Camposaurus

Type Species: Camposaurus arizonensis

Classification: Dinosauria - Saurischia - Theropoda- Coelophysoidea - Coelophysidae 

Time Period: Late Triassic

Location: North America

Diet: Carnivore

Camposaurus emerged in the Norian stage of the Late Triassic of North America. These feisty carnivores belonged to a group of theropods called the coelophysids; these were slender, carnivorous dinosaurs that include Coelophysis, Procompsognathus, and Liliensternus. Some coelophysoids lived in packs, but not necessarily all. They may have had scales, pebbly hides, or even feathers. Camposaurus, as one of the earliest coelophysoids, has been regarded by many paleontologists as the oldest known neotheropod (a group of theropods that emerged during the Upper Triassic and would spawn the dilophosaurs, ceratosaurs, and tetanurans – the latter of which continues to the present day in the form of birds). 

We have only fragmentary remains of this carnivorous dinosaur – mostly partial leg bones – so our knowledge of this creature isn’t spectacular. What is known is that it was small, but not much else. Its classification in the ‘dinosaur family tree’ has been here and there over the years. In 1995 it was considered a Ceratosaur; slightly later it was identified as simply another species of the infamous Coelophysis. In 2011, based upon phylogenic studies, it was distinguished from Coelophysis but only by a hair’s breadth, making them closely related. Because of its close affinity with Coelophysis, scientists guess that Camposaurus may have been a social animal that lived in packs and that it would’ve fed on small mammals, insects, fish, and the plethora of amphibians of the Upper Triassic ecosystems.

Anchisaurus

Type Species: Anchisaurus polyzelus
Classification: Dinosauria - Saurischia - Sauropodomorpha - Prosauropoda
Time Period: Early Jurassic
Location: North America & Africa
Diet: Herbivore

Two species of this Lower Jurassic dinosaur have been identified; the first clocks in at around eight feet long and sixty pounds, and the other comes in around eight to 13 feet long. Their remains have been found in both North America and Africa, and some curious-looking track-ways as far north as Nova Scotia may belong to an Anchisaurus. Anchisaurus had narrower feet than most prosauropods, and while it probably spent most of its time on all fours, it could rear up on its hind legs to reach higher vegetation. Its blunt, spoon-shaped teeth numbered fewer than most prosauropods, and its body would’ve hugged the ground while it walked. 

Its name means “Close Lizard,” named by Charles Marsh, who suspected that Anchisaurus was a “transitional creature” or “missing link” between primitive dinosaurs and the more derived kinds. While this title is no longer relevant (we know that Anchisaurus showed up near the end of the first quarter of dinosaur history), it may yet prove to be apt, on two accounts. Anchisaurus didn’t jump-start the dinosaur family tree, but it may have been a “link” between prosauropoda and sauropoda; furthermore, some scientists even argue that Anchisaurus may have been a progenitor of the ornithischian (or “bird-hipped”) dinosaurs. This connection, they argue, is seen in a flurry of peculiar characteristics shared between them and early ornithopods. Ornithischian origins remains a mystery, but perhaps Marsh was onto something after all, though not in a way he anticipated: Anchisaurus may be a “missing link” in ornithischian origins.