coipasa in Bolivia. The small village of Pagador lies west-southwest of the volcano, but the whole region is overall thinly inhabited. The name means "Father Sabaya"; the term "Sabaya" may be the Aymara corruption of the Quechua term for "devil", "demon". The volcano is a topic in local myths, where it is sometimes personified.
Tata Sabaya is part of the Central Volcanic Zone of the Andes, which consists of a volcanic arc that mainly follows the Western Cordillera. There are about 44 Holocene volcanoes, however the remoteness of the region and dry climate has restricted scientific research of these volcanoes; among the better known are Lastarria, the Nevados de Payachata, Ollagüe, San Pablo, San Pedro and Socompa.
Tata Sabaya is a volcano which reaches a height of . Five lava flows extend north from the summit and display levees and flow fronts, the flows reaching a maximum length of . The top of these flows is cut by a collapse scar that extends east and west of the edifice in the form of scarps up to high. The space between the scarps is in turn filled by more recent lava flows with a blocky appearance. Farther away of the edifice, the scarp is more noticeable and reaches a height of about on the southeastern side of the volcano.
A large deposit south of the volcano, originally interpreted as a nuee ardente deposit, is actually a landslide deposit which extends over a length of and a width of ; its volume is about . The landslide incorporated material from the salar, and its rocks reflect in part the layering and structure of the pre-collapse volcano. The deposit is one of the more conspicuous of its type, to the point that it was observed and identified on low-resolution Landsat images. It consists of material that forms hummock-like deposits, with individual hummocks becoming smaller the farther away from the edifice they are. The deposit extends into the Salar de Coipasa where it is confined by faults and is in part covered by lacustrine sediments such as tufa.
Geology.
Off the western coast of South America, the Nazca Plate subducts beneath the South America Plate at a rate of about . This subduction process is responsible for the volcanism in the Andean Volcanic Belt, which occurs in a Northern Volcanic Zone in Ecuador and Colombia, a Central Volcanic Zone in Peru, Bolivia, Chile and Argentina and a Southern Volcanic Zone in Chile and Argentina. These volcanic zones are separated by gaps without volcanism, where the subduction process is shallower.
Several phases of tectonic and volcanic activity have been identified in the Central Volcanic Zone. An earlier phase of volcanism in the Cordillera de la Costa commenced in the Jurassic but is considered separate from the Central Volcanic Zone magmatism proper. After an erosional hiatus during the Oligocene, volcanic arc activity increased during the Miocene and culminated in a phase of strong ignimbrite eruptions, which originated in calderas. This phase was associated with a substantial thickening of the crust in the Central Andes. During the Pleistocene ignimbrite volcanism waned again and stratovolcanoes began to develop.
Tata Sabaya lies along a crustal transition area which separates a younger crust farther south from an older (Proterozoic) crust in the north, which is made up by the Chilenia terrane and the Arequipa-Antofalla craton, respectively. This transition area appears to coincide with a chain of volcanoes that Tata Sabaya is part of and which extends from Cerro Saxani in the east to Isluga in Chile, as well as with the northern end of the Pica gap where no recent volcanism occurs in the volcanic arc.
The basement of the volcano is formed by the ignimbritic Altos de Pica formation, although outcrops of granite have been observed in the region; one of these outcrops may be a Precambrian granite subsequently thermally modified in the Toarcian. This basement is covered by younger volcanic rocks, alluvium and sediments of the Salar de Coipasa. Seismic tomography suggests that molten magma exists in the regional crust.
Composition.
Tata Sabaya has produced "two-pyroxene" andesite and porphyritic andesite. Minerals contained within the rock are augite, biotite, hornblende, hypersthene, plagioclase and titanomagnetite with only little variation between rocks erupted during separate stages of volcanic activity. The erupted volcanites define a potassium-rich calc-alkaline suite. Inclusions of more mafic rocks in the erupted material may indicate that mafic magma was injected into the magma chamber of Tata Sabaya. The magma genesis at Tata Sabaya has been explained with magma mixing processes, which gave rise to a fairly uniform composition of the eruption products.
Climate and vegetation.
The region is dry with precipitation mainly falling during southern hemisphere summer, and has little vegetation cover. "Polylepis tarapacana" trees grow on the slopes of Tata Sabaya; these trees form the highest woodlands in the world. Other aspects of regional vegetation are the so-called puna steppe, which is characterized by grass and shrub vegetation.
Eruption history.
Of all volcanoes in Bolivia, Tata Sabaya is the only one with Holocene activity which is not on the border with another country. The young age of the mountain has been inferred from the lack of glaciation and moraines on the mountain, unlike neighbouring summits.
The earliest activity at Tata Sabaya constructed a pyroclastic shield, which crops out as a thick sequence of block-and-ash flows fallout deposits and pumice deposits in the northern sector of the volcano. Effusive eruptions then built up a volcanic cone on top of this shield; the five northerly lava flows were emplaced during this phase of activity. Some lava flows from this stage were unstable and collapsed, covering the northern parts of the volcano with debris.
This effusive activity eventually oversteepened the cone, causing its southern sector to collapse. During this collapse and landsliding, large toreva blocks developed from sectors of the cone which slid down undeformed, while other material from the cone formed the hummocks in the sector collapse deposit; there was no explosive eruption at the time of the collapse. The configuration of the deposit indicates that the debris entered the Salar when it was filled with water; the height of the tufa deposits imply that water levels were about above sea level. This and the lake terraces that the landslide overran marks the collapse as synchronous with the Lake Tauca episode 12,000-12,360 years ago when water levels in the Salar de Coipasa reached their maximum. The onset of such collapses on volcanoes is often determined by faulting, climate change or eruption of the volcano; at Tata Sabaya earthquakes and the injection of new magma has been invoked to explain the destabilization of the edifice.
After the collapse, Holocene activity filled the scar with lava domes and lava flows, cancelling the traces of the collapse; some of these in turn collapsed as well and gave rise to hot avalanche deposits. Radiocarbon dating for a pyroclastic flow has yielded an age of 6,000 years before present, implying that the volcano may be still active. Reportedly, when in 1600 Huaynaputina erupted in Peru a volcano named Sabaya erupted in Oruro and destroyed a village.


