Comparative analyses of a new Miocene petrel (Aves: Procellariidae) from Patagonia, Argentina

PIRO, ALEJANDRA; ACOSTA HOSPITALECHE, CAROLINA ILEANA ALICIA

Oxford

Conferencia; . Annual Meeting of the Palaeontological Association; 2020

Procellariiformes are important components of South American modern assemblages buttheir Argentinian fossil record is scarce and poorly understood. A right carpometacarpusMLP 10-XII-11-1 from the early Miocene Gaiman Formation was examined and assigned,after extensive comparisons and morphogeometrical analyses, to Procellariidae. It shareswith Procellariiformes a truncated os metacarpale alulare, a wide spatium intermetacarpale,a similar extension of metacarpalia, the absence of the processus intermetacarpalis, theventral rim of the trochlea carpalis more caudally projected, a marked fossa infratrochlearisleaving cranially a crest bearing the processus pisiformis, and a sulcus extended proximallyand along the synostosis metacarpalis distalis. The assignment to Procellariidae issupported by a sulcus tendineus restricted to the distal half, a small crest belonging to them. ulnometacarpalis dorsalis scar, a notch and a tubercle on the ventral rim of the trochleacarpalis, a wide fovea carpalis caudalis not proximally delimited, a rounded, shallow, andproximo-cranial fossa supratrochlearis, and pneumatic foramina within the small foveacarpalis caudalis. Concordantly, the morphogeometric analyses show clear affinitieswith Procellariidae, and locate MLP-10-XII-11-1 close to Daption capense. To conclude,although the carpometacarpus is not a diagnostic element, MLP-10-XII-11-1 is definitivelydifferent from all Procellariidae and represents a new species.