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Secondary bone formation in dinosaurs

Ben Creisler

A new online paper:

Kevin Padian, Sarah Werning & John R. Horner (2015)
A hypothesis of differential secondary bone formation in dinosaurs.
Comptes Rendus Palevol (advance online publication)

We propose the hypothesis that in the long bones of large, rapidly
growing animals, secondary osteons may form to a greater degree in
smaller bones than in larger ones for reasons that may have more to do
with the interplay between element-specific growth rates and
whole-body metabolic rates than with mechanical or environmental
factors. We predict that in many large animals with rapid growth
trajectories and some disparity in size in the long bones and other
skeletal elements, the largest bones will show less secondary
remodeling than smaller ones. The reason is that, whereas the largest
bones are increasing their dimensions too rapidly to accommodate much
secondary reworking (until they approach full size), the smaller bones
that are not increasing in size as rapidly must still process the flow
of metabolites through their elements, and this is manifested in
secondary remodeling. This hypothesis does not contradict or undermine
other explanations, but rather adds an additional one that focuses
more on growth and metabolic rates with respect to bones of different
size in the same skeleton. Because the timing of onset of remodeling
and the pace of its progression both vary by element, caution must be
taken when using secondary remodeling to infer the overall ontogenetic
stage of the animal.