recursal/Fanatic-Fandom huggingface dataset:
Archaeothyris

Archaeothyris is an ophiacodontid pelycosaur synapsid from the Pennsylvanian of Canada, Czech Republic, and the United States of America. It was named in 1972 by Robert R. Reisz. It was one of the oldest synapsids, and despite being primitive, it was more advanced than early sauropsids.

## Physiology

Archaeothyris resembled the generic monitor lizard. It was a reptile with 4 legs, a long tail, a broad body, and a long head with mid-sized jaws. It body would have been covered in scaly skin.

## Diet

Archaeothyris was a predator, preying on insects and other arthropods. Its jaws had small and sharp teeth designed for catching arthropod prey, as well as for crushing them.

## Ecology

Not much is known about Archaeothyris, although it can be inferred that it lived very similarly to modern lizards, quickly scampering across through the swampy terrain and eating arthropods whenever it was hungry, as well as climbing up trees and hiding in fallen logs in order to escape hungry predators.
Atopodentatus

Atopodentatus is a reptile from the Middle Triassic of China. It was named in 2014 by L. Cheng and his crew. It was one of the earliest herbivorous marine reptiles to exist, and was once thought to have a strange, zipper-like upper jaw, right before they discovered that its skull was crushed.

## Physiology

Atopodentatus was a reptile with a slender body, short legs, a long tail, and a mid-sized head with wide, hammer-shaped jaws. Its body would have been covered in scaly skin.

## Diet

Atopodentatus was an herbivore, feeding on algae. Its small teeth were shaped like chisels, and were used to scrape plant matter off the rocky seafloor.

## Ecology

When Atopodentatus was first discovered, people had thought it to have had a unique, zipper-like upper jaw, hence the meaning of its name, "strange toothed". Due to this, they had assumed that it was a sediment feeder, using its jaw to grab a large pile of sediment and filter all the silt and mud out, trapping any small invertebrates in its jaws. 2 years later, however, a new fossil discovery had shown that the reptile had a wide, hammer-shaped jaw, and that the original skull was badly crushed. Adding onto the fact that its teeth were so differently shaped from what everyone thought them out to be, it is now reconstructed as an aquatic herbivore, using its jaws to scrape algae off the seafloor.
Tanystropheus

Tanystropheus is a tanystropheid protorosaurian reptile from the Middle-Late Triassic of Italy, Switzerland, Germany, Israel, and China. It was named in 1852 by Christian Erich Hermann von Meyer. It was a unique protorosaur, as it had the longest neck length of any organism in the animal kingdom.

## Physiology

Tanystropheus was a reptile with a slender body, short legs, a long tail, and a small head with a mouth filled with sharp, interlocking teeth. Perhaps the most defining trait of Tanystropheus was its absurdly long neck, which accounted for about 50% of its body length. Its body would have been covered in scaly skin.

## Diet

Tanystropheus was a carnivore, preying on fish and cephalopods. Its sharp teeth were used to get a hold of slippery fish, and its long neck would have helped it reach deep down into the water to catch passing prey.

## Ecology

Tanystropheus was once thought to be an entirely aquatic reptile, leading a lifestyle similar to that of most plesiosaurs; this was presumed due to the notion that its neck would have made it too front-heavy to effectively walk on land. However, recent studies have shown that even though the neck was long, it only accounted for 20% of its body mass; as well as this, its legs were poorly equipped for living in the water. However, its teeth were very similar to that of many fish-eating reptiles; as a result, we can infer that it hunted very similarly to a heron, stalking prey that got too close to the shore before snatching them with its jaws and gobbling them up. As well as this, it would have stayed near tidal pools, constantly checking for new populations of prey before hunting.

## In popular culture

Tanystropheus was featured in the 1st episode of the 2003 documentary *Chased by Sea Monsters*, where it is depicted as a fully aquatic reptile. As well as this, it is depicted as shedding its tail in order to escape predators such as Cymbospondylus; again, this is wishful thinking, as protorosaurs were outside of the phylogenetic bracket for tail-shedding (it was restricted to lizards).
Eudimorphodon

Eudimorphodon is a eudimorphodontid pterosaurian reptile from the Late Triassic of Italy. It was named in 1973 by Rocco Zambelli. It was another early pterosaur, and even had another defining trait that would carry on in pterosaur evolution for a long time.

## Physiology

Eudimorphodon had a build true to its primitive origins, with 4 legs (2 of which served as wings), 4 fingers on each hand (one of which was elongated and supported the wing membrane), a small body, a long tail with a diamond-shaped vane on its end, and a long, conical head with large jaws. Most of its body (excluding its snout, wings, and vane) would have been covered in a fur-like covering called pycnofibers.

## Diet

Eudimorphodon was a predator, preying on fish and small arthropods. Its jaws had 2 types of small, conical teeth, all of which were used for getting a hold of and making short work of struggling prey.

## Ecology

Unlike its arboreal, land-hunting counterpart, Peteinosaurus, Eudimorphodon was an aerial hunter that hunted closer to the water. In order to catch fish, it would fly close to the surface of a large body of water before plucking a fish out of the water with its multi-toothed jaws. Many of its teeth had two points, which were perfect for snatching fish; as well as this, wear marks on its teeth meant that the eudimorphodontid was able to crush or chew its aquatic prey. These conditions also allowed for it to prey on hard-shelled arthropods.
Utahraptor

Utahraptor is a dromaeosaurid theropod dinosaur from the Early Cretaceous of the United States of America. It was named in 1993 by James Kirkland, Robert Gaston, and Donald L. Burge. It was the biggest dromaeosaurid to ever exist, as well as one of the most unique.

