Paleontologists: 80 million years ago, this monster ate dinosaurs

Monday, July 27, 2020

Deinoschus illustrations
An illustration of Deinosuchus from the journal's cover.
(Illustration by Tyler Stone BA '19, art and cinema
see his website)

This thing ate dinosaurs. University of Iowa-based research can prove it.

Adam Cossette, who earned his PhD in geoscience from the UI in 2018, and his graduate advisor, Professor Christopher Brochu of the UI Department of Earth and Environmental Sciences, have co-authored a paper that sheds new light on the monstrous creature. Cossette is assistant professor in the Department of Basic Science in the New York Institute of Technology College of Osteopathic Medicine at Arkansas State University (Jonesboro).

The research, which grew out of Cossette's UI doctoral dissertation, is published in the Journal of Vertebrate Paleontology (the issue's cover features artwork by another UI grad, Tyler Stone)It revises what we know about Deinosuchus—one of the largest, if not THE largest, crocodylian genera known.

Adam Cossette, a vertebrate paleobiologist, earned his PhD in geoscience from Iowa in 2018.

Now he's shaping his discipline as an assistant professor at a research institution.

Read more about the new blockbuster "Terror Crocodile" study by Dr. Cossette and UI Professor Chris Brochu on the NPR and New York Times websites.

Some species of Deinosuchus, which prowled coastal wetlands in North America between 75 and 82 million years ago, may have reached 35 feet in length. They were the largest predators in their ecosystem, outweighing even the largest predatory dinosaurs living alongside them. Based on the study of cranial remains and bite marks on dinosaur fossil bones, paleontologists have long speculated that the massive beasts preyed on dinosaurs. Now Cossette has proved that they had the head size and crushing jaw strength to do that. 

Adam Cossette
Adam Cossette

Deinosuchus was a giant that must have terrorized dinosaurs that came to the water’s edge to drink,” said Cossette, the primary author of the study. “Until now, the complete animal was unknown. New specimens reveal a bizarre, monstrous predator with teeth the size of bananas.”

Stephanie Drumheller-Horton, who also earned her PhD in geoscience from Iowa (in 2012), is a paleontologist at the University of Tennessee. “Deinosuchus seems to have been an opportunistic predator, and given that it was so enormous, most everything in its habitat was on the menu," she said. "We actually have multiple examples of bite marks made by D. riograndensis and a species newly described in this study, D. schwimmeri, on turtle shells and dinosaur bones.”

In spite of the genus's name, which means “terror crocodile,” they were actually more closely related to alligators. Based on its enormous skull, it looked like neither an alligator nor a crocodile. Its snout was long and broad, but inflated at the front around the nose in a way not seen in any other crocodylian, living or extinct. The reason for its enlarged nose is unknown.

Professor Christopher Brochu, University of Iowa
Christopher Brochu

“It was a strange animal,” said co-author Brochu. “It shows that crocodylians are not ‘living fossils’ that haven’t changed since the age of dinosaurs. They’ve evolved just as dynamically as any other group.”

The study also reveals that more than one kind of “terror crocodile” has been found. Two species lived in the west, ranging from Montana to northern Mexico. Another lived along the Atlantic coastal plain from New Jersey to Mississippi. At the time, North America was cut in half by a shallow sea extending from the Arctic Ocean south to the present-day Gulf of Mexico.

Christopher Brochu joined the University of Iowa faculty in 2001. His research explores the phylogeny and historical biogeography of crocodyliforms—alligators, crocodiles, gharials, and their close relatives.

The University of Iowa Graduate College manages the enrollment and degree progress for nearly 5,000 students from over 100 graduate programs in 10 different colleges, spanning the arts and humanities, biological sciences, health sciences, engineering, education, physical sciences, social sciences, and business.

by Nic Arp

The University of Iowa College of Liberal Arts and Sciences offers about 70 majors across the humanities; fine, performing and literary arts; natural and mathematical sciences; social and behavioral sciences; and communication disciplines. About 15,000 undergraduate and nearly 2,000 graduate students study each year in the college’s 37 departments, led by faculty at the forefront of teaching and research in their disciplines. The college teaches all Iowa undergraduates through the college's general education program, CLAS CORE. About 80 percent of all Iowa undergraduates begin their academic journey in CLAS. The college confers about 60 percent of the university's bachelor's degrees each academic year.