OK, so it’s no Sue. In fact, a fossil set to go on display next month at the Field Museum couldn’t be more different from a ferocious carnivore–it appears to be a vegetarian crocodile.
Still, the fossil of a pug-nosed, extinct croc is helping show scientists how and when a single landmass made up of Africa, Antarctica, South America and Australia broke into separate continents.
Roosevelt University paleontologist Gregory Buckley two years ago was a part of an expedition that found the odd-looking, 3-foot long, 70-million-year-old fossilized creature in Madagascar. Buckley is the lead author of an article describing the fossil–an oddball croc that preferred burrowing in dry land over a life of floating in swamps–in the Thursday edition of the science journal Nature.
Crocodiles predate even dinosaurs. Even the earliest ones sported nasty, snaggle-toothed snouts designed to rip through flesh.
Simosuchus (see-mo-SUE-cuss), as the newly discovered vegetarian crocodile has been named, lived at the end of the age of dinosaurs and presented a somewhat less nasty visage.
“This is not something, if it was alive today” said Buckley of Simosuchus, “that people would be running scared from.”
One of his co-authors, Field Museum paleontologist and crocodile expert Chris Brochu, calls the new find “the strangest croc I have ever seen.”
“My wife, who is so sick of crocodile fossils after years of seeing me work with them, actually likes this one,” said Brochu. “With its pug nose, she calls it a `puppy croc.’ It’s got teeth shaped like maple leaves.”
The fossil will be put on temporary exhibit at the Field sometime in July.
If Simosuchus was a plant-eater rather than a meat-eater, and Buckley is convinced it was vegetarian, it would be only the second vegetarian croc known to science.
Simosuchus’ teeth strongly resemble those of plant-eating dinosaurs, he said, particularly stegosaurs and ankylosaurs.
“Teeth of this form (leaf-shaped and multicusped for puncturing and shredding) are typically regarded as indicative of an exclusively to predominantly herbivorous diet,” he writes in Nature.
When it lived, an age called the Late Cretaceous, Simosuchus had to compete for food and territory with six other crocodile species in Madagascar, Buckley said.
“Simosuchus went to the extreme, taking advantage of one food source that other crocodiles weren’t after,” he said, “That is, plants.
More Top Picks How To Handle Homework Meltdowns Without Yelling
“The Late Cretaceous crocodiles of Madagascar illustrate evolution in the same way that Charles Darwin’s famous Galapagos finches did. They show us that a lot of closely related species living in the same place will adapt to be able to eat different foods.”
Madagascar, a large island off the east coast of Africa, has long fascinated scientists, much like Darwin’s Galapagos islands off South America.
Many of Madagascar’s plants and animals are unlike any found elsewhere in the world, including nearby Africa, indicating that those plants and animals evolved on their own for tens of millions of years.
The same seems to have been true for Madagascar late in the dinosaur age–when Simosuchus lived–with animals, including dinosaurs, having evolved much differently than they did in Africa.
Geologists long have tracked fossil plants and animals for clues to the formation of the earth’s landmasses. Up to 180 million years ago, plants and animals throughout the world were fairly similar, when all the continents were joined together in a single supercontinent called Pangea.
Pangea split in two 180 million years ago. A supercontinent called Laurasia, made up of Europe, Asia, North America and Greenland, began drifting north, its animals and plants diverging down new evolutionary paths.
The same happened in a southern supercontinent called Gondwanaland, containing Africa, Antarctica, South America, Australia, India and Madagascar.
Between 150 and 165 million years ago, Africa split off on its own. There is still some dispute how and when South America drifted off on, but the presence of Simosuchus 70 million years ago seems to argue that South America remained linked to Antarctica, Australia, India and Madagascar longer than previously thought.
David Krause, leader of the 1998 Madagascar expedition and a co-author of the Nature paper, is a paleontologist at State University of New York in Stony Brook and a leading expert on continental movement charted by fossil finds.
“We have several independent lines of evidence from the Late Cretaceous period showing very closely related animals in South America and Antarctica,” said Krause.
The most closely related animal to Simosuchus known to science is a small, terrestrial, short-snouted (but carnivorous) croc that lived in South America. That they both lived in the same time period, said Buckley, is a good clue that animals still could move overland from South America across Antarctica to Madagascar.
Eventually Antarctica separated and moved to its present South Pole position, and South America and Australia drifted their own ways.
For a time, India and Madagascar remained attached as a single large island, but India eventually tore away, drifted north, and collided with Asia’s underbelly, the impact creating the Himalayan mountain chain. Madagascar drifted to its place next to Africa.