Visual cliff

The Visual Cliff is an apparatus created by psychologists Eleanor J. Gibson and Richard D. Walk at Cornell University to investigate depth perception in human and animal species. The visual cliff apparatus allowed them to conduct an experiment in which the optical and tactile stimuli associated with a simulated cliff were adjusted while protecting the subjects from injury. The visual cliff consisted of a sheet of Plexiglas that covers a cloth with a high-contrast checkerboard pattern. On one side the cloth is placed immediately beneath the Plexiglas, and on the other it is dropped about below. Using a visual cliff apparatus, Gibson and Walk examined possible perceptual differences at crawling age between human infants born preterm and human infants born at term without documented visual or motor impairments.
Visual Cliff Study (1960).
Gibson and Walk (1960) hypothesized that depth perception is inherent as opposed to a learned process. To test this, they placed 36 infants, six to fourteen months of age, on the shallow side of the visual cliff apparatus. Once the infant was placed on the opaque end of the platform, the caregiver (typically a parent) stood on the other side of the transparent plexiglas, calling out for them to come or holding an enticing stimulus such as a toy. This allowed so the infant would be motivated to crawl across towards them. It was assumed if the child was reluctant to crawl to their caregiver, he or she was able to perceive depth, believing that the transparent space was an actual cliff. The researchers found that 27 of the infants crawled over to their mother on the "shallow" side without any problems. A few of the infants crawled but were extremely hesitant. Some infants refused to crawl because they were confused about the perceived drop between them and their mothers. The infants knew the glass was solid by patting it, but still did not cross. In this experiment, all of the babies relied on their vision in order to navigate across the apparatus. This shows that when healthy infants are able to crawl, they can perceive depth. However, results do not indicate that avoidance of cliffs and fear of heights is innate.
Infant Studies.
During early development, infants begin to crawl, sit, and walk. These actions impact how the infants view depth perception. Thus, infant studies are an important part of the visual cliff. When an infant starts to engage in crawling, to sit, or walking, they use perception and action. During this time, infants begin to develop a fear of height. The everyday exploration of infants gives them clues about things or objects to avoid when exploring. Other research that has used the visual cliff focuses on preterm infants, prelocomotor Infants, and maternal signaling.
Preterm Infants.
Sixteen infants born at term and sixteen born preterm were encouraged to crawl to their caregivers on a modified visual cliff. Successful trials, crossing time, duration of visual attention, duration of tactile exploration, motor strategies, and avoidance behaviors were analyzed. A significant surface effect was found, with longer crossing times and longer durations of visual attention and tactile exploration in the condition with the visual appearance of a deep cliff. Although the two groups of infants did not differ on any of the timed measurements, infants born at term demonstrated a larger number of motor strategies and avoidance behaviors by simple tally. This study indicates that infants born at term and those born preterm can perceive a visual cliff and change their responses accordingly.
Prelocomotor Infants.
Another study measured the cardiac responses of human infants younger than crawling age on the visual cliff.
This study found that the infants exhibited distress less frequently when they were placed on the shallow side of the apparatus in contrast to when they were placed on the deep side. This means that prelocomotor infants can discriminate between the two sides of the cliff.
Maternal Signaling.
James F Sorce et al. tested to see how maternal emotional signaling affected the behaviors of one-year-olds on the visual cliff. To do this they placed the infants on the shallow side of the visual cliff apparatus and had their mothers on the other side of the visual cliff eliciting different emotional facial expressions. When the mothers posed joy or interest most of the babies crossed the deep side but if the mothers posed fear or anger, most of the babies did not cross the apparatus.
On the contrary, in the absence of depth, most of the babies crossed regardless of the mother's facial expressions. This suggests that babies look to their mother's emotional expressions for advice most often when they are uncertain about the situation. Joseph J. Campos research focuses on facial expressions between the caregiver and infant. Specifically his researcher shows that the infants will not crawl if the caregiver expresses a signal of distress. If the caregiver gives the infant a positive facial expression the child is more likely to crawl across the visual cliff.
Visual Cliff Experiments with Animals.
Before Gibson and Walk conducted their study with human infants, multiple experiments were conducted using rats, one-day-old chicks, newborn kids, kittens, pigs, adult chickens, dogs, lambs, and monkeys. Overall, most species would avoid the deep side of the visual cliff, some right after being born. The first visual cliff experiment was conducted with rats who were raised in the dark and in the light. The results were that both groups of rats would walk all over the shallow and deep parts of the cliff without an issue, which surprised Gibson, Walk, and Thomas Tighe (a research assistant). A later experiment with kittens raised in the dark and then placed on the visual cliff showed that depth perception was not innate in all species as the kittens would walk on either side of the visual cliff. After six days of being in the light, the kittens would avoid the deep side of the visual cliff (Rodkey, 2015). Later researchers conducted experiments using other species.
Rats.
Rats do not depend upon visual cues like some of the other species tested. Their nocturnal habits lead them to seek food largely by smell. When moving about in the dark, they respond to tactual cues from their stiff whiskers (vibrissae) located on the snout. Hooded rats tested on the visual cliff show little preference for either side of the visual cliff apparatus as long as they could feel the glass with their vibrissae. When placed upon the glass over the deep side, they move about as if there was no cliff.
Cats.
Cats, like rats, are nocturnal animals, sensitive to tactual cues from their vibrissae. But the cat, as a predator, must rely more on its sight. Kittens were observed to have excellent depth-discrimination. At four weeks, the earliest age that a kitten can skillfully move about, they preferred the shallow side of the cliff. When placed on the glass over the deep side, they either freeze or circle backward until they reach the shallow side of the cliff.
Turtles.
The late Robert M. Yerkes of Harvard University found in 1904 that aquatic turtles have somewhat worse depth-discrimination than land turtles. On the visual cliff one might expect an aquatic turtle to respond to the reflections from the glass as it might to water and prefer the deep side for this reason. They showed no such preference; 76% of the aquatic turtles crawled onto the shallow side. The large percentage that choose the deep side suggests either that this turtle has worse depth-discrimination than other animals, or that its natural habitat gives it less occasions to "fear" a fall.
Cows.
The ability for cows to perceive a visual cliff was tested by NA Arnold et al. Twelve dairy heifers were exposed to a visual cliff in the form of a milking pit while walking through a milking facility. Over this five-day experiment the heifers’ heart rates were measured along with the number of times they stopped throughout the milking facility. Dairy heifers in the experimental group were exposed to a visual cliff while dairy heifers in the control group were not. The experimental group was found to have significantly higher heart rates and stop more frequently than the heifers in the control group. Depth exposure did not have any effect on cortisol levels or the ease of handling of the animals. These findings provide evidence of both depth perception and acute fear of heights in cows. This may lead to a reorganization of the way milking factories function.
Criticisms.
One of the criticisms of the visual cliff study was whether the research in the study really supported the hypothesis that depth perception was innate in humans. One issue was about the glass over the deep part of the visual cliff. By covering up the deep side with glass the researchers enabled the babies to feel the solidity of the glass before they would cross over. This response was repeated over and over again in tests. Another criticism has to do with the experience of the infant. Infants who learned to crawl before 6.5 months of age had crossed the glass, but the ones that learned to crawl after 6.5 months of age avoided crossing the glass. This helps support the hypothesis that experience does influence avoidance of the glass, rather than just being innate.


