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Dino papers in the latest Paleobiology



Greetings,

The latest issue of Paleobiology offers three papers on dinosaur
paleontology:

Paul, G.S. & P. Christiansen. 2000.  Forelimb posture in neoceratopsian
dinosaurs: implications for gait and locomotion.  Paleobiology 26: 450-465.

Argues for parasagittal forelimbs in ceratopsids and other quadrupedal
neoceratopsians, and suggests that problems with mounting said dinosaurs in
this pose stem from inappropriate rib and vertebral articulation.  Greg &
Per point out that "parasagittal" in this sense is not columnar-ly upright,
but does involve some aversion of the elbow: hence the fact that ceratopsid
trackways show the manus slightly lateral to the pes prints.

Martin Sander, P. 2000.  Longbone histology of the Tendaguru sauropods:
implications for growth and biology.  Paleobiology 26: 466-488.

Specimens of growth series of _Brachiosaurus_, _Barosaurus_, and
_Dicraeosaurus_ (and two "_Janenschia_" bones: don't know the current status
of these particular limb bones, as I haven't seen that paper in which
_Tendaguria_ was proposed) were cored and their bone histology examined.  As
in previous studies of dino bone histology, different growth stages have
different bone type: this includes an L-Z (lamellar-zonal) type which seems
to represent the end to substantial growth.  Martin Sander's data suggests
that adult bone type (and thus, perhaps, sexual maturity) appears when the
individuals are no more than 70% maximum size: in fact, the _Brachiosaurus_
and _Barosaurus_ humeri that first show "adult" bone texture are nearly the
same size, suggesting that _Brachiosaurus_ had a long period of growth after
it had reached sexual maturity.

Carrano, M.T.  2000.  Homoplasy and the evolution of dinosaur locomotion.
Paleobiology 26: 489-512.

More good stuff from Matt Carrano: it combines phylogenetic and functional
morphological information to track the parallel evolution of key locomotor
features associated with an enhanced parasagittal gait in the various clades
of dinos.  These parallelisms include a fully medial femoral head
(Neornithischia, Sauropoda, Neotetanurae (aka Avetheropoda... ;-));
anterior expansion of ilium (Ornithischia, Sauropoda, Neotheropoda);
posterior exansion of ilium (Neornithischia, Sauropodomorpha, Neotheropoda);
and various character states involving the lesser trochanter.  This paper
parallels some work done by other authors on hindlimb evolution within
Archosauria and its various subclades: more about those in the (hopefully)
near future.

(Reference in the Carrano paper to a Forster paper in J. African Earth
Sciences on dinosaur biogeography that came out last year: I'm off to the
library!).

                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