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Neovenatoridae and Megaraptora: now it can be told!



Just out in Early View on Naturwissenschaften (and I'm so glad I can
publically talk about this now!):

Benson, R.B.J., M.T. Carrano & S.L. Brusatte. 2009. A new clade of archaic
large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to
the latest Mesozoic. Naturwissenschaften doi:10.1007/s00114-009-0614-x
Abstract  Non-avian theropod dinosaurs attained large body sizes,
monopolising terrestrial apex predator niches in the Jurassic-Cretaceous.
>From the Middle Jurassic onwards, Allosauroidea and Megalosauroidea
comprised almost all large-bodied predators for 85 million years. Despite
their enormous success, however, they are usually considered absent from
terminal Cretaceous ecosystems, replaced by tyrannosaurids and abelisaurids.
We demonstrate that the problematic allosauroids Aerosteon, Australovenator,
Fukuiraptor and Neovenator form a previously unrecognised but ecologically
diverse and globally distributed clade (Neovenatoridae, new clade) with the
hitherto enigmatic theropods Chilantaisaurus, Megaraptor and the
Maastrichtian Orkoraptor. This refutes the notion that allosauroid
extinction pre-dated the end of the Mesozoic. Neovenatoridae includes a
derived group (Megaraptora, new clade) that developed long, raptorial
forelimbs, cursorial hind limbs, appendicular pneumaticity and small size,
features acquired convergently in bird-line theropods. Neovenatorids thus
occupied a 14-fold adult size range from 175 kg (Fukuiraptor) to
approximately 2,500 kg (Chilantaisaurus). Recognition of this major
allosauroid radiation has implications for Gondwanan paleobiogeography: The
distribution of early Cretaceous allosauroids does not strongly support the
vicariant hypothesis of southern dinosaur evolution or any particular
continental breakup sequence or dispersal scenario. Instead, clades were
nearly cosmopolitan in their early history, and later distributions are
explained by sampling failure or local extinction.

Includes MAJOR new phylogentic analyses (combining the ongoing work of the
three authors).

Neovenatoridae includes Neovenator, Chilantaisaurus, and Megaraptora. The
latter is a clade of gracile forms including Megaraptor, Fukuiraptor,
Australovenator, Aerosteon, and (Maastrichtian) Orkoraptor.

Neovenatoridae is the sister taxon to Carcharodontosauridae in a larger
Carcharodontosauria (= "Carcharodontosauridae" as I used it in Dinosauria
II).

Other tidbits in the phylogenetic analysis in the supplementary data:
Sinraptoridae includes Lourinhasaurus, Poekilopleuron, and
Metriacanthosaurus.

Megalosauroidea (aka Spinosauroidea) has the following structure (once
Chuandongocoelurus and Pivetausaurus are a posteriori deleted):
+--Neotetanurae
`--+--+--Xuanhanosaurus
   |  `--+--Marshosaurus
   |     `--+--Condorraptor
   |        `--Piatnitzkysaurus
   `--+--Monolophosaurus
      `--+--Spinosauridae
         `--+--+--Eustreptospondylus
            |  `--+--Magnosaurus
            |     `--Streptospondylus
            `--+--Duriavenator
               `--+--+--Afrovenator
                  |  `--Dubreuillosaurus
                  `--+--Megalosaurus
                     `--Torvosaurus

I've known about this analysis for awhile and am very happy to see it out,
but (I'm sure) not as much as the authors.

Congratulations on a very interesting study!

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, Earth, Life & Time Program, College Park Scholars
http://www.geol.umd.edu/~jmerck/eltsite/
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