Sauropods of Cuba: phylogenetic position.

APESTEGUÍA, SEBASTIÁN; CEBALLOS IZQUIERDO, YASMANI; ITURRALDE-VINENT, MANUEL

san luis

Encuentro; Reunión de comunicaciones de la Asociación Paleontológica Argentina.; 2017

universidad de san luis

Between western Laurasia and Gondwana evolved a marine corridor where the fossil-bearing Jagua Formation of western Cuba was deposited during mid to late Oxfordian times. The Jagua Formation has provided a variegate assemblage of terrestrial, coastal, and open marine specimens, including reptiles, fish and invertebrates. From this formation, De la Torre y Callejas reported in 1949 an isolated dinosaur bone, 40 cm long, now missing, which was referred as a diplodocid sauropod humeros. Recently, this fossil was identified as a camarasauromorph metacarpal. The achievement of a eugraviportal forelimb was a unique event evidenced in metacarpal morphology. Within Macronaria, metacarpals became long, robust, and with undivided condyles in Titanosauriformes. Between Somphospondyli and Titanosauria digits reduce to disappear and metacarpal distal ends turned square and bigger laterally. Fifth metacarpal enlarged equaling the first one, and the latter bowed in relation to an asymmetrical and short first phalanx. The bowed first metacarpal is present only in sorne basal somphospondylians and most basal titanosaurs, such as Andesaurus Calvo & Bonaparte 1991, Ligabuesaurus Bonaparte, González-Riga & Apesteguía 2006, and Argyrosaurus Lydekk:er 1893, and reverses in derived forms. The strong curvature in the frontal side of the Cuban metacarpus suggests that it probably belongs to the first metacarpal of a basal somphospondylian, a clade not recorded yet for the Jurassic neither in North or South America. An alternative view is that it could represent a quite early record of the titanosaurian clade.