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That's what *Anchiornis* means. And, sitting behind a university proxy
server here in Vienna, I have full online access.
Xu Xing, Zhao Qi, Mark Norell, Corwin Sullivan, David Hone, Gregory
Erickson, Wang Xiaolin, Han Fenglu & Guo Yu: A new feathered maniraptoran
dinosaur fossil that fills a morphological gap in avian origin, Chinese
Science Bulletin, 6 pages, accepted November 15, 2008, published online
Recent fossil discoveries have substantially reduced the morphological gap
between non-avian and avian dinosaurs, yet avians including *Archaeopteryx*
differ from non-avian theropods in their limb proportions. In particular,
avians have proportionally longer and more robust forelimbs that are capable
of supporting a large aerodynamic surface. Here we report on a new
maniraptoran dinosaur, *Anchiornis huxleyi* gen. et sp. nov., based on a
specimen collected from lacustrine deposits of uncertain age in western
Liaoning, China. With an estimated mass of 110 grams, *Anchiornis* is the
smallest known non-avian theropod dinosaur. It exhibits some wrist features
indicative of high mobility, presaging the wing-folding mechanisms seen in
more derived birds and suggesting rapid evolution of the carpus. Otherwise,
*Anchiornis* is intermediate in general morphology between non-avian and
avian dinosaurs, particularly with regard to relative forelimb length and
thickness, and represents a transitional step toward the avian condition. In
contrast with some recent comprehensive phylogenetic analyses, our
phylogenetic analysis incorporates subtle morphological variations and
recovers a conventional result supporting the monophyly of Avialae.
"Locality and horizon" are given as "Yaolugou locality, Jianchang county,
western Liaoning, China; lacustrine deposits of uncertain
Jurassic-Cretaceous age." The first keyword is "Early Cretaceous", but
that's it; there is no further information on stratigraphy or age. (Even
though the paper is in the "Geology" section of the journal.) I suppose the
locality was newly discovered and hasn't yet been correlated to anything.
The head, the end of the tail, and the right forearm & hand of the only
known specimen are not preserved, but the rest of the skeleton is almost
completely articulated, so the absence of a sternum (and uncinate processes,
not mentioned in the paper) can probably be taken at face value and is
compared to troodontids and *Archaeopteryx*. "Preserved soft tissues include
horny sheaths around the pedal unguals, and patches of feathers.
Specifically, extremely faint carbonized feather impressions are preserved
dorsal to the presacral vertebral column and average about 20 mm in length,
but their detailed structure is not clear."
Despite being tiny (total length estimated at 34 cm), the individual was
almost or completely adult, as shown by its fused neurocentral sutures and
by bone histology (yes, they cut up one of the femora). That makes it the
smallest nonavian dinosaur so far, for some values of "nonavian" at least.
The forelimb is about 80 % as long as the hindlimb, the humerus is as long
and thick as the femur, and the hand is about 130 % as long as the femur.
The authors therefore speculate that *Anchiornis* might have been able to
fly or perform some other activity that requires a "functional airfoil".
The tibiotarsus is 150 % the length of the femur. The first toe is preserved
lying medial to metatarsal II. The metatarsals are not fused and are
subarctometatarsal. The 2nd claw is considerably bigger than the others, but
has the same shape; the 2nd toe is shorter than the 4th, even though their
metatarsals end at the same level.
The semilunate carpal is laterally positioned so that it has little contact
with metacarpal I. Metacarpals II and III seem to be fused at their proximal
ends. "Manual phalanx II-1 is much thicker than all of the other manual
phalanges and nearly as thick as the ulna."
Phylogenetic analysis from either the original *Microraptor paper* or the
*Buitreraptor* paper -- the text contradicts the figure legend! -- plus 10
taxa and 48 characters:
| `--Aves [sensu Sereno]
| | `--*Protopteryx*
| `--+--*Confuciusornis sanctus*
| `--+--*Microraptor zhaoianus*
| | `--*Mei*
| `--+--"EK troodontid"
| `--+--*Saurornithoides mongoliensis*
| `--*Saurornithoides junior*
| |--*Velociraptor mongoliensis*
Nice to see confirmation for the position of *Jinfengopteryx*. Strange to
see that *Rahonavis* has jumped back (this is part of what the last sentence
of the abstract means by "monophyly of Avialae"). Bizarre to see
*Protopteryx* as the sister-group of *Sapeornis*. Frustrating to see the
polytomy that is Deinonychosauria.
I have no idea what the outgroup was; the authors don't say. In the figure
legend, the corresponding author (Xu) asks to be contacted "for detailed
information of the phylogenetic analysis".
"Wrist characters account for a significantly higher percentage of
synapomorphies diagnosing the Avialae than either the Paraves or Aves,
suggesting rapid evolution of the carpal region at the base of Avialae".
Avialae evidently means Aves + *Anchiornis*, and Paraves has to mean the
entire shown tree...
Anyway, *Anchiornis* is a great way to begin the new year!