New issue of Nature: Dinosaur and Bird Growth

[bh480@scn.org]

From: Ben Creisler bh480@scn.org
Subject: New issue of Nature: Dinosaur and Bird Growth

The new July 26, 2001 issue of Nature has three articles 
of interest:

GREGORY M. ERICKSON, KRISTINA CURRY ROGERS & SCOTT A. 
YERBY, 2001. Dinosaurian growth patterns and rapid avian 
growth rates  Nature 412, 429 - 433
"All dinosaurs grew at accelerated rates relative to the 
primitive condition seen in extant reptiles. Small 
dinosaurs grew at moderately rapid rates, similar to those 
of marsupials, but large species attained rates comparable 
to those of eutherian mammals and precocial birds. Growth 
in giant sauropods was similar to that of whales of 
comparable size. Non-avian dinosaurs did not attain rates 
like those of altricial birds. Avian growth rates were 
attained in a stepwise fashion after birds diverged from 
theropod ancestors in the Jurassic period."

KEVIN PADIAN, ARMAND J. DE RICQLÈS & JOHN R. HORNER, 
2001.Dinosaurian growth rates and bird origins. Nature 
412, 405 - 408 
"Dinosaurs, like other tetrapods, grew more quickly just 
after hatching than later in life. However, they did not 
grow like most other non-avian reptiles, which grow slowly 
and gradually through life. Rather, microscopic analyses 
of the long-bone tissues show that dinosaurs grew to their 
adult size relatively quickly, much as large birds and 
mammals do today. The first birds reduced their adult body 
size by shortening the phase of rapid growth common to 
their larger theropod dinosaur relatives. These changes in 
timing were primarily related not to physiological 
differences but to differences in growth strategy."
ANUSUYA CHINSAMY AND ANDRZEJ ELZANOWSKI, 2001.Bone 
histology: Evolution of growth pattern in birds. Nature 
412, 402 - 403 
"Bone histology has revealed that pre-avian theropods also 
grew fast for most of the postnatal period, but that this 
growth was usually intermittent and probably extended for 
more than one year1-3. We have found surprising evidence 
for an early postnatal slowing-down of growth in two 
lineages of flying basal birds, which suggests that birds 
may have started their evolution as precocious fliers."

For a wire-story version of the dinosaur growth article, 
go to:
Dinosaurs gained up to 100 pounds a day, study finds 
http://www.nandotimes.com/healthscience/story/49992p-
748158c.html