## Physiology

Utahraptor was a heavily-built dromaeosaur, with a bulky body, semi-short, stocky legs with a sickle-shaped claw on each foot, moderately long arms with 3 fingers on each hand, a short neck, and a large head with a mouth filled with lots of teeth. In comparison to other dromaeosaurs (such as Velociraptor and Deinonychus), which were lightly-built, Utahraptor was extremely robust to the point where it had a passing resemblance to larger theropods such as Tyrannosaurus and Giganotosaurus. Most of its body (excluding some of its legs, all of its snout, and possibly all of its head and neck) would have been covered in long, vaned feathers.

## Diet

Utahraptor was a predator, preying on mid-sized ornithischians, mid-sized sauropods, and smaller theropods. Its teeth had knife-like serrations from back to back, and its sickle claw was used for stabbing larger prey and restraining smaller prey.

## Ecology

Unlike the other raptors, which were very lightly-built (and in some cases, fleet-footed), Utahraptor was a large, hulking juggernaut; its stocky legs and heavy build probably impeded its movement, but also allowed it to withstand and dish out a lot of force on its prey items, as well as to drive its killing claw deeper into the skin of its prey items. Due to this extreme girth, Utahraptor was possibly able to hunt more powerful game, such as armored ankylosaurs like Gastonia or even larger herbivores such as Iguanacolossus and juvenile Cedarosaurus. A massive block of sandstone containing many Utahraptor suspended around a Hippodraco was once discovered, and most likely represented a quicksand trap where all the dinosaurs died; due to having so many Utahraptor individuals, this block of sandstone may lead people to believe that Utahraptor definitely hunted in packs. However, while pack-hunting is suitable for any theropod, it is possible that the raptors were simply led to the drowning Hippodraco before getting caught in the trap, and were independent of each other's influences.

## In popular culture

Utahraptor was first introduced to the public through the 4th episode of the 1999 documentary *Walking with Dinosaurs*, where it is depicted with scaly skin and a similar build to Deinonychus (based on outdated research); while this was somewhat acceptable at the time, it was depicted as living in what is now England (as opposed to what is now its namesake home state, Utah) and hunting down Iguanodon in small packs. This was another blatant error, similar to the 25 meter, 150-tonne Liopleurodon and the extremely fanciful head restorations of all the large theropods.
Placodus

Placodus is a placodontid placodontian reptile from the Middle-Late Triassic of Germany, France, Poland, and China. It was named in 1833 by Louis Agassiz. It was a unique reptile, as unlike the other reptiles of its time (which caught fish with their sharp), it crushed mollusks with flat teeth.

## Physiology

Placodus resembled a marine iguana, with a broad body, short legs, a long tail, and a small head with small jaws. However, it had a few major differences; for example, instead of having sharp teeth all over its jaws, it had laterally compressed incisors at the front of its jaws, while flattened teeth were present at the back of its jaws. Its body was covered in scaly skin, with a row of crocodile-like scutes running down its back.

## Diet

Placodus was a predator, preying on bivalves. At the front of its jaws, it had chisel-like incisors designed for picking bivalves off the seafloor, while at the back of its jaws (and the roof of its mouth), it had flattened teeth designed for crushing them.

## Ecology

Due to its dense bones and heavy armor, Placodus could sink without trying to keep a light, air-filled body, and so, it would have had no problem staying near the seafloor to feed. As well as this, when swimming, it moved its tail from left to right, while its legs were used to steer itself by pushing against the water; however, this method of swimming meant that it could not venture out into the open ocean, and only stayed near the seashore. As well as this, its short legs did allow it to clamber onto land; however, due to the fact that they weren't really strong, it had to drag itself across the ground in a similar manner to turtles. While feeding, Placodus used its legs to float in the water while picking shellfish off the seafloor; as well as this, a parietal eye would have helped the reptile orient itself correctly when it needed to return to the surface, which would be especially useful when floating face down near the seafloor.
Gallimimus

Gallimimus is an ornithomimid theropod dinosaur from the Late Cretaceous of Mongolia. It was named in 1972 by Halszka Osmólska. It was the largest ornithomimid discovered, and it had a unique lifestyle that may have differed from other ornithomimids.

## Physiology

Gallimimus was an ostrich-like theropod with long legs, a long tail, long, slender arms, a moderately long neck, and an elongated, bird-like head with large eyes and a toothless beak. As well as this, it was unique in the sense that the interior portion of its beak had ridges, and that its hands were proportionally smaller than those of other ornithomimids. Most of its body (excluding most of its legs and all of its beak) would have been covered in short, fuzz-like feathers; however, its arms would have had long, vaned feathers, similar to all other advanced theropods.

## Diet

Gallimimus would have been an herbivore, feeding on leaves and fruits by grabbing them with its beak before swallowing them. However, some may speculate that it, like most herbivorous birds, would have also supplemented its diet with animal protein, snacking on insects, crustaceans, lizards, small mammals, and eggs from time to time.

