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RE: dracrorex and National Geographic



What the abstract says (note it is Horner, Goodwin and Woodward and is
presented as a hypothesis):

Technical Session IX, Friday 11:15
SYNONOMY CONSEQUENCES OF DINOSAUR CRANIAL ONTOGENY HORNER, John, Montana
State University, Museum of the Rockies, Bowman, MT USA; GOODWIN, Mark,
University of California, Berkeley, Museum of Paleontology, Berkeley,
CA, USA: WOODWARD, Holly, Montana State University, Museum of the
Rockies, Bozeman, MT USA
The effect of cranial allometry during the growth of dinosaurs cannot be
overlooked in distinguishing taxonomic differences from individual,
ontogenetic, or sexual variation. This ontogenetic problem was
recognized in tyrannosaurids from the Nemegt Formation of Mongolia by
Rozhdestevensky in 1965, and quantitatively resolved in lambeosaurine
hadrosaurs by Dodson in 1975. Subsequently, additional discoveries of
various ontogenetic series, such as the recently described cranial
series of Triceratops, confirm Dodson's findings that dinosaur juvenile
morphology was retained for an extended period, until the skulls
attained nearly adult proportions (based on average adult cranial
dimensions). Several groups of dinosaurs hatched from their eggs, grew
to approximately 3/4 adult size while retaining many juvenile cranial
morphologies, and then underwent rapid cranial development of adult
characteristics (hypothesized as display features). The severity of this
cranial allometric transformation is well illustrated in our
hypothesized ontogenetic stages of Pachycephalosaurus. Comparative
cranial morphology supplemented by computerized tomography and
osteohistology of the taxa Dracorex, Stygimoloch and Pachycephalosaurus,
all from the Upper Cretaceous Hell Creek Formation of Montana, and
adjacent states, support an alternative interpretation that these taxa
form an ontogenetic series of the single taxon Pachycephalosaurus.
Extreme ontogenies such as this have important consequences for many
current phylogenetic, ecologic, and evolutionary hypotheses relating to
dinosaurs.
JVP 27(suppl. To 3): 92A





Kenneth Carpenter, Ph.D.
Curator of Lower Vertebrate Paleontology & Chief Preparator
Department of Earth Sciences
Denver Museum of Nature & Science
2001 Colorado Blvd.
Denver, CO 80205 USA

Office phone: 303-370-6392
Museum fax: 303-331-6492
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For PDFs of some of my publications, as well as information of the Cedar
Mountain Project:
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The scientific method is a myth:
http://www.dharma-haven.org/science/myth-of-scientific-method.htm
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