LAUSR

ABSTRACT The fossil-bearing Jagua Formation of western Cuba was deposited during the early Late Jurassic (middle to late Oxfordian) in the marine corridor developed between western Laurasia and Gondwana, providing a rich assemblage of terrestrial to marine fossils including reptiles, fish and invertebrates. From this formation, De la Torre y Callejas reported in 1949 an isolated dinosaur bone, now missing, originally identified as ‘Diplodocus’ or ‘Brontosaurus’ humerus. Later, this fossil was referred as a camarasauromorph metacarpal. Within Macronaria, metacarpals became long and robust in Titanosauriformes. The strong curvature of the Cuban metacarpus suggests that it probably belongs to the first or second metacarpal of a somphospondylan. The achievement of a eugraviportal forelimb in Sauropoda was a unique event evidenced in metacarpal morphology. The bowed first metacarpal is present only in somphospondylans, particularly in some basal titanosaurs, and reverses in derived forms. Somphospondylans were not recorded yet for the early Late Jurassic neither in North nor in South America. GRAPHICAL ABSTRACT