Re: Hoatzin & Archaeopteryx

[Mickey Mortimer <Mickey_Mortimer111@msn.com>]

Amtoine Grant wrote-

> Sorry, I realize that I meant to say "has anybody compared the
> skeletons of Archaeopteryx and the Hoatzin".

I'm sure people have, many decades ago.  The bottom line is that the hoatzin
resembles other living birds in nearly all respects where they differ from
Archaeopteryx.  For instance, using Mayr and Clarke's (2003) data matrix,
the hoatzin is like modern birds and unlike Archaeopteryx in the following-
- toothless premaxilla.
- neognathous palate.
- basipterygoid articulation absent.
- ossified eustachian tubes.
- frontals and parietals fused.
- distinct medial head on quadrate.
- ossified dentary symphysis.
- cervical ribs fused to vertebrae.
- less presacral vertebrae.
- notarium.
- dorsal vertebrae heterocoelous.
- supracoracoid foramen absent.
- more costal processes on sternum.
- uncinate processes present, fused to ribs.
- pneumotricipital foramen on humerus.
- scapulotricipital sulcus on humerus.
- more sacral vertebrae.
- closed iliosynsacral canal.
- ilioischiadic foramen closed.
- hypotarsus with well developed cristae and sulci.
I'd be willing to bet hoatzins also have many fused skull elements,
toothless maxillae and dentaries, reduced temporal arches, heterocoelous
cervicals, a pygostyle, fused (meta)carpal and (meta)tarsal elements, a
trochanteric crest, reduced fibulae, no fifth metatarsal, an alula, and
plenty of other characters of living birds absent in Archaeopteryx.

Mickey Mortimer
Undergraduate, Earth and Space Sciences
University of Washington
The Theropod Database - http://students.washington.edu/eoraptor/Home.html