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

PRIETO, M.C.; ELISSAMBURU, A.

Tandil

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

FCV - UNCPBA

Macrauchenia patachonica is a South American extinct ungulate, and the last representative of the order Litopterna. Due to its morphological features 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 morphological analysis, 16 long bones were measured with a digital caliber (0,01 mm); these results were used to calculate 13 indices: shoulder moment index (SMI), humerus transverse robustness and anteroposterior robustness indices (HRI, APHI), epicondyle index (IE), radius-ulna transverse robustness and anteroposterior robustness indices (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 crural index (CI). The indices were compared by difference of means between M. patachonica and living ungulates. The SMI, OI, APRUI and LTI values were similar to those of living ungulates, indicating that cursorial adaptations, like limb stability and speed changes adaptations were present in M. patachonica. The other indexes aremajor or less (IC) than the average of ungulates; IE, RURI and BI indices indicate a forelimb larger robustness and a forelimb largest transverse development than in living ungulates, although with a cursorial adaptation. IRF, ITR and IC indices indicate a hind limb adaptation to corporal mass support, with major values than in ungulates. As a preliminary result, M. patachonica would be a graviportal animal with cursorial features.