Liliensternus

a pair of feathered Liliensternus circle a Plateosaurus

Type Species: Liliensternus liliensterni

Classification: Dinosauria - Saurischia - Theropoda - Neotheropoda

Time Period: Late Triassic

Location: Europe

Diet: Carnivore

Liliensternus could grow up to nearly seventeen feet in length and, like Coelophysis, had a penchant for fossilization. It’s one of the better-known Triassic theropods from Europe – and one of the largest Triassic theropods. It was an active bipedal carnivore that likely preyed upon the larger herbivores in its environment, including archosaurian aetosaurs and the prosauropod Plateosaurus. It lived in ancient floodplains that were abundant with reptiles, therapsids, and a favorite roaming ground of Plateosaurus. Its slashing teeth would’ve enabled it to take down large prey, and its swift speed would enable it to chase down swift creatures.

a skull of Liliensternus; shadowed parts are hypothetical

A few pieces of interesting anatomy have led some paleontologists to speculate that Liliensternus was a transitional creature between more basal theropods and the early Jurassic Dilophosaurus. In both Liliensternus and Dilophosaurus the tibia is shorter than the femur, which isn’t the case in the coelophysoids. Its hip bone (ilium) is also unusually short, a shared characteristic between Liliensternus and Dilophosaurus. Though Liliensternus’ skull is not well-known, many reconstructions give it a head crest similar to that of Dilophosaurus – the crest, however, is a matter of conjecture born out of the ‘transitional link’ hypothesis. Liliensternus had five fingers on each hand, akin to its Upper Triassic contemporaries, but its fourth and fifth digits are smaller – again, this is argued to be a transitional feature, this time between the five-fingered Triassic theropods and the three-fingered theropods of the Jurassic.

Coelophysis

Type Species: Coelophysis bauri

Classification: Dinosauria - Saurischia - Theropoda - Coelophysoidea - Coelophysidae 

Time Period: Late Triassic to Early Jurassic

Location: Southwestern U.S.A. and Africa

Diet: Carnivore

Coelophysis fossils have been found in the southwestern United States and in South Africa and Zimbabwe. It was a small, slender bipedal carnivore that could grow up to nearly ten feet in length and was about three feet in height at the hips. It appeared in the Upper Triassic of the Norian stage and survived through the Triassic-Jurassic extinction before dwindling to extinction in the Jurassic. Coelophysis probably weighed around forty pounds and was a fast, agile runner. Coelophysis’ anatomy was advanced from that seen in the Carnian-era’s Eoraptor and Herrerasaurus, and the type species (Coelophysis bauri) already had a wishbone (the earliest example in dinosauria, and which would become a central piece of bird anatomy). Coelophysis’ forelimbs were designed for grasping prey. The long tail had an unusual structure within its interlocking prezygapophysis (the ‘pipe-fitting’ of vertebrae) creating a semi-rigid lattice that prevented the rigid tail from moving up and down. Its head was nearly a foot long with large, forward-facing eyes that provided stereoscopic vision and excellent depth perception. Its sclerotic rings indicate that it was a diurnal (it was most active during daytime and likely slept at night). A study of its sclerotic rings further indicate that its vision was far superior to that of lizards and ranked up with those of birds of prey; Coelophysis’ orbital structure closely resembles those of eagles and hawks. It probably had poor night vision.

Gregarious behavior for Coelophysis is hotly debated

Coelophysis’ teeth indicate it was carnivorous: the teeth were blade-like and recurved with sharp, jagged serrations. It likely preyed on small, lizard-like animals, and many scientists believe it could run in packs and coordinate with others of its pack to bring down larger prey; however, because its forelimbs – despite a wide range of motion – were weak, and because its teeth were relatively small, it’s likely that it spent most of its time chasing after small prey. This doesn’t mean, of course, that Coelophysis wasn’t gregarious: the Ghost Ranch bone-bed of New Mexico contains over a thousand of Coelophysis remains, and it may very well  be that Coelophysis ‘flocked’ like modern birds. Another theory is that Coelophysis generally hunted on their own but congregated around watering-holes. It may be the case that Ghost Ranch is the scene of a one-up tragedy: while gathering together to feed on a spawning run of fish before being buried in a catastrophic flash flood. Proponents of gregarious behavior among Coelophysis point to sexual dimorphism as evidence: two ‘morphologies’ of Coelophysis exist, and these may indicate a male or female species. Dimorphism among a species usually indicates gregarious behavior, and a further study of sexual dimorphism among this dinosaur showed that the different morphologies were split close to half-and-half of the population – exactly what you’d expect in a gregarious social hierarchy. A wrench in the theory, however, is the growth rates of Coelophysis: hatchlings grew rapidly during the first year of life and likely reached adulthood by their third birthday. Such fast growth is seen in animals that need to fend for themselves upon birth. A 2009 comparative study between Coelophysis and modern birds and reptiles indicates that Coelophysis laid between 24-26 eggs in each clutch and that parental care was necessary to nurture the relatively small hatchlings during the first year of life. When all these threads come together, there’s no consensus on whether Coelophysis was gregarious – further study (and discoveries) are needed.

a lone Coelophysis on the prowl

Thecodontosaurus

Type Species: Thecodontosaurus antiquus
Classification: Dinosauria - Saurischia - Sauropodomorpha - Prosauropoda
Time Period: Late Triassic
Location: England
Diet: Herbivore

