The T. Rex Might Have Made A Surprising Effect On The Fossil Record

You don't get named "Tyrannical king" for nothing. According to Smithsonian magazine, a full-grown Tyrannosaurus rex weighed in at a terrifying 12,000 to 18,000 pounds, and a recent study has found even more ways that the monstrous dinosaur lived up to its future taxonomy. Researchers at the Universities of New Mexico and Nebraska found that the T. rex had an astounding and authoritarian effect on the food chain way back when.

Published in the journal Science, the study aimed to account for an odd lack of medium-sized predators — ranging from 220 to 2,200 pounds — in the fossil record. Such a sizable gap in predators goes against what scientists have observed in modern food chains dominated by predators. Animals like wild dogs, hyenas, and servals make up the mid-sized predators between mongooses and lions in the African Serengeti, for example. So how was T. rex, the comparative lion of its day, responsible for this lack of medium-sized meat-eaters millions of years ago?

Apparently, T. rex wasn't only tyrannical as an adult. The study found that while on its way to weighing almost 20,000 pounds, the juvenile T. rex was such a dominant predator that it basically left no room for anyone else. That's right, T. rex was so terrible and fierce that it dominated several levels of the food chain at different stages of its life cycle. And as lead researcher Katlin Schroeder told Live Science, this most likely had a serious effect on the food chain and subsequent fossil record.

"Juvenile megatheropods may have outcompeted other medium-sized dinosaurs, resulting in deflated global dinosaur diversity," she said. Since the teenage T. rex ate different prey than its gargantuan parents, the same species ended up taking up multiple spots on the food chain, leaving little or no room for other species that may have taken occupied that spot as adults. They were basically prehistoric bullies. "Bottom line is that throughout that entire time, it's difficult to be a medium-sized carnivore," said Shroeder.