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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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6 Comments

There's also the respiratory system, for which the fossil evidence indicates was actually present in at least 3 branches of Archosauria. And going via evolutionary reasoning, was possibly present also in some form in the rest of Archosauri.

http://svpow.wordpress.com/2009/05/08/x-men-origins-pneumaticity/
http://people.eku.edu/ritchisong/birdrespiration.html
http://sauroposeidon.net/Wedel2006-origin-of-pneumaticity.pdf
http://oak.cats.ohiou.edu/~ridgely/OconnorClaessensairsacs.pdf

And yeah, without detailed understandings of the regulatory genetics and Gattaca style genetics technology, this idea seems to me to be a pipe-dream. A nice pipe dream, that can probably draw in the private funding, and unravel some more of vertebrate developmental biology, but a pipe dream non-the-less.

Thanks for this & the extra references, Nick - I will have to do some more reading :-)
What do you think of that recent claim (can't remember just where I saw it) that the avian gas exchange system relies on the fact (?) that birds' femurs don't move much if at all when they're walking/running?

PS should have added: & that thus dinosaurs couldn't have had the same or a similar system... *blush*

Not a problem.

And on Ruben's "stuff" summed up nicely and more in-depth that I can possibly do on TetZoo;
http://scienceblogs.com/tetrapodzoology/2009/07/birds_cannot_be_dinosaurs.php

There were some real, utterly stupid howlers in Ruben's press release...

Wow - that is a great post! Thank you very much indeed for providing the link :-)

Cheers!

Also, Darren's got a post or two on the "Birds Are Not Dinosaurs" hypothesis and why it's wrong if you're interested in knowing a bit more about the BANDit's. Along with some nice posts on feathered dinosaurs.

So many wonderful things to read, so little time... But yes, I am interested. I did know about the 'birds aren't dinos' camp but wasn't familiar with some of the recent stuff that's come from that direction. I'll give the links to my colleague who teaches vertebrate evolution; she will find them very useful :-)

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  • Alison Campbell: So many wonderful things to read, so little time... But read more
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  • Alison Campbell: Wow - that is a great post! Thank you very read more
  • NickS: Not a problem. And on Ruben's "stuff" summed up nicely read more
  • Alison Campbell: Thanks for this & the extra references, Nick - I read more
  • NickS: There's also the respiratory system, for which the fossil read more