Lateral ventricles

The lateral ventricles are the two largest ventricles of the brain and contain cerebrospinal fluid (CSF). Each cerebral hemisphere contains a lateral ventricle, known as the left or right ventricle, respectively.
Each lateral ventricle resembles a C-shaped cavity that begins at an inferior horn in the temporal lobe, travels through a body in the parietal lobe and frontal lobe, and ultimately terminates at the interventricular foramina where each lateral ventricle connects to the single, central third ventricle. Along the path, a posterior horn extends backward into the occipital lobe, and an anterior horn extends farther into the frontal lobe.
Structure.
Each lateral ventricle takes the form of an elongated curve, with an additional anterior-facing continuation emerging inferiorly from a point near the posterior end of the curve; the junction is known as the "trigone of the lateral ventricle". The centre of the superior curve is referred to as the "body", while the three remaining portions are known as "horns" ("cornua" in Latin); they are usually referred to by their position relative to the "body" (anterior, posterior, or inferior), or sometimes by the lobe of the cerebral cortex into which they extend. Though somewhat flat, the lateral ventricles have a vaguely triangular cross-section. Ependyma, which are neuroepithelial cells, line the ventricular system including the lateral ventricles.
Between the inferior horn and the main body of the ventricle is the putamen, which emerges from the head of the caudate nucleus, and sits above the tapetum; a small number of further connections passing through the occipital tapetum to join the putamen to portions of the caudate nucleus tail adjoining the anterior horn. Below the putamen sits the globus pallidus, with which it connects. These structures bounding the lateral ventricles form a frame curving around the thalamus, which itself constitutes the main structure bounding the third ventricle. Were it not for the choroid plexus, a cleft-like opening would be all that lay between the lateral ventricle and the thalamus; this cleft constitutes the lower part of the choroid fissure. The thalamus primarily communicates with the structures bounding the lateral ventricles via the globus pallidus, and the anterior extremities of the fornix (the mamillary bodies).
Anterior horn of lateral ventricle.
The anterior horn of the lateral ventricle is also known as the "frontal horn" as it extends into the frontal lobe. The anterior horn connects to the third ventricle, via the interventricular foramen. This portion of the lateral ventricle impinges on the frontal lobe, passing anteriorly and laterally, with slight inclination inferiorly. It is separated from the anterior horn of the other lateral ventricle by a thin neural sheet - septum pellucidum, which thus forms its medial boundary. The boundary facing exterior to the ventricle curvature is formed by the corpus callosum - the "floor" at the limit of the ventricle is the upper surface of the rostrum (the reflected portion of the corpus callosum), while nearer the "body" of the ventricle, the "roof" consists of the posterior surface of the "genu". The remaining boundary - that facing interior to the ventricle curvature - comprises the posterior edge of the caudate nucleus.
Body of the lateral ventricle.
The body of the lateral ventricle, or central part is the part of the ventricle between the anterior horn and the trigone. Its roof is bound by the tapetum of the corpus callosum - and is separated medially from the other lateral ventricle by the septum pellucidum. The tail of the caudate nucleus forms the upper portion of the lateral edge, but it is not large enough to cover the whole boundary. Immediately below the tail of the caudate nucleus, the next portion of the lateral edge is formed by the comparatively narrow stria terminalis, which sits upon the superior thalamostriate vein. The main part of the fornix of the brain forms the next narrow portion of the lateral boundary, which is completed medially by a choroid plexus, which serves both ventricles.
Trigone of lateral ventricle.
The trigone of the lateral ventricle is the area where the part of the body forms a junction with the inferior horn and the posterior horn. This area is referred to as the atrium of the lateral ventricle, and is where the choroid plexus is enlarged as the choroid glomus. As a triangular surface feature of the floor of this part of the lateral ventricle it is known as the collateral trigone.
Posterior horn of lateral ventricle.
The posterior horn of lateral ventricle, or "occipital horn", impinges into the occipital lobe in a posterior direction, initially laterally but subsequently curving medially and lilting inferiorly on the lateral side. The tapetum of the Corpus Callosum continues to form the roof, which due to the lilt is also the lateral edge. However, the posterior and anterior ends of the Corpus Callosum are characterised by tighter bundling, known as "forceps" (due to the resulting shape), to curve around the central sulci; the edge of these "forceps" form the upper part of the medial side of the posterior horn. The remainder of the medial edge of the ventricle is directly in contact with white matter of the cortex of the occipital lobe.
Inferior horn of lateral ventricle.
The inferior horn of the lateral ventricle, or "temporal horn", is the largest of the horns. It impinges on the temporal lobe in a lateral and anterior direction, initially inferiorly, until it comes within 2.5 cm. of the lobe's apex; its direction is fairly well indicated on the brain surface by the superior temporal sulcus. The horn lilts inferiorly towards its lateral edge. As a continuation of the interior side of the ventricular curve, the floor of the body of the ventricle becomes the roof of the inferior horn, hence the tail of the caudate nucleus forms the lateral edge of the inferior horn's roof, until, at the extremity of the ventricle, the caudate nucleus becomes the amygdala. The stria terminalis forms the remainder of the roof, which is much narrower than at the body - the choroid plexus moves to the medial wall. The tapetum for the temporal lobe comprises the lateral boundary of the inferior horn, on its way to join the main tapetum above the body of the ventricle (passing over the Caudate Nucleus as it does so). The majority of the inferior horn's floor is formed by the fimbria hippocampi (from which the fornix emerges), and then, more anteriorly, by the hippocampus itself. As with the posterior horn, the remainder of the boundary - in this case the lateral side of the floor - is directly in contact with the white matter of the surrounding lobe.
Development.
The lateral ventricles, similarly to other parts of the ventricular system of the brain, develop from the central canal of the neural tube. Specifically, the lateral ventricles originate from the portion of the tube that is present in the developing prosencephalon, and subsequently in the developing telencephalon.
During the first three months of prenatal development, the central canal expands into lateral, third, and fourth ventricles, connected by thinner channels. In the lateral ventricles, specialized areas – choroid plexuses – appear, which produce cerebrospinal fluid. The neural canal that does not expand and remains the same at the level of the midbrain superior to the fourth ventricle forms the cerebral aqueduct. The fourth ventricle narrows at the obex (in the caudal medulla), to become the central canal of the spinal cord.
During development, pressure from exterior structures causes a number of concave bulges to form within the lateral ventricles, which can be extremely variable in their degree of development; in some individuals they are ill-defined, while in others they can be prominent:
Fetal lateral ventricles may be diagnosed using linear or planar measurements.
Clinical significance.
The volume of the lateral ventricles are known to increase with age. They are also enlarged in a number of neurological conditions and are on average larger in patients with schizophrenia, bipolar disorder, major depressive disorder and Alzheimer's disease.
Asymmetry as an anatomical variation, in the size of the lateral ventricles is found in about 5–12% of the population. This has been associated with handedness, where right-handed people have been found to have a larger right lateral ventricle and a longer left posterior horn, whereas left-handed people have been found to have longer right posterior horns. A severe asymmetry, or an asymmetry with midline shift or diffuse enlargement, may indicate brain injury early in life, particularly in cases of a longer right posterior horn.

Trachymetopon

Trachymetopon is an extinct genus of prehistoric coelacanth from the Early Jurassic Posidonia Shale of Germany and the Middle Jurassic of France. Only one species has been named, "Trachymetopon liassicum", described by Henning in 1951 from an almost complete specimen found in the Lower Toarcian of Ohmden in Baden-Württemberg. Another specimen is known from the same site, and two older specimens come from the Sinemurian of Holzmaden. The holotype of this species is in length. A giant specimen of an undetermined species of "Trachymetopon" is known from the Middle Jurassic (Late Callovian) of Normandy. This specimen, composed of a 53 cm long palatoquadrate, belongs to an individual in length. A study published in 2015 revealed that this coelacanth belongs to the Mawsoniidae. "Trachymetopon" is one of the few known mawsoniids to have been exclusively marine (with an indeterminate form from the Triassic of France), while most of the other members of the group have lived in fresh and brackish waters.
Phylogeny.
A phylogenetic analysis of the mawsoniids published in 2020 found a polytomy grouping together "Trachymetopon" and the Cretaceous genera “"Lualabaea"”, "Axelrodichthys", and "Mawsonia". The genus “"Lualabaea"” could be congeneric with "Axelrodichthys".


Poekilopleuron

Poekilopleuron (meaning "varied ribs") is a genus of megalosauroid dinosaur, which lived during the middle Bathonian of the Jurassic, about 168 to 166 million years ago. The genus has been used under many different spelling variants, although only one, "Poekilopleuron", is valid. The type species is "P. bucklandii", named after William Buckland, and many junior synonyms of it have also been erected. Few material is currently known, as the holotype was destroyed in World War II, although many casts of the material still exist.
Discovery and naming.
"Poekilopleuron" is a genus of theropod with a long and complex history. The genus was first named and described by Jacques-Amand Eudes-Deslongchamps in a report published in 1836, based on holotype material that is now destroyed. In 1837, Eudes-Deslongchamps published a more detailed account of this discovery in a monograph which was also inserted next year in volume 6 of the "Mémoires de la Société Linnéenne Normandie".
The holotype, which was housed in Musée de la Faculté des Sciences de Caen and destroyed during World War II, included gastralia, phalanges, a left forelimb, caudal vertebrae, chevrons, ribs and a hindlimb. Of all the material, few is still preserved, although the gastralia, phalanges and forelimb were cast and now represent the plastotype, with casts in the Muséum National d'Histoire Naturelle (specimen MNHN 1897-2) and Yale Peabody Museum (specimen YPM 4938). The original material was uncovered in a layer of the Calcaire de Caen in Normandy, France. "Poekilopleuron" can be assigned to the middle Bathonian in age, about 167.7 to 166 million years ago.
In the same 1836 publication, Eudes-Deslongchamps also named the type species of "Poekilopleuron", "P. bucklandii". Eudes-Deslongchamps noted similarities with some material of "Megalosaurus bucklandii" and "Poekilopleuron", and chose the species name "bucklandii" for "Poekilopleuron", so that if the two genera were synonymized, only the genus name would be suppressed. The generic name is derived from Greek ποίκιλος, "poikilos", "varied", and πλευρών, "pleuron", "rib", a reference to the three types of rib present. The specific name, honouring William Buckland, was deliberately identical to that of "Megalosaurus bucklandii".
Description.
The most distinctive feature of "Poekilopleuron" were its forelimbs. Their length, about 60 cm, was a sign of this theropod's more original build. Unlike later Theropoda, whose forelimbs tended toward reduction in length in proportion to the animals' size, "Poekilopleuron"'s were long and, by implication, potent. The length mostly resided in the elongated but powerfully muscled humerus. The antebrachia (forearms) were markedly short and robust, a characteristic shared with "Poekilopleuron's" slightly later and considerably larger American cousin "Torvosaurus". A unique feature is a lack of the olecranon process on the ulna.
The fossil of "Poekilopleuron" showed a rare complete set of gastralia: fourteen pair of belly ribs supported the body of the animal.
Classification.
"Poekilopleuron" is a difficult taxon to classify, as its original material is lost, and few casts are known. "Poekilopleuron" has a history of being renamed under different species and genera, most of which are now its junior synonyms.
Eudes-Deslongchamps thought the specimen might well be proven to belong to this earlier named species; if so, merely the generic name would have to be changed. Indeed, following 1879 "Poekilopleuron" was often subsumed under "Megalosaurus bucklandii". Eudes-Deslongchamps' choice caused problems however, when Friedrich von Huene in 1923 concluded it was part of "Megalosaurus" but as a separate species within that genus. As both species carried the same epithet "bucklandii", they could no longer be distinguished. Von Huene therefore renamed the species into "Megalosaurus poekilopleuron". Most later authors continued using the generic name "Poekilopleuron".
Another problem was caused by the fact that the name was only partially Latinised. In correct Greek it would have been "poikilopleuron", in Latin "poecilopleurum". This induced later writers to improve the spelling, leading to such variants as "Poecilopleuron" and "Poikilopleuron" (still used as late as 2006). However, the original name has priority and is valid.
Five other species would be named in the genus. In 1869 Edward Drinker Cope renamed "Laelaps gallicus" into "Poekilopleuron gallicum". In 1870 Joseph Leidy created a "Poicilopleuron valens" based on a fossil probably belonging to "Allosaurus". In 1876 Richard Owen named a "Poikilopleuron pusillus", in 1879 renamed by Cope to "Poekilopleuron minor"; in 1887 Harry Govier Seeley made it a separate genus: "Aristosuchus". In 1883 W.A. Kiprijanow created a "Poekilopleuron schmidti", of which the specific name honours Friedrich Schmidt, based on some indeterminate ribs and a sauropod metatarsal. This chimaera is a "nomen dubium". A much later named species is "Poekilopleuron valesdunensis" created by Ronan Allain in 2002. In 2005 it was renamed "Dubreuillosaurus".
Because the original fossil was destroyed and no other remains of "Poekilopleuron" have since been found, and also because of its name change, there is much controversy surrounding its classification that cannot be resolved. Traditionally it has been assigned to the Megalosauridae, but some recent analyses showed a position in the Sinraptoridae; others had as result it was a member of Megalosauroidea, in a basal position or in the Eustreptospondylinae. Benson "et al." (2010) found it and "Lourinhanosaurus" to belong to Sinraptoridae. An earlier study found that it was a primitive allosauroid outside Sinraptoridae.
Paleobiology.
The material of "Poekilopleuron bucklandii" includes two tail vertebrae with the chevron of one vertebra ankylosed to the centrum of the next within the development of an exostosis. Two phalanges also preserve pathologies. One probable pedal phalanx shows three low, irregular exostosis-like projections. A second probable manual phalanx exhibits a "low rounded projection resembling a callus." Ralph Molnar considered the occurrence of three pathologies in one individual to be "noteworthy". Sadly the specimens cannot be examined further to determine the etiology of the pathologies because of their destruction during the British bombing raid in 1944.