Bolotridon

Bolotridon is an extinct genus of epicynodontian cynodont. It was renamed from its original genus designation of "Tribolodon" (Harry Govier Seeley, 1895), which was already occupied by a genus of cyprinid fish named in 1883 by Sauvage. The name "Bolotridon" was coined by Brian W. Coad in a 1977 publication as an anagram of "Tribolodon".
Fossils of the genus were found in the Anisian "Cynognathus" Assemblage Zone of the Burgersdorp Formation of South Africa.


Cerro Escorial

Cerro Escorial is a stratovolcano at the border of Argentina and Chile. It is part of the Corrida de Cori volcanic group and its youngest member. A well-preserved crater forms its summit area. Lava flows are found on the Chilean and smaller ones on the Argentinian side, the former reaching as far as from the volcano. One of these is dated 342,000 years ago by argon-argon dating.
Off the western coast of South America, the Nazca Plate subducts beneath the South America Plate. This process has given rise to the Andes mountain chain and the Altiplano-Puna high plateau, which formed through shortening of the crust that lasted until 1 million years ago. Cerro Escorial rises from the Puna, which is dissected at Cerro Escorial by the Archibarca lineament; it is a strike-slip fault that has facilitated the ascent of magma.
Andesite lavas were erupted during the Miocene and Pliocene. A Plinian eruption on Escorial was the source of the dacitic Escorial ignimbrite, which is also known as the Corrida de Cori ignimbrite or Caletones Cori ignimbrite. Pulsed changes in the magma supply during the eruption generated a radial ignimbrite structure which was deposited in various flows. The source magma underwent significant crustal contamination and contains quartz veins, indicating that the ignimbrite interacted with a buried hydrothermal system. Lithic clasts including basement material are also present. The ignimbrite has a volume of about and was erupted 460,000±10,000 years ago. The eruption of the ignimbrite was followed by more lava eruptions and the formation of a Holocene cinder cone. Present-day activity is of hydrothermal nature.
A sulfur mine lies southwest of Escorial. Mining ceased about 1983.


Douiret Formation

The Douiret Formation is a geologic formation in Tunisia, near the Berber village of Douiret. It is part of the larger Continental Intercalaire Formation, which stretches from Algeria and Niger in the west to Egypt and Sudan in the east. The Douiret Formation is located in the Tataouine basin in southern Tunisia, stretching into Algeria and Libya, and is part of the Merbah el Asfer Group of rock formations. The Douiret is 80 metres thick and consists of a 30-metre layer of sand beneath a 50-metre layer of clay.
A few fossil-bearing beds have been discovered in the sand layer. The fossils range from the Aptian to Albian period and include freshwater and marginal marine sharks, skates, fish, turtles, crocodilians, pterosaurs, bivalves, pollens and plants, including trees. The fish are the most abundant type of fossil found. The orientation of the fossils suggests the earlier ones were deposited by a westward flowing paleocurrent while the later ones were laid down in waves. Dinosaur remains are also among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.
The green clay layer contains plant remains (ferns and conifers), but no vertebrate or flowering plant remains.
The Douiret formation dates from the Early Cretaceous period, more than 100 million years ago. Scientists have dated the sandy layer to the Hauterivian, Barremian or Aptian periods (132 to 113 million years ago) and the clay layer to the Barremian or Aptian periods (130 to 113 million years ago).
Based on both the geology of the formation and the fossils found, scientists agree that the sandy part of the Douiret Formation was a lush coast or more likely river delta on the shore of the Tethys Sea, but by the time of the clay layer, tectonic subsidence and the northward migration of the Tethys Sea had turned the area into a huge freshwater lagoon that periodically dried into a salt flat, hostile to vegetation.


Iberosuchus

Iberosuchus (meaning "Iberian crocodile") is a genus of extinct sebecosuchian mesoeucrocodylian found in Western Europe from the Eocene. Remains from Portugal was described in 1975 by Antunes as a sebecosuchian crocodilian. This genus has one species: "I. macrodon" (meaning "large toothed). "Iberosuchus" was a carnivore, unlike the crocodilians today, they are not aquatic and are instead terrestrial.
The first of its fossils were cranial remains found in Portugal, and later more fossils were found in France and Spain. They are only known from very fragmentary fossils, elements of the skull, dentary, teeth and osteoderm.
History and discovery.
Remains of a mesocrocodylian were found in Portugal, it was named "Iberosuchus macrodon" in 1975 by Antunes, and is assigned as the type species. It was reclassified as a baurusuchid by Robert Carroll in 1988. In 1996 Ortega and colleges extended their range to France, they analyzed the fragmentary fossils of "Atacisaurus crassiproratus" (originally assigned to the tomistomine genus "Atacisaurus" by Astre 1931) and now consider it as cf. "Iberosuchus".
Description.
"Iberosuchus" has ziphodont teeth that have a laterally compressed tooth crown that had a distally curved apex; anterior-posteriorly elongated dorsal osteoderms that have a keel running through the central median; rugose ornamentations with no pits and cupules; osteoderm lack anterolateral process; the skull is vermiculated; spoon-like premaxilla palatal shelf or mandibular symphysis; notch between premaxilla and maxilla or large 4th mandibular tooth; deep rostrum or mandible.
It also had traits that it shared with other metasuchians, the dentary had lateral depressions and had a prolongation that extends dorsally behind the tooth row; the splenials are robust, had a big slot-like foramen intermandibularis oralis; had anteriorposteriorly elongated glanoid fossa on articular.
Though only known by skull fragments and osteoderms, many artistic reconstructions use its close relatives such as Sebecus which has post cranial remains found as a reference.
Cranial fossils.
Premaxilla.
There are 3 fossils of the premaxilla excavated from Aumelas, one consisting a close to complete right element, a fragmentary right element, and one with both elements pressed up against one another; they all display a very vermiculated surface texture and contain a concave dent where the dentary tooth lay. Premaxilla foramen is also visible on right element fossil's palatal view and the nares are anterior pointing, the lateral surface has very distinct ornamentation composed of bony ridges that make up the nares lateral margin. The premaxilla contains five alveoli, they increase in diameter towards the distal end and the fourth one being the largest, the last is the same size as the third and does not line up with other alveoli. There are two deep pits lingually right next to the third and fourth alveoli.
Maxilla.
There are two maxilla fossils excavated from Robiac and Saint-Martin-de-Londres, both being a fragment of the maxilla. The Robiac specimen is from the right maxilla, a fragment of the posterior part, with two ziphodont tooth crowns that are broken still on it. The Saint-Martin-de-Londres specimen is also the right maxilla, but larger. Both specimen display a vermiculated surface texture; no palatal processes are visible, but ectopterygoid is visible. There are six alveoli on the maxilla, they are compressed and have an oblique shape, with the third one being the largest. There is a dent visible in collars of the alveoli when viewed medially, the walls of the alveoli are clearly separated and is as tall as the maxilla.
Nasal.
There is a fragment of the paired nasals recovered from Aumelas, it has a slight convex shape on its dorsal surface. On the center of each nasal is a pair of ventrally opening foramina, each nasal is vertically concaved with a lateral oblique wall, the nasals are narrower in their anterior portion.
Postorbital.
There is a close to complete postorbital fossil found in Aumelas, its dorsal surface is vermiculate and bares a distinct anterolateral process with a concave notch that possibly where the palpebral bone sat. The post orbital is orientated vertically, and the cross section has a triangular shape with both sides concaved; the supratemporal fenestra's anterior-lateral edge is formed by the postorbital. In the dorsal view, the posterior of the postorbital insets into a concave and smooth structure deeply.
Mandible.
The mandible specimen was found in the "Lutetian" fossil site of Issel in France. It has a symphysis that has a spoon-like shape that reaches the 8th alveoli and is the thickest in with at the 4th tooth, the splenial is one-half the length of the symphysis. The dentary has light started ornamentations and vermiculation, there are a row of vascular foramen that open backwards on the upper part of the dentary, and the lower half has longitudinal depressions on the lateral. There is a surface full of wrinkles on the lateral dorsal side, for muscle attachment to surangular.
Teeth.
The teeth that are recovered are all labiolingually compressed with denticles along the edges, hence they are ziphodont, and the crown curves distally.
Osteoderm.
Multiple osteoderm are found in Robiac. They have a tall ridge surrounded by smaller ridges. In some smaller osteoderms, a ridge runs along the length of the osteoderm, joining with two smaller accessory processes and form a cross shape in the dorsal view, ventral side is concaved. Larger osteoderms also have a similar shape, but the main body is flatter with an indented outline, ventral side is flat.
Phylogeny.
Below is a simplified cladogram from Pol and Powell (2010) showing the relationship between "Iberosuchus" and other sebecosuchians.
Geology and paleoenvironment.
Portugal.
The first fossil of "Ibersosuchus" consisting of cranial remains was excavated in the Feligueira Grande Formation located in Praia de Vale Furado in the Leiria District of Portugal. Formation consists of sandstone, with gravel and silt, and in the site various mammals and turtles were found such as Paralophiodon cf. leptorhynchum. The formation is composed of ante-Bartonian rocks.
Spain.
The fossils of "Ibersosuchus" excavated in Spain includes a mandibular element, a snout fragment, teeth and osteoderms. The mandibular element was found in Caenes, Salamanca Province in Spain; it from the Bartonian age in MP 16 (mammal Paleogene zone), which is roughly 44 to 39 million years ago. The other is snout fragment Tosalet del Morral of Lerida province in Spain, from the Lutetian age. The teeth and osteoderms are from Cuenca del Duero, Spain from Lutetian age, MP13-14 which is in the mid-Eocene.
France.
The fossils of "Ibersosuchus" from France include postcranials, cranial elements, teeth, mandibular elements and osteoderm. In La Livinière, Hérault, France, the postcranials, jugal, and some teeth are found in a fossil site of rocks from late Lutetian age, MP 15. The site is 1.5 km west of a village in La Livinere, in a bank of the Ognon river; in the same site there are many Lophiodon, as well as artiodactyls. Mandibular elements were recovered in Issel, Aude, France, from late Lutetian age, MP 14. Osteroderm are uncovered in Lissieu, Rhône, France from late Lutetian age, MP 14. The site was in central eastern France but no longer exists; was located west of Mount d'Or Lyonnais which is a small mount made of limestone 10 km north-northwest of Lyon. Along with Iberosucus, the site yielded fossils of squamates, such as iguanids, Varanoid, serpents etc. Many cranial elements, osteoderm and teeth were found in southern France in Laguedoc; Aumelas site has the oldest fossils found at the site were dated back to mid Lutetian age, MP 13; Saint-Martin-de-Londres site was dated to later Lutetian or Bartonia at around MP 15, this site is composed of a base of limestone with many freshwater gastropods, many mammals, birds, and many reptilian fauna; Robiac site was dated to be in the Bartonian age, MP 16.


Ajkaceratops

Ajkaceratops (pronounced "oi-ka-sera-tops") is a genus of ceratopsian dinosaur was described in 2010. It lived during the Late Cretaceous in what is now Europe, in what was then the western Tethyan archipelago. The type species, "A. kozmai", is most closely related to forms in east Asia, from where its ancestors may have migrated by island-hopping. The generic name, "Ajkaceratops", honors Ajka, a town in Hungary near Iharkút, where the fossils were discovered, combined with the Greek "ceratops", meaning "horned face". The specific name, "kozmai", honors Károly Kozma.
Description.
The holotype, cataloged as MTM V2009.192.1. It consists only of a few skull fragments, including
rostral bones, fused premaxillae, and maxillae fragments (the beak and jaw fragments). These fossils are kept in the Hungarian Natural History Museum, in Budapest. Although the fossils are fragmentary, the paper describing "Ajkaceratops" estimated a body length of . Other material includes four predentary bones, cataloged as MTM V2009.193.1, V2009.194.1, V2009.195.1, and V2009.196.1; these are also believed to have belonged to "Ajkaceratops", although they are proportionately smaller, and probably came from other individuals of the genus.
Classification.
The fossils most closely resemble those of the Asian bagaceratopsids "Bagaceratops" and the "Magnirostris". Those similarities indicate "Ajkaceratops" is a ceratopsian related to the bagaceratopsids, but more primitive than the "Zuniceratops" and the Ceratopsidae.
Palaeoecology.
The fossils of "Ajkaceratops" were discovered in the Csehbánya Formation, which is interpreted as "a floodplain and channel deposit formed by variegated clay, silt with interbedded grey and brown sand, and sandstone beds". This strata dates to the Santonian stage, around 86 to 84 mya (million years ago). "Ajkaceratops" shared its environment with other dinosaurs such as "Rhabdodon", nodosaurid ankylosaurs, Non-Avian theropods and enantiornithine birds, as well as eusuchian crocodiles, azhdarchid pterosaurs, bothremydid turtles and teiid lizards.


Rhourde El Baguel oil field

Rhourde El Baguel Oil Field (REB) is an oil field located in Ouargla Province, Algeria. It was discovered in 1963 by Edward Chittick under Sinclair International and developed by ARCO (now part of BP) and Sonatrach in 1996. API oil (40.2 Deg) is produced from a Cambrian formation at a depth of .
It is the second largest field in Algeria. REB's recovery rate declined to 18% of its maximum by 1995. In 1996, it was producing less than 25,000 barrels per day. On February 15, 1996, ARCO signed a 25-year production sharing contract (PSC) valued at $1.3 billion with Algeria. In 1995 it paid a signature bonus of $225m and agreed to pay a $300m entrance fee. It was to invest in an enhanced oil recovery system and further development, including 38 new wells, but this work did not take place.
After acquiring ARCO, BP raised the field's output by gas injection to 85,000 b/d peak for a few months in early 2000. Encouraged by this success, BP decided to increase the pressure of the injected gas to optimize the production. This led to a total failure and cracks inside the field. Its sustainable capacity was never more than 18,000 b/d. As of 2011, production averaged 20,000 b/d. The EOR technique failed due to the existence of cracks in the bottom well rock formation that led to the loss of the majority of the oil reserves.
BP and Sonatrach are going through arbitration over the objectives that were initially set in the PSC and never met by BP.
The total proven reserves of field are around 3 billion barrels (410 million tonnes).


Poros

Poros () is a small Greek island-pair in the southern part of the Saronic Gulf, about (31 nautical miles) south from Athens' port of Piraeus and separated from the Peloponnese by a wide sea channel, with the town of Galatas on the mainland across the strait. Its surface area is about and it has 3,780 inhabitants. The ancient name of Poros was Pogon. Like other ports in the Saronic, it is a popular weekend destination for Athenian travellers.
Poros consists of two islands: Sphaeria (, ), the southern part, which is of volcanic origin, where today's city is located, and Kalaureia (, ), also Kalavria or Calauria (meaning 'gentle breeze'), the northern and largest part. A bridge connects the two islands over a narrow strait.
Poros is an island with rich vegetation. Much of the northern and far eastern/western sides of the island are bushy, whereas large areas of old pine forest are found in the south and center of the island. It has a good road network and adequate tourist infrastructure, which makes it a popular resort for short holidays.
Geography.
The land area of the municipality (which includes the islands and part of the adjacent Peloponnese coast) is . The landscape is very hilly and mountainous. The highest peak is the Vigla (358 m) in the west-central part. Following the island's topography and geology, small creeks and seasonal streams flow through steep valleys of the southern and northeastern part. The western and northern part of the island feature smooth hills and shallow valleys. Sandy beaches are restricted to the southern shore of the island, except for a bay in the northern part called Vayionia.
Poros contains the following villages:
Geology.
The geology of the island comprises Mesozoic to Cenozoic sedimentary rocks (limestone, and Flysch-type sandstone) and ophiolites, as well as Neogene volcanic rocks on Sferia. The island is tectonically dissected and part of a Tertiary tectonic mélange. There are karstic sinkholes in the island's central limestone massif, and limestone caves with stalactites. Visible marine fossils are mainly found in the limestone, no occurrences of precious stones or ore deposits are known.
History.
In the northeastern part of the island, in a location called “Kavos Vasili”, the archaeologists have discovered the ruins of a settlement of the Early Bronze Period. This settlement is the oldest of the wider area of Trizinia, Peloponnese, and is believed to be interrelated with the wreck found on the nearby Dokos island which dates to the same period.
Antiquity.
Poros was divided in two islands during the antiquity: Sphairia (also known by its modern Greek form Sfairia) and Calauria (also known by its ancient Greek form Kalaureia and its modern Greek form Kalavria). Sphairia consisted of the area of the modern island which includes its current capital. Calauria was the larger part of the island to its north. During the period of Mycenaean dominance (1400-1100 BC) Calauria was quite powerful and the most important naval base of region was located on islet Monti or Liontari on its eastern coast. The city-state of Calauria was home to an asylum dedicated to Poseidon, the ruins of which are still accessible on a hilltop close to the town. This asylum may have been linked to the sanctuaries at Geraistos and Tainaros. Ancient historians stated that Calauria was the center of an amphictyony, a religious alliance between its city-state and those of Athens, Poros, Aegina, Epidaurus, Hermione, Troezen, Nauplio, Orchomenus, and Prasaiai. Modern archaeology has discovered no evidence for its actual existence, however, and now believe the "Calaurian League" to have been a later Hellenistic invention. An enormous feast was found dating to the Hellenistic period in the ruins of the Calaurian asylum, along with a plaque celebrating the "revival" of its amphictyony.
During the 5th century, the Persian Empire annexed the Greek cities of western Anatolia. Athenian help for a revolt then drew them into a general war with mainland Greece and the Greek states on the Aegean islands. At the beginning of the Peloponnesian War, Troezen and Calauria offered asylum to an anti-Macedonian politician who eventually became the tyrant of the region. After the death of Alexander the Great in 323 BC, the Ptolemies of Egypt occupied Calauria. Around the same time, the Athenian orator Demosthenes came to the island, where some report his suicide. In 273 BC, the last explosion of the Methana volcano dramatically changed the morphology of Poros and the wider region.
The Sanctuary of Poseidon has been excavated by Swedish archaeologists. The 1894 field season is considered to be the first Swedish archaeological campaign in Greece. Swedes have continued excavations from 1997 in collaboration with the Greek National Heritage Board.
Roman and Byzantine times.
During the Roman period (86 BC to 395 AD) Poros was part of the Roman Empire along with Trizina, to which it was a tributary.
In Byzantine times, Poros and other islands were often raided by the pirates that dominated the Aegean Sea.
Venetian period.
In 1484 the Venetians occupied Poros and used it as a strategic port in their sea battles with the Ottomans. Poros was the most powerful city of the wider area, also governing Methana Island, Epidaurus, Damalas (Trizina), Fanari and Valario. During that time, the island had about 15,000 inhabitants, making it one of the largest cities in Greece. Venetian rule ended in 1715.
Ottoman period.
The Ottoman Period began in 1715, much later in Poros than in the rest of Greece. Shipping and commerce were the inhabitants’ main activities, but Poros’ fleet wasn’t as famous as Hydra’s or Spetses’ fleet, due to the fact that it did not participate in many sea battles.
The Greek Revolution.
Poros had an important role during the Greek Revolution in 1821, due to its strategic position. The Greek revolutionary leaders, often met in Poros to discuss and plan their future actions. The first Greek naval base was established in Poros in 1828 and remained there until 1878. In September 1828, the ambassadors of England, France and Russia met in Poros with Ioannis Kapodistrias in order to determine the borders of the future Greek state, which was established two years later, in 1830.
Russian Naval Base.
With the Treaty of Kuchuk Kainarji, Russia secured free shipping for its navy, war and merchant alike, throughout the waters of the Ottoman Empire. As Russian naval activity grew, need arose for a supply station, and land was acquired at the edge of Poros town. Extensive materiel, coal, and food storage facilities were built, as well as a hardtack baking factory. After Greek independence, Governor Capodistrias requisitioned the facilities for use of the Greek war navy, and offered the Russians an alternative location in a nearby cove. The new facilities were far larger, and were used by Russian ships throughout the 19th century. The number of Russian residents of Poros increased and even a Russian school was established. Then as Russian naval activity declined, so did the base and by the early 20th century only a single Russian watchman was left guarding it. It was then granted to the Greek Navy by the Czar but was never put to actual use, and the abandoned buildings were left to decay. The ruins, in elaborately carved stone, were listed as protected architectural monuments in 1989.
Twentieth century.
In the beginning of the 20th century, among the activities of the Poros’ inhabitants were agriculture (mainly wheat, grapevines and olives), livestock, fishing and shipping.
Transportation.
Poros is linked to mainland Greece by a car ferry to Galatas. Poros has no airport but is easily accessible from Athens by ferry or hydrofoil.
There is local bus service on the island from Poros harbor to Neorio and Monastiri.


