[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Sinusonasus, Aberratiodontus and other birds



David Marjanovic wrote-

> Many thanks to everyone for the pdfs... *Sinusonasus* seems to be more
> derived than *Sinovenator* (with which it co-occurs) and *Sinornithoides*,
> but less than the rest.

I'm not sure how Sinusonasus relates to Sinornithoides and Byronosaurus.
Though the authors find it to be more derived than Sinornithoides, the
subnarial premaxilla-nasal contact, larger external naris, unserrated
anterior teeth, unhooked serrations, shorter tail, and lower amount of
caudals with transverse processes are more primitive.
http://students.washington.edu/eoraptor/Troodontidae.htm#Sinusonasusmagnoden
s

> *Aberratiodontus* (real spelling) has a huge
> postorbital, but the lower half is almost completely missing and may or
may
> not have contacted the thin jugal... Teeth of different sizes are
> distributed much like in mammals. The sternum is quite big, much like in
> ornithurines, but has a short keel restricted to the caudal end (now I
just
> hope the specimen is really in ventral view!) The feet say "shorebird" --
> long toes, small claws --, "but not a very specialized one". The authors
say
> in passing that *Yanornis* should be considered a synonym of
> *Songlingornis*.

Aberratiodontus is odd.  The cranial reconstruction is terrible (see
http://students.washington.edu/eoraptor/Aberratiodontus%20color.psd.jpg for
my interpretation of the in situ specimen, I'll do a reconstruction soon).
The "prefrontals" look like the anterior portion of frontals to me.  I don't
see clear evidence for a postorbital, the structure identified as such could
easily be a quadrate instead.  As for what its phylogenetic relationships
are, I'm not sure yet.  Some characters are primitive (eleven cervical
vertebrae; sternal keel restricted posteriorly; metatarsus only fused
proximally) but others are derived (strongly curved scapula; U-shaped
furcula; reduced hypocleidium; broad postacetabular process).  Maybe it's
just basal to Ornithuromorpha.  No enantiornithine synapomorphies are
mentioned.  The description itself is poorly written, using a lot of
seemingly out of place technical terminology (while describing dental
morphology and replacement), uselessly vague details and inaccurate word
choice.  The authors could have benefited from an English-speaking reviewer.
Yanornis is, of course, distinct from Songlingornis.  The latter actually
resembles Yixianornis more.
http://students.washington.edu/eoraptor/Pygostylia.htm#Aberratiodontuswui

> > The earliest neornithine seems to be Gallornis (Neocomian),
>
> If we really think "a fragment of the proximal femur and an indeterminate
> portion of the humerus"
> (http://wiki.cotch.net/wiki.phtml?title=The_Neornithine_'Big_Bang') are
> diagnostic to that level.

Hope (2002) notes the presence of an elevated trochanteric crest and
anteroposteriorly expanded antitrochanteric facet, both supposedly
restricted to neornithines.

> > then a Bissekty tibiotarsus (Coniacian; Nessov, 1992).
>
> Hmmm... does it have things like the bridge over the extensor tendons?

Not sure, I'd have to check my refs.  It was originally part of the type of
Lenesornis maltshevskyi.

> > Besides these records, there are many Campanian taxa.
>
> "Many"? *Palintropus* (a ?galliform) and?

An unnamed Japanese taxon (Kakegawa, 1999), a Barungoyot tarsometatarsus
(Kurochkin, 1995), a Judith River coracoid (Hope, 2002), Cimolopteryx sp.
nov. (Hope, 2002), and possibly the two named Mesozoic loons.

Mickey Mortimer