Lectavis

Lectavis is a genus of enantiornithine birds. Their fossil bones have been recovered from the Late Cretaceous (Maastrichtian, c. 70.6 – 66 mya) Lecho Formation at "estancia" El Brete, Argentina. The genus contains a single species, Lectavis bretincola.
Description.
Etymology: "Lecho Formation bird living at El Brete". "Lectavis", after Latin "lectus" ("bed") = Spanish "lecho" + Latin "avis", "bird". "bretincola", after the type locality "estancia" El Brete + Latin "incola", "inhabitant".
The presently only known fossil bones (PVL-4021-1) are mostly of the left tibiotarsus (lower leg) and tarsometatarsus (upper foot) of a single individual. "L. bretincola" was a sizeable bird, with a tibiotarsus and a tarsometatarsus which if complete must have been nearly long (Chiappe 1993); this would make it roughly similar to a large curlew in size and at least in leg shape. It possesses a hypotarsus, which it evolved autapomorphically from modern birds, as it covers the upper end of the second, not the third, toe's bones. This structure serves to attach and arrest the posterior cruciate ligament, which in turn prevents the lower and upper leg from shifting out of position during walking.
Thus, it can be concluded that "L. bretincola" was a much more terrestrial species than its relative "Yungavolucris brevipedalis" which lived at the same time and place. Its habitat was a richly vegetated coastal area that was dotted by – possibly brackish – lakes or small rivers (Chiappe 1993), and it might thus be that the present species represents a case of parallel evolution with waders and similar semi-aquatic forms, or even a running bird similar to an oversized courser, and quite unlike anything living today.
It was a rather advanced species of enantiornithine and possibly quite closely related to "Enantiornis" and "Avisaurus", but more likely closer to other Euenantiornithes (Sanz "et al." 1995). Its exact relationships, as with most enantiornithine birds, are unresolved however.


Balaenotus

Balaenotus is an extinct genus of cetaceans from the Pliocene of Belgium.
Classification.
"Balaenotus" is known only from the type species "B. insignis".


Preondactylus

Preondactylus is a genus of long-tailed pterosaurs from the Late Triassic (late Carnian or early Norian age, about 228 million years ago) that inhabited what is now Italy. It contains a single known species, Preondactylus buffarinii, which was discovered by Nando Buffarini in 1982 at the Forni Dolostone near Udine in the Preone valley of the Italian Alps.
Discovery.
When Buffarini first discovered "Preondactylus", the thin slab of bituminous, dolomitic limestone containing the fossil was accidentally broken into pieces while being extracted. After reassembly the rock was cleaned with water by him and his wife and the marl and in it the bone was washed away and lost. All that was left was a negative imprint on the stone, of which a silicon rubber cast was made to allow for subsequent study of the otherwise lost remains. Most of the skeleton is known, but the posterior portions of the skull have not been preserved. This first specimen is the holotype: MFSN-1770.
A second, disarticulated specimen, MFSN-1891, was found at the same locale in 1984 about 150–200 meters (490–650 ft) deeper into the strata than the original find. The second specimen appears to have been preserved in the gastric pellet of a predatory fish, which had consumed the pterosaur and vomited up the indigestible pieces that would later fossilize. More detailed knowledge of the variability of Triassic pterosaurs has made the identification of this specimen as "Preondactylus" uncertain, and it may even be that the remains are not those of a pterosaur at all.
A third specimen is MFSN 25161, a partial skull, lacking the lower jaws.
Description.
"Preondactylus" had single cusp teeth, meaning they had one point on each tooth. Its diet either consisted of fish, insects or both, but there is still debate going on as the tooth structure could indicate either diet (or both). It had short wings, whose total span was only 45 cm (18 in), and relatively long legs. The short wings were a "primitive" feature for pterosaurs, but "Preondactylus" was a fully developed flier.
Phylogeny.
The species was described and named by Rupert Wild in 1984. The genus name refers to Preone, the specific name honours Buffarini. Rupert classified the new species within Rhamphorhynchidae, of which group very old species are known such as "Dorygnathus", but soon it was understood the form was much more basal. A cladistic analysis by David Unwin found "Preondactylus" as the most basal pterosaur, and the species was accordingly used by him for a node clade definition of the clade Pterosauria. Other analyses however, have found a somewhat more derived position for "Preondactylus".
The following phylogenetic analysis follows the topology of Upchurch "et al." (2015).


Sork Ale

Sork Ale (also known as Asdaga or Sorcali) is a sicilic stratovolcano located in the Danakil Horst at the southern end of the Danakil Alps near the Ethiopia/Eritrea border. It makes up part of the Bidu volcanic complex (with the Nabro Volcano, Bara Ale and Mallahle).
The volcano has scoria cones suggesting Strombolian eruptions. At the top of the volcano is a 1 km wide 300m steep sided caldera there are satellite vents on the south east flank. The volcano lies on the western end of lava field.


Sierra Negra

Sierra Negra (also, and perhaps more properly, Cerro La Negra) is an extinct volcano located in the Mexican state of Puebla, close to the border with Veracruz. At officially above sea level, it is the fifth-highest peak in Mexico. However, because it is overshadowed by nearby Pico de Orizaba (5,610 m/18,406 ft), it is not too well known and often left out of lists of Mexico's mountains.
Overview.
Sierra Negra is located within the Pico de Orizaba National Park. The mountain is the site for two of the world's premier astronomical instruments, the Large Millimeter Telescope and the High Altitude Water Cherenkov Observatory. Therefore, the access to the mountain is restricted and has to be applied for at least a week in advance. The service road for this facility is claimed to be the highest road in North America. A part of the telescope facility is visible as a white dot in the first picture below and more clearly in the second picture.
The Spanish word "sierra" is usually applied to mountain ranges or ridges. However, a few mountains were given the name "sierra" after the Conquest, like "Sierra de Tlaxcala" or "Sierra de Tolocan" (now outdated names for Malinche and Nevado de Toluca, respectively). As listed by the Mexican geographical institute INEGI, the official name for the Sierra Negra ("Black Mountains") is Cerro La Negra ("Black Lady Hill"), although the latter is largely unused in common speech. The Nahuatl names Tliltépetl ("Black Mountain") or Atlitzin ("Our Lord (or Lady) of the Waters") are sometimes attached. Speakers of Orizaba Nahuatl called the mountain "Iztactepetl Icni" ("Sibling of the White Mountain"; the "White Mountain" being the Pico de Orizaba).
The mountain range to the east of the city of Tehuacán (south of but still in sight of the Pico de Orizaba), with such principal towns as Zoquitlán and Coyomeapan, is also known as the "Sierra Negra", which (unsurprisingly) can cause confusion.


Tritheledon

Tritheledon is an extinct genus of cynodonts that lived during the Lower Jurassic. Fossils were found in the Elliot Formation, South Africa. Like all cynodonts, it had many traits shared by mammals. Tritheledonts were probably insectivores, and nocturnal animals.


Vollen Formation

The Vollen Formation is a geologic formation in Norway. It preserves fossils dating back to the Ordovician period.