Cerro Bravo Alto

Cerro Bravo Alto is a mountain in the Andes Mountains of Chile. It has a height of .


Dienstina

Dienstina is a trilobite in the order Phacopida, that existed during the lower Devonian in what is now Germany. It was described by Richter and Richter in 1931, and the type species is "Dienstina diensti", which the authors had originally assigned to the genus "Phacopidella" in 1923. The type locality was in Oberscheld, Rhenish Massif.


Mount Silali

Mount Silali is a dormant volcano in the Gregory Rift Valley, near Kapedo, Kenya. Silali is south of the Suguta Valley, which reaches northward to Lake Turkana, and is about north of Lake Baringo.
Geology.
Mount Silali is part of a group of volcanoes, the others being Paka and Korosi, in the Loyamoruk Plains of the eastern Nginyang Division of Baringo County.
Silali is a recent volcano that became active from 400,000 to 220,000 years ago, and was still active 7,000 years ago. It is the largest caldera volcano in the Gregory Rift Valley. Its pre-caldera development began with mainly peralkaline trachyte lavas and pyroclasts, succeeded by mildly alkaline to transitional basalts. The basalts of the mountain are similar in composition to oceanic island basalts, but have a range of isotopes indicating a variety of origins.
The Kenya rift is oriented north-south, and in the past the minimum horizontal tectonic stress direction was east-west, the direction of extension. The alignment of rows of recently formed small vents, cones, domes and collapse pits in the Silali region indicates that the minimum horizontal stress direction has changed to NW-SE within the last half million years.
Environment.
Mean annual temperature in the Loyamoruk Plains is , rising to in the hot season. Rainfall averages , with wide variations.
The thorn-bush savannah plain has no permanent source of water, with the Nginyang River flowing only after rains.
There are some highland pastures on Mount Silali with perennial grasses.
From oral accounts, the environment has become significantly drier in the last few decades, and with less grass and fewer types of grass.
Energy potential.
The mountain is potentially a source of geothermal energy. There are hot springs at Kapedo to the west with temperatures of to . The eastern part has many fumaroles and hot and altered grounds with temperatures that range from to .
In September 2011 the Geothermal Development Company (GDC) of Kenya said that 19 companies had submitted bids to develop geothermal power plants at Lake Bogoria and at Silali. GDC intended to choose eight companies, each to build one 100 MW power plant. They expected the plants to start coming on line in 2017.


Paso de Los Patos

The Paso de Los Patos "(Passage of the Ducks)" is an Andean mountain pass between Argentina and Chile, used by the main column of the Army of the Andes to cross the Andes in early 1817, in order to liberate Chile from Spain. It is located to the interior of the town of Putaendo, to the north of the city of San Felipe, Valparaíso Region, Chile, and framed by the imposing Valle de Los Patos Sur (Southern Valley of Ducks), SW of the Province of San Juan, Argentina. Other names are used for the same pass: the passages of Llaretas, Ortiz, the Honda and the Valle Hermoso.


