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Re: semilunate carpal




Dinogeorge wrote:

ALL the most birdlike theropods appear in the fossil record AFTER
Archaeopteryx and cannot possibly be its ancestors.

This may have more to do than the inadequacy of the Middle Jurassic terrestial fossil record than any *real* absence of pre-_Archaeopteryx_ maniraptorans. There is tantalizing evidence of Jurassic maniraptorans (sensu Sereno, 1999 - oviraptorosaurs + deinonychosaurs + birds)... _Palaeopteryx_, _Nuthetes_ (though the paper has yet to come out, AFAIK), perhaps _Ozraptor_. And that's just the skeletal-based taxa. There's quite a number of teeth from various Jurassic sites (Guimarota and Morrison spring to mind, but there are others) which may pertain to maniraptorans.


In BCF, this HAS to
happen, because the birdlike theropods >descended from< the dino-birds. The
fossil record, taken at face value, DIRECTLY CONTRADICTS ground-up/BADD.

Taken at "face value", yes. But this is a pretty hefty caveat. Isn't this the purpose of character analysis - to see if our "face-value" interpretations of the data hold up to scrutiny?


The
cladistics requires EVERY KNOWN theropod to have a substantial ghost lineage
to the point of its divergence from the dinosaur-to-birds lineage.

The ghost lineage separating _Archaeopteryx_ and basal dromaeosaurids (or basal deinonychosaurs) such as _Microraptor_ and _Sinornithosaurus_ may only be around 5-10 million years. Is this really all that bad? Compare (for example) the ghost lineage that links _Homo sapiens_ to chimpanzees (_Pan_).


Not only is Archaeopteryx an advanced
maniraptoran, it is also the EARLIEST ONE known, save perhaps for a few
small, nondescript teeth of about the same age.

_Archaeopteryx_'s integument is highly derived, but its osteology is much less so (hence its "mosaic" morphology). As I said in a previous response, _Archaeopteryx_'s skeleton is not all that different from that of many non-avian maniraptorans. (Professor Ostrom, take a bow.)



Tim



---------------------------------------------------------------------

Timothy J. Williams

USDA-ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163




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