Pisanosaurus

our feathered friend Pisanosaurus

Type Species: Pisanosaurus mertii

Classification: Dinosauria - Ornithischia - Heterodontosauridae*

Time Period: Late Triassic

Location: Argentina

Diet: Herbivore

several Pisanosaurus flee a roving rauisuchian

The small, herbivorous dinosaur Pisanosaurus lived in what is now Argentina during the Carnian stage of the Late Triassic, around 228 to 216 mya. This dinosaur was lightly-built and grew to about three feet in length and probably weighed around five to twenty pounds. Pisanosaurus was found in a locale that, during its day, was a volcanically active floodplain covered by dense forests with a warm and humid climate subject to seasonally strong rainfalls. As a ground-dwelling herbivore it likely fed on ferns and horsetails, and it may have sought to hide from the fast-moving theropods Herrerasaurus and Eoraptor by seeking sanctuary in the giant conifers of the highland forests that grew up along the riverbanks. It may have competed with other Carnian herbivores such as the crocodile-like rhynchosaurs, the armored aetosaurs, and two-tusked dicynodonts. It would’ve kept a close lookout for the top predators of its day: the heavyweight rauisuchians and the dreaded pseudosuchian Sarchosuchus, the Top Dog in the volcanic basin (though given Pisanosaurus’ size and agility, it may have feared being trampled more than being hunted!).

a single Pisanosaurus seeks shelter among the giant conifers
of Argentina's Late Triassic volcanic basin

Up until 2017 Pisanosaurus was viewed by most paleontologists as the oldest known ornithischian dinosaur. Ornithischians were the ‘bird-hipped’ dinosaurs, as opposed to the ‘lizard-hipped’ saurischians. Ornithischians of the later Mesozoic included ornithopods and lambeosaurs, ceratopsians and pachycephalosaurs, and stegosaurs and ankylosaurs. The dominant dinosaurs of the Late Triassic were the saurischian prosauropods and theropods, so Pisanosaurus’ presence in the Late Triassic is important (for a long time it was thought that ornithischians didn’t appear until the Jurassic). In recent years, however, some scientists have argued that Pisanosaurus wasn’t a dinosaur at all but a silesaurid. The silesaurids were ‘wanna-be’ dinosaurs, cousins to the lineage that would eventually dominate the Mesozoic. Debate still rages: “Is Pisanosaurus the earliest and most primitive ornithischian, or is it an impostor whose family line was doomed to extinction?”

* If Pisanosaurus is not a dinosaur after all (see paragraph above!), then it's classification would be more like Dinosauriformes - Dracohors - Silesauridae

Gojirasaurus

Type Species: Gojirasaurus quayi

Classification: Dinosauria - Saurischia - Theropoda - Coelophysoidea

Time Period: Late Triassic

Location: New Mexico

Diet: Carnivore

Gojirasaurus’ name means ‘Godzilla lizard’ and is named after (unsurprisingly) the infamous Japanese monster (Gojira is the Japanese name for Godzilla). One might think, then, that it was discovered in Asia, but its remains were actually uncovered in New Mexico. Why, then, the Japanese connection? The answer is two-fold: first, this predatory theropod was a monster for its time – a ‘Godzilla’, if you will. Second, a theropod dinosaur with the name Godzillasaurus exists in the Heisei era of Godzilla films, and in that continuity is explained to be the un-mutated form of Godzilla; thus the naming of this creature Gojirasaurus is, in essence, a play on Japanese film: “Here is the creature from which Godzilla mutated!” This is why, when searching for images of Gojirasaurus, you’ll come across a lot that have Godzilla’s spinal decorations. Alas, these additions are callbacks to Japanese cinematography rather than deciphered from the fossil record.

a rendition of Gojirasaurus that is heavy on the Godzilla connection

Gojirasaurus lived in the Norian stage of the Late Triassic around 228 to 208 mya. It was one of the largest meat-eating dinosaurs of its time (if not the largest): it dwarfed Liliensternus and grew just shy of the length enjoyed by the early Jurassic Dilophosaurus. Scientists estimate it grew up to eighteen feet long and weighed between 330-440 pounds. Features of the pelvis and ankle suggest to some that the fossil specimen we have is from a juvenile; if that’s the case, an adult Gojirasaurus would’ve grown much larger, perhaps dwarfing even Dilophosaurus and its kin. For this reason it might be considered the ‘Allosaurus’ of its time.

Euodromaeus

Type Species: Eodromaeus murphi

Classification: Dinosauria - Saurischia - Theropoda

Time Period: Late Triassic

Location: Argentina

Diet: Carnivore

Eodromaeus name means ‘dawn runner,’ and it’s apt: though for years the Triassic theropod Eoraptor was considered one of the earliest dinosaurs, Eodromaeus appears as to be a better candidate (hence it finds its place at the ‘dawn’ of the dinosaur age; in the words of paleontologist Paul Sereno, it may very well be the ‘Eve’ of the dinosaurs, a common ancestor to all other dinosaurs). As far as running goes, it was a swift runner that could likely clock speeds up to twenty miles per hour, giving Eoraptor – once again! – a run for its money.

Eodromaeus lived in Argentina during the Carnian stage of the Late Triassic around 232-229 mya. When its remains were first discovered, it was thought to belong to a new species of Eoraptor; closer examination showed they belonged to a different creature altogether. Eodromaeus was small, reaching just under four feet head-to-tail, and weighed only about eleven pounds. It was long and slender and able to run on two legs (its hind-limbs were much longer than its front limbs). It had sabre-shaped teeth and sharp-clawed five-fingered hands (though two of its digits were greatly reduced), and it likely preyed upon small or juvenile reptiles. 

Efraasia

Type Species: Efraasia minor
Classification: Dinosauria - Saurischia - Sauropodomorpha - Prosauropoda
Time Period: Late Triassic
Location: Germany
Diet: Herbivore

Efraasia was a prosauropod herbivore that lived during the middle Norian stage of the Late Triassic (around 210 mya). Several specimens have been discovered in Germany, and though these were attributed to various species of Efraasia, recently they were combined into one species: Efraasia minor. Like Mussaurus, Efraasia was considered to be a ‘small fry’ that reached only about seven to ten feet in length. Upon further examination, however, it became apparent that the fossils belonged to a juvenile; adult length has been estimated around twenty-one feet. Efraasia was lightly-built with gracile hands and feet. It had long fingers and mobile thumbs, with which it could grasp food, and the anatomy of its wrists may have enabled it to walk on all fours. Its skull was small, pointed, and triangular. Its neck was only moderately elongated and thin. A cluster of gastroliths (stomach stones) was found near one specimen.