A new study shows that medium-sized predators all but disappeared late in dinosaur history wherever Tyrannosaurus rexand its close relatives rose to dominance. In those areas -- lands that eventually became central Asia and Western North America -- juvenile tyrannosaurs stepped in to fill the missing ecological niche previously held by other carnivores.

 

The research conducted by Thomas Holtz, a principal lecturer in the University of Maryland's Department of Geology, verified previous anecdotal reports of a dramatic drop-off in diversity of medium-sized predator species in communities dominated by tyrannosaurs. Diversity of prey species, on the other hand, did not decline. This suggests that medium-sized predators did not disappear because of a drop off in their prey, and that something else -- likely young tyrannosaurs -- stepped in to fill their ecological role. The study was published online on June 17, 2021, in the Canadian Journal of Earth Sciences.