Thecodontosaurus

Thecodontosaurus ("socket-tooth lizard") is a genus of herbivorous basal sauropodomorph dinosaur that lived during the late Triassic period (Rhaetian age).
Its remains are known mostly from Triassic "fissure fillings" in South England. "Thecodontosaurus" was a small bipedal animal, about 2 m (6.5 ft) long. It is one of the first dinosaurs to be discovered and is one of the oldest that existed. Many species have been named in the genus, but only the type species "Thecodontosaurus antiquus" is seen as valid today.
Discovery and naming.
"Thecodontosaurus antiquus".
In the autumn of 1834, surgeon Henry Riley (1797–1848) and the curator of the Bristol Institution, Samuel Stutchbury, began to excavate "saurian remains" at the quarry of Durdham Down, at Clifton, presently a part of Bristol, which is part of the Magnesian Conglomerate. In 1834 and 1835, they briefly reported on the finds. They provided their initial description in 1836, naming a new genus: "Thecodontosaurus". The name is derived from Greek θήκή, ', "socket", and οδους, ', "tooth", a reference to the fact that the roots of the teeth were not fused with the jaw bone, as in present lizards, but positioned in separate tooth sockets. "Thecodontosaurus" was the fifth dinosaur named, after "Megalosaurus", "Iguanodon", "Streptospondylus" and "Hylaeosaurus", though Riley and Stutchbury were not aware of this, the very concept of Dinosauria only being created in 1842. In 1843, in his catalogue of British fossils, John Morris provided a complete species name: "Thecodontosaurus antiquus". The specific epithet, "antiquus", means "ancient" in Latin.
The original type specimen or holotype of "Thecodontosaurus", BCM 1, a lower jaw, fell victim to heavy World War II bombings. Many remains of this dinosaur and other material related to it were destroyed in November 1940 during the Bristol Blitz. However, most bones were salvaged: today 184 fossil bones are part of the collection of the Bristol City Museum and Art Gallery. Later, more remains were found near Bristol at Tytherington. Currently about 245 fragmentary specimens are known, representing numerous individuals. In 1985, Peter Galton designated another lower jaw, a right dentary, as the neotype, BCM 2. The remains had been found in chalkstone infillings, breccia deposited in fissures in older rocks. The age of these deposits was once estimated as old as the late Carnian, but recent studies indicate that they date from the Rhaetian.
Other species.
Apart from the original type species, "Thecodontosaurus antiquus", Riley and Stutchbury also found some teeth of carnivorous phytosaurians that they named "Palaeosaurus cylindrodon" and "P. platyodon". In the late nineteenth century, the theory became popular that such remains belonged to carnivorous prosauropods: animals with the body of "Thecodontosaurus", but with slicing teeth. In 1890, Arthur Smith Woodward accordingly named a "Thecodontosaurus platyodon," and in 1908 Friedrich von Huene named a "Thecodontosaurus cylindrodon". Though still defended by Michael Cooper in 1981, the hypothesis that such creatures existed has now been totally discredited.
On one occasion, material of "Thecodontosaurus" was, by mistake, described as a separate genus. In 1891, Harry Govier Seeley named "Agrosaurus macgillivrayi", assuming the remains had been collected in 1844 by the crew of HMS "Fly" on the northeast coast of Australia. It was long considered the first dinosaur found in Australia, but in 1999 it was discovered that the bones probably belonged to a lot sent by Riley and Stutchbury to the British Museum of Natural History and then mislabelled. In 1906, von Huene had already noted the close resemblance and renamed the species "Thecodontosaurus macgillivrayi". It is thus a junior synonym of "Thecodontosaurus antiquus".
Presently, the only valid species is thus "T. antiquus".
Misassigned species.
"Thecodontosaurus caducus" was named by Adam Yates in 2003 for a juvenile specimen found in Wales; in 2007 this was made the separate genus "Pantydraco". However, Ballell, Rayfield & Benton (2020) considered "Pantydraco caducus" to be a taxon of uncertain validity, and considered it possible that it might represent a juvenile of "Thecodontosaurus antiquus".
Description.
From the fragmentary remains of "Thecodontosaurus", most of the skeleton can be reconstructed, except for the front of the skull. "Thecodontosaurus" had a rather short neck supporting a fairly large skull with large eyes. Its jaws contained many small- to medium-sized, serrated, leaf-shaped teeth. This dinosaur's hands and feet each had five digits, and the hands were long and rather narrow, with an extended claw on each. This dinosaur's front limbs were much shorter than the legs, and its tail was much longer than the head, neck and body put together. On average, it was long, or 1 ft. tall, and weighed . The largest individuals had an estimated length of .
In 2000, Michael Benton noted the existence of a robust morph in the population, seen by him as a possible second species or, more likely, an instance of sexual dimorphism. Benton also indicated some unique derived traits, or autapomorphies, for the species: a long basipterygoid process on the braincase; a dentary that is short in relation to the total length of the lower jaw; an ilium that has a back end that is subquadrate instead of rounded.
The small size has been explained as an instance of insular dwarfism.
Phylogeny.
Riley and Stutchbury originally saw "Thecodontosaurus" as a member of the Squamata, the group containing lizards and snakes. This did not change when Richard Owen coined the term Dinosauria in 1842, because Owen did not recognise "Thecodontosaurus" as a dinosaur; in 1865, he assigned it to the Thecodontia. It was not until 1870 that Thomas Huxley became the first person to understand that it was a dinosaur, though referring it incorrectly to the Scelidosauridae. Later, it was be placed in either the Anchisauridae or its own Thecodontosauridae alongside "Agrosaurus".
Modern exact cladistic analyses have not been conclusive. Although not actually the earliest member of the group, "Thecodontosaurus" is sometimes placed in a very basal position among the sauropodomorph dinosaurs. It was earlier included under the Prosauropoda, but more recently it has been suggested that "Thecodontosaurus" and its relatives preceded the prosauropod-sauropod split. New reconstructions show that its neck is proportionally shorter than those in more advanced early sauropodomorphs.
The Bristol Dinosaur Project.
"Thecodontosaurus" has formed the basis of a massive public engagement exercise, the Bristol Dinosaur Project, that has run since 2000. In 2009, HLF core funded the Bristol Dinosaur Project, which allowed for the hiring of an Educational Officer and a Fossil Preparator to further develop the project. This funding resulted in three and a half years of extensive laboratory, research, and outreach work that presented the project to thousands of people all around the world.


Ernst Friedrich Glocker

Ernst Friedrich Glocker (1 May 1793 – 18 July 1858) was a German mineralogist, geologist and paleontologist.
Biography.
From 1810 he studied theology, philosophy and sciences at the University of Tübingen, and afterwards continued his education at Halle. In 1823 he obtained his habilitation with the dissertation thesis, "De Gemmis Plinii inprimis de Topazio", and he later served as a professor at the Magdalene gymnasium in Breslau. In 1834 he became a full professor at the University of Breslau, where he was also director of the mineral cabinet.
During his scientific excursions, he collected minerals and fossils in Silesia, Lusatia, Moravia and the Sudetenland. He is credited with coining the mineral terms: pyrargyrite (1831), ozokerite (1833), sepiolite (1847), halite (1847), sphalerite (1847), arsenopyrite (1847) and liparite (1847). He also conducted research in the field of botany — in 1836 paleobotanist Heinrich Göppert named the plant genus "Glockeria" in his honor.


Androgynoceras

Androgynoceras is an extinct genus of cephalopod belonging to the Ammonite subclass. The Green Ammonite Beds of the Dorset Coast are named after "Androgynoceras lataecosta" which has chambers filled with green calcite.
Distribution.
Jurassic of Austria, France, Germany, Serbia and Montenegro, Spain, Switzerland and the United Kingdom


Francis Eustace Baker

Francis Eustace Baker (born 19 April 1933) is a British businessman who was the Governor of Saint Helena, Ascension and Tristan da Cunha between 1984 and 1988. While he was Governor, he implemented a '3 day working scheme' to help tackle unemployment and announced the plans to build the 2nd RMS St Helena, which was, up until the construction of St Helena's airport, the main link between the territory and the rest of the world. He received the Order of the British Empire (OBE) in 1979 and the CBE in 1984.


Isluga

Isluga () is a stratovolcano located in Colchane, west of the Chile-Bolivia border and at the west end of a group of volcanoes lined up in an east-west direction, which also includes the volcanoes Cabaray and Tata Sabaya. Isluga has an elongated summit area and lies within the borders of Volcán Isluga National Park in Chile's Tarapacá Region.
Geography.
Isluga lies in the commune of Colchane, Iquique Province of the Tarapaca Region, Chile. The volcano is part of the Volcán Isluga National Park, which was created in 1985. The volcano can be accessed through the International Route 55.
Isluga is part of the Andean Volcanic Belt, the volcanic zone on the western side of South America where the Nazca plate is subducted beneath the South American plate. Isluga is part of the segment named the Central Volcanic Zone. In the Tarapaca region other volcanoes have been active in the Holocene, such as Guallatiri, Parinacota and Taapaca.
There are several volcanic units in the Isluga area. A pre-Isluga unit containing Cabay volcano, northeastern Carcanchuni and southern Cerro Blanco are not stratigraphically controlled. The Enquelga unit is the first Isluga unit proper. Further, Isluga and Tata Sabaya and some other volcanoes form a lineament which may coincide with the suture between the Chilenia terrane and the Arequipa-Antofalla block.
Being about high over its base, Isluga has five craters, a main crater wide at the end of snowcovered summit ridge and underwent caldera collapse. The volcano itself is constructed from lava domes and flows on top of Miocene ignimbrites. Several stages of eruptive activity are recognized, some of them exposed through erosion. A northwestern debris avalanche has been found on Isluga, on top of which the recent volcano is constructed. The fumarolically active crater region has been buried with surge deposits from phreatomagmatic activity, and the northern ridge is covered by Holocene lavas. A glaciated dacitic lava flow is dated 0.096±0.006 Ma by K-Ar analysis. North of Isluga lies the dissected Quimsachatas volcano, which has been dated at 0.566±0.017 Ma. Both the summit crater and the area below the crater on the southern flank are faintly fumarolically active, with yellow sulfur deposits observed. The fumaroles appear to produce water vapour.
Eruptive activity.
Isluga erupted in February 1878 following the 1878 Tarapaca earthquake. Voluminous lava emissions destroyed the towns of Carima, Cariquima, Chiapa, Libiza and Sotoca, and the eruption was accompanied with strong earthquake activity in Cariquima. Other eruptions have been reported in August 1863, a major eruption in 1868 and August 1869, 1877 and 1878 and minor eruptions in 1863 and 1885.
Isluga last erupted in 1913, but ongoing volcanic earthquake activity has been observed. The volcano hosts some of the Andes' largest thermal anomalies in satellite images and increased fumarolic activity in 2002–2003 was reported. Some earthquake activity may be associated with neighbouring hydrothermal fields. A phreatic eruption was observed in 2005; whether it was related to the 2005 Tarapacá earthquake half a year earlier is unclear.
Petrology.
Isluga's lavas are andesitic to trachyandesitic in composition with SiO2 contents between 56-61%. The andesites are porphyritic with more than half phenocrysts and high potassium content (2.7-3.6%), moderate aluminium and high magnesium, although some hornblendes have high Na/K ratios. The petrology of the Isluga lineament lavas indicates an origin either in 3-5% partial melting of the mantle, or by a 15% partial melting of a granite-containing mantle with subsequent fractionation of mafic components.
Climate.
The climate of the region varies by altitude; between lies a borderline desert area with temperatures ranging from below to , with most precipitation () falling in summer. A similar climate lies on the eastern part of the mountains between , with precipitation. Above lies a region of steppe vegetation with temperatures of and about precipitation also during summer, and above lies perennial snow.
Mythology and archeology.
Also named Laram Qhawani, the volcano dominating the village of Enquelca is a sacred mountain, responsible for health, wealth and rain. It is considered a female spirit married to Cabarray. While no archeological remains have been found on its summit, a triangular stone structure resembles the patterns drawn when making offerings to spirits. One of the ends of the triangular structure points to Cerro Cariquima, another sacred mountain. Another archeological place was found at ca. 5,200 m (17,056') on the southern ridge, probably serving as protection against wind and with a niche in the walls that probably served ritual purposes.
Threats.
Threats from future eruptions of Isluga consist primarily in the contamination of aquifers and destruction of agricultural areas by ash falls, both limiting factors in the desertic environment surrounding the volcano. Additionally, the cultural value of the region would be endangered, also given the relative lack of documentation thereof.