## Ecology

Gallimimus' forearms were weaker and had shorter hands than those of other ornithomimids, which meant that it wouldn't have used its hands to pull down branches so it can freely eat from them; some scientists speculate that it may have used its hands to dig or rake the ground in order to get food instead. Due to a large bonebed containing many individuals, we can assume that Gallimimus lived in flocks; the fact that the animals died at the same time only solidifies this hypothesis, and such a social nature may be plausible for other ornithomimids. A fossil skull of this dinosaur had columnar ridges on the inner portion of its beak, which were said have been analogous to the filter-feeding lamellae (thin plate-like structures) of a dabbling duck known as the Northern shoveler; in addition to its swampy habitat, this could have meant that Gallimimus dabbled for food in the water, swinging its beak from side to side in order to strain food from the water. However, many turtles (some of which are herbivores), as well as hadrosaurs such as Edmontosaurus also had these ridges, and are not known to dabble for food in the water, so it could be likely that Gallimimus simply fed on fibrous plants.

## In popular culture

Gallimimus was first introduced to the public in the 1993 science fiction movie, *Jurassic Park*, where it was portrayed with scaly skin, and it was shown stampeding down a hilly prairie in large flocks in order to evade predators such as Tyrannosaurus. This portrayal is part of what made the Jurassic Park dinosaurs seem so bird-like during a time when dinosaurs would no longer be perceived as slow, cold-blooded giants, and so, Gallimimus itself saw a massive boost in popularity, appearing in many other pieces of media about dinosaurs.
Arthropleura

### Location

United States of America, Canada, Germany, France, United Kingdom, Poland, Czech Republic, Kazakhstan

### Diet

??? (presumed omnivore)

Arthropleura is an arthropleurid arthropleurid millipede arthropod from the Mississippian-Cisuralian of the United States of America, Canada, Germany, France, the United Kingdom, Poland, Czech Republic, and Kazakhstan. It was named in 1853 by Christian Erich Hermann von Meyer. It was the biggest land arthropod of all time; however, it was beaten by the aquatic Jaekelopterus in terms of size.

## Physiology

Arthropleura resembled a large polydesmidan millipede. It was a myriapod with a elongated, flat body, broad plates protruding from the sides of each segment and running down its body, multiple pairs of walking legs, a moderately large head with short antennae and small eyes, and a semi-circular plate sitting atop its head. Its body would have been covered in a hard, chitinous exoskeleton.

## Diet

Arthropleura's diet remains unknown, although some may speculate that it was an omnivore, primarily feeding on ferns, but also preying on reptiles and small amphibians.

## Ecology

Arthropleura grew to large sizes due to a lack of terrestrial predators to prey on it, as well as a lack of competition from other giant herbivores. A parallel trackway indicates that it was able to quickly crawl across the forest floor, avoiding any trees and rocks in the way. For a while, it has been suspected that Arthropleura was an herbivore, as ferns were seemingly found in its guts; however, those ferns were discovered to have been accidentally fossilized together with the millipede, leaving some questions about whether it was a carnivore, an herbivore, or an omnivore. Either way, it would have lived by rivers and streams, as both ferns and amphibians were plentiful there.

## In popular culture

Arthropleura was first introduced to the public in the 2nd episode of the 2005 documentary *Walking with Monsters*, where it is depicted as a territorial herbivore with an ability to rear up like a cobra and an extreme vulnerability to attack from predatory amphibians. Since then, it has made appearances in major pieces of media such as *Prehistoric Park* (where it is shown as being capable of rearing up once again, as well spraying cyanide onto attackers in a similar manner to modern millipedes), *Primeval* (where it is depicted as a hyperaggressive, centipede-like animal armed with a venomous bite), and *First Life*.
Edestus

Edestus is an edestid eugenodontid cartilaginous fish from the Pennsylvanian of the United States of America, the United Kingdom, and Russia. It was named in 1855 by Joseph Leidy. It was a very strange eugenodontid notable for its shear-like jaws, and is often times confused for being a shark (despite being in a separate subclass).

## Physiology

Edestus resembled a shark, with a torpedo-shaped body, triangular pectoral and dorsal fins, a crescent-shaped caudal fin, and a mid-sized head with big jaws. However, it had one major defining characteristic: its curved jaws had only one linear row of teeth, which gave them the appearance of a pair of pinking shears. Its body would have been covered in scaly skin.

## Diet

Edestus was a predator, preying on smaller fish. Its shear-like jaws had serrated teeth designed for cutting prey, as well as for ripping them apart.

## Ecology

Edestus's hunting method remains open to debate. Some speculate that it had just swam up to fish and cut them in half with its jaws, while others say that it swam at high speed to slam into them, much like a serrated battering ram. More recent studies seem to have shown that it probably used neither method, opening its jaws and thrashing them up and down to slash its prey into pieces instead. As well as this, unlike modern sharks, it did not shed worn teeth; rather, newer teeth grew in the back of its gums, eventually pushing the old teeth forward.
Hibbertopterus

### Location

United Kingdom, Belgium, United States of America, Ireland, Czech Republic, and South Africa

### Physical Dimensions

1.8 meters long for *H.scouleri*
80 centimeters long for *H.stevensoni*
1.4 meters long for *H.wittebergensis*

### Diet

Carnivore

Hibbertopterus is a hibbertopterid eurypterid merostomate arthropod from the Middle Devonian-Mississippian of the United Kingdom, Belgium, the United States of America, Ireland, Czech Republic, and South Africa. It was officially named in 1959 by Erik Norman Kjellesvig-Waering. Alongside its semi-distant relative, Stylonurus, it was a unique eurypterid, as well as one of the largest, rivaling Pterygotus in size.

## Physiology

Hibbertopterus looked more like a horseshoe crab than the generic eurypterid. It had a large, rounded cephalothorax, mid-sized eyes, a pair of arms bearing blades, 3 pairs of walking legs, and a mid-sized tail ending in a spear-like telson. Its body would have been covered in a hard, chitinous exoskeleton.

