Re: The Size of Birds

["Mickey_Mortimer" <Mickey_Mortimer@email.msn.com>]

Dan Bensen wrote-

> Those species aren't valid?

Nope.  C. chuonzhous was based on a pes and distal tibiotarsus.  Three
characters supposed to distinguish C. chuonzhous from C. sactus were: three
phalanges on pedal digit I (one is actually metatarsal I); unfused proximal
tarsals (cannot be proven); pedal claws less curved (not true).
C. suniae was based on a complete skeleton supposed to be distinguished by
many features either also present in C. sanctus (V-shaped notch at tip of
snout; longer nasal processes on premaxillae; low and wide cervicals with
reduced spinal processes) or variable in C. santus (stronger long bones;
smaller humeral fenestra; shorter tarsometatarsus; more recurved manual
unguals).  Also, the supposedly diagnostic heart-shaped sternum is too
fragmentary to confirm.

> I would be _very_ surprised if C. dui and C. sanctus were found to be
> synonomous.  I've seen HP Tracy Ford's diagram of C. dui and it looks
_nothing_
> like C. sanctus.  Based on that reconstruction, I wouldn't have put them
in the
> same genus.

Well, let's see what we find when the description of C. dui is examined.
The supposed autapomorphies are:
- 15% smaller than holotype of C. santus
- mandible more slender anteriorly without anteroventral expansion
- upper jaw more pointed anteriorly
- manual ungual I not enlarged
- sternum more elongate with anterior notch and pair of short lateral
processes
- tarsometatarsus shorter than pygostyle

Examining the illustrations and photos of C. santus in Chiappe et al. shows
that characters 1, 3 and 6 are not distinctive.  GMV-2153 for instance is
only 8% larger than C. dui.  The beak may be slightly more slender than the
skulls of C. sactus that are illustrated, but not enough to be more than
individual variation.  The tarsometatarsus is shorter than the pygostyle in
at least one C. sanctus specimen (GMV-2133).  Characters 2, 4 and 5 (the
anterior notched part) do appear distinctive, at least with respect to the
illustrated and photographed specimens of C. sanctus in Chiappe et al..  One
odd observation I have is that in the figure of C. dui's sternum, the
sternal ribs are attached to the lateral sternal processes.  In C. sanctus
however, they are articulated with the sternal body anterior to the lateral
processes.  I believe this is the normal configuration for birds and thus
find it probable that the figure of C. dui's sternum in Hou (1999) is
incorrect.  So, Confuciusornis dui can be distinguished from C. sanctus by:
- mandible without anteroventral expansion
- manual ungual I not as large
- sternum with anterior notch
Whether this falls in the range of individual variation of C. santus I
coudn't say, but based on published illustrations and photos, it does not.
The length, by the way, is 180 mm.

Mickey Mortimer