Wimanius

Wimanius is a mixosaurid ichthyosaur, and the only genus in the family Wimaniidae. It existed during the Triassic Period in what is now Switzerland. It was described by Maisch and Matzke in 1998 based on fossils found in the Monte San Giorgio Formation, and the type species is "Wimanius odontopalatus".


Viedma Glacier

Viedma Glacier is a large glacier that is part of the huge Southern Patagonian Ice Field, located at the southern end of mainland South America. Viedma Glacier is a valley glacier and its moraine-rich terminus flows into the western end of Lake Viedma, which is fed primarily by its melting ice. Viedma Glacier is located in the undefined part of the limit between Chile and Argentina, in argentinian legislature it's in Los Glaciares National Park which was declared a World Heritage Site in 1981. in Chilean legislature part of it is in Bernardo O'Higgins National Park. The Southern Patagonian Ice Field is ; Viedma Glacier is one of the Ice Field's 48 outlet glaciers that have more than of ice field area each.
Glacier terminus.
Viedma Glacier's glacier terminus is about wide at the point it enters Lake Viedma. Chunks of ice fall off the terminus and float off into the lake, eventually melting. Glacial moraines are glacial debris of soil and rock that collect in front of, and along the sides of, the glacier as it flows across the land.
The dark parallel lines inside the white central mass of the Viedma Glacier show where the debris-filled moraines have become entwined within the center of the new glacial ice mass as it forms. At right angles to the glacial moraines in the middle, crevasses, large, canyon-sized cracks, are apparent in the grey-brown ice that can be seen along the sides of the glacier. These cracks are formed from the stress arising between ice along the valley walls (that is slower moving as the friction is greater) and the relatively fast moving ice at the glacier's center. On the southwestern side of the glacier terminus, calving of ice is visible. The glacier terminus ends in a cliff.


Amanzia

Amanzia (after Swiss geologist Amanz Gressly) is a genus of turiasaurian sauropod dinosaur from the Reuchenette Formation in Moutier, Switzerland. The type and only species is Amanzia greppini, originally named as a species of "Ornithopsis" and "Cetiosauriscus".
Discovery and naming.
The holotype remains were originally discovered in the 1860s, by workers in a limestone quarry in the Basse Montagne. Some of the remains were sold to collectors; when geologist Jean-Baptiste Greppin heard of this situation, he acquired all remaining bones and added them to the collection of the "Naturhistorisches Museum Basel". Due to being found in association with the theropod tooth MH 350 found near Moutier that probably belonged to "Ceratosaurus" or an indeterminate member of the Ceratosauria, they were misidentified as belonging to a predatory dinosaur, for which Greppin in 1870 coined the name "Megalosaurus meriani" (named after Peter Merian). In 1920, Werner Janensch reassigned the tooth to the genus "Labrosaurus". However, in 1922, Janensch realized the vertebrae belonged to a sauropod, so he wrote to Friedrich von Huene, who gave them the name "Ornithopsis greppini". In 1927, von Huene assigned the species to his new genus "Cetiosauriscus". From then on it has received little attention, with the few papers that mention it usually calling it a "nomen dubium" without further comment.
After its fossils were for the first time cleaned and prepared, in 2003 by Antoine Heitz, it was realized not to be closely related to "Cetiosauriscus". In 2005, a master thesis by C. Hofer was dedicated to the subject. In 2007, the rare presence of fossilised cartilage in a limb joint was reported. In 2020, Daniela Schwarz, Philip D. Mannion, Oliver Wings and Christian A. Meyer gave it the genus name "Amanzia", after Swiss geologist Amanz Gressly, who was the first to discover dinosaur bones in Switzerland. "Amanzia" is itself the first sauropod named from Swiss remains.
In 2020, no lectotype was selected, the naming authors maintaining the original syntype series indicated by von Huene, consisting of forty-nine bones. The Reuchenette Formation in which they were found dates from the early Kimmeridgian, about 157 million years old. They include some neck vertebrae, many tail vertebrae and material from the shoulder girdle, the pelvis and limbs. Seventy-five additional sauropod specimens in the collection of the museum, from the same site as the syntypes, were in 2020 referred to the species. These also include some limited skull material and a broken tooth. The bones are not articulated, have generally been strongly compressed and had often been damaged when being forcefully removed from the rock. Von Huene had already concluded that the material represented two or three individuals; in 2020 this was increased to a minimum of four. Of these, individuals "A" and "B" have about the same size, while an individual "C" is 15% longer and an individual "D" 20% shorter. None of the specimens are clearly juvenile.


Magnus Bromelius

Magnus Bromelius, ennobled Von Bromell, born in Stockholm in 1679, died in 1731, was a Swedish physician and paleontologist. He was the son of the physician and botanist Olof Bromelius and Agnes Svinhufvud af Qvalstad.
Bromelius became a doctor of medicine in 1703 in Reims, and was appointed a member of the Collegium medicum in 1705. At the same time he inherited a considerable fortune, which allowed him to devote his time to enlarge the collections of natural objects, coins and medals, he inherited from his father. He was appointed Professor of Anatomy in Stockholm in 1716, but soon left for a position at Collegium medicum, where he became president in 1724. He was elevated in 1726 to nobility.
Bromelius wrote many papers in numismatics, medicine and science. Some of them are contained in the "Acta Literaria et Scientiarum Sveciæ", including "Introduction to essential knowledge to recognize and order all sorts of rocks, metals and fossils, etc." (1730). According to Elias Fries he was the first Swede to describe plant fossils. In "Lithographia Suecana" (1727) Bromelius discusses fossil trilobites, corals and shells from Gotland, graptolites, and plant fossils. The mineral bromellite was named in his honour.