## Diet

Hibbertopterus was a predator, feeding on small invertebrates by sifting through the seafloor and catching them with the blades on it arms. As well as this, it would sometimes settle for detritus suspended in the water.

## Ecology

Like Stylonurus, Hibbertopterus did not have a pair of paddles for swimming like older eurypterids did, relying on its legs for walking and its tail for swimming. Unlike most eurypterids, it only truly had 6 legs, and its tail was not that long compared to the tails of other eurypterids. In general, Hibbertopterus lived at the bottom of rivers, swamps, and freshwater lakes, ravaging carcasses and using its bladed arms to catch small invertebrates. A parallel trackway indicates that it was able to crawl out of the water and onto dry land, much like modern horseshoe crabs.
Polacanthus

Polacanthus is a nodosaurid ankylosaurian thyreophoran dinosaur from the Early Cretaceous of the United Kingdom. It was named in 1865 by Richard Owen. It was one of the first dinosaurs to be discovered, and it, much like most other early-discovered dinosaurs, remains incomplete and is modeled off its relatives.

## Physiology

Polacanthus was a broad, robust thyreophoran with 4 erect legs and an almost completely armored body. It had a wide skull with a small beak in front of its mouth, as well as large, thorn-like spikes running down its back. Most of its body would have been covered in scaly skin, with a large clump of osteoderms covering its lower back.

## Diet

Polacanthus was an herbivore, feeding on leaves. Its wide snout was used for browsing on plants low to the ground, and the many cheek teeth in the back of its mouth were used for processing plants.

## Ecology

So far, all we know about Polacanthus is that the many spikes running down its back were used for defense, as predators such as Eotyrannus and Neovenator would have had a hard time biting into spiky hide.

## In popular culture

Polacanthus was featured in the 4th episode of the 1999 documentary *Walking with Dinosaurs*, where it is shown migrating alongside a herd of Iguanodon. Unfortunately, the migration takes place in what is now the United States, while Polacanthus truly lived in England.
Placochelys

Placochelys is a placochelyid placodontian reptile from the Late Triassic of Hungary and Germany. It was named in 1902 by Otto Jaekel. It was another highly evolved placodont, as its feeding style was slightly different from that of Placodus.

## Physiology

Like its cousin, Henodus, Placochelys resembled a turtle, with a broad, shell-covered body, large flippers, a short tail, and a small head with small jaws. However, it had a few differences; its shell was differently shaped from those of living turtles, and its flippers still had claws on them. Its body was covered in scaly skin, and mostly covered by its hard shell.

## Diet

Placochelys was a predator, preying on bivalves. Instead of having normally shaped jaws with chisel-like incisors on the front of them, it had a small beak used for picking bivalves off the seafloor; however, it still had flat back teeth designed for crushing them.

## Ecology

Placochelys was one of the most turtle-like placodonts to swim the Triassic oceans, as it had a large shell for protection as well as long flippers for swimming. However, its flippers weren't fully evolved, and still had claws on them; this tells us that it would have spent a reasonable amount of time on land. As well as this, its feeding style was slightly different from that of Placodus; instead of picking shellfish from the seafloor with chisel-like incisors, it picked them up with a small, turtle-like beak before passing them into the mouth. However, it did still crush them with its flat back teeth.

## In popular culture

Placochelys was featured in the *Rite of Spring* segment of the 1940 Disney musical movie, *Fantasia*. There, it is depicted as having a build somewhat similar to that of a tortoise; as well as this, it clambers out of the water to view a bloody fight between a Stegosaurus and a Tyrannosaurus.
Psittacosaurus

Life-size reconstruction of Psittacosaurus lujiatunensis (credits to Robert Nicholls)

## Other Attributes

### Diet

Herbivore

Psittacosaurus is a psittacosaurid ceratopsian marginocephalian dinosaur from the Early Cretaceous of Mongolia, Russia, and China. It was named in 1923 by Henry Fairfield Osborn. It is perhaps the most species-rich dinosaur genus in science; as well as this, it is one of the most extensively-studied ceratopsians, even being studied to the point where we know its color.

## Physiology

Psittacosaurus was a bipedal marginocephalian with a barrel-shaped body, moderately long legs with a flap of skin stretching from the creature's ankles to the base of its thick, moderately long tail, moderately long arms. Perhaps the most defining trait of Psittacosaurus was its round head with large jugal (cheek) horns and a small, finch-like beak in the front of its mouth; how long or round the head was varied within every species. Its body would have been covered in scaly skin, with a row of quills running down the base of its tail; one species, *Psittacosaurus lujiatunensis*, would have been brown in color, with a tan underside, a black face, black specks on its shoulders, and a black cloaca (excretory and reproductive organ similar to the penis of a theriiform mammal).

## Diet

Psittacosaurus was an herbivore, feeding on nuts, seeds, and leaves. Its short, blunt beak was used to crack the shells of hard nuts, while the many teeth in the back of its mouth were used for shearing soft leaves.

