Tuesday, November 06, 2007

Mesozoic Birds Looked to the Skies But Lived On The Ground

Foraging modes of Mesozoic birds and non-avian theropods. 2007. C.L. Glen, and M. B. Bennett. Current Biology Vol 17, R911-R912, 06 November 2007.

Earliest birds acted more like turkeys than common cuckoos
From the press release:

By comparing the claw curvatures of ancient and modern birds, the researchers provide new evidence that the evolutionary ancestors of birds primarily made their livings on the ground rather than in trees.

“The claws of Mesozoic birds and their immediate ancestors, the non-avian theropods, are relatively ‘straight’—most like [those] of birds that are now either specialized for walking on the ground or have a preference for it, rather than the highly curved claws of birds that spend a lot of time in trees,” said Christopher Glen.

“In summary,” they concluded, “since claw angle is independent of body size and the evolutionary relationships among species, it is a reliable indicator of the predominant behavior reliant upon hind-limb locomotion, and can make an important contribution to reconstructing the ‘ecomorphology’ of fossil species—how they lived and used their environments. Our findings suggest early birds foraged predominantly on the ground, rather than supporting previous suggestions of arboreal claw adaptations, which appear to have evolved later in the lineage.”