ALGUNAS CONSIDERACIONES TEÓRICAS SOBRE LOS ANDARES DE LOS DINOSAURIOS SAURISQUIOS. IMPLICACIONES FILOGENÉTICAS

Abstract

OME THEORETICAL CONSlDERATIONS ON THE GAITS OF THE SAURISCHIAN DINOSAURS. PHYLOGENETICAL IMPLlCATIONS: The paper is based on the analysís of trackways of a small (supposed to be the smallest known ) quadrupedal dinosaur from the Míddle Jurassic of Santa Cruz Province (Patagonia), previous described by the authcr with the name of Delatorrichnus goyenechei (1964). The paper beginns with a revisión of the general taxinomical problems arised bythe recent papers of Colbert (1964) an:l Charig, Attridge y Crompton (1965), ancl then the author remarks previous observations of Romer and himself about the probable existence of "preadaptatíons" in the autopode of certains groups of Saurischia. On the base of the quadrupedalísm ancl the correlated reduction of the fingers (to three centrals in manus and pes) present in Delatorrizhr.us, the author concludes by poínting that among the members of the Coelurosauria (as wej] as in the Prosauropoda) must have coexistecl bipedal and quadrupedal forms (and w.the high probability mixecl ones ). The paper encls by calling the attention about the dangers of the negative fossil register, the potentialities of the bíologícal world and the exceptional interest of the paleoichnology on these respects.