Geology of the Northland Region

New Zealand's Northland Region is built upon a basement consisting mainly of greywacke rocks, which are exposed on the eastern side of the peninsula. In-place Eocene coal measures crop out at Kamo, near Whangarei, and Oligocene limestone crops out at Hikurangi, near Whangarei.
A subduction zone is believed to have existed to the northeast of Northland in early Miocene times, causing the Northland Allochthon to thrust over much of the peninsula and volcanic belts to develop on either side of the peninsula. Intra-plate basaltic volcanic activity has occurred around Kaikohe, the Bay of Islands, and Whangarei since late Miocene times. Sand dunes sourced from volcanoes further south occupy much of the western coast, and the Aupouri Peninsula joins previously separate islands to the mainland to form a large tombolo.
Basement rocks.
As with most of New Zealand, the basement rocks of the Northland Region are mainly composed of greywacke (indurated sandstone), argillite, and chert, together with volcanic rocks, such as basalt pillow lava. The basement rocks are divided into a number of terranes, that are believed to have been combined together by subduction or strike-slip processes, by mid Cretaceous times (100 Ma).
Murihiku Terrane rocks lies beneath the Northland Region on the western side, but do not crop out. The Murihiku Terrane was formed in Late Triassic to Late Jurassic times (220–145 Ma).
A line of Dun Mountain-Maitai Terrane rocks pass NNW-SSE through the centre of the Northland Region, separating the Murihiku Terrane from the more easterly terranes, and produce a detectable Junction Magnetic Anomaly (JMA), but do not crop out.
Caples Terrane rocks crop out to form the Waipapa Horst (Omahuta and Puketi forest area). The Caples Terrane was formed in Permian to Triassic times (300–200 Ma).
Hunua Terrane rocks (part of the Waipapa Composite Terrane) crop out throughout much of eastern Northland, south of Whangaroa. The rocks are generally fine grained and highly deformed. The Hunua Terrane was formed in Triassic to Jurassic times (250–145 Ma).
Mount Camel Terrane rocks crop out near Mount Camel and the Karikari Peninsula. They were formed in the early Cretaceous (131–104 Ma).
Te Kuiti group coal and limestone.
The Te Kuiti Group Rocks overlie the basement rocks, and are present in Northland, Auckland, the Waikato, and King Country, although they have often been eroded or covered. Rocks containing coal were formed from swampland in Late Eocene times (37–34 Ma). The land sank, the sea transgressed, and calcareous sandstone, mudstone, and limestone were deposited in Oligocene times (34–24 Ma).
Eocene coal measures crop out in the east, between Kerikeri and Waipu. Coal has been mined around Kamo, north of Whangarei.
Limestone crops out around Whangarei, with an interesting display at the Waro Rocks Scenic Reserve, north of Hikurangi.
The Northland Allochthon.
In Early Miocene times (24–21 Ma), a series of thrust sheets was emplaced over Northland, extending as far south as the Kaipara Harbour and Albany areas. The rocks came from the northeast (perhaps beyond the Vening Meinesz Fracture Zone), and were emplaced in reverse order, but the right way up. The original rocks are of Cretaceous to Oligocene age (90–25 Ma), and include mudstone, limestone and basalt lava. The allochthon includes displaced Te Kuiti group rocks. The basalt lava of the Tangihua Complex is believed to represent sea floor, that has been obducted onto Northland to form high standing massifs, such as the Reinga, Ahipara, Warawara, Mangakahia, and Maungataniwha massifs. Isolated bodies of serpentine occur at North Cape, and south of Maungaturoto.
The Northland and East Cape Allochthons are assumed to constitute part of a single allochthon, that have later separated, due to the clockwise rotation of the eastern part of the North Island, relative to the western part.
Early Miocene volcanism.
A subduction-related volcanic belt became active to the west of the current land in Northland in Miocene times (23 Ma), and gradually moved south down to Taranaki. It produced mainly andesitic stratovolcanoes. Most of these volcanoes have been eroded, but remnants form the Waipoua Plateau (basaltic, 19–18 Ma), and Waitākere Ranges (andesitic, 22–16 Ma).
An eastern volcanic belt formed mainly andesitic volcanoes around Karikari (22.3–19.8 Ma), Whangaroa (20.5–17.5 Ma), Whangarei Heads (21.5–16.1 Ma), Bream Head, and created the Hen and Chicken Islands (19.5–16.5 Ma).
Waitemata sandstone.
Miocene volcanoes and the Northland Allochthon eroded to form the Waitemata sandstone, between Whangarei and Auckland, on the eastern side of Northland.
Uplift.
By middle Miocene, Northland was uplifted above sea level, with a slight westward tilt, exposing basement rocks on the eastern side, and resulting in a tendency for rivers to flow in a westerly direction.
Recent basaltic volcanism.
Intra-plate basaltic volcanism has occurred in Northland from late Miocene to Quaternary times. The Kerikeri volcanic group covered the area from Kaikohe, Kerikeri, to Whangarei. Activity began about 9 Ma, and the youngest cones are probably only tens of thousands of years old.
Little Barrier Island is the emergent part of a large dacitic-rhyodacitic stratovolcano, formed through two eruptive periods (3 Ma, and 1.6–1.2 Ma).
Coastal dunes.
The coastal barriers north and south of the entry to the Kaipara Harbour, are essentially consolidated sand dunes, built up over the last few million years. Similar dunes have formed in the north from Ahipara to Cape Reinga, connecting what used to be isolated islands to the rest of the North Island, thus creating a large tombolo. Sand on the eastern coast tends to be more pure quartz, and appears white.
Geothermal areas.
Hot springs exist at Ngawha Springs, with temperatures around 40–50 °C. There are also hot springs at Waiwera and Parakai, in the southern part of the Northland Peninsula, in the Auckland Region. All are used for hot pools. The Ngawha geothermal field is also used for the generation of electricity.
Geological resources.
Copper has been mined at Kaeo, silver, gold and mercury at Puhipuhi, and antimony at Russell.
Coal has been mined at Kawakawa, Hikurangi, Kamo and Kiripaka.
The Northland Basin, to the west of the Northland Peninsula is considered as having potential for oil and gas.
Halloysite clay is mined at Matauri Bay and Mahimahi.
High quality quartz sand is dredged from near Parengarenga Harbour.
Geological hazards.
The main geological hazard in Northland is the potential for landslides, particularly in mudstones and sandstones of the Northland Allochthon. Northland has the least incidence of earthquakes of anywhere in New Zealand. However, tsunamis generated by earthquakes around the Pacific can occur on the east coast.
Geological sites of interest.
Hunua Terrane can be seen along much of the coast between the Bay of Islands and Whangarei. Mount Camel Terrane can be seen at Parerake Bay, Karikari Peninsula.
Kamo coal measures can be seen near Kamo. Whangarei Limestone can be seen at Waro Rocks Scenic Reserve, north of Hikurangi.
Many of the hills in Northland are formed from the Tangihua Complex rocks of the Northland Allochthon.
Maungaraho, north of Tokatoka, gives a good example of a remnant of an early Miocene andesitic volcano. Whangarei Heads represents another example.
Sand dunes can be seen on either side of the coast between Kaitaia and Cape Reinga.
Maps.
Geological maps of New Zealand can be obtained from the New Zealand Institute of Geological and Nuclear Science (GNS Science), a New Zealand Government Research Institute.
GNS provides a free Map of New Zealand's Geological Foundations.
The main maps are the 1 : 250 000 QMap series, which will be completed as a series of 21 maps and booklets in 2010. Low resolution versions of these maps (without the associated booklet) can be downloaded from the GNS site for free.
The map for the Kaitaia Area was published in 1996.
The map for the Whangarei Area was published in 2009.
The map for the Auckland Area was published in 2002.
There is also a 1 : 25 000 map of the Whangarei Urban Area, published in 2003.


