Fw: Atrociraptor marshalli: A New Dromaeosaurid

["David Marjanovic" <david.marjanovic@gmx.at>]

Just in case it still hasn't got through to everyone.

----- Original Message -----
From: "Dino Guy Ralph" <ralph.miller@alumni.usc.edu>
Sent: Monday, April 19, 2004 8:24 PM

I can't believe nobody has reported it yet, but here goes!  _Feathered
Dragons: Studies on the Transition from Dinosaurs to Birds_, edited by
Philip J. Currie, Eva B. Koppelhus, Martin A. Shugar, and Joanna L. Wright,
was released last week.  I have it in my greedy little manus as I write.
The book, which is based on the "Florida Symposium on Dinosaur Bird
Evolution" that celebrated _Bambiraptor feinbergi_ and an exhibition of some
of the Liaoning specimens, has many highlights, which I will not detail now
for lack of time.  Hopefully, someone else on the list will buy the book and
offer their comments.  (It goes for around $50 US).

I quote the first paragraph from the _Atrociraptor_ paper, which is on pp.
112-132:

"4. A New Dromaeosaurid from the Horseshoe Canyon Formation (Upper
Cretaceous) of Alberta, Canada
Philip J. Currie and David J. Varricchio

Abstract
The discovery of a new dromaeosaurid in the Horseshoe Canyon Formation
(uppermost Campanian-lowermost Maastrichtian, Upper Cretaceous) increases
the known diversity of this interesting group of theropods, considered by
many as the closest non-avian theropod relatives of _Archaeopteryx_ and
other derived birds.  The new animal, known from a partial skull, is
relatively small.  It differs from the contemporary _Bambiraptor_,
_Saurornitholestes_, and _Velociraptor_ in having a short, deep face.  The
teeth are more strongly inclined toward the throat than they are in most
other dromaeosaurids, and are all almost the same size.  Phylogenetic
analysis suggests that the new dromaeosaurid may represent an independent
lineage having origins back in the early Cretaceous."

More:

"Taxonomy
Dinosauria Owen,1842
Saurischia Seeley, 1888
Theropoda Marsh, 1881
Dromaeosauridae Matthew and Brown, 1922
Velociraptorinae Barsbold, 1983
_Atrociraptor marshalli_, new genus, new species

Etymology:
"Atroci" is a Latin word meaning savage, whereas "raptor" is Latin for
robber.  The species is named after Wayne Marshall of East Coulee, Alberta,
who discovered the type specimen.

Holotype:
TMP 95.166.1, a partial skull that includes premaxillae, the right maxilla,
the right dentary, portions of the left dentary, teeth, and numerous bone
fragments.

Locality and age:
The holotype was recovered from strata about 5 m above the Daly Coal Seam #7
(Gibson 1977) in the Horseshoe Canyon Formation (upper Campanian or lower
Maastrichtian, Upper Cretaceous) at UTM 12U 372,125E,5,708,055 N, which is
about 5 km west of the Royal Tyrell Museum of Paleontology in Drumheller,
Alberta.

Diagnosis:
Small velociraptorine, dromaeosaurid theropod that differs from
_Saurornitholestes_ and _Velociraptor_ in having a shorter, deeper face.
Subnarial body of premaxilla is taller than its anteroposterior length as in
_Deinonychus_ and possibly _Dromaeosaurus_.  Internarial and maxillary
processes of premaxilla subparallel and oriented more dorsally than
posteriorly.  Larger maxillary fenestra than in any other velociraptorines.
Maxillary fenestra is directly above the promaxillary fenestra, rather than
well behind it as in all other dromaeosaurids.  Maxillary teeth more
strongly inclined toward the throat than in all other dromaeosaurids except
_Bambiraptor_ and _Deinonychus_.  Maxillary dentition is essentially
isodont."

The cladogram, Figure 4.8, shows it as a sister taxon to _Deinonychus_.
Based on the Philip Currie's reconstruction, Figure 4.7, the skull would
have been approximately 21 cm long.  I had the pleasure of seeing a display
of the holotype when I visited the Royal Tyrell last summer, so I knew it
was coming!  By the way, I think that Michael Skrepnick's fluffy color
portrait of _Atrociraptor_ on page 178 is adorable.

--------
"Dino Guy" Ralph W. Miller III
Docent at the California Academy of Sciences
proud member of the Society of Vertebrate Paleontology