Re: Caenagnathus species (pardon, long!)

["Jaime A. Headden" <qilongia@yahoo.com>]

To Dinogeorge, Grant Harding, and Tim Williams,

  Apologies for the late reply, I was caught offline
for a few days, thanks to my own stupidity.

  On the matter of N.Amer. *Chirostenotes*, it's a
sordid little bit of taxonomy that I do not see
resolved in the latest papers. Here goes my take on
it:

  The Players
  Chirostenotes pergracilis Gilmore, 1924
  "Ornithomimus" elegans Parks, 1933
  Macrophalangia canadensis Sternberg, 1934
  Caenagnathus collinsi Sternberg, 1940
  Elmisaurus rarus Osmolska, 1971
  Caenagnathus sternbergi Cracraft, 1972

  Okay, by 1972 we've got a happy little bunch of
theropods (or birds, considering Joel Cracraft's past
take on Caena). Currie and Russell (1988) synonymized
Macro with Chiro on the basis on a new skeleton; no
more Macro. Paul (1988) synonymized Chiro and Elmi on
the basis of the tarsometatarsi; relatively sound,
seconded (in a sense) by Currie (1989) -->. Currie
(1989) synonymized "O." elegans with Elmi based on the
similarity of the tarsometatarsi compared to Chiro
(more later); no more "O.", now E. elegans. Sues
(1997) synonymized Caena and Chiro, long suspected but
improvable until then; no more Caena. This made all
Caena's species Chiro's, so for the moment, the list
might go this way:

  Chirostenotes pergracilis [+ Caena, + Macro]
  Chirostenotes collinsi [= Caena]
  Chirostenotes sternbergi [= Caena]

  Sues took E. elegans and made it a species of Chiro,
arguing that he percieved no great distinction between
the two species, and promptly, on basis of size,
synonymized C. sternbergi and E. elegans; the latter,
by facter of being named first, became the valid name.
Currie (1989) placed E. elegans with Elmi on basis of
distinct fused distal tarsals forming a cap over the
metatarsus, and by possessing a posteromedial "tongue"
(E. rarus is larger, more robust, and has a posterior
ridge on the distal tarsals, rather like *Avimimus*
and parvicursorids (see Osmolska, 1971)).

  Relative slenderness in elegans as compared to rarus
and [Chiro] pergracilis argues for some distinction
from either as a species, but closer to rarus than to
pergracilis, despite that it's N.American, not Asian.
Such stratigraphic separation is not sufficient (given
LK transitional Berring bridges) for combining N.Amer.
species into a genus. C. sternbergi jaws are different
from C. pergracilis in that they have a shorter, wider
articular face, and relatively deeper and wider
surangular (e.g. more "robust") coupled with smaller
size and similar degree of fusion between the
elements. Refered jaw _may_ or _may not_ belong to the
species, but Cracraft's reasons to naming a new
species seem to me to be valid (based on proportions).
So, therefore, I'm more inclined to believe the
following to be closer phylogenetically:

Caenagnathidae
   Elmisaurus
      E. elegans
      E. rarus
   Chirostenotes (incl. Macrophal. and Caenagna.)
      C. pergracilis (incl. C. collinsi)
      C. sternbergi
      C. sp (unique, deeper jaw (no "beak" preserved))
      C. "new species?" (spade?-tipped jaw)
   new giant caenagnathid

  End.

===
Jaime A. Headden

"May I lure us, ere the mote ends us?"

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