## Ecology

Psittacosaurus was equipped with good olfactory senses, and its (likely) large eyes meant that it would have had acute vision; however, seeing as it was a small herbivore, these sharp senses may have evolved to help it avoid predators like Yutyrannus or Sinornithosaurus rather than to locate prey. Although there is no direct evidence for parental care in Psittacosaurus, its EQ (Encephalization Quotient, determines the possible intelligence or cognition of an animal) was shown to be a relatively high 0.31 (only slightly lower than the 0.36 of most birds, and marginally higher than the Tyrannosaurus's 0.30), and so, it is very likely that Psittacosaurus was able to build nests and care for its young; in terms of how different babies and adults were in their lifestyle, babies moved around on all fours (due to their long forelimbs), while adults were fully bipedal (due to how short their arms were, as well as their limited range of motion). As well as this, one species of Psittacosaurus, the aforementioned *P.lujiatunensis*, had intricate color patterns on its scales, and each distinct color brought a potential benefit for the animal; its darker-colored back and its lighter-colored underside is a great case of countershading (a method of camouflage that animals evolve in order to sneak up on prey or hide from predators more effectively), its black face may have been used for display, and the patch of black on its cloaca may have served an antimicrobial (preventing microorganisms from growing) function. A comparison of its sclerotic rings to those of modern reptiles and birds indicates that it was cathemeral.
Leaellynasaura

Leaellynasaura is a dinosaur from the Early Cretaceous of Australia. It was named in 1989 by Tom Rich and Patricia Vickers-Rich. It was one of the few dinosaurs reported to have lived in the cold climate of the South Pole, and thus may have had adaptations for surviving it.

## Physiology

Leaellynasaura was an ornithischian with a slender body, long legs, a long tail, semi-short arms, a small beak in front of its mouth, and large, eagle-like brows near the top of its eyes. Most of its body (excluding most of its legs and all of its beak) would have been covered in short, fuzz-like feathers.

## Diet

Leaellynasaura was an herbivore, feeding on plants low to the ground. Its big beak was used for shredding leaves, while the many cheek teeth in the back of its mouth were used for chewing on plants.

## Ecology

So far, all we know about Leaellynasaura is that its long legs allowed it to run at swift speeds, it relied on speed and agility to evade predators, and that, due to experiencing different lighting conditions from most other dinosaurs, it likely could have been either cathemeral or nocturnal.

## In popular culture

Leaellynasaura was featured in the 5th episode of the 1999 documentary *Walking with Dinosaurs*, where it is portrayed as living in small clans led by a single matriarch; this kind of social organization allows it to make the most out of scarce resources and also establish some lookouts for predators. As well as this, it is shown as being able to hibernate in small clusters during the winter, something that a small, active, warm-blooded dinosaur like Leaellynasaura might not have been able to do in real life.
Ichthyosaurus

Ichthyosaurus is an ichthyosaurid ichthyosaurian reptile from the Late Triassic-Early Jurassic of the United Kingdom, Germany, Belgium, and Switzerland. It was named in 1821 by Henry De la Beche and William Daniel Conybeare. It was the first marine reptile (nicknamed antediluvian reptile at the time) known to science, and, like any early-known Mesozoic animal, it was a wastebasket taxon.

## Physiology

Ichthyosaurus resembled a mix between a shark and a dolphin. It had a sleek, streamlined body, 4 flippers, a long tail with a shark-like fin on its end, a large fin on its back, and a conical head with large jaws. Its body would have been covered in scaly skin.

## Diet

Ichthyosaurus was a predator, preying on fish and cephalopods. Its teeth were small yet sharp, and were used to get a hold of slippery prey.

## Ecology

Like other advanced marine reptiles, Ichthyosaurus would have had a build that rendered it extremely adapted to life in the water (in this case, a streamlined, fish-like body and large fins), and so, it would have been unable to clamber onto dry land. Due to this, it gave birth to live young; Ichthyosaurus pups were delivered tail-first in order to eliminate any chances of drowning. Due to its large eyes (which were protected by bony shields), it was a visually-oriented predator; however, it also had solid ear bones, and so, it could have "heard" its prey through vibrations in the water. As well as this, its streamlined build and large tail fin allowed it to swim at swift speeds, much like sharks and dolphins today.

## In popular culture

Ichthyosaurs was the 1st Mesozoic animal discovered, so it was featured in Crystal Palace Park (a pleasure ground in London), alongside Iguanodon (depicted as a horned dragon), Megalosaurus (also depicted as a dragon), Pterodactylus, Plesiosaurus, and Mosasaurus (depicted as a giant, iguana-like squamate). Since then, it has been featured in major pieces of media such as the original *Journey to the Center of the Earth* novel (where it engaged in combat with a Plesiosaurus), *The Lost World* novel, and *Moschops*; it was even planned to be in *Jurassic World* before it got cut.
Leedsichthys

Leedsichthys is a pachycormid pachycormiform ray-finned bony fish from the Middle-Late Jurassic of the United Kingdom, Germany, Chile, and France. It was named in 1889 by Arthur Smith Woodward. It was the largest bony fish to exist, and was originally thought to be 25 meters long; however, scientists now agree that it was 9 meters shorter.

## Physiology

Leedsichthys' build was just as great as its size. It was a large fish with a bulky, torpedo-shaped body, thin, skinny fins, and a mid-sized head with large jaws. Its body would have been covered in scaly skin, with bony plates surrounding a region behind its head.

## Diet

Leedsichthys was a predator, preying on small invertebrates. Its large mouth would have been used to filter plankton from the water, while the large, broad teeth on its upper jaw were used to crush harder-bodied prey like small fish and mollusks.

