LAG

[GSP1954 <GSP1954@aol.com>]

To clarify some points that have been made on the list about my comments at
Dinofest on dinosaur/early bird microstructure, including lines of arrested
growth. In most tetrapods the bone walls are thick, so much of the bone
deposited during juvenile grwoth remains intact at the onset of maturity. The
pattern of juvenile growth is therefore recorded, at least until bone
remodeling alters the bone matrix as the animal ages. 

The problem with the work by Chinsamy et al on early bird bones is that the
bones are thin walled. The birds sampled are also fairly large at 500-2500 g.
Therefore the birds were probably adults. If so, then the deep bone deposited
during growth was lost, in which case we have no idea how fast the birds grew
up. The seemingly reptile-like LAG may therefore reflect slow, indeterminate
adult growth. There are no metabolic implications to be derived from such
data. 

GSPaul