Another notable herbivorous dinosaur was the prosauropod Thecodontosaurus, which appeared in the Norian and became widespread in the following Rhaetian. It was bipedal and averaged about four feet in length (though one particular individual reached up to eight feet long), one foot in height, and weighed about twenty-four pounds. Most of its skeleton can be reconstructed, except for the front part of its skull. From the fossils available, we know that Thecodontosaurus had a rather short neck and a large skull with large eyes. Its jaws contained many small- to medium-sized serrated, leaf-shaped teeth. Its hands and feet each had five digits, and the hands were long and narrow with an extended claw on each. Its front limbs were much smaller than its hind limbs, and the tail comprised more than half the length of its body. Continuing research on Thecodontosaurus has shown that there were two main morphologies, one much more robust than the other. Some paleontologists believe these two morphologies represent separate species; others argue that it’s a matter of sexual dimorphism, which would imply that Thecodontosaurus engaged in gregarious (or social) behaviors like the much-larger prosauropod Plateosaurus. 

Staurikosaurus

Type Species: Staurikosaurus pricei
Classification: Dinosauria - Saurischia - Theropoda - Herrerasauridae
Time Period: Late Triassic
Location: Brazil
Diet: Carnivore

Staurikosaurus was a small and agile predator that reached about seven and a half feet in length, about two and a half feet in height, and clocked in around sixty pounds. Staurikosaurus is based on fragmentary material, but enough has been found to know that it was a quick-running carnivore with serrated teeth that curved back towards the throat, enabling it to catch and hold onto prey; though this teeth feature would disappear in later theropods, it was common among those of the Upper Triassic. A sliding joint in its jaw allowed the jaw to move backwards and forwards, as well as up and down, so that smaller prey could be worked backwards towards the throat. It had a long tail that it held off the ground as it ran; the rear part of its tail was stiffened and acted as a dynamic stabilizer enabling the creature to run and leap with precise agility. It would’ve preyed on small and medium-sized animals.

Herrerasaurus

Type Species: Herrerasaurus ischigualastensis
Classification: Dinosauria - Saurischia - Theropoda - Herrerasauridae
Time Period: Late Triassic
Location: Argentina
Diet: Carnivore

Herrerasaurus lived in the Upper Triassic of Argentina and reached up to twenty feet in length and up to 750 pounds in weight. This predator was lightly built with a long tail and a relatively small head. It was fully bipedal with strong hind limbs and long feet. The feet had five toes, but only the middle three bore weight. The tail, partially stiffened by overlapping vertebral projections, balanced the body and was an adaptation for speed. Herrerasaurus’ upper arms and forearms were rather short, but the hands were elongated. The first two fingers and the thumb ended in curved, sharp claws used for slashing and gripping prey. The other fingers were small stubs without claws. Its long, narrow skull lacked most of the specializations seen in later dinosaurs, but it had a flexible joint in the lower jaw that could slide back and forth to deliver a grasping bite. Its jaws had large serrated teeth for biting and tearing, and its slender neck was flexible. It lived in the same environment as Eoraptor and likely preyed upon the Upper Triassic's super-salamanders and herbivorous dicynodonts; it would’ve competed with rauisuchians and phytosaurs for food.

Eoraptor

Type Species: Eoraptor lunensis
Classification: Dinosauria - Saurischia - Theropoda
Time Period: Late Triassic
Location: Argentina
Diet: Omnivore

Eoraptor lived in what is modern-day Argentina. It had a slender body that reached about three feet in length and weighed around twenty pounds. Its skull was lightly built and similar to those of the later coelophysoids. Like all dinosaurs it had a digitigrade stance, walking upright on its toes, and it stood upright on its hind legs. All of its long bones had hollow shafts and hollow central vertebrae. It had five digits on each ‘hand,’ the three longest of which ended in large claws presumably used to handle prey. It had heterodont teeth (meaning it had multiple types of teeth), so it’s speculated that it was omnivorous. It had serrated, recurved teeth in its upper jaws (like those of later theropods) and leaf-shaped teeth in the lower jaw (like those of prosauropods). It was a fast runner and could use its claws and teeth to tear prey apart. Unlike later theropods, it lacked a sliding joint at the articulation of the lower jaw that would enable it to hold large prey. Its remains have been found in what was once a volcanically-active floodplain covered by forests with a warm and humid climate subject to monsoons. It lived among ferns, horsetails, and giant conifers of the highland forests that stretched along the banks of rivers. It was likely preyed upon by another (and much larger) early theropod, Herrerasaurus. Eoraptor would’ve shared its environment with Carnian therapsids, rauisuchians, and archosaurs. Dinosaurs, of which Eoraptor was a part, represent only six percent of the fauna found in Argentina. It certainly wasn’t the dominant creature.

Daemonosaurus

Type Species: Daemonosaurus chauliodus
Classification: Dinosauria - Saurischia - Theropoda
Time Period: Late Triassic
Location: North America
Diet: Carnivore

Daemonosaurus lived during the Late Triassic of Mexico. It’s considered a basal theropod that lies outside the clade Neotheropoda; in other words, it was closely related to the family line that would survive into the Jurassic and diversify into the ceratosaurs and tetanurans, but it was part of the ‘old breed’ that wouldn’t make it past the Triassic-Jurassic extinction event. Daemonosaurus had a short skull and long protruding teeth, making it vividly different than the slender-skulled theropods that dominated the Late Triassic. It may have reached up to five feet in length, but many paleontologists believe it was shorter than this. It lived in the area of Ghost Ranch among such Late Triassic citizens as the rhynchosaurs, archosaurs, pseudosuchians, and primitive crocodilians – not to mention Coelophysis.