Kentrosaurus

Kentrosaurus ( ) is a genus of stegosaurian dinosaur from the Late Jurassic of Tanzania. The type species is K. aethiopicus, named and described by German palaeontologist Edwin Hennig in 1915. Often thought to be a "primitive" member of the Stegosauria, several recent cladistic analyses find it as more derived than many other stegosaurs, and a close relative of "Stegosaurus" from the North American Morrison Formation within the Stegosauridae.
Fossils of "K. aethiopicus" have been found only in the Tendaguru Formation, dated to the late Kimmeridgian and early Tithonian ages, about 152 million years ago. Hundreds of bones were unearthed by German expeditions to German East Africa between 1909 and 1912. Although no complete skeletons are known, the remains provided a nearly complete picture of the build of the animal.
"Kentrosaurus" generally measured around in length as an adult, and weighed about . It walked on all fours with straight hindlimbs. It had a small, elongated head with a beak used to bite off plant material that would be digested in a large gut. It had a, probably double, row of small plates running down its neck and back. These plates gradually merged into spikes on the hip and tail. The longest spikes were on the tail end and were used to actively defend the animal. There also was a long spike on each shoulder. The thigh bones come in two different types, suggesting that one sex was larger and more stout than the other.
Discovery and species.
The first fossils of "Kentrosaurus" were discovered by the German Tendaguru Expedition in 1909, recognised as belonging to a stegosaur by expedition leader Werner Janensch on 24 July 1910, and described by German palaeontologist Edwin Hennig in 1915. The name "Kentrosaurus" was coined by Hennig and comes from the Greek '/, meaning "sharp point" or "prickle", and '/ meaning "lizard", Hennig added the specific name "aethiopicus" to denote the provenance from Africa.
From 1909 onwards, "Kentrosaurus" remains were uncovered in four quarries in the "Mittlere Saurierschichten" (Middle Saurian Beds) and one quarry in the "Obere Saurierschichten" (Upper Saurian Beds). During four field seasons, the German Expedition found over 1200 bones of "Kentrosaurus", belonging to about fifty individuals, many of which were destroyed during the Second World War. Today, almost all remaining material is housed in the Museum für Naturkunde Berlin (roughly 350 remaining specimens), while the museum of the Institute for Geosciences of the University of Tübingen houses a composite mount, roughly 50% of it being original bones.
Although no complete individuals were found, some material was discovered in association, including a nearly complete tail, hip, several dorsal vertebrae and some limb elements of one individual. These form the core of a mount in the Museum für Naturkunde by Janensch. The mount was dismantled during the museum renovation in 2006/2007, and re-mounted in an improved pose by Research Casting International. Some other material, including a braincase and spine, was thought to have been misplaced or destroyed during World War II. However, all the supposedly lost cranial material was later found in a drawer of a basement cupboard.
The type and sole accepted species of "Kentrosaurus" is "Kentrosaurus aethiopicus", named by Hennig in 1915. Fragmentary fossil material from Wyoming, named "Stegosaurus longispinus" by Charles Gilmore in 1914, was in 1993 classified as a North American species of "Kentrosaurus", as "K. longispinus". However, this action was not accepted by the paleontological community, and "S. longispinus" has been assigned to its own genus, "Alcovasaurus", differing from "Kentrosaurus" in having more elongated tail spikes and the structure of the pelvis and vertebrae.
Type specimens and type locality.
In the original description, Hennig did not designate a holotype specimen. However, in a detailed monography on the osteology, systematic position and palaeobiology of "Kentrosaurus" in 1925, Hennig picked the most complete partial skeleton, today inventorised as MB.R.4800.1 through MB.R.4800.37, as a lectotype (see syntype). This material includes a nearly complete series of tail vertebrae, several vertebrae of the back, a sacrum with five sacral vertebrae and both ilia, both femora and an ulna, and is included in the mounted skeleton at the Museum für Naturkunde in Berlin, Germany. The type locality is Kindope, Tanzania, near the Tendaguru hill.
Unaware that Hennig had already defined a lectotype, Peter Galton selected two dorsal vertebrae, specimens MB.R.1930 and MB.R.1931, from the material figured in Hennig's 1915 description, as 'holotypes'. This definition of a holotype is not valid, because Hennig's selection has priority. In 2011, Heinrich Mallison clarified that all the material known to Hennig in 1915, i.e. all the bones discovered before 1912, when Hermann Heck concluded the last German excavations, are paralectotypes, and that MB.R.4800 is the correct lectotype.
Naming controversy.
Soon after its description, a controversy arose over the stegosaur's name, which is very similar to the ceratopsian "Centrosaurus". Under the rules of biological nomenclature, forbidding homonymy, two animals may not be given the same name. Hennig renamed his stegosaur "Kentrurosaurus", "pointed-tail saurian", in 1916, while Hungarian paleontologist Franz Nopcsa renamed the genus "Doryphorosaurus", "lance-bearing saurian", the same year. If a renaming had been necessary, Hennig's would have had priority. However, because the spelling is different, both "Doryphorosaurus" and "Kentrurosaurus" are unneeded replacement names; "Kentrosaurus" remains the valid name for the genus with "Kentrurosaurus" and "Doryphorosaurus" being its junior objective synonyms.
Description.
"Kentrosaurus" was a small stegosaur. It had the typical dinosaurian body bauplan, characterised by a small head, a long neck, short forelimbs and long hindlimbs, and a long, horizontal and muscular tail. Typical stegosaurid traits included the elongation and flatness of the head, the powerful build of the forelimbs, erect and pillar-like hindlimbs and an array of plates and spikes running along both sides of the top mid-line of the animal. Only a single complete tooth was known when Hennig published his monography in 1925. Later, a part of a dentary, the tooth-bearing bone of the front lower jaw, was found, which bears a just emerging tooth, and some tooth fragments were recovered from matrix sticking to other bones. The deep dentary is almost identical in shape to that of "Stegosaurus", albeit much smaller. Similarly, the tooth is a typical stegosaurian tooth, small with a widened base and vertical grooves creating five ridges.
Size and posture.
"Kentrosaurus aethiopicus" was smaller than "Stegosaurus ungulatus", "Hesperosaurus mjosi", "Dacentrurus armatus" and "Tuojiangosaurus multispinus", and about as large as "Huayangosaurus taibaii". The total length of a composite skeletal mount in the Museum für Naturkunde Berlin, Germany, from the tip of the snout to the tip of the tail is . Slightly more than half of this length is made up by the tail. Larger single elements were found, so that the animal could probably attain a total length of . In 2010, Gregory S. Paul estimated the weight of a "Kentrosaurus" at . An estimate for the 4.5 m long composite mount in the Museum für Naturkunde Berlin by Mallison, on the basis of a virtual 3D skeleton and 3D model, varied between 1073 L and 1267 L, and a body mass between , depending on the amount of musculature reconstructed for the tail.
The long tail of "Kentrosaurus" results in a position of the center of mass that is unusually far back for a quadrupedal animal. It rests just in front of the hip, a position usually seen in bipedal dinosaurs. However, the femora are straight in "Kentrosaurus", as opposed to typical bipeds, indicating a straight and vertical limb position. Thus, the hindlimbs, though powered by massive thigh muscles attached to a long ilium, did not support the animal alone, and the very robust forelimbs took up 10 to 15% of the bodyweight.
Distinguishing features.
"Kentrosaurus" can be distinguished from other members of the Stegosauria by a number of extensions of the vertebrae, which in the tail do not run sub-parallel, as in most dinosaurs. In the front third of the tail, they point backwards, the usual direction. In the middle tail, however, they are almost vertical, and further back they are hook-shaped and point obliquely forward. Also typical is that the dorsal (back) vertebrae have a neural arch more than twice as high as the centrum, the vertebral body, and almost completely occupied by the extremely spacious neural canal. The preacetabular process, front blade, of the ilium widens laterally, to the front outer side, and does not taper.
Furthermore, there is a unique combination of traits not in themselves unique. The transverse processes, the side extensions, of the tail are present up to the 28th vertebra of the series. The transverse processes of the front tail vertebrae are rod-shaped with narrow bases and do not touch the plate formed by the fusion of the processes of the sacral vertebrae. The chevrons, bones pointing to below from the bottom side of the tail vertebrae, have the shape of an inverted T. The length of the ilium equals, or is greater than, that of the thigh bone.
Armour.
Typically for a stegosaur, "Kentrosaurus" had extensive osteoderm (bony structures in the skin) covering, including small plates (probably located on the neck and anterior trunk), and spikes of various shapes. The spikes of "Kentrosaurus" are very elongated, with one specimen having a bone core length of 731 millimetres. The plates have a thickened section in the middle, as if they were modified spines. The spikes and plates were likely covered by horn. Aside from a few exceptions they were not found in close association with other skeletal remains. Thus, the exact position of most osteoderms is uncertain. A pair of closely spaced spikes was found articulated with a tail tip, and a number of spikes were found apparently regularly spaced in pairs along the path of an articulated tail.
Hennig and Janensch, while grouping the dermal armour elements into four distinct types, recognised an apparently continuous change of shape among them, shorter and flatter plates at the front gradually merging into longer and more pointed spikes towards the rear, suggesting an uninterrupted distribution along the entire body, in fifteen pairs. Because each type of osteoderm was found in mirrored left and right versions, it seems probable that all types of osteoderms were distributed in two rows along the back of the animal, a marked contrast to the better-known North American "Stegosaurus", which had one row of plates on the neck, trunk and tail, and two rows of spikes on the tail tip. There is one type of spike that differs from all others in being strongly, and not only slightly, asymmetrical, and having a very broad base. Because of bone morphology classic reconstructions placed it on the hips, at the iliac blade, while many recent reconstructions place it on the shoulder, because a similarly shaped spike is known to have existed on the shoulder in the Chinese stegosaurs "Gigantspinosaurus" and "Huayangosaurus".
Phylogeny.
"Kentrosaurus" was by Hennig assigned to the Stegosauridae in 1915. This is confirmed by modern cladistic analyses, although in 1915 Stegosauridae was a far more inclusive concept. A consecutive narrowing down of this concept caused "Kentrosaurus", until the 1980s to be seen as a typical "primitive" stegosaurian, to be placed in a more derived, higher, position in the stegosaur evolutionary tree. Derived traits include a sacral yoke, a long prepubic process, a long thighbone and two rows of plates or spikes. A study by Octávio Mateus e.a. in 2009 recovered "Kentrosaurus" in a basal position in the Stegosauridae as shown by this cladogram:
Earlier analyses had shown "Kentrosaurus" closer in the tree to "Stegosaurus". Basal traits include a prominent paraquadratic foramen at the quadrate in the skull; maxillary teeth with only seven denticles at the margin; and a shoulder spine.
Paleobiology.
Feeding.
Like all ornithischians, "Kentrosaurus" was a herbivore. The fodder was barely chewed and swallowed in large chunks. One theory on stegosaurid diet holds that they were low-level browsers, eating foliage and low-growing fruit from various non-flowering plants. "Kentrosaurus" was capable of eating at heights of up to when on all fours. It may also have been possible for it to rear up on its hindlegs to reach vegetation higher in trees. With its centre of mass close to the hind-limbs, the animal could potentially support itself as it stood up. The hips were likely capable of allowing a vertical trunk rotation of about 60 degrees and the tail probably would either have been fully lifted, not blocking this movement or have enough curvature to rest on the ground; thus it could have provided additional support, though precisely because of this flexibility it is not certain whether much support was actually provided: it was not stiff enough to function as a "third leg" as had been suggested by Robert Thomas Bakker. In this pose, "Kentrosaurus" could have fed at heights of .
Defense.
Because the tail had at least forty caudal vertebrae, it was highly mobile. It could possibly swing at an arc of 180 degrees, covering the entire half circle behind it. Swing speeds at the tail end may have been as high as 50 km/h. Continuous rapid swings would have allowed the spikes to slash open the skin of its attacker or to stab the soft tissues and break the ribs or facial bones. More directed blows would have resulted in the sides of the spikes fracturing even sturdy longbones of the legs by blunt trauma. These attacks would have crippled small and medium-sized theropods and may even have done some damage to large ones. Earlier interpretations of the defensive behaviour of "Kentrosaurus" included the suggestion that the animal might have charged to the rear, to run through attackers with its spines, in the way of modern porcupines.
Though "Kentrosaurus" likely stood with forelimbs erect like in other dinosaurs, it is hypothesised that the animal adopted a sprawling posture when defending itself. Its neck was flexible enough to allow it to keep sight of predators, as it could reach the sides of its body with its snout and look over the back. In addition, the posterior position of the center of mass may not have been advantageous for rapid locomotion, but meant that the animal could quickly rotate around the hips by pushing sideways with the arms, keeping the tail pointed at the attacker. "Kentrosaurus" was nevertheless not invulnerable. A quick predator could have made it to the tail base (where the impact speed would be much lower) when the tail passed and the neck and upper-part of the body would have been unprotected by the tail swings. A successful predation of "Kentrosaurus" may have required group hunting. Compared to the more robust spikes of "Stegosaurus", the thinner spikes of "Kentrosaurus" were at greater risk of bending.
Growth.
In 2013, a study by Ragna Redelstorff e.a. concluded that the bone histology of "Kentrosaurus" indicated that it had a higher growth rate than reported for "Stegosaurus" and "Scutellosaurus", in view of the relatively rapid deposition of highly vascularised fibrolamellar bone. As "Stegosaurus" was larger than "Kentrosaurus", this contradicts the general rule that larger dinosaurs grew quicker than smaller ones.
Sexual dimorphism.
Differences in the proportions, not the size, of the femurs (thighbones) led Holly Barden and Susannah Maidment to realize that "Kentrosaurus" probably showed sexual dimorphism. This dimorphism of the femurs consisted in them being either more or less robust than the other. The occurrence ratio of the robust morph to the gracile one was 2:1, and it is likely that the higher percentage of animals were females. Because of this ratio, it was considered reasonable to assume that in their society, "Kentrosaurus" males mated with more than one female, a behaviour also found in other vertebrates.
The problem posed by the ratio is that the multiple specimens studied, died in the same place, but probably not in a sudden mass-death and so do not represent a single herd or contemporary population. The results may have been distorted by a greater chance for robust animals of getting fossilised or discovered. In an earlier study by Galton in 1982, it was suggested that individual difference in the sacral rib count of both "Kentrosaurus" and "Dacentrurus" might be an indication of dimorphism: females would have had an extra pair of sacral ribs, having also the first sacral vertebra connected to the ilium, in addition to the subsequent four sacrals.
Reproduction.
As the plates and spikes would have been obstacles during copulation, it is possible that pairs mated back-to-back with the female staying still in a lordosis posture as the male manoeuvres this penis into her cloaca. The shoulder spikes would have made the female unable to lay on her side during mating as is proposed for "Stegosaurus".
Paleoecology.
"Kentrosaurus" lived in what is now Tanzania in the Late Jurassic Tendaguru Formation. The main "Kentrosaurus" quarries were located in the Middle Saurian Beds dating from the upper Kimmeridgian. Some remains were found in the Upper Saurian Beds dating from the Tithonian. Since 2012, the boundary between the Kimmeridgian and Tithonian is dated at 152.1 million year ago.
The Tendaguru ecosystem primarily consisted of three types of environment: shallow, lagoon-like marine environments, tidal flats and low coastal environments; and vegetated inland environments. The marine environment existed above the fair weather wave base and behind siliciclastic and ooid barriers. It appeared to have had little change in salinity levels and experienced tides and storms. The coastal environments consisted of brackish coastal lakes, ponds and pools. These environments had little vegetation and were probably visited by herbivorous dinosaurs mostly during droughts. The well vegetated inlands were dominated by conifers. Overall, the Late Jurassic Tendaguru climate was subtropical to tropical with seasonal rains and pronounced dry periods. During the Early Cretaceous, the Tendaguru became more humid. The Tendaguru Beds are similar to the Morrison Formation of North America except in its marine interbeds.
"Kentrosaurus" would have coexisted with fellow ornithischians like "Dysalotosaurus lettowvorbecki"; the sauropods "Giraffatitan brancai", "Dicraeosaurus hansemanni" and "D. sattleri", "Janenschia africana", "Tendaguria" "tanzaniensis" and "Tornieria africanus"; theropods "Allosaurus" "tendagurensis", "Ceratosaurus" "roechlingi", "Ceratosaurus" "ingens," "Elaphrosaurus bambergi", "Veterupristisaurus milneri" and "Ostafrikasaurus crassiserratus"; and the pterosaur "Tendaguripterus recki". Other organisms that inhabited the Tendaguru included corals, echinoderms, cephalopods, bivalves, gastropods, decapods, sharks, neopterygian fish, crocodilians and small mammals like "Brancatherulum tendagurensis".


