Re: Dinosaur growth pattern

[Sarah Werning <swerning@gmail.com>]

Hello,

Some people have hypothesized that dinosaurs were "ever-growing", but
histological evidence shows that many dinosaurian taxa (probably all)
did not continue growing through life. The distance/area between
adjacent/subsequent growth lines (meaning, the amount of new bone
deposited each year) does increase early in life and into
subadulthood, but then decreases significantly as animals get older.
The external fundamental system (EFS) discussed and illustrated in
Horner et al (1999), Erickson et al (2004), Sander et al (2006), and
other articles is another piece of evidence that indicates that
skeletal growth was determinate in dinosaurs.

Even "ever-growing" vertebrates do not exhibit indeterminate growth in
the same sense that plants do, because they slow their rate of growth
significantly later in life. And while most reptiles, amphibians, and
fish exhibit this pattern, there are many taxa in these groups
(including some anoles and mouth-brooding fish) that definitely
exhibit determinate growth.

Hope this helps,
Sarah Werning

--
Sarah Werning
reply to: swerning@berkeley.edu
Museum of Paleontology and Department of Integrative Biology
University of California, Berkeley
1101 Valley Life Sciences Building
Berkeley, CA 94720-4780



On 6/29/07, Jean-Michel BENOIT <s.aegyptiacus@wanadoo.fr> wrote:

Dear DMLers,
I was wondering if dinos are thought to have grown all along their
life like crocs, turtles, and TMK snakes, lizards and fish. I don't
know about birds but I think they don't. Could this trait be related
to ectothermy strictly

Cheers,
Jean-Michel