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Gigantic dinosaur(?) bone material from Triassic



From: Ben Creisler
bcreisler@gmail.com

A new advance online paper:


Ragna Redelstorff, P. Martin Sander, and Peter M. Galton (2012)
Unique bone histology in partial large bone shafts from Aust Cliff
(England, Upper Triassic): an early independent experiment in
gigantism.
Acta Palaeontologica Polonica (in press)
doi: http://dx.doi.org/10.4202/app.2012.0073
http://app.pan.pl/article/item/app20120073.html


Two giant partial bone shafts, possible femora, from the Rhaetian Bone
Bed (Upper Triassic) of Aust Cliff in SW England continue to conceal
their origin. The most striking characteristic of these bones is their
size, showing that dinosaur-like gigantism had already evolved by the
Late Triassic. Based on their characteristic, columnar shaft
morphology, Galton (2005) suggested they came from a prosauropod or
stegosaur. The bone histology of both specimens is very similar: the
cortex is always rather thin, not exceeding 10 mm, and is of
fibrolamellar type with longitudinal primary osteons. The primary
osteons show a rather unusual feature, the development of a secondary
osteon inside the primary one. The bone surface in both specimens
shows open vascular canals, suggesting that the animals were still
growing at the time of death, but an external fundamental system (EFS)
is visible in the outermost cortex of specimen BRSMG Cb3870. The
external cortex shows dense growth marks, but their annual nature is
difficult to ascertain. The bones are probably dinosaurian, as
indicated by the fibrolamellar bone, and possibly belong to an unknown
basal sauropodomorph lineage. Alternatively, some very large
pseudosuchians may have evolved fibrolamellar bone independently as an
adaptation for reaching giant size.