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Nanotyrannus skull CT scan and other new papers



From: Ben Creisler
bh480@scn.org


First a small correction. The better link for the new Manidens abstract is:
http://www.springerlink.com/content/7747k1mm52628161/


A few recent dinosaur papers that don't appear to have been mentioned on
the DML yet (although the Nanotyrannus paper has been on a number of blog
sites):


Witmer, Lawrence M. & Ridgely, Ryan C. (2010)
The Cleveland tyrannosaur skull (Nanotyrannus or Tyrannosaurus): new
findings based on ct scanning, with special reference to the braincase. 
Kirtlandia 57: 61-81  
NOTE: The pdf won't be posted until November 2011 according to the website:
http://www.cmnh.org/site/ResearchAndCollections/Publications.aspx

Abstract:
The Cleveland Museum of Natural History?s skull of a small tyrannosaurid
theropod dinosaur (CMNH 7541) collected from the Hell Creek Formation has
sparked controversy, with competing hypotheses suggesting that it
represents a separate taxon of dwarf tyrannosaurid (Nanotyrannus
lancensis), a juvenile specimen of Tyrannosaurus rex (the only other
acknowledged Hell Creek tyrannosaurid), or a compromise position (a
juvenile Nanotyrannus). Beyond this controversy, CMNH 7541 holds importance
because of the anatomical information that such a well preserved skull can
provide, and it is in this context that we have sought to probe the
structure of the braincase region (e.g., pneumatic sinuses, cranial nerve
foramina), as well as other regions of the skull.

We subjected the skull to computed x-ray tomography (CT scanning), followed
by computer analysis and 3D visualization. The braincase and a number of
other bones (e.g., vomer, quadrate, quadratojugal, palatine, mandible) were
digitally "extracted" from the CT datasets. Although the new findings
strongly confirm the long-held view that CMNH 7541 pertains to a
tyrannosaurid, the mosaic of characters it presents makes finer taxonomic
assignment difficult. For example, some characters support affinities with
T. rex, yet other characters argue for a much more basal position.

The key question that awaits resolution is whether the differences observed
can be attributed to juvenility, and such resolution will require
information from new, as yet unpublished specimens. Nevertheless, some of
the differences seen in CMNH 7541 (e.g., the pattern of pneumatic foramina
in the basicranium) are highly divergent and are harder to attribute to
ontogeny. Among other findings, we report here thin, laminar structures
within the main nasal airway that are interpretable as being respiratory
turbinates, which have potential implications for metabolic physiology.

==

John R. Hutchinson, Karl T. Bates, and Vivian Allen (2011)
Tyrannosaurus rex Redux: Tyrannosaurus Tail Portrayals
The Anatomical Record (advance online publication)
Article first published online: 17 MAR 2011
DOI: 10.1002/ar.21356
http://onlinelibrary.wiley.com/doi/10.1002/ar.21356/abstract
(Comment on "The Tail of Tyrannosaurus: Reassessing the Size and Locomotive
Importance of the M. caudofemoralis in Non-Avian Theropods"; no abstract
text)



Ralph E. Molnar (2011) 
Sauropod (Saurischia: Dinosauria) material from the Early Cretaceous Griman
Creek Formation of the Surat Basin, Queensland, Australia .
Alcheringa: An Australasian Journal of Palaeontology (advance online
publication)
First published on 11 March 2011 
DOI: 10.1080/03115518.2010.533975 
http://www.informaworld.com/smpp/content~db=all~content=a934968090~frm=title
link

An isolated ischium and possible neural arch recovered from the
lower-middle Albian Griman Creek Formation near Surat, are the only
sauropod postcranial elements from that unit in Queensland. This is the
southernmost occurrence of sauropod post-cranial remains in eastern
Australia. Comparison with other sauropod remains suggests that the ischium
might represent an indeterminate titanosaur that is different from taxa
previously named from Australia. 




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