Fossil Friday: Eopneumatosuchus

Species: Eopneumatosuchus colberti (Ee-noo-ma-toh-soo-kus kol-brr-tye)

What it means: Pneumatic passage crocodile

Other species: None

Where I live: Arizona in the U.S.A.- The Kayenta formation

When to find me: The Early Jurassic period, about 196 million years ago.

My favorite food: I like fish the best! I’m a pisciivore.

My neighborhood: The Kayenta formation used to be a tropical floodplain, a bit like African savannah today- but no grass or flowers. Ferns cover the open plains, dotted with islands of spiky cycad groves. Rivers crisscross the land with lush tree ferns, ginkgo trees, and conifers. Every year during the wet season the plains turn into a flooded marsh, but the hottest months bring no rain, and the rivers shrink until the plains are almost as dry as the great desert that lies to the north.

A few of my neighbors: I’m surrounded by big and scary dinosaurs like Dilophosaurus, Coelophysis, and Kayentavenator, so I stay out of their way. Sarahsaurus (an early sauropod) and Scelidosaurus (armored dinosaur) are plant eaters, but also pretty tough neighbors. Little Scutellosaurus (small armored dinosaur) is quite a bit more friendly, and if I’m lucky might even join me for lunch. Mostly I hang close to the river with the frogs, turtles, or fellow crocodile cousins. I’ll often see a long-tailed pterosaur flying overhead for insects like beetles, dragonflies, an ancient cousin of the moth, and something called a snakefly.

Fun Facts:

  • I look a bit like a crocodile, but I’m not! You might say we’re distant cousins.
  • Even though there are very few fossils, paleontologists still try to make a good guess at who my closest relatives are. At first they thought I was related to a crocodile-ish critter called Protosuchus. But the latest theory is that I’m from a family called Teleosaurs. They’re crocodile-ish critters that look a lot like the modern gharial (think croc, but with a super skinny and long snout), and they specialized in living out on the ocean. Some of them look a bit like crocs trying to play shark.
  • My name basically describes the bones that the paleontologists found. Eo (Latin for passage/ “to move along” + pneumaticus (latin for “operated with air pressure”). Describing the part of the skull that was found. The tympanic synuses in a crocodilian are at the very back of the head, almost where the neck connects. Suchus is from the Greek souchos, which is Greek for crocodile, and is pretty common in the names of croc-ish things.

Fossil Finds: A few fragmentary fossils from the back of the skull.


Lucas, Spencer & Heckert, Andrew & Tanner, Lawrence. (2005). ARIZONA’S JURASSIC FOSSIL VERTEBRATES AND THE AGE OF THE GLEN CANYON GROUP. New Mexico Museum of Natural History and Science. 29. 94-103.

Gay, Robert & Milner, Andrew. (2015). The first report of an archosaur from the Kayenta Formation of Washington County, Utah. 10.7287/PEERJ.PREPRINTS.848V1.

“Eopneumatosuchus.” Wikipedia,