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At long last: Fruitadens!!

Just in time to make it into the heterodontosaur part of my talk this

Butler, R.J., P.M. Galton, L.B. Porro, L.M. Chiappe, D.M. Henderson, and
G.M. Erickson. 2009. Lower limits of ornithischian dinosaur body size
inferred from a new Upper Jurassic heterodontosaurid from North America.
Proceedings of the Royal Society B 10.1098/rspb.2009.1494


The extremes of dinosaur body size have long fascinated scientists. The
smallest (<1 m length) known dinosaurs are carnivorous saurischian
theropods, and similarly diminutive herbivorous or omnivorous ornithischians
(the other major group of dinosaurs) are unknown. We report a new
ornithischian dinosaur, Fruitadens haagarorum, from the Late Jurassic of
western North America that rivals the smallest theropods in size. The
largest specimens of Fruitadens represent young adults in their fifth year
of development and are estimated at just 65-75 cm in total body length and
0.5-0.75 kg body mass. They are thus the smallest known ornithischians.
Fruitadens is a late-surviving member of the basal dinosaur clade
Heterodontosauridae, and is the first member of this clade to be described
from North America. The craniodental anatomy and diminutive body size of
Fruitadens suggest that this taxon was an ecological generalist with an
omnivorous diet, thus providing new insights into morphological and
palaeoecological diversity within Dinosauria. Late-surviving (Late Jurassic
and Early Cretaceous) heterodontosaurids are smaller and less ecologically
specialized than Early (Late Triassic and Early Jurassic)
heterodontosaurids, and this ecological generalization may account in part
for the remarkable 100-million-year-long longevity of the clade. 



These specimens were collected before the first and third authors were even
born: part of the LACMs digs at the Fruita from back in the 1970s. They've
been referred to in the literature as the "Fruita Echinodon" or "Morrison
Echinodon" in previous reports.

Additional commentary at:


Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
Faculty Director, Science & Global Change Program, College Park Scholars
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA