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Gasparinisaura bone microstructure in new JVP

From: Ben Creisler

In the new issue of Journal of Vertebrate Paleontology:

Ignacio A. Cerda & Anusuya Chinsamy (2012)
Biological implications of the bone microstructure of the Late
Cretaceous Ornithopod Dinosaur Gasparinisaura cincosaltensis.
Journal of Vertebrate Paleontology 32(2): 355-368

Here we present the bone histology of Gasparinisaura cincosaltensis, a
basal ornithopod from the Late Cretaceous of Patagonia, and discuss
its biological implications. The sample includes axial and
appendicular elements from several specimens of different ontogenetic
stages. The cortex of most bones consists of fibro-lamellar tissue,
with mainly longitudinally oriented vascular spaces, which suggests
rapid osteogenesis and fast growth. However, the fibro-lamellar bone
is commonly interrupted by lines of arrested growth and/or annuli
composed of parallel-fibered bone that indicates that the rapid growth
was periodic. Although a true outer circumferential layer was not
recorded in any of the sampled elements, in several of the larger
samples the woven-fibered matrix of the inner and middle cortex grades
into a parallel-fibered tissue, which suggests that the attainment of
sexual maturity occurred before skeletal maturity. The growth dynamics
of Gasparinisaura are similar to those reported in other basal
ornithopods. Inter-elemental, as well as intraspecific, variations in
histology were observed in Gasparinisaura. Such variation could be the
result of sexual dimorphism, or the effect of localized conditions of
growth, or perhaps plasticity in growth in response to local
environmental conditions.