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Re: Introducing Mahakala omnogovae, little dromaeosaurid of Mongolia



----- Original Message ----- From: "Thomas R. Holtz, Jr." <tholtz@umd.edu>
Subject: Introducing Mahakala omnogovae, little dromaeosaurid of Mongolia


Inclusion of the data into the latest AMNH Theropod working group matrix
reveals it to be the basalmost dromaeosaurid, despite its age. More derived
dromaeosaurids are better resolved phylogenetically than earlier versions of
this matrix: a clade comprised of Unenlagiinae (Shanag + Buitreraptor +
(Rahonavis + Unenlagia)) + Sinornithosaurus + Microraptorinae (Microraptor
gui + Microraptor zhaoianus + Graciliraptor), and a clade of "classic
dromaeosaurids": Velociraptorinae (Tsaagan + (Saurornitholestes +
(Velociraptor + Deinonychus))) + Dromaeosaurinae (Adasaurus + Dromaeosaurus
+ (Achillobator + Utahraptor)).

The resolution is further increased by the fact that the tree in the paper is not the strict consensus. It is the Adams consensus (of 1296 trees). Supplementary information, p. 27: "Strict consensus differs in reduced resolution within the *Adasaurus*, *Dromaeosaurus*, *Achillobator*, *Utahraptor* clade due to lability in placement of *Dromaeosaurus*; reduced resolution within the *Unenlagia*, *Rahonavis*, *Buitreraptor*, *Shanag* clade due to lability in placement of *Shanag*; and reduced resolution within the oviraptorosaurs more derived than *Incisivosaurus gauthieri*."


The Velociraptorinae-Dromaeosaurinae split is real, though, and so are the positions of *Jeholornis* and *Jinfengopteryx*.

Given the size of the basal members of each clade ((Archaeopteryx +
Jeholornis) + Pygostylia); (Mei + Sinovenator) + Jinfengopteryx; Mahalaka),
the basal eumaniraptoran would seem to be a small Archaeopteryx-sized
critter.

Not just "seem". They calculate that using a sophisticated method that is... completely different from that used in Laurin 2004 (body size evolution of, uh, limbed vertebrates, Devonian to Middle Permian, Systematic Biology) and my M.Sc. thesis. :-o Will be interesting to compare. It apparently doesn't take branch lengths into account.