Phil Beradelli reported in ScienceShot today on new research into the hunting style of certain phorusrhacid “terror birds” that were important predators on the Argentinian plains about 6 million years ago.
These flightless running birds were fast, ostrich-like hunters that sported massive hooked beaks. A new paper in the journal PLoS ONE describes the likely hunting style of one genus of these birds, Andalagornis.
Lead author Frederico Degrange and colleagues used CT scanning of three Andalagornis (and near relative) skulls to assess the cranial flexibility and estimate bite force. They found that the skulls were rigidly built and not particularly robust at handling lateral forces, though quite robust to dorsoventral forces. Thus, they could have been effective for repeated, overhead stabbing motions, but would not have been effective for grabbing and subduing large, struggling prey items.
The estimated bite force of 133 Newtons is a lot for a bird, but not necessarily that much for a 40-kg bird, and on par with that of much smaller mammalian predators such as foxes and jaguarundis. The authors conclude that, despite representations of the terror birds as vicious predators of large mammals, more likely prey items were small vertebrates easily subdued with a quick bite. Large prey items might have been chased and stabbed repeatedly, but the terror birds probably didn’t pounce and grab prey items nearly as large as themselves because the struggle might likely have cracked their skulls.