Re: Distribution of manal phalanges in birds

[Mickey Mortimer <Mickey_Mortimer111@msn.com>]

Jason Michalak wrote-


> I was wondering if someone could help me with this. I know Archaeopteryx
and
> Confuciusornis had a phalangeal formula of 2-3-4, with curved unguals on
all
> three digits. Basal enantiornithines had 2-3-1, with claws on the first
two.
> What about the birds im missing, in particular the more derived ones? What
> are their phalangeal formulas, and do they have curved unguals?

curved unguals on all digits
2-3-4 - Archaeopteryx, Wellnhoferia, Shenzhouraptor, Confuciusornis
(=Jinzhouornis), Changchengornis
?-3-3(+?) - Yandangornis, "Proornis"
2-3-2(+?) - Jixiangornis

sort of ambiguous *
2-3-2 - Sapeornis, Protopteryx, Longipteryx, Eocathayornis
2-3-3 - Jibeinia

unknown
2-1(+?)-1(+?) - Longchengornis (at least one curved ungual)
?-3-? - Patagopteryx, Ambiortus (ungual on digit II straight)

curved unguals on digits I and II only
2-3-0(?) - Omnivoropteryx
2-3-1 - Concornis, Eoalulavis, Eoenantiornis, Sinornis, Yanornis,
Yixianornis, Ichthyornis **
?-1(+)-1- Gobipteryx

none- Hesperornithes ***

* The distal phalanges of digit III in basal birds are usually not described
or illustrated well enough to tell if they are unguals or not, or how curved
they are.  Sapeornis has a narrow tapering distal phalanx that doesn't look
ungual-like.  Jibeinia's appears to be a stout isoscleles triangle, which
may be a straight ungual in lateral view or a small curved one in dorsal
view.  Longipteryx's looks to be a very tiny curved ungual.  Protopteryx's
is a tiny elongate impression that could be either.  In Eocathayornis, it's
a tiny, seemingly curved element, perhaps an ungual.
** No unguals are preserved in Ichthyornis, but the well developed
ginglymoid articular surface of II-2 with deep flexor depressions indicates
a "well developed claw" according to Clarke (2002).
*** If I recall correctly, Hesperornis lacks a manus and Baptornis lacks
phalanges at least.

For modern birds, the condition varies somewhat.  None have more than one
phalanx on digit III, though I'm not sure how many lose this phalanx.  Only
a few birds are known to have unguals on digit II (natal anseriformes, the
hoatzin, occassional specimens of natal Circus, natal Otus, Rallus, adult
Corygyps).  Manual unguals on the first digit are usually found in basal
orders (galliformes, anseriformes, 'ciconiiformes', 'gruiformes', gaviids,
falconiformes, strigiformes, charadriiformes) but never in a lot of the
"higher landbirds" (columbiformes, 'coraciiformes', trogonids, piciformes,
passeriformes).  Unguals can be straight or curved, often varying in the
same genus.  I don't know exactly which birds reduce the number of
non-ungual phalanges on digits I and II, and how much they do so.
See - Fisher, 1940. The occurrence of vestigial claws on the wings of birds.
American Midland Naturalist. 23(1) 234-243.

Mickey Mortimer
Undergraduate, Earth and Space Sciences
University of Washington
The Theropod Database - http://students.washington.edu/eoraptor/Home.html