At long last! Turner, Makovicky & Norell on dromaeosaurids

["Thomas R. Holtz, Jr." <tholtz@umd.edu>]

A major monograph, based in large part on Turner's dissertation work. Includes 
the first detailed osteologies for Adasaurus, updated
Achillobator images, some taxonomic revisions, and more:

http://www.bioone.org/doi/abs/10.1206/748.1

Turner, A.H., P.J. Makovicky, and M.A. Norell. 2012. A review of dromaeosaurid 
systematics and paravian phylogeny. Bulletin of the
American Museum of Natural History 371:1-206. 
doi: http://dx.doi.org/10.1206/748.1


Abstract

Coelurosauria is the most diverse clade of theropod dinosaurs. Much of this 
diversity is present in Paraves-the clade of dinosaurs
containing dromaeosaurids, troodontids, and avialans. Paraves has over 160 
million years of evolutionary history that continues to
the present day. The clade represents the most diverse living tetrapod group 
(there are over 9000 extant species of Aves-a word used
here as synonomous with "bird"), and it is at the root of the paravian 
radiation, when dromaeosaurids, troodontids, and avialans
were diverging from one another, that we find the morphology and soft tissue 
changes associated with the origin of modern avian
flight. Within the first 15 million years of known paravian evolutionary 
history members of this clade exhibited a difference of
nearly four orders of magnitude in body size, a value that is similar to the 
extreme body size disparity present today in mammalian
carnivorans, avians, and varanoid squamates. In this respect, Paraves is an 
important case study in characterizing the patterns,
processes, and dynamics of evolutionary size change. This last point is of 
particular interest because of the historical
significance placed on the role of body size reduction in the origin of powered 
avian flight.

Our study reviews and revises the membership of Dromaeosauridae and provides an 
apomorphy-based diagnosis for all valid taxa. Of the
currently 31 named dromaeosaurid species, we found 26 to be valid. We provide 
the most detailed and comprehensive phylogenetic
analysis of paravians to date in order to explore the phylogenetic history of 
dromaeosaurid taxa. The general pattern of paravian
relationships is explored within the broader context of Coelurosauria with an 
emphasis on sampling basal avialans, because of their
importance for character optimizations at the base of Paraves.

A large dataset was constructed by merging two datasets, one examining 
coelurosaur relationships broadly (based on previous TWiG
datasets) and the other examining avialan relationships specifically (Clarke et 
al., 2006). This merged dataset was then
significantly revised and supplemented with novel character analysis focusing 
on paravian taxa. During character analysis,
particular attention was given to basal members of Dromaeosauridae, enigmatic 
basal paravians such as Jinfengopteryx elegans and
Anchiornis huxleyi, and the incorporation of new morphological information from 
two undescribed troodontid species from the Late
Cretaceous of Mongolia. A final dataset of 474 characters scored for 111 taxa 
was used to address paravian evolution. This dataset
is important in that it bridges a phylogenetic gap that had persisted between 
studies on birds and studies on all other
coelurosaurs. Most scorings in this matrix were based on the direct observation 
of specimens.

All most parsimonious trees recovered in the cladistic analysis support the 
monophyly of Paraves, Troodontidae, Dromaeosauridae, and
Deinonychosauria. A new clade of basal troodontids is discovered including two 
undescribed Mongolian troodontids and Jinfengopteryx
elegans. Xiaotingia and Anchiornis form a clade at the base of Troodontidae. 
Recently proposed relationships within Dromaeosauridae
are further supported and a succession of clades from Gondwana and Asia form 
sister taxa to a clade of Laurasian dromaeosaurids.
Avialan monophyly is strongly supported with Archaeopteryx, Sapeornis, 
Jeholornis, and Jixiangornis forming the successive sister
taxa to the Confuciusornis node. This topology supports a more basal position 
for Sapeornis than previous phylogenetic analyses and
indicates a progressive acquisition of a fully "avian" shoulder morphology.

------------------
Taxonomic issues: 
In this monograph, they sink Linheraptor into Tsagaan mangas; Microraptor gui 
into M. zhaoianus; Sinornithosaurus haoiana into S.
millenii; Variraptor considered a nomen dubium; Saurornitholestes robustus as a 
nomen dubium.

A new clade Jinfengopteryginae is coined for all taxa closer to Jinfengopteryx 
than to Troodon formosus, Passer domesticus, and
Sinovenator changii. 

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA