BIOMECHANICAL AND MORPHOFUNCTIONAL ANALYSIS OF THE APPENDICULAR SKELETON OF Macrauchenia patachonica OWEN 1840 (MAMMALIA, LITOPTERNA): PRELIMINARY RESULTS

PRIETO, CECILIA; ELISSAMBURU ANDREA

Tandil

Congreso; «Sierras del Tandil» First Meeting on Morphological Sciences; 2011

Macrauchenia patachonica is a South American extinct ungulate,and the last representative of the order Litopterna. Due to its morphologicalfeatures it is included in the Quaternary megaherbivore.The goal of this work is to infer the locomotor features of M.patachonica using its limb morphometric features. For the morphologicalanalysis, 16 long bones were measured with a digitalcaliber (0,01 mm); these results were used to calculate 13 indices:shoulder moment index (SMI), humerus transverse robustness andanteroposterior robustness indices (HRI, APHI), epicondyle index(IE), radius-ulna transverse robustness and anteroposterior robustnessindices (RURI, APRUI), olecranon index (OI), brachial index(BI), femur robustness index (FRI), lesser trochanter index (LTI),tibia robustness index (TRI), tibia spine index (TSI), and cruralindex (CI). The indices were compared by difference of means betweenM. patachonica and living ungulates. The SMI, OI, APRUIand LTI values were similar to those of living ungulates, indicatingthat cursorial adaptations, like limb stability and speed changesadaptations were present in M. patachonica. The other indexes aremajor or less (IC) than the average of ungulates; IE, RURI and BIindices indicate a forelimb larger robustness and a forelimb largesttransverse development than in living ungulates, although with acursorial adaptation. IRF, ITR and IC indices indicate a hind limbadaptation to corporal mass support, with major values than in ungulates.As a preliminary result, M. patachonica would be agraviportal animal with cursorial features.