from chickens to dinosaurs?

In today’s Royal Society news clippings was an item concerning a scientist’s intention to manipulate chickens to get dinosaurs. Intriguing! A quick google search found a number of news items like this one – the researcher concerned believes that by flicking various switches during an embryo chicken’s development, he’ll be able to ‘reproduce the dinosaur anatomy’.

Well! Birds are actually very dinosaur-like in a lot of their anatomy anyway, & in fact that’s part of the evidence supporting the hypothesis that birds evolved from dinosaurs, rather than some other branch of the reptilian family tree. Not just any old dinosaur, either, but almost certainly a maniraptor (the same lineage as the raptors of Jurassic Park. Among the features that maniraptorian dinosaurs & birds have in common are:

  • an erect posture, with the hinge-like ankle high off the ground & feet positioned under the body
  • a neck with a distinct S-shape to it
  • a flexible wrist that allows the forearms to be tucked up close to the body
  • bones that are both thin-walled & hollow
  • large orbits, which house(d) correspondingly large eyes)
  • collarbones fused into what we know as a ‘wishbone’ (the furcula)
  • and – quite likely – feathers

and like all dinosaurs, birds have what’s known as a ‘diapsid’ skull (this refers to the number of apses, or openings, in the superficial bones of the skull), and an opening in the ‘cup’ of the pelvis where the major pelvic bones come together. In fact, the similarities are so great that at least one Archaeopteryx skeleton was originally classifed as a small theropod dinosaur.

So, while birds have some features in common with all dinosaurs, they most closely resemble one particular lineage, with its own specialised features. Consequently the statement that we can tweak developing chickens to get ‘the’ dinosaur anatomy is a bit misleading (especially because, under all those feathers, we already have some of it!). What we might get is something looking like one of those maniraptors. But dinosaurs were rather disparate in their body form, the the idea of fiddling with a chicken & getting something vaguely resembling a Triceratops or a Diplodocus is a bit to much to swallow.

The other thing I’d want to know is whether, in ‘the’ chicken genome, we actually know which genetic switches do what. This is not a trivial question – as I’ve said before, we are so much more than the sum of the bases in our genetic code. It’s one thing to have the full sequence of bases, & quite another to know which bits do what.

That’s not to say this sort of thing can’t be done. It’s already possible, for example, to grow hen’s teeth – this despite the fact that modern birds are toothless & have been that way for many millions of years. But I suspect we’re a while yet from seeing this happen.

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