Abdounodus

Abdounodus ("Abdoun tooth") is an extinct genus of mammal known from the middle Paleocene of northern Africa. The sole species, "A. hamdii", is known from teeth discovered in the Ouled Abdoun Basin of present-day Morocco in 2001. Traditionally considered a mioclaenid "condylarth", recent studies place it as a basal afrothere closely related to "Ocepeia", demonstrating the close convergent evolution between perissodactyls and herbivorous afrotheres and bridging paenungulates with other afrotheres.


Parasabatinca

Parasabatinca is an extinct genus of small primitive metallic moths within the extant family Micropterigidae or extinct family Eolepidopterigidae, containing two species. The first is Parasabatinca aftimacrai, of which fossil remains have been found in Lebanese amber and have been dated to the Lower Cretaceous.
Description.
These fossil moths have similarly shaped wings and wing scales, with abundant microtrichia on the wing membrane, comparable with recent Micropterigidae species such as "Sabatinca" and "Micropteryx", but differences from them by the lack of ocelli and the apparent absence of a branch of the subcostal vein. The species is close to "Sabatinca" with which it has more characters in common than with "Micropterix".
Parasabatinca caldasae is known from two specimens from the Crato Formation in Brazil. The age of the fossil has been estimated to be between 125-112 Ma, since it was discovered in Crato fossil beds (Lower Cretaceous, Aptian).


Magnapaulia

Magnapaulia is a genus of herbivorous lambeosaurine hadrosaurid dinosaurs known from the Latest Cretaceous Baja California, of northwestern Mexico. It contains a single species, Magnapaulia laticaudus. "Magnapaulia" was first described in 1981 as a possible species of "Lambeosaurus" by William J. Morris, and was given its own genus in 2012 by Prieto-Márquez and colleagues.
Discovery and naming.
Between 1968 and 1974, a team of the Natural History Museum of Los Angeles County headed by geologist William J. Morris excavated giant lambeosaurine remains from a site near El Rosario in Baja California. Morris named them "Lambeosaurus laticaudus" in 1981, based on type specimen LACM 17715, a partial skeleton with partial skull. Morris added a question mark to the front of the generic name to indicate its provisional nature: because no complete crest had been found for his species, and without it a definitive assignment could not be made. From what was known of the skull, he considered it to be most like "Lambeosaurus". The specific name is derived from the Latin "latus", "broad", and "cauda", "tail". Morris interpreted this species as water-bound, due to features like its size, its tall and narrow tail (interpreted as a swimming adaptation), and weak hip articulations, as well as a healed broken thigh bone that he thought would have been too much of a handicap for a terrestrial animal to have survived long enough to heal. Between 1981 and 2012, other authors accepted it as a potential species of "Lambeosaurus", suggested it could instead be a species of "Hypacrosaurus", or questioned its validity.
In 2012 it was named as a separate genus by Albert Prieto-Márquez, Luis Chiappe, and Shantanu Joshi. The generic name is a combination of the Latin "magnus", "large", and the first name of Paul G. Haaga, Jr., the president of the board of trustees of the Los Angeles County Museum of Natural History. The 2012 study indicated that the remains had been found in a layer of the El Gallo Formation, dating to the late Campanian, about 73.6 to 73 million years old. The study referred numerous other specimens to the species: LACM 17698, 17699, 17700, 17702–17713, 17716 and 17717; LACM 20873-20876; and LACM 20883-20885. These had been found within a distance of three metres to the holotype and consist of partial skeletons, separate bones and skin impressions from several individuals, varying in size. In 2012 a complete redescription of the body parts was given.
Description.
"Magnapaulia" is noted for its great size and the tall profile of its tail, which had elongated chevrons and vertebral spines like those of "Hypacrosaurus". Its size was estimated by its original describer as between 15 m (49.2 ft) and 16.5 m (54.1 ft) long, with a weight of up to 23 metric tons (25.4 tons); Prieto-Márquez "et al." provided a smaller estimate of around , still among the longest ornithischians and representing the largest known lambeosaurine. The largest known specimen is LACM 17712, which includes a humerus with an estimated original length of 803 millimetres.
The redescription of 2012 established two autapomorphies, unique derived traits: the presence of chevrons at the tail base that were four times as long as the vertebral centra; and the possession at the tail base vertebrae of front joint processes, prezygapophyses, the inner bases of which formed a bowl-shaped depression that extended upwards into a deep trough on the front surface of the spine.
On the vertebral column, from at least the middle of the back to over the middle of the tail, a tall crest of almost continuous height was present formed by spines that were about four times as high as the vertebral centra.
"Magnapaulia" is among the many hadrosaurids that have preserved skin impressions; the tail of specimen LACM 17712 had large scales up to four centimeters wide that were surrounded by one centimeter-wide hexagonal and rounded scales.
Phylogeny.
In 2012 "Magnapaulia" was assigned to the Lambeosaurinae. The 2012 study contained a cladistic analysis which found it to be closest to "Velafrons", also from Mexico, with this sister species forming a separate southern clade, itself the sister group of a clade of more northern Asian and North-American forms, including "Lambeosaurus", "Corythosaurus", "Hypacrosaurus" and "Olorotitan". The cladogram below follows this analysis.


