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RE: New review paper of tyrannosaur paleobiology in Science, with new phylogeny



Guy Leahy wrote-

> I have a couple of related questions; are good juvenile specimens of 
> Daspletosaurus known? If so, is the immature skull of this genus also long 
> and low compared to the adults? Are there any published references with 
> photos/illustrations?

Yes, yes and yes. RTMP 94.143.1, as illustrated by Currie (2003), which not 
only has a long and low skull, but also has Alioramus-like nasal crests.

Currie, 2003. Cranial anatomy of tyrannosaurid dinosaurs from the Late 
Cretaceous 
  of Alberta, Canada. Acta Palaeontologica Polonica. 48(2), 191–226.

Mickey Mortimer

> Guy Leahy
>
>
> > Date: Sun, 19 Sep 2010 15:02:27 -0700
> > From: mickey_mortimer111@msn.com
> > To: dinosaur@usc.edu
> > Subject: RE: New review paper of tyrannosaur paleobiology in Science, with 
> > new phylogeny
> >
> >
> > I'll second Denver's observation here. Analyzing a known young specimen 
> > (based on histology) as an adult is simply improper and bound to result in 
> > incorrect phylogenetic placements. The fact Carr's own analysis incorrectly 
> > places juvenile Tyrannosaurus (in the same position Alioramus emerges in) 
> > should all the proof one needs. I still believe Alioramus is probably a 
> > juvenile Tarbosaurus (and that A. altai is certainly a junior synonym of A. 
> > remotus). As I said on my site, the
> > fact most differences could be explained by ontogeny, coupled with the 
> > unique
> > similarities present in Alioramus and the contemporaneous Tarbosaurus
> > strongly suggest the former is a juvenile of the latter. The alternative 
> > presented
> > by Brusatte et al., where a distinct genus known only from juvenile 
> > specimens
> > and based on characters largely found in juvenile tyrannosaurs is 
> > contemporaneous
> > with a taxon it is not the sister group of yet shares autapomorphies with, 
> > is
> > considered unlikely.
> >
> > http://home.comcast.net/~eoraptor/Tyrannosauroidea.html#Alioramusremotus
> >
> > Mickey Mortimer
> >
> > ----------------------------------------
> > > Date: Thu, 16 Sep 2010 18:35:38 +0000
> > > From: df9465@yahoo.co.uk
> > > To: dinosaur@usc.edu
> > > Subject: Re: New review paper of tyrannosaur paleobiology in Science, 
> > > with new phylogeny
> > >
> > > Can somebody explain to me the weird trend in Brusatte tyrannosaur 
> > > articles
> > > where he ignores some of his own points about ontogeny.
> > >
> > >
> > > On the one hand, he states that tyrannosaurid skulls elongate through 
> > > ontogeny,
> > > teeth become more robust, yet on the other hand claims these same 
> > > characters are
> > > important features of Alioramus, which the authors acknowledge is based 
> > > on a
> > > juvenile specimen and derives form the same deposits as Tarbosaurus. IIRC
> > > Alioramus is justified by the apparent elaborate skull ornamentation. 
> > > However,
> > > skull ornamentation in dinosaurs can often be less pronounced/elaborate in
> > > adults (Horner & Goodwin, Triceratops). Brusatte cites this in the 
> > > Alioramus
> > > description, but makes the opposite claim.
> > >
> > >
> > > ----------------------------------
> > > Denver Fowler
> > > df9465@yahoo.co.uk
> > > http://www.denverfowler.com
> > > -----------------------------------
> > >
> > >
> > >
> > > ----- Original Message ----
> > > From: "Thomas R. Holtz, Jr."
> > > To: DML
> > > Sent: Thu, 16 September, 2010 12:18:55
> > > Subject: New review paper of tyrannosaur paleobiology in Science, with new
> > > phylogeny
> > >
> > > http://www.sciencemag.org/cgi/content/full/329/5998/1481
> > >
> > > Brusatte, S.L., M.A. Norell, T.D. Carr, G.M. Erickson, J.R. Hutchinson, 
> > > A.M.
> > > Balanoff, G.S. Bever, J.N. Choiniere, P.J. Makovicky, & X. Xu. 2010. 
> > > Review:
> > > Tyrannosaur Paleobiology: New Research on Ancient Exemplar Organisms.
> > > Science 329: 1481-1485.
> > >
> > > Tyrannosaurs, the group of dinosaurian carnivores that includes
> > > Tyrannosaurus rex and its closest relatives, are icons of prehistory. They
> > > are also the most intensively studied extinct dinosaurs, and thanks to 
> > > large
> > > sample sizes and an influx of new discoveries, have become ancient 
> > > exemplar
> > > organisms used to study many themes in vertebrate paleontology. A 
> > > phylogeny
> > > that includes recently described species shows that tyrannosaurs 
> > > originated
> > > by the Middle Jurassic but remained mostly small and ecologically marginal
> > > until the latest Cretaceous. Anatomical, biomechanical, and histological
> > > studies of T. rex and other derived tyrannosaurs show t
> > > rapidly, were capable of crushing bite forces,
> > > had accelerated growth rates and keen senses, and underwent pronounced
> > > changes during ontogeny. The biology and evolutionary history of
> > > tyrannosaurs provide a foundation for comparison with other dinosaurs and
> > > living organisms.
> > >
> > > -----
> > >
> > > A review paper, not new research as such. But Brusatte & Carr have pooled
> > > their resources to produce a new phylogeny:
> > >
> > > Tyrannosauroidea
> > > |--Proceratosauridae
> > > | |--Kileskus
> > > | `--+--Proceratosaurus
> > > | `--+--Guanlong
> > > | `--Sinotyrannus
> > > `--+--Dilong
> > > `--+--+--Eotyrannus
> > > | `--Stokesosaurus
> > > `--+--Xiongguanlong
> > > `--+--Dryptosaurus
> > > `--+--Raptorex
> > > `--+--Appalachiosaurus
> > > `--+--Bistahieversor
> > > `--Tyrannosauridae
> > > |--Albertosaurinae
> > > | |--Albertosaurus
> > > | `--Gorgosaurus
> > > `--Tyrannosaurinae
> > > |--Alioramus
> > > `--+--Utah taxon
> > > `--+--Daspletosaurus
> > > `--+--Tarbosaurus
> > > `--Tyrannosaurus
> > >
> > > Congrats, folks!
> > >
> > > 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
> > >
> > >
> > >
> >