Salar de Quisquiro

Salar de Quisquiro, also known as Salar de Loyoques, is a salt pan in northern Chile and covers an area of around . The average surface elevation of its drainage basin is , being the summit of Cerro Purifican at , the highest point of this basin.
The salt pan is located within La Pacana caldera, south of Salar de Tara.


Bruce W. Hayward

Bruce William Hayward (born 1950) is a New Zealand geologist, marine ecologist, and author. He is known as a leading expert on living and fossil foraminifera.
Education and career.
At the University of Auckland, Bruce W. Hayward graduated in geology with B.S. in 1971 and Ph.D. in 1975. In 1976–1977 he was a postdoc at the Smithsonian Institution in Washington, D.C.
Hayward was from 1978 to 1991 a micropaleontologist for the New Zealand Geological Survey, Lower Hutt, from 1991 to 1997 curator of marine invertebrates at the Auckland Institute and Museum, and from 1997 to 2002 a self-employed research associate in the Geology Department of the University of Auckland, as well as from 1998 to 2000 a James Cook Research Fellow at the University of Auckland. In 2003 he became the Founder and Principal Scientist of Geomarine Research, located in Auckland. He was the Principal Scientist for three Marsden Fund grants: from 2000 to 2002 "Foraminifera and paleoceanography of Bounty Trough, east New Zealand", from 2003 to 2005 "The last global marine extinction: causes and consequences for global biodiversity", and from 2007 to 2010 "Causes of evolution and global extinction in the deep sea". In addition to his research on foraminifera, he has done research on "northern New Zealand geology and landforms, marine invertebrate ecology, industrial archaeology and lichens."
Hayward was from 1980 to 1989 an editor for the Geological Society of New Zealand, from 1988 to 2012 an associate editor for the "Journal of Foraminiferal Research", and from 2010 chief editor for Foraminifera, World Register of Marine Species. He is the author or co-author of "over 1000 publications, including more than 280 peer-reviewed papers, hundreds of popular articles and more than 20 popular books."


Oku Volcanic Field

The Oku Volcanic Field or Oku Massif is a group of volcanoes based on a swell in the Cameroon Volcanic Line, located in the Oku region of the Western High Plateau of Cameroon.
The Mount Oku stratovolcano rises to 3,011 m above sea level.
The massif has a diameter of almost 100 km and contains four major stratovolcanoes: Mount Oku, Mount Babanki 15 km SW of Oku, Nyos and Nkambe.
Rocks in the massif have ages from 24.9 to 22.1 million years ago, but more recent activity has occurred.
The massif is composed of rhyolitic and trachytic rock, and contains many maars and basaltic cinder cones.
The Oku Volcanic Field includes two crater lakes, Lake Nyos to the north and Lake Monoun to the south.
On 15 August 1984, an earthquake and landslide triggered a major release of carbon dioxide from Lake Monoun, killing several people.
Lake Nyos is inside a maar formed by an explosion about 400 years ago, and is about 1,800 m wide and 208 m deep. There is a low-temperature reservoir of free carbon dioxide below the lake bottom, which seeps into the lake through a volcanic pipe.
On 21 August 1986, Lake Nyos released a massive amount of carbon dioxide which killed at least 1,700 people by suffocation, possibly triggered by a force 5 earthquake along the Foumban Shear Zone, which runs under the massif.


List of volcanoes in Cameroon

This is a list of active and extinct volcanoes in Cameroon.


Pampa Alta Pass (Puesto Viejo)

Pampa Alta Pass (Spanish: "Paso Pampa Alta"), also known as Puesto Viejo ("Old Post"), is a boundary pass between Argentina and Chile, joining Aysén del General Carlos Ibáñez del Campo Region and Chubut Province. The elevation of the pass is 865 metres (2,838 feet) above sea level. The pathway in this locality is a gravel road and the traffic is permanent between 8 am and 8 pm in winter and between 8 am and 10 pm in summer. To leave Chile, it is necessary to obtain a pass from the international police in Coihaique. The nearest police assistance is situated 4 km (2.5 mi) away from the pass and the closest inhabited places are Balmaceda and Coihaique, in Chile.
Geography.
Climate.
The climate in Pampa Alta Pass is subarctic ("Csc/Dsc", according to the Köppen climate classification), with drier summers than winters and frequent snowfalls.


Guichenia

Guichenia is a trilobite in the order Phacopida (family Dalmanitidae), that existed during the middle Ordovician in what is now France. It was described by Henry in 1968, and the type species is "Guichenia dufouri", which was originally described under the genus "Dalmanites" by Tromelin and Lebesconte in 1876. The type locality was the Calymènes Shale, in Loire-Atlantique.