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Megalancosaurus (Drepanosauromorpha) forelimb in prey capture



Ben Creisler
bcreisler@gmail.com

A new paper:

Marco Castiello, Silvio Renesto & S. Christopher Bennett (2015)
The role of the forelimb in prey capture in the Late Triassic reptile
Megalancosaurus (Diapsida, Drepanosauromorpha).
Historical Biology (advance online publication)
DOI:10.1080/08912963.2015.1107552
http://www.tandfonline.com/doi/full/10.1080/08912963.2015.1107552


The pectoral girdle and forelimb of the Late Triassic
drepanosauromorph reptile Megalancosaurus are redescribed and their
function reinterpreted. The whole skeleton of this diapsid is highly
specialised for arboreal life, and also the peculiarities of the
shoulder girdle and forelimb were interpreted as adaptations for a
limb-based locomotion using gap-bridging to move from one support to
another, as in chameleons. Re-examination of the pectoral girdle and
forelimb revealed the presence of clavicles fused into a furcula-like
structure, a saddle-shaped glenoid and a tight connection between the
radius and ulna that strengthened the forearm but hindered pronation
and supination movements at that joint. The new information plus a
reconstruction of the pectoral and forelimb musculature suggests that
the forelimb was also specialised for grasping and raking in addition
to climbing and thus prey capture may have been an important function
for the forelimb. The new functional interpretation fits well with the
overall body architecture of Megalancosaurus’ skeleton, suggesting
that this reptile was an ambush predator that may have assumed a
stable tripodal position, secured by the hooked tail and hind limbs,
freeing its forelimbs to catch prey by sudden extension of the arm and
firm grasping with the pincer-like digits.