Re: New alvarezsaurid

["Matthew Troutman" <m_troutman@hotmail.com>]

>Derived characters on the bird's part. These are derived animals, don't 
>forget, as compared to theropods in the classic sense (before many of 
>these new-fangled birds poked their skulls out of the limestone).

 Very derived. They show some features in the palate and mandible that 
are similiar to dicynodonts, but nobody has suggested relationship with 
these synapsids ( for obvious reasons.)


><Avimimids are chimeras.>
>
>I was pretty sure of this when I first heard of it, some time ago, but 
I 
>couldn't resist drawing Avi as all those specimens recontructed him. 
May 
>I ask which are referred to what? I know the pelvis is theropod, the 
>carpometacarpus is avian, and the skull...well, that has theropod 
>attributes _and_ avian ones. Incidentally, much of my theories with Avi 
>and Ovi concentrate on the pelvis and skull, so I would like to know 
the 
>present view on what belonged to who, so I can correct my illustrations 
>and notes before I've truly sunk myself without a lifevest on.

    Perle has said the skull is that of a juvenile oviraptorid. The 
carpometacarpus and ulna are that of a bird ( Parvicursor has been 
suggested ) and the pelvis and rest of the body is up for grabs ( I 
think oviraptorid too ).


><Lacking many, many, many, many, many, many, avain characters 
>excludes them from Aves.>
>
>Granted, yet Aves is highly derived from the condition of, say, 
>*Deinonychus* and even *Archaeopteryx*, who lack many, many, many, many 
>avian characters as well.

    Deinonychus and dromaeosaurs in general lack many avain attributes, 
but Archaeopteryx has features that clearly link it with other birds:

  1) Crocodilian-like teeth with a triangular shape, lack of serrarions, 
consticted neck between root and crown, and replacement pits that are 
closed ventrally and contain teeth.
  2) Reduced postorbital bar that fails to reach the jugal.
  3) Loss of squasmol-quadratojugal bar. 
  4) Loss of ascending process of the jugal. 
  5) Quadrate with large orbital process.
  6) Triradiate palatine. 
  7) Hypertrophy of the forelimb. 
  8) Heart-shaped ulnarae. 
  9) Single sternal element.
 10) Caudal vertebra number less then 25.

And Peter Bulsholtz's ( sp ) pelvic characters:

 a) Loss of cranial pubic foot ( also seen in Unenlagia and dromaeosaurs 
).
 b) Anterodorsal ischial process.
 c) Distal migration of the obtutator process.

><The evidence is still misinterpreted. What you are viewing as valid 
>characters are demonstratebly convergences when you look at the avian 
>family tree.>
>
>_Birds_ demostrate convergences to the point of icredulity among 
>themselves, so much that we can hardly tell one fossil in a Holocene 
>rock from a livinf descendang or relative (the answer's not in yet on 
>*Diatryma* or *Titanis*, so....).

    Yes, they do show convergences, but these convergences are 
traceable.

><Chickens still do fly for short distances. Anyway a paedomorphic 
>change is associated with the loss of flight and this includes loss of 
a 
>carina.>
>
>And they are such ridiculous flyers that woodcocks with short little 
>keels appear like lightning bolts in comparison.

    There are many reasons for the disparity in sternal structure in 
birds ( lung ventilation, type of lifestyle, etc. ). Loss of a carina is 
always associated with loss of flight.

MattTroutman

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