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Orodromeus downsized



From: Ben Creisler bh480@scn.org

Orodromeus down-sized:
The following article in the new Journal of Vertebrate 
Paleontology contains of a revised size for Orodromeus 
that somehow escaped my notice in any earlier literature. 
Since the femur-to-total-body length ratio in typical 
hypsilophodonts is approximately 1/10, that means adult 
Orodromeus were likely around 1.7 meters (5.6 ft) long, 
not 2.5 (8 ft) as now generally indicated...unless 
Orodromeus had a exceptionally long tail.


VARRICCHIO, DAVID J., JOHN R. HORNER, and FRANKIE D. 
JACKSON, 2002. EMBRYOS AND EGGS FOR THE CRETACEOUS 
THEROPOD DINOSAUR TROODON FORMOSUS. Journal of Vertebrate 
Paleontology 22(3): 564-576.

"Two discoveries in the mid 1990s led to the reexamination 
and eventual reidentification of the MOR 246 embryos. 
First, study of Orodromeus osteology and ontogeny 
indicated that this hypsilophodont attained a 
comparatively small adult size (Scheetz, 1999 ), 
significantly smaller than earlier estimates (Horner, 
1994 ). The femur of mature individuals (e.g., MOR 473) 
measures only 17 cm compared to the previously 
hypothesized 30 cm. For these 12 cm long eggs to belong to 
Orodromeus would imply an exceptionally 
large egg to adult body size ratio...... "

Citing:
Scheetz, R. D. 1999, Osteology of Orodromeus makelai 
and the phylogeny of basal ornithopod dinosaurs: Ph.D. 
dissertation, Montana State University, Bozeman, 186 pp.