Proportions and function of the limbs of glyptodonts, Mammalia, Xenarthra

VIZCAÍNO S. F.; BLANCO E.; BENDER J.B.; MILNE N.

LETHAIA

WILEY-BLACKWELL PUBLISHING, INC

Año: 2011 p. 93 - 101

0024-1164

This study examines the limb bone proportions and strength of glyptodonts (Xenarthra, Cingulata).  Two methods are used to estimate the body mass and location of the centre of gravity of the articulated specimens.  These estimates, together with measurements of the femur and humerus, are used to calculate strength indicators.  The other long bones of the limbs are used to calculate limb proportion indices that give an indication of digging ability, speed, and limb dominance in armadillos, glyptodont’s living closest relatives.  The results show that regardless of how the body mass and centre of gravity are calculated, the majority of the glyptodont’s weight is borne by the hind limbs.  The strength indicator calculations show that femora are sturdy enough to bear these loads. The fact that the femora have higher strength indicators than the humerii indicates that sometimes the hindlimbs are required to bear an even greater proportion of the body weight, possibly when rising to a bipedal posture or pivoting on their hindlimbs to deliver a blow with their amoured tail.  The analysis of limb proportions indicates that both the hindlimb and the forelimb have proportions that correlate strongly with body mass.  This outcome supports the other results, but also shows that forelimbs must be also involved in maneuvering the glyptodont body.