New sauropod pneumaticity paper

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

Greetings,

I don't think I've seen this listed yet on the DML, so...

Wedel, M.J. 2003. Vertebral pneumaticity, air sacs, and the physiology of
sauropod dinosaurs.   Paleobiology 29: 243?255.

Matt examines the anatomy of modern bird vertebral pneumaticity, and
compares these to the possible osteological correlates of such pneumaticity
in sauropods.  He looks at ontogeny of these structures in modern birds, and
compares them to ontogenetic and phylogenetic distributions in sauropods.
Among other observations and conclusions:
* Pneumatic fossae, camerate, and camellate structures are not discrete
conditions, but grade into one another in ontogeny in modern birds, and
(based on some observations) in sauropods.
* Trends in the distribution of pneumatization in sauropods start in the
neck and anterior dorsals, and spread into the posterior dorsals and sacrals
in advanced forms (paralleling theropod history)
* Contrary to previous thoughts, the above observations do NOT require the
presence of an abdominal air sac in sauropods, but could be equally well
explained by simply a cervical air sac system.  Indeed, Matt sets up
potential tests for future discoveries that could demonstrate the separate
existence of an abdominal air sac
* The recognition of primitively-developed pneumatization in erythrosuchids
and _Thecodontosaurus_ requires either/or multiple origins or multiple
losses of postcranial skeletal pneumatization in archosaurs.  Following the
ontogentic pattern in birds (air sacs first, diveritcula second, invasion of
diverticula into bone last), he suggests that the air sac system was present
in forms for which we don't see pneumatic bones.
* The presence of an avian-style respiratory system in sauropods would have
allowed this beasties to overcome the problems of breathing through such a
long neck, and indeed have helped supported a higher metabolic rate than
some have assumed.

Really cool stuff.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796