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RE: Archaeopteryx bone physiology



> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] 
> On Behalf Of Michael Erickson
>
> This makes no sense. The authors claim that the slow growth 
> nature of *Archaeopteryx* bone is consistent with non-avian 
> dinosaur bone? Dinosaurs were VERY fast growers, according to 
> all studies I am aware of.

But no non-avian dinosaur grows at the phenomenal rates like modern
altricial birds, nor even as fast as precocial birds. Look at the right hand
plot of Fig. 9: the uppermost dashed line is altricial bird growth rates,
and the next highest dashed line (for most of the figure: crosses under
placental mammals above the 10 ton range) is precocial birds. Note that the
figure for Archie (the open diamond) is well below both lines

> And how could Archaeopteryx (and 
> non-avian dinosaurs for that matter) possibly be ectothermic? 

Note what they state: "Growth analysis for Archaeopteryx suggests that these
animals showed exponential growth rates like non-avialan dinosaurs, three
times slower than living precocial birds, but still within the lowermost
range for all endothermic vertebrates."

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
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
http://www.geol.umd.edu/~jmerck/eltsite/
Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
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