## Ecology

Like the largest marine organisms to exist, Leedsichthys would have mainly been filter-feeder, using an array of gill rakers in its throat to filter zooplankton (small, planktonic animals) from the water; however, it also had a row of broad, sturdy teeth on its upper jaw, which was used for crunching down on fish, ammonites, and other hard-bodied animals. It would normally feed by making water pass through its gills by quickly swimming forward (causing small animals to flow into its mouth), but would sometimes actively pump water through its gills in order to achieve a similar purpose; due to the teeth on its upper jaw, it is likely that it did the latter to stir up movements in the seafloor and uncover previously buried bivalves, which it would then eat. A Leedsichthys bone with a Metriorhynchus tooth has been found, and was once thought to show that the metriorhynchid preyed on the pachycormid; however, the bone didn't heal, and so, it is now assumed that the marine crocodylomorph had scavenged the fish's carcass. Despite this, Leedsichthys wasn't entirely safe from predators when alive, as more advanced thalattosuchians like Dakosaurus would have been able to prey on mid-sized individuals, while pliosaurids like Liopleurodon and Pliosaurus would have been able to pose as a threat to larger ones.

## In popular culture

Leedsichthys was featured in the 3rd episode of the 2003 documentary *Chased by Sea Monsters*, where it is shown as a large fish that travels in small schools; as well as this, it was oversized to a length of 28 meters. Soon, a weak and dying individual is attacked by a Metriorhynchus and a Hybodus; after the two smaller animals leave, a Liopleurodon (also oversized) comes to eat the giant fish.
Paleogene

After the Mesozoic Era ended, the Paleogene period started. During this period, the Earth was still recovering from the devastating meteor strike that defined the Cretaceous extinction. The mammals, formerly small, nocturnal, rodent-like creatures, had started to diversify in order to fill the niches the dinosaurs left behind, while the birds also flourished in order to rule the skies after the pterosaurs' extinction; as well as this, this period is split into three major epochs, the Paleocene (early Paleogene), Eocene (mid-Paleogene), and Oligocene (late Paleogene). During the Paleocene, the mammals and birds had continued to remain small (only diversifying later in the epoch); the reptiles, however, had still managed to attain respectable sizes and a near-global distribution even after the end of their Cretaceous heydays. The Eocene was when the mammals had already diversified to take up many different niches, from hoofed herbivores that fed from low-growing vegetation and agile predators that preyed on everything they could find to arboreal primates that used their prehensile fingers and toes to move around from tree to tree; most important of them all were a large group of small, hoofed predators that had slowly returned to an aquatic lifestyle, and would soon evolve into the first whales. During the Oligocene, the climate had significantly cooled down from the hot temperatures of the Eocene; with the cooling temperatures came the decline of tropical forests and the rise of more open habitats such as deserts and scrublands, which caused a diversification and decline of various classes of animals. Soon, climate change and a continental drift would sweep this period, driving many species to extinction and giving rise to the Neogene.

**Lasted from 66-23.03 mya**

## Paleocene Animals (note that those are not all the ones that exist)

* Cerrejonisuchus
* Carbonemys
* Anthracosuchus
* Acherontisuchus
* Titanoboa

## Eocene Animals (note that those are not all the ones that exist)

* Gastornis
* Physogaleus
* Mongolonyx
* Leptictidium
* Titanomyrma
* Godinotia
* Andrewsarchus
* Ambulocetus
* Propalaeotherium
* Palaeotherium
* Anthropornis
* Hyaenodon
* Dorudon
* Basilosaurus
* Llanocetus
* Cynodictis
* Entelodon
* Mongolestes
* Embolotherium
* Moeritherium
* Anoplotherium
* Arsinoitherium
* Sarkastodon
* Otodus auriculatus
* Paraceratherium
* Palaeeudyptes

## Oligocene Animals (note that those are not all the ones that exist)

* Apidium
* Chalicotherium
* Pelagornis
* Quinkana
Moschops

Moschops is a tapinocephalid therapsid synapsid from the Guadalupian of South Africa. It was named in 1911 by Robert Broom. It is one of the most famous synapsids to exist, only being overshadowed by Dimetrodon.

## Physiology

Moschops was a dinocephalian with 4 erect legs, a short tail, a broad, bulky body, and a mid-sized head. Its most notable feature is the large, bony dome atop its forehead. Its body would have been covered in smooth skin.

## Diet

Moschops was an herbivore, feeding on tough vegetation. Its teeth were small and stout, and were used to process vegetation before the synapsid swallowed it.

## Ecology

Moschops had short, stout teeth and strong jaw muscles that allowed it to chew on tough, fibrous plants like cycads; however, due to the lack of nutrients in plants like these, it would have needed to eat for a long time. As well as this, its anatomy allowed it to open up its elbow joint, allowing it to walk with a more erect gait than most other tetrapods of the time; however, it would have been a slow runner, as its bulk would have impeded its movement. Some scientists even say that Moschops, along with all other dinocephalians, would have been semi-aquatic; to add onto this, its heavy head would have been useful for diving down in search of (possibly more nutritious) aquatic plants. However, the bony dome atop its head tells us that the dinocephalian also spent a reasonable amount of time on land; during mating season, rival males would have either butted heads like a goat or pushed heads like an ox.

