On a dicraeosaurid specimen from the Mulichinco Formation (Valanginian, Neuquén Basin) of Argentina and phylogenetic relationships of the South American dicraeosaurids (Sauropoda, Diplodocoidea)

WINDHOLZ, GUILLERMO J.; CORIA, RODOLFO A.; BELLARDINI, FLAVIO; BAIANO, MATTIA A.; PINO, DIEGO; ORTEGA, FRANCISCO; CURRIE, PHILIP J.

COMPTES RENDUS PALEVOL

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2022

1631-0683

The osteology of Pilmatueia faundezi, a dicraeosaurid sauropod from the Lower Cretaceous of Patagonia, is reassessed from the perspective of a new specimen (MLL-Pv-010) that provides additional information on the axial skeleton and the pectoral girdle. MLL-Pv-010, is composed of three articulated anterior-middle cervical vertebrae (with their respective ribs in position and an associated fourth rib), seven dorsal vertebrae with associated dorsal ribs, a distal caudal vertebra, a left scapula and the proximal end of a right scapula. The new specimen shows features, especially in the middle cervical vertebrae, that link it to Pilmatueia faundezi. Additionally, MLL-Pv-010 shows features previously unknown for the species, such as the morphology and orientation of the bifid neural spines of the anterior and mid-cervical vertebrae. The information obtained from MLL-Pv-010 allows us to propose an expanded diagnosis of Pilmatueia faundezi. Moreover, two phylogenetic analyses focusing on South American dicraeosaurids shows that Pilmatueia is well nested within Dicraeosauridae. One of our phylogenetic hypotheses differs from previous contributions in showing South American dicraeosaurids as a monophyletic group. However, in the second hypothesis these are not recovered as a natural group. We think that it is reasonable to recover a South American dicraeosaurid clade, and that eventually it will be best supported once more evidence is recovered.