The simulations supported the CT-based anatomical results.
"Relative to the other birds considered in the study, the terror bird was well-adapted to drive the beak in and pull back with that wickedly recurved tip of the beak," remarked Wroe, "but when shaking its head from side to side, its skull lights up like a Christmas tree."
A key part of the analysis was determining how hard a bite Andalgalornis could deliver.
To examine bite force in birds in general, Degrange and Tambussi worked with zookeepers at the La Plata Zoo to get a seriema and an eagle to chomp down on their bite meter.
"We discovered that the bite force of Andalgalornis was a little lower than we expected, and weaker than the bite of many carnivorous mammals of about the same size," Degrange said.
"Andalgalornis may have compensated for this weaker bite by using its powerful neck muscles to drive its strong skull into prey like an axe."
The team's results give new insight into the lifestyle of a unique avian predator.
Its skull, though strong vertically, was weak from side to side; its hollow beak was in danger of catastrophic fracture if Andalgalornis grappled too vigorously with large struggling prey.
Instead, the study shows that the terror bird engaged in an elegant style more like that of Muhammad Ali--a repeated attack-and-retreat strategy with well-targeted, hatchet-like jabs.
Once killed, the prey would have been ripped into bite-sized morsels by the powerful neck pulling the head straight back or, if possible, swallowed whole.
Feeding on a diversity of now-extinct mammals and competing with the likes of saber-tooth marsupials, terror birds became top predators in their environment.
At least one gigantic terror bird, Titanis, invaded No
|Contact: Cheryl Dybas|
National Science Foundation