Inferring locomotor behavior in Miocene porcupine Steiromys duplicatus Ameghino (Rodentia, Erethizontidae).

CANDELA, A.; PICASSO, M. B. J.; ABELLO, A.

Puerto Madryn, Argenina

Otro; Reunión anual de comunicaciones de la APA (Asociación Paleontológica Argentina) Puerto Madryn; 2005

 Postcraial anatomy of porupines is relatively poorly knonw and has not beeb evaluated from a functional-adaptative. Steiromys duplicatus Ameghino, on of the most abundant porcupines in the Miocene faunas of Patagonia. Osteological and  myologycal anatomy of  living porcupines was analyzed and used as a rnodel to interpret the funclional signifieane of  the postcranium os S.duplicatus. Several features, specially those of the joints; are indicative of the ability of  this poreupine to climb. The humeral head  is rounded and lhe tuberosities are low, suggesting a mobile gleno-humeral joint, compatible wilh a broad  range f movements; the delto-pectornl crest indicates a strong development of the pecto  ral muscle which is  partcular1ly active during climbing in living poreupines; the humero-ulnar and humero-radial joints, are indicative of  pronation and supination movements; the well-marked lateral epicondylar ridge  and the medially protruding medial enteplcondile  suggest an important development of Ihe muscles branchiorradial, supinator, flexor digitorum profundus and pronator teres. the morphology of the hip, knee, and cruro astragaler,  calcaneo-astragalar, and calcaneo-navicular joints would have allowed abduction and rotational movements, but  in a lesser degree than the arboreal living  Coendu ssp. Some features fo the foot of S.duplicatus (e.g. a large medial sesamnid bone, a medial orientation of  astragalar head) are indicative of rasping ability but in a lesser degree than in Coendu ssp.