Albertosaurus, a 30-foot-long cousin of Tyrannosaurus that stalked North America about 80 million years ago, most likely would have made short shrift of most animals that crossed its path. But even these creatures may have met their match in Deinosuchus rugosus, a 30-foot-long, three-ton crocodile. Paleontologist David Schwimmer of Columbus State University in Georgia has found evidence that this monstrous crocodile may have outcompeted Albertosaurus--and even eaten juvenile albertosaurs--in the southeastern coastal swamps of North America during the Cretaceous Period.
In nearly 20 years of fossil hunting in stream valleys in southwestern Georgia and eastern Alabama--sites that were once swamps and salt marshes--Schwimmer has found bones and teeth of more than 100 Deinosuchus. In contrast to this crocodile trove, he has found remnants of fewer than a dozen albertosaurs, all of them juveniles. The largest would have weighed less than half a ton--several times smaller than
D. rugosus. That the area was not inhospitable to dinosaurs is clear: the deposits abound in bones from adult hadrosaurs, duck-billed herbivorous dinos from the same period.
The rarity of adult Albertosaurus in the southeast is all the more strange, says Schwimmer, given that in other coastal areas--from New Jersey to Texas--it is the crocodile bones that are uncommon and the fossils of carnivorous dinosaurs that are abundant.
What accounts for this absence of albertosaurs? Schwimmer believes that D. rugosus, a semiaquatic animal, may have been the more successful and better adapted predator of this wet, tropical ecological niche. It may have gobbled up the albertosaurs’ food source--the marine turtles of the region. (Turtle shells riddled with crocodile bite marks are common in the area.) Schwimmer speculates that the albertosaur bones are the remains of juveniles who strayed into the region and couldn’t find enough prey to survive until adulthood.
He also believes it’s time to recast the role of Albertosaurus in the southeast: as dinner rather than diner. He found crocodile tooth marks on one bone of a carnivorous dinosaur. This leads him to believe that D. rugosus may have preyed on young dinosaurs. I’m giving an unappreciated large predator its due, he says. Everyone’s so excited about dinosaurs that they don’t think about some of the other great killers of the time.