Pietschellus

Pietschellus is an extinct genus of enigmatic bony fish which existed in northern Italy during the early Eocene epoch (Ypresian age). It is known from a single well-preserved nearly complete specimen recovered from the Monte Postale site of the Monte Bolca locality. It was first named by Alexandre F. Bannikov and Giorgio Carnevale in 2011 and the type species is "Pietschellus aenigmaticus".


Coal in Ukraine

Coal mining is an important industry in Ukraine.
Coal mining in Ukraine is often associated with coal-rich Donets basin. However this is not the only coal mining region, other being Lviv-Volhynian basin and Dnieper brown coal mining basin. The Donets basin located in the eastern Ukraine is the most developed and much bigger coal mining region in the country.
Ukraine was until recently, the third largest coal producer in Europe. In 1976, national production was 218 million metric tonnes. By 2016, production had dropped to 41 million metric tonnes. The Donets Black Coal Basin in the eastern Ukraine, with 90% of the nation's reserves, suffers from three connected problems: (1) mines are not profitable enough to sustain capital investment, resulting in twenty-year old mining equipment and processes, (2) the government, taking advice from the International Monetary Fund, has discontinued $600 million annual mining subsidies, and (3) the Ukrainian government refuses to buy from mines controlled by the self-proclaimed Donetsk People's Republic and Luhansk People's Republic.
History.
Coal mining began in Ukraine in 1870. In 1913, Donetz produced 87% of the coal in the Russian Empire. It produced 50% of the metallurgical coal of the USSR. Like other Soviet enterprises, coal companies provided social facilities including schools and hospitals
Coal reserves.
Ukraine's coal reserves are estimated at 60 billion tonnes, of which 23 billion are proven and probable, and 10 billion tonnes are economically extractable. According to the Ukrainian mining trade union, coal constitutes 95% of Ukraine's domestic energy resources.
Ninety percent of Ukraine's coal reserves are located in the Donets Coalfield (easternmost part of the country). Control of this portion of the country is disputed. Russian-backed rebels claim sovereignty over the region. Mid-March 2017 Ukrainian President Petro Poroshenko signed a decree on a temporary ban on the movement of goods to and from territory controlled by the self-proclaimed Donetsk People's Republic and Luhansk People's Republic meaning that since then Ukraine does not buy coal from the Donets Black Coal Basin.
Two other coalfields include one in the northwest, the Lviv-Volhynian Coalfield, between Lviv and Volodymyr-Volynskyi. Another, the Dnieper Coalfield in central Ukraine, offers lignite (brown coal), but the mining of lignite stalled in the 1990s.
Coal mining.
"n.b.: 2014, 2015, and 2016 do not include extraction in the territory occupied by the separatists."
Coal mining is one of the largest employers in Ukraine. The country's coal industry employs about 500,000 people.
In July 2014, several mines were closed in Eastern Ukraine because of fighting during the 2014 pro-Russian conflict in Ukraine. Because of this War in Donbass (according to the Ukrainian Energy and Coal Industry Ministry) raw coal production in Ukraine dropped by 22.4% from 2013, to 64.976 million tonnes. As a result, Ukraine begun importing power-generating coal from South Africa and Russia. Lack of coal for Ukraine's coal-fired power stations and a shut down of one of the six reactors of the Zaporizhzhia Nuclear Power Plant lead to rolling blackouts throughout the country from early till late December 2014.
Consumption, import and export.
Coal consumption in 2012 grew to 61.207 million tonnes, up 6.2% compared with 2011. Most is used for public utilities and for power generation. However local coal only provides 50% of the country’s electricity needs, therefore requiring Ukraine to import from Russia and Poland.
As of 2013, the Ukrainian government plans to completely replace the natural gas used in the steel industry and some other economic sectors with coal.
Coal powered 38% of Ukrainian electrical generation in 2014. The relative cost of domestic coal versus imported coal, nuclear and gas, made it unworkable. In 2016, the nation imported 15.648 million tonnes of coal and anthracite worth of $1.467 billion. In the year before the current Ukrainian crisis, 2013, Ukraine exported 500 thousand tonnes and imported 25 million tonnes. In 2016, Ukraine exported 520,585 tonnes of coal and anthracite worth of $44.762 million.
In June 2020, the Government of Ukraine prioritized the usage of coal at Ukrainian power stations to reduce the import of natural gas used at the power stations for electricity production.
Mine safety.
Mine safety is the result of geology and human factors. The geology of Ukrainian coal mines is not favorable: seam thickness is small, seams are deep, and methane is common. The coal mines of Donbas are one of the most hazardous in the world due to enormous working depths (down from 300 to 1200 m) as a result of natural depletion, as well as due to high levels of methane explosion, coal dust explosion and rock burst dangers. As the "Economic Review" points out, "Since 1991, up to 300 [miners] have died at work every year".
Low profitability of Ukrainian mines has not attracted capital investment. As a result, the machinery and the processes used to dig coal are twenty years old. These methods are less safe on a per-miner basis and require more miners.
The Zasyadko Mine stands as an example of Donbass mine safety. It was opened in 1958 and privatized in 1992, since which time it has had seven major accidents, including the 2007 Zasyadko mine disaster (101 workers killed) and the 2015 Zasyadko mine disaster (17 killed).
Corruption and illegal mining.
Ukrainian mines are sometimes run by mafia-like organizations. Often, these organizations derive large incomes from the mines that belong to the government. As a result, underfinancing causes many employees to have to wait to receive their monthly salary for weeks or even months. Additionally, a lack of financing influences the condition of many coal mines. Old mines don’t receive the necessary financial aid, therefore they are not being renovated or remodeled annually. All these problems together with other challenges have resulted in "gradually declining production capacity and a loss of global market share".
In the Donets Basin there are many extremely dangerous illegal mines.


Franz Toula

Franz Toula (20 December 1845 in Vienna – 3 January 1920 in Vienna) was an Austrian geologist, mineralogist and paleontologist.
Beginning in 1863 he studied at the Polytechnic Institute in Vienna (later on, known as "Technische Hochschule Wien"), where he was a pupil and assistant to Ferdinand von Hochstetter. Later on, he worked for several years as a gymnasium instructor in Vienna. In 1880 he became an associate professor at the "Technische Hochschule", where from 1884 to 1917 he served as a full professor of mineralogy and geology. In 1893/94 he served as academic rector. He was co-founder of the "Naturwissenschaftlichen Orientverein".
From the 1870s onward, he performed geological investigations in the Balkans, about which, he was the author of numerous publications. Later on, he expanded his research to include the Ottoman Empire and Crimea. He also conducted significant stratigraphic-paleontological studies in the vicinity of Vienna.


Batrachomimus

Batrachomimus is an extinct genus of neosuchian crocodyliform known from the Late Jurassic Pastos Bons Formation of northeastern Brazil. It contains a single species, Batrachomimus pastosbonensis, with the specific name referring to the formation, which was first described and named by Felipe C. Montefeltro, Hans C. E. Larsson, Marco A. G. de França and Max C. Langer in 2013. It is known from a nearly complete skull, osteoderms and limb bones. "Batrachomimus" belongs to the family Paralligatoridae and predates all other members of the family and its immediate sister group, Eusuchia, by 30 million years.
Description.
"Batrachomimus" is known from a single holotype skull known as LPRP/USP-0617, which preserves most of the skull and lower jaws except for the skull table, braincase, and the left temporal region. The skull is about , giving an estimated total body length of about . "Batrachomimus" has a narrow snout with wavy margins around the teeth. It is unique in having a smooth area of bone on the maxilla, near the back of the snout; most crocodyliforms have heavy pitting covering the entire upper surface of the skull, including all of the maxilla. Another unique feature or autapomorphy of "Batrachomimus" is the hourglass-shape of its choanae, which are two holes on the underside of the skull that are openings for the nasal passages. Other distinguishing features of "Batrachomimus" are its lack of antorbital and mandibular fenestrae (holes in front of the eyes and at the back of the lower jaw, respectively), and a backward extension of the premaxilla bone on the snout to the level of the fifth tooth of the maxilla bone behind it.
Etymology.
The genus name "Batrachomimus" means "batrachian mimic" in Greek, a reference to the holotype specimen originally being identified as that of a temnospondyl, a type of prehistoric amphibian that vaguely resembles modern batrachians (frogs and toads). In addition to being considered a temnospondyl, the holotype was thought to have come from the Pedra de Fogo Formation, which dates back to the Permian, a time when temnospondyls were the dominant form of large semi-aquatic animals. The genus name also alludes to crocodyliforms replacing temnospondyls as semi-aquatic predators during the Jurassic.
Phylogeny.
The phylogenetic analysis of Montefeltro "et al." (2013) placed "Batrachomimus" as the most basal member of the group Paralligatoridae, which also includes the genera "Shamosuchus" and "Rugosuchus" from the Cretaceous of Asia. Below is a cladogram showing the results of the analysis:


Hyperokynodon

Hyperokynodon is an extinct genus of trematosaurian temnospondyl within the family Trematosauridae. Fossils have been found in Germany. While most trematosaurids existed during the Early Triassic, "Hyperokynodon" has been found in Late Triassic deposits, making it the youngest known trematosaurid. "Hyperokyodon" was known since 1852, but it was not identified as a trematosaurid until 1987. The type and only species is "H. keuperinus".
Description.
"Hyperokynodon" is known only from two specimens: a holotype snout and a cast of the underside of the skull roof. The holotype was found in Heilbronn, Germany, in the mid-1800s. It likely came from deposits in the Wartberg, a mountain that had several active quarries at the time. The cast, known as SMNS 55910, was found in a sandstone quarry east of the city of Heilbronn. SMNS 55910 is an impression of the underside of the skull table and includes parts of the palate and the edge of the orbit.
Based on the cast, the total skull length is estimated to have been around . The total body length based on related trematosaurs is estimated to have been to . Like other trematosaurids, "Hyperokynodon" has a narrow skull. The back portion, however, is unusually narrow, approaching that of "Cosgriffius", a lonchorhynchine trematosaurid with a very narrow skull. The snout is moderately elongated with a wide tip. The anterior palatal openings, two holes at the front of the palate, are widely spaced. The vomerine and palatal fangs, two sets of teeth on the roof of the mouth, are very large and laterally compressed. "Hyperokynodon" shares several characteristics with the related "Tertrema", such as the absence of teeth between the choanae.
Classification.
The fragmentary nature of specimens belonging to "Hyperokynodon" has led to difficulty in classification. The genus was placed in the capitosaur family Mastodonsauroidea for many decades. In 1987, it was given a more specific classification as a tertremine trematosaurid.
German paleontologist Eberhard Fraas referred SMNS 55910 to the metoposaur "Metopias" in 1889. Schoch "et al." (2002) considered the cast to belong to "H. keuperinus" because it was the only other trematosaurid known from Heilbronn. Schoch "et al." also raised the possibility that it was a lonchorhynchine, which would imply that both the lonchorhynchine and tertremine lineages survived into the Late Triassic. Schoch "et al." considered the cast to belong to a tertremine, however, because of its large size and distinctive features.


