News Paleontology

‘Thunder beast’ fossils show how some mammals might have gotten big

Rather than a straightforward march, evolving to be big sometimes involved getting smaller

illustration of Megacerops kuwagatarhinus with small, striped mammals in the foreground and background

Extinct brontotheres like Megacerops kuwagatarhinus (illustrated) were once titans weighing a metric ton or more. But the mammals’ evolutionary history wasn’t a straight path to gigantism.

Oscar Sanisidro © 2018, KU Biodiversity Institute/The University of Kansas

By Elise Cutts

For some mammals, the evolutionary path to gigantism after the dinosaurs’ demise wasn’t always a straight road.

Species of extinct, hefty, rhinoceros-like creatures called brontotheres evolved into both bigger and smaller forms over their 22-million-year run, researchers report in the May 12 Science.