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RE: Zoological Journal of the Linnean Society 149 (4)
Gishlick, A. D., & J. A. Gauthier. 2007. On the manual morphology of
_Compsognathus longipes_ and its bearing on the diagnosis of
Compsognathidae. Zoological Journal of the Linnean Society 149 (4):
Gauthier and Gishlick (2007) write-
"To complicate matters, neither ?Compsognathus?
nor ?Compsognathidae? has ever been based on
anything more than plesiomorphic resemblances. Several
apomorphic details of manual morphology, especially
in the first metacarpal, can now be used to
diagnose a discrete tetanuran clade containing Compsognathus
longipes Wagner, 1861. Following the precepts
of the PhyloCode (Cantino & deQueiroz, 2000),
we will accordingly affix ?Compsognathidae? to this
clade by an apomorphy-based definition as follows:
Compsognathidae Marsh 1882 (Converted Clade
All tetanuran theropods stemming from the first
ancestor possessing an enlarged thumb with metacarpal
I novelties homologous to those in Compsognathus
longipes Wagner, 1861 (BSP 1563), including the
following (Fig. 12): metacarpal I very short (MII/
MI < 35% (26% in Compsognathus; 35% in Sinosauropteryx
prima), with discrete extensor tubercle
directed proximo-radially (ratio 1.8?1.4 proximally to
radially), and barely asymmetrical distal condyles
(< 5° offset ulnar to radial condyles)."
Ack!! First, Compsognathidae HAS been diagnosed with derived characters
before (e.g. Currie and Chen, 2001; Hwang et al., 2004; Holtz et al., 2004).
Indeed, the authors themselves note this on the previous page.
Three different characters?! Manual element ratios show interspecific
variation in coelurosaurs. For instance, Archaeopteryx's metacarpal I varies
from 25-30% of metacarpal II in length. Deinonychus' 46-52%, Gorgosaurus'
49-67%, Gallimimus' 88-97%, and Ornithomimus' 103-109%. And why choose <35%
when one of your two taxa has a ratio of 35%? Nqwebasaurus has the extensor
process, but not the short mcI or symmetrical condyles. Scipionyx has the
synmmetrical condyles, but not the short mcI or extensor process. Birds like
Ichthyornis and Iaceornis have the short mcI and extensor process, but not
the symmetrical condyles. *sigh*
The metacarpal I of Compsognathus wasn't even recognized as such until the
1990's (it was a "mystery element" in Ostrom's paper). Its odd morphology
has nothing to do with the concept of Compsognathidae.
At least Compsognathidae already has a phylogenetic definition (Holtz et
al., 2004)- (Compsognathus longipes <- Passer domesticus) .