Courtessolium

Courtessolium is a genus of trilobites in the order Phacopida that existed during the lower Ordovician in what is now France. It was described by Pribyl and Vanek in 1985, and the type species is "Courtessolium prepater", which was originally described under the genus "Pateraspis" by Courtessole and Pillet in 1975, and was later renamed under the genus "Pseudosphaerexochus". The new generic name, "Courtessolium", honours one of the original authors of the species.
It was described from the Tremadoc erratic in Hérault.


Erythrotherium

Erythrotherium is an extinct genus of basal mammaliaforms from the Late Triassic to Lower Jurassic. It is related to "Morganucodon". Only one species is recorded, "Erythrotherium parringtoni", from Red Beds, Stormberg Group, Mafeteng, Upper Elliot and Clarens Formations, from Lesotho and South Africa.
The single jaw of "Erythrotherium" was found in the matrix surrounding a dinosaur fossil, by the person preparing the dinosaur, Mr C. Gow.


Teraterpeton

Teraterpeton (meaning "wonderful creeping thing" in Greek) is an extinct genus of trilophosaurid archosauromorphs. It is known from a partial skeleton from the Late Triassic Wolfville Formation of Nova Scotia, described in 2003. It has many unique features seen in no other related form, including an elongated, toothless snout and large openings for the nostrils. Because of this, "Teraterpeton" was originally placed in its own family, Teraterpetidae, related to "Trilophosaurus". Newer studies generally place it within Trilophosauridae.
Description.
Skull.
"Teraterpeton" had an unusual appearance compared to other early archosauromorphs. Members of the genus had a long skull with no teeth at the ends of the upper and lower jaws. Over each eye socket is a bony projection formed by the lacrimal and prefrontal bones. At the back of the jaws are a set of small, sharp, closely spaced teeth. They continue below the level of the eye, an unusual trait among early archosauromorphs. The upper tooth row does not run along the edge of the jaw, but is inset closer to mouth. An additional tooth row on the palate runs alongside the maxillary tooth row of the upper jaw. The teeth of the upper jaws fit closely, or occlude, with the teeth of the lower jaw. The upper jaw teeth have sharp cusps with indentations in front of them, while the lower jaw teeth have cusps with indentations behind them. The cusps of the upper teeth fit into the indentations of the lower teeth, while the cusps of the lower teeth fit into the indentations of the upper teeth.
"Teraterpeton" has an uncommon feature compared to most archosauromorphs: a euryapsid-type skull. Euryapsids have a single hole at the back of the skull called the supratemporal fenestra, which is located toward the top of the head. "Teraterpeton" evolved from diapsid reptiles with two holes at the back of their skull, the supratemporal fenestra and an infratemporal fenestra below it. Although it lacks an infratemporal fenestra, "Teraterpeton" still belongs to Diapsida because it is a descendant of true diapsids. Most other euryapsids such as the marine plesiosaurs and ichthyosaurs are not closely related to "Teraterpeton". However, the euryapsid archosauromorph "Trilophosaurus" has been identified as a close relative.
Another unusual feature of "Teraterpeton" is the large size of its narial fenestra, a hole in the skull that serves as the opening for the nostril. This hole is positioned directly in front of the eyes and extends to the level of the toothless portion of the snout. It is positioned where the antorbital fenestra would normally be. In fact, Hans-Dieter Sues, the original describer of "Teraterpeton," first considered the hole to be an antorbital fenestra before revising his hypothesis. The narial fenestra of "Teraterpeton" is approximately 1.5 times longer than the eye socket.
Postcranial skeleton.
A string of eight cervical (neck) vertebrae are preserved in the holotype. They have large neural spines, and the second to fourth vertebrae have additional blade-like structures directly behind the neural spines. Overall, the neck is similar to that of the early rhynchosaur "Mesosuchus". The cervical ribs are completely fused to the large rib facets of the vertebrae. Isolated dorsal (back), sacral (hip), and caudal (tail) vertebrae are also preserved. Caudal vertebrae from a referred specimen had very long transverse processes (column-like rib facets). The scapula (shoulder blade) is long and narrow. The unguals (claws) of both the hands and feet are deep and blade-like, a morphology described as "trenchant".
The preacetabular process (i.e. the front blade of the ilium bone of the hip) was large, thin and had a convex upper edge. This is in contrast to the small, bump-like preacetabular process of "Trilophosaurus", and more similar to that of advanced rhynchosaurs like "Hyperodapedon". The pubis and ischium bones of the hip were vertically oriented and separated by a tall, rectangular gap likely homologous with the thyroid fenestra of lepidosauromorphs and tanystropheids, rather than the lack of separation present in other early archosauromorphs. Also like tanystropheids, the fifth metatarsal of the foot was thick, short, and straight.
The simple femur and compact hip supports the interpretation that "Teraterpeton" had a sprawling gait. However, the modified and expanded ilium suggests that "Teraterpeton"'s hindlimb musculature (as well as that of rhynchosaurs) was well-adapted for protracting and retracting during more erect forms of locomotion. Some paleontologists have argued that expanded leg musculature in rhynchosaurs was an adaptation for scratch-digging rather than an upright posture. While this may apply to thick-legged rhynchosaurs, digging was less likely for "Teraterpeton", which had rather slender hindlimbs by comparison.
History.
"Teraterpeton" is primarily known from a single partial holotype skeleton referred to as NSM 999GF041. This skeleton was found in a sea cliff in Burntcoat Head, Nova Scotia. The deposit from which it was found is part of the late Carnian Wolfville Formation, comprising a section of the larger Newark Supergroup that stretches across Canada and the eastern United States. The formation is located in the Fundy Basin, a rift basin which, like other Newark basins, opened as Pangaea began to break apart at the end of the Triassic. The Wolfville Formation contains a diverse assemblage of Triassic tetrapods that includes temnospondyl amphibians, procolophonid reptiles, and traversodont cynodonts. Based on the presence of the temnospondyl "Koskinonodon" (a common Triassic index fossil), the assemblage is dated to the Carnian stage of the Late Triassic.
The type species of "Teraterpeton", "T. hrynewichorum", was named in 2003. It is named after George P. Hrynewich and his son Sandy Hrynewich, fossil collectors who discovered the bones at Burntcoat Head in 1999.
Postcranial remains from a referred specimen, NSM 018GF010.002, as well as an isolated cervical vertebra (NSM 018GF010.001) were described by Pritchard & Sues in 2019.
Classification.
A phylogenetic analysis was provided in the original description of "Teraterpeton" in 2003. It placed "Trilophosaurus" as the closest relative of the genus. Together, these two forms comprise an archosauromorph clade that is more derived than protorosaurians and more basal than rhynchosaurs. Below is a cladogram modified from the 2003 analysis:


Holoptychius

Holoptychius is an extinct genus of porolepiform lobe-finned fish from the Middle Devonian to Carboniferous (Mississippian) periods. It is known from fossils worldwide. The genus was first described by Louis Agassiz in 1839.
Description.
"Holoptychius" was streamlined predator about long (though largest specimen could grew up to ), which fed on other bony fish. Its rounded scales and body form indicate that it could have swum quickly through the water to catch prey. Similar to other rhipidistians, it had fang-like teeth on its palate in addition to smaller teeth on the jaws. Its asymmetrical tail sported a caudal fin on its lower end. To compensate for the downward push caused by this fin placement, the pectoral fins of "Holoptychius" were placed high on the body.
Species.
Of the genus "Holoptychius" the following species have been described:
Distribution.
Fossils of "Holoptychius" have been found in the Mississippian of the United Kingdom and the Devonian of Belgium, Colombia (Cuche Formation, Boyacá), Norway, the Russian Federation, and the United States (Pennsylvania).


Ornithomerus

Ornithomerus is a genus of iguanodont dinosaurs from the Late Cretaceous.
Discovery and species.
In 1859 coal mine administrator Pawlowitsch notified the University of Vienna that some fossils had been found in the "Gute Hoffnung" mine at Muthmannsdorf in Austria. A team headed by geologists Eduard Suess and Ferdinand Stoliczka subsequently uncovered numerous bones of several species, among them those of a euornithopod dinosaur. Stored at the university museum, the finds remained undescribed until they were studied by Emanuel Bunzel from 1870 onwards. Bunzel in 1871 referred PIUW 2349/3 (identified by him as a thoracal rib) to "Lacerta" sp. In 1881 Harry Govier Seeley recognized PIUW 2349/3 as a femur belonging to Dinosauria and erected the new genus and species "Ornithomerus gracilis" for it. The generic name is derived from Greek "ornithos", "bird", and "meros", "shin". Norman and Weishampel (1990) and Norman (2004) listed "Ornithomerus", along with "Oligosaurus" and "Mochlodon", as a synonym of "Rhabdodon". However, Sachs and Hornung (2006) assigned "Ornithomerus" to "Zalmoxes" sp. along with the "Mochlodon suessi" holotype.
The type specimen PIUW 2349/3 was found in the Grünbach Formation of the Gosau Group dating from the Lower Campanian, about 80 million years old.


Janassa

Janassa is an extinct genus of petalodont cartilaginous fish that lived in marine environments in what is now central United States of America and Europe during the Carboniferous and upper Permian. It is known from teeth and a few poorly preserved body fossils from Germany (Kupferschiefer, Upper Permian) and England (Marl Slate, Upper Permian). According to the fossils, "Janassa" had a body plan very similar to that of the modern skate. Its teeth suggest it crushed and ate shellfish, such as brachiopods.