Our feathered friends?

This one isn't strictly curriculum-related – but it's such a neat bit of palaeontological detective work, I thought it was worth sharing 🙂

When I first saw Jurassic Park I was struck with the very bird-like way the raptors were presented – those quick head flicks & rapid leaps. I just loved it. Now a new paper (Turner, Makovicky & Norell, 2007) suggests that the film-makers didn't go far enough – it seems that Velociraptor might have had feathers.

The idea that at least some dinosaurs might have had feathers isn't new. After all, without its feathers, Archaeopteryx very closely resembles a small theropod dinosaur. So closely, in fact, that one Archaeopteryx fossil was originally filed away as a Compsognathus. More recently, a number of small dinosaurs have been found with either true feathers, or feathery filaments, on parts of their bodies. These remains have added further support to the hypothesis that birds evolved from theropod dinosaurs (there's a lot of other supporting anatomical evidence for the idea). But until now scientists have been uncertain as to whether the larger theropods – things like the raptors, and also T. rex – were also feathered.

Turner & his co-authors describe a fossil of Velociraptor mongoliensis that appears to have quill knobs on the ulna (one of the bones of its forearm). A number of modern birds also have this feature: the quill knobs are where the secondary flight feathers are fastened to the bone. The authors state that the knobs are evidence of the presence of feathers in this particular dinosaur.

This leads to the question – why would dinosaurs be feathered anyway? At 2m long, and weighing an estimated 25kg, Velociraptor would never have been able to fly! No, but the fact that both birds and some dinosaurs were feathered suggests that feathers had some other function when they initially evolved, and were later co-opted for flight (an example of an exaptation). Feathers on the body would almost certainly act as insulation – which in turn implies that some dinosaurs were endotherms. Wing feathers wouldn't be much good at insulating the body; Turner et al. suggest that they could have been used in display or acting a bit like a spoiler on racing car when the animal was running (keeping it on the ground, rather than lifting it off).

As a famous palaeontologist once said, rather than a slow, plodding 5-ton lizard, maybe T.rex was more like a 10,000 lb chicken from hell!

Reference: A.H. Tuner, P.J. Makovicky, & M.A. Norell (2007) Feather quill knobs in the dinosaur Velociraptor. Science 317: 1721.


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