Paleo Profile: The Dawn Rough Tooth

The reconstructed skull of Eotrachodon. From Prieto-Márquez et al., 2016.
The reconstructed skull of Eotrachodon. From Prieto-Márquez et al., 2016.

Eastern dinosaurs are hard to find. Between geologic happenstance, suburban sprawl, and forests that blanket what would otherwise be promising outcrop, we know frustratingly little about the dinosaurs of Appalachia compared to their relatives exposed in the deserts to the west. But every now and then paleontologists are able to pull a prize out of the difficult eastern exposures. The hadrosaur Eotrachodon is one such case.

Paleontologists  Albert Prieto-Márquez, Gregory Erickson, and Jun Ebersole named the dinosaur earlier this year from bones found in Alabama. The remains are pretty scrappy, which is typical for Appalachian finds, but Eotrachodon is nevertheless known from a nearly-complete skull that provides a rich source of osteological comparison for other hadrosaurs. After all, most hadrosaurs are primarily identified by their skulls – different ornamentation on a very conservative chassis.

At about 85 million years old, Eotrachodon lived about 10 million years before the great profusion of its more famous cousins in the west like Parasaurolophus, Lambeosaurus, and their ilk. In fact, Prieto-Márquez and colleagues found, Eotrachodon seems to fall right outside the split between the major crested and crestless hadrosaur lineages, hinting that the eastern half of North America was the place hadrosaurs started to take off before conquering so much of the west.

But there’s another reason I picked Eotrachodon for this week’s Paleo Profile. When I was a kid the hadrosaur Trachodon often made appearances in books and movies, but paleontologists abandoned the name. That’s because the name Trachodon is formally chained to a handful of isolated teeth that can’t be tied back to a body. By coining the name Eotrachodon, however, Prieto-Márquez and coauthors found a workaround to revive the classic title and give poor “Trachodon” a new dawn.

The right maxilla of Eotrachodon. From Prieto-Márquez et al., 2016.
The right maxilla of Eotrachodon. From Prieto-Márquez et al., 2016.

Fossil Facts

Name: Eotrachodon orientalis

Meaning: Eotrachodon means “dawn Trachodon” (or “dawn rough tooth” fully translated), and orientalis is a reference to the fact this dinosaur was found in America’s southeast.

Age: About 85 million years ago.

Where in the world?: Montgomery County, Alabama.

What sort of critter?: A hadrosaur, or “duck-billed” dinosaur.

Size: Comparable to other North American hadrosaurs such as Hadrosaurus and Gryposaurus.

How much of the creature’s body is known?: A nearly-complete skull and fragmentary elements of the postcrania.


Prieto-Márquez, A., Erickson, G., Ebersole, J. 2016. A primitive hadrosaurid from southeastern North America and the origin and early evolution of ‘duck-billed’ dinosaurs. Journal of Vertebrate Paleontology. doi: 10.1080/02724634.2015.1054495

Prieto-Márquez, A., Erickson, G., Ebersole, J. 2016. Anatomy and osteohistology of the basal hadrosaurid dinosaur Eotrachodon from the uppermost Santonian (Cretaceous) of southern Appalachia. PeerJ. doi: 10.7717/peerj.1872

Previous Paleo Profiles:

The Unfortunate Dragon
The Cross Lizard
The South China Lizard
Zhenyuan Sun’s dragon
The Fascinating Scrap
The Sloth Claw
The Hefty Kangaroo
Mathison’s Fox
Scar Face
The Rain-Maker Lizard
“Lightning Claw”
The Ancient Agama
The Hell-Hound
The Cutting Shears of Kimbeto Wash
The False Moose
“Miss Piggy” the Prehistoric Turtle
Mexico’s “Bird Mimic”
The Greatest Auk
Catalonia’s Little Ape
Pakistan’s Butterfly-Faced Beast
The Head of the Devil
Spain’s Megatoothed Croc
The Smoke Hill Bird
The Vereda Hilarco Beast
The North’s Sailback
Amidala’s Strange Horn
The Northern Mantis Shrimp
Spain’s High-Spined Herbviore
Wucaiwan’s Ornamented Horned Face
Alcide d’Orbigny’s Dawn Beast
The Shield Fortress
The Dragon Thief
The Purgatoire River’s Whale Fish
Russia’s Curved Blade
The Dawn Mole
The Oldest Chameleon
The Wandering Spirit
Teyú Yaguá
New Caledonia’s Giant Fowl
The Giant Tarasque Tortoise
The Giant, Bone-Crushing Weasel

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