## In popular culture

Due to books about dinosaurs and other ancient animals, Moschops has climbed to a great height among popular synapsids, only being overshadowed by the aforementioned Dimetrodon. The two big appearances it made were in the 1983 stop motion kid's show *Moschops* (where it is featured alongside Allosaurus, Diplodocus, Triceratops, Tyrannosaurus, and Ichthyosaurus) and the 1998 first person shooter game *Carnivores* (where it is featured as a skittish herbivore that flees at the smallest slight).
Reptile

The reptiles are the most evolutionarily important group of animals. They have limbs for walking, and they usually have dry, scaly skin, so they don't have to be in the water for most of the time. However, most of them (save for the dinosaurs, as well as the pterosaurs, plesiosaurs, and ichthyosaurs) have prevalent cold-blooded habits, and so, they must rest in the sun frequently. Having been descended from amphibians in the Carboniferous, the reptiles started out small, bested by the arthropods, fish, and amphibians. However, soon, they evolved into synapsids, which were animals that were very much akin to today's mammals. After the catastrophic mass extinction that culminated the Permian, they still continued their dominion of the Earth, and grew into many forms; some grew to large sizes, some returned to the oceans and became formidable predators, and some even grew membranous wings and took to the skies. As time would pass, the synapsids would evolve into mammals, while a few of the reptiles would evolve into a highly lauded group of animals: the dinosaurs.

## Reptiles Throughout Time (note that those are not all the ones that exist)

### Carboniferous Reptiles

* Hylonomus
* Petrolacosaurus

### Permian Reptiles

* Bradysaurus
* Pareiasaurus
* Scutosaurus

### Triassic Reptiles (excluding dinosaurs)

* Proterosuchus
* Atopodentatus
* Euparkeria
* Tanystropheus
* Placodus
* Batrachotomus
* Nothosaurus
* Cymbospondylus
* Henodus
* Shastasaurus
* Poposaurus
* Desmatosuchus
* Scleromochlus
* Saltopus
* Ornithosuchus
* Shuvosaurus
* Smilosuchus
* Placochelys
* Postosuchus
* Peteinosaurus
* Stagonolepis
* Drepanosaurus
* Psephoderma
* Eudimorphodon
* Ichthyosaurus

### Jurassic Reptiles (excluding dinosaurs)

* Plesiosaurus
* Temnodontosaurus
* Dimorphodon
* Steneosaurus
* Teleosaurus
* Cryptoclidus
* Liopleurodon
* Ophthalmosaurus
* Darwinopterus
* Kimmerosaurus
* Metriorhynchus
* Dakosaurus
* Scaphognathus
* Pliosaurus
* Harpactognathus
* Plesiosuchus
* Anurognathus
* Pterodactylus
* Rhamphorhynchus
* Aegirosaurus

### Cretaceous Reptiles (excluding dinosaurs)

* Leptocleidus
* Sarcosuchus
* Istiodactylus
* Tupandactylus
* Guidraco
* Kronosaurus
* Tapejara
* Tropeognathus
* Longirostria
* Kaprosuchus
* Dolichorhynchops
* Tylosaurus
* Pteranodon
* Nyctosaurus
* Styxosaurus
* Eonatator
* Prognathodon
* Protostega
* Elasmosaurus
* Mosasaurus
* Deinosuchus
* Archelon
* Quetzalcoatlus
* Hatzegopteryx

### Paleogene Reptiles

* Cerrejonisuchus
* Carbonemys
* Anthracosuchus
* Acherontisuchus
* Titanoboa
* Puppigerus
* Gigantophis
* Quinkana

### Neogene Reptiles

* Wonambi
* Gryposuchus
* Langstonia
* Purussaurus
* Mourasuchus
* Stupendemys
* Crocodylus thorbjarnarsoni
Thelodus

Thelodus is a coelolepid thelodontiform jawless fish from the Llandovery-Early Devonian of the United Kingdom, Canada, Estonia, Norway, Russia, Sweden, and Ukraine. It was named in 1839 by Louis Agassiz. It was one of the many jawless fishes to swim in the Silurian seas, as well as one of the more advanced ones.

## Physiology

Even though Thelodus had many generic jawless fish traits, such as a mobile tail, a large, oval-shaped body, and eyes positioned near the sides of its head, it was slightly more advanced as well. It had a larger tail fin, a dorsal (back) and anal (near the base of the tail) fin, tiny pectoral (arm) fins, and a forward-facing mouth (rather than one that faced downwards). Its body would have been covered in scaly skin.

## Diet

Thelodus was a planktivore, sucking up colonies of plankton drifting through the water. Its small, toothless mouth would have been used to filter plankton from the water.

## Ecology

So far, all we know about Thelodus is that it would have had a build that rendered it extremely adapted to life in open water (in this case, a larger tail fin for faster swimming, a dorsal and anal fin, and small pectoral fins for steering), and that it had a forward-facing mouth that made it easier for it to filter plankton from the water; as well as this, due to the fact that it had a more slender body than other jawless fishes, it would have relied on swift swimming speed rather than thick armor to escape predators such as Pterygotus.
Pterygotus

### Location

United Kingdom, Czech Republic, United States of America, Canada, Bolivia (possibly Australia, Estonia)

### Physical Dimensions

1.6 meters long for *P.anglicus*
60 centimeters for *P.arcuatus*
1.4 meters for *P.cobbi*
50 centimeters for *P. kopaninensis*
1.3 meters for *P.barrandei*
90 centimeters for *P.floridanus*
1.2 meters for *P.denticulatus*
75 centimeters for *P.lightbodyi*
55 centimeters for *P.bolivianus*

### Diet

Carnivore

Pterygotus is a pterygotid eurypterid merostomate arthropod from the Wenlock-Late Devonian of the United Kingdom, Canada, Czech Republic, Bolivia, the United States of America, and possibly Australia and Estonia. It was named in 1844 by Louis Agassiz. It was a truly big arthropod, and it was one of the most successful giant eurypterids, lasting for nearly 2 periods; as well as this, it was confused for being a giant fish (hence the meaning of its name, "winged fish"), right before people discovered that it was a eurypterid.

## Physiology

Pterygotus resembled the generic eurypterid. It was a large chelicerate with a rounded cephalothorax, large eyes, long arms with serrated claws, 4 pairs of walking legs, a pair of paddles for swimming, and a long tail ending in a paddle. Its body would have been covered in a hard, chitinous exoskeleton.

## Diet

Pterygotus was a predator, preying on fish, trilobites, aquatic scorpions, small orthoconic cephalopods, and smaller eurypterids. Its serrated claws were used for getting a hold of any struggling prey, as well as crushing them and ripping them apart.

## Ecology

Pterygotus was a fast swimmer, using its paddles and tail to propel itself through the water. A study on all pterygotid eurypterids had shown that it had robust claws designed for crushing, and that its eyesight was on par with that of modern predatory arthropods, such as dragonflies and mantids; this condition was similar to Jaekelopterus, and contrasted with Acutiramus, which had weaker eyesight and claws. In order to hunt, Pterygotus would bury itself in the sand, waiting for any unsuspecting fish, trilobites, cephalopods, or small chelicerates to get close. Once they did, it would rise up, grab them, and rip them apart with its claws, allowing it to eat their innards.

## In popular culture

Pterygotus was featured in the 1st episode of the 2005 documentary *Walking with Monsters*, where it rises out of the sands to kill an unsuspecting Brontoscorpio; as well as this, it was shown as being a motherly eurypterid, sharing the scorpion's innards with its young. It appeared again in another documentary, *First Life*, where a few small individuals scavenge the dead body of a large one, right before an even bigger one attacks them.
Titanichthys

Titanichthys is a titanichthyid arthrodire placoderm fish from the Late Devonian of the United States of America, Poland, and Morocco. It was named in 1885 by John Strong Newberry. It was the biggest placoderm to exist, surpassing even the Dunkleosteus.

## Physiology

Titanichthys had a build very similar to generic placoderms (a modern-looking fish with an armored head, toothless jaws, and an upward-facing tail). However, it had a few major differences; for example, its pectoral fins were much larger than those of Dunkleosteus, and instead of the sharp bony plates that most arthrodire placoderms had, it had rather blunt ones. Its body would have been covered in scaly skin, with bony plates protecting its head.

## Diet

Titanichthys was a predator, feeding on small fish and small invertebrates. Since it did not have the sharp bony mouth plates of most arthrodire placoderms, it relied on its huge mouth to engulf tiny prey whole.

## Ecology

Titanichthys shared most of its physical features with Dunkleosteus, as both were gigantic fish with big heads and huge mouths. However, Titanichthys's aforementioned blunt mouthparts had disqualified it from apex predator status (as opposed to Dunkleosteus). Instead, Titanichthys would have been a whale-like filter feeder, sucking in small fish and plankton with its big mouth. This lifestyle would make it one of the first filter-feeding fish.
Rhamphorhynchus

Rhamphorhynchus is a rhamphorhynchid pterosaurian reptile from the Late Jurassic of Germany and the United Kingdom. It was named in 1846 by Christian Erich Hermann von Meyer. It was one of the first pterosaurs known to science (alongside Pterodactylus); in fact, it was thought to be a species of Pterodactylus before finally being described as its own genus.

## Physiology

While still retaining the appearance of a bat-like bird, Rhamphorhynchus looked slightly more draconic. It had 4 legs (two of which served as wings), 4 fingers on each hand (one of which was elongated and supported the wing membrane), a small body, a long tail with a triangular vane on its end, a moderately long neck, and a small head with a large, curved beak covered with sharp, interlocking teeth. Most of its body (excluding its beak and wings) would have been covered in a fur-like covering called pycnofibers.

## Diet

Rhamphorhynchus was a predator, preying on fish and cephalopods as an adult, and subsisting on arthropods as a juvenile. Its teeth were large and sharp, and were used to get a hold of slippery prey.

## Ecology

Rhamphorhynchus's early life stages were unique compared to most other pterosaurs; juveniles, neither altricial (requiring care from parents) nor able to fly the moment they hatched, grew fast until they reached a size half of that of adults (and finally became able to fly), in which they started to grow at a much slower rate. It has long been suspected that Rhamphorhynchus fed by projecting its lower jaw into the water and catching any fish that swam into it; however, recent studies have shown that this would cause the pterosaur to experience so much drag that it would fall face-first into the water, and that it probably floated on the water and caught any nearby fish with its toothy beak instead. As well as this, a close look at its ear structure tells us that it held its head at a horizontal position when moving about; this contrasts to later pterosaurs such as Pteranodon, which held their heads at a oblique position. A comparison of its sclerotic rings to those of modern reptiles and birds indicates that it was nocturnal; this lifestyle benefitted the animal, as it would avoid competition with Pterodactylus, a fellow fish-eating pterosaur that preferred to hunt during the day.

## In popular culture

Rhamphorhynchus was first introduced to the public in the *Rite of Spring* segment of the 1940 Disney musical movie, *Fantasia*. Since then, it has become one of the most popular pterosaurs (after Pteranodon), being featured in major pieces of media such as *One Million Years B.C*, *The Land that Time Forgot*, and *Walking with Dinosaurs*; with the very latter being the exception, all of these pieces of media show it as a giant, vicious, eagle-like predator, flying at helpless cavemen and snatching them with its talons. Among this, its long, vaned tail is commonly seen as another trait that makes it inherently devilish, and so, is added to every pterosaur; even short-tailed pterosaurs such as Pteranodon get this long tail.