INVESTIGADORES
MUZZOPAPPA Paula
congresos y reuniones científicas
Título:
A NEW BROAD-HEADED HYPEROSSIFIED FROG FROM THE EOCENE OF PATAGONIA
Autor/es:
GÓMEZ, RAÚL ORENCIO; BÁEZ, ANA MARÍA; NICOLI, LAURA; MUZZOPAPPA, PAULA
Lugar:
Bristol, UK
Reunión:
Congreso; SVP 69th Annual Meeting and the 57th Symposium of Vertebrate Palaeontology and Comparative Anatomy (SVPCA); 2009
Institución organizadora:
Society of Vertebrate Paleontology
Resumen:
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We report on the discovery of anuran remains in the
lacustrine layers of the Ventana Formation that have yielded the highly diverse
flora of Río Pichileufú (RP), Rio Negro Province, northwestern Patagonia,
Argentina. Radimetric ages of tuff beds from this succession indicate a
depositional age of 47.46 ± 0.05 Ma (middle Eocene, Lutetian). A single
specimen that consists of an incomplete articulated skeleton (SVL ca 110 mm) is
considered to represent a new taxon. One of the most conspicuous features of
this frog is its wide, heavily ossified skull whose roofing bones have a
pit-and-ridge sculpture. The combined presence of eight presacral vertebrae
bearing equally developed transverse processes, bicondylar articulation between
the sacrum and urostyle