manderguy

I'm talking about this with a creationist on another board and I need someone to double check what I know and fill in the gaps please.

As I understand it, during early mammalian circulatory development one of the aortic arches (are these the same as the gill arches found in embryos?) descends into the chest with the heart and it forms the aorta. Since the laryngeal nerve innervates that arch, it descends as well forming one of Oolon's suboptimal designs.

What happens to the other aortic arches?

And does anyone have Ergaster's graphic showing hte broken primate genes all broke in the same way (and it'd be really cool if it had the guinea pig LGGLO gene lined up as well)?

manderguy

doghouse

There are 6 pairs of aortic arches in the embryo.

I: Eventually become the external carotid arteries
II: Regress
III: Become portions of the common and internal carotid arteries
IV: On the left side, forms the aortic arch. On the right it forms the proximal portion of the right subclavian artery. And yes, the left recurrent laryngeal nerve travels around the aortic arch, although it doesn’t provide innervation to the arch. The right recurrent laryngeal nerve hooks around, but does not innervate the right subclavian artery.
V: Regress
VI: Become the pulmonary arteries and ductus venosus

I think this is accurate for humans and most domestic mammals, but it may vary with different species.

Gills are related to pharyngeal arches, which are different. These are also called branchial arches. In mammals, these develop into things other than gills, such as the eardrum and muscles of the face and jaw.

lpetrich

Here's the most detailed discussion that I could find, complete with diagrams.

Note that birds also have only one systemic arch -- the right one instead of the left one as in mammals. And that most other vertebrates have both systemic arches.

Coragyps

The sequences for the urate oxidase genes/pseudogenes in humans and three primates were posted here maybe a year ago, on the previous incarnation of this board. The poster was from Australia, but I can't recall his/her nick. I borrowed some of the data then and posted it halfway down the page, over there. Not remotely as good as the posting here, though - it had an owl monkey's working gene side-by-side with human and two ape pseudogenes.

Peez

And crocs have a four-chambered heart, just like birds and unlike almost all other "reptiles." I wonder why a god would do that? To trick us into accepting evolution? Perhaps that is why this god (or gods) also made crocs more genetically similar to birds than to snakes, as indicated in the creationist site Darwinism -- The forbidden subject:Sadly, the creationist cannot see that this is just more evidence for evolution, not evidence against it.

Peez

Wounded King

What sort of circulatory system did the larger dinosaurs have? Did they have ancilliary hearts or somesuch?

Doubting Didymus

I very nearly dropped dead when I first saw that quote. I think the original version I saw contained the words "less similar to a crocodile, a fellow reptile".

Just another "I told you so" for cladists, really.

I'm STILL utterly dumbfounded, by the way. What kind of delusions of grandeur must these people have to be interpreting the results of molecular biology papers, whilst retaining such utter ignorance of the most basic taxonomy. Did these people even go to school?