Paleo-ecologists from The University of New Mexico and at the University of Nebraska-Lincoln have demonstrated that the offspring of enormous carnivorous dinosaurs, such as Tyrannosaurus rex may have fundamentally re-shaped their communities by out-competing smaller rival species.
The study, released in the journal Science, is the first to examine community-scale dinosaur diversity while treating juveniles as their own ecological entity.
"Dinosaurs have been a life-long passion. I was, and still very much am a 'dinosaur kid.' My interest in dinosaur diversity came about when I realized that no one was really looking at dinosaurs the way we look at modern mammals and birds." Kat Schroeder said. "
"Dinosaur communities were like shopping malls on a Saturday afternoon jam-packed with teenagers" explained Kat Schroeder, a graduate student in the UNM Department of Biology who led the study. "They made up a significant portion of the individuals in a species and would have had a very real impact on the resources available in communities."
Because they were born from eggs, dinosaurs like T. rex necessarily were born small, about the size of a house cat. This meant as they grew to the size of a city bus, these "megatheropods," weighing between one and eight tons, would have changed their hunting patterns and prey items. It's long been suspected by paleontologists that giant carnivorous dinosaurs would change behavior as they grew. But how that might have affected the world around them remained largely unknown.
"We wanted to test the idea that dinosaurs might be taking on the role of multiple species as they grew, limiting the number of actual species that could co-exist in a community," said Schroeder.
The number of different types of dinosaurs known from around the globe is low, particularly among small species.
"Dinosaurs had surprisingly low diversity. Even accounting for fossilization biases, there just really weren't that many dinosaur species," said Felisa Smith, professor of Biology at UNM and Schroeder's graduate advisor.
To approach the question of decreased dinosaur diversity, Schroeder and her coauthors collected data from well-known fossil localities from around the globe, including over 550 dinosaur species. Organizing dinosaurs by mass and diet, they examined the number of small, medium and large dinosaurs in each community.
