Bonitasaura (Sauropoda) bone histology

[Ben Creisler <bcreisler@gmail.com>]

From: Ben Creisler
bcreisler@gmail.com

A new paper (in Spanish) in Ameghiniana:

Pablo Ariel Gallina (2012)
Histología ósea del titanosaurio Bonitasaura salgadoi (Dinosauria:
Sauropoda) del Cretácico Superior de Patagonia. [Bone histology of the
titanosaur Bonitasaura salgadoi (Dinosauria: Sauropoda) from the Upper
Cretaceous of Patagonia]
Ameghiniana 49(3): 289-302
http://www.ameghiniana.org.ar/index.php/ameghiniana/article/view/519




The bone histology analysis of the titanosaur Bonitasaura salgadoi,
from Río Negro Province, Argentina, was analysed in detail. It
represents the first complete histological characterization of a South
American sauropod based on a single specimen. Multiple samples were
taken from different parts of the skeleton according to available
fragmentary elements as well as to their paleohistological importance.
The femur and humerus are characterized by a wide cortex mainly
composed of primary, highly vascularized fibrolamellar tissue,
interrupted by at least one growth mark. None of the samples show
external avascular lamellar tissue (EFS). Samples from the ulna, one
metacarpal and a caudal vertebral zygapophysis show histological
similarities, allowing recognition of great internal remodeling with
several generations of secondary tissue. Although very reduced, the
primary fibrolamellar tissue was recognized with a LAG or annuli. In
contrast, samples of dorsal ribs show a significant intraelemental
variability. Only in proximal sections the fibrolamellar tissue has a
notorious banding of longitudinal vascular canals, accompanied by at
least two LAGs and a line of resorption. These features show that
differential modeling process acted in the construction of these
complex osseous elements. Finally, the recognized microstructural
features allow the assignation of this specimen to a HOS (Histological
Ontogenetic Stage) 9. The comparison with other known sauropod growth
curves also allows inferring the adult femur length of this species
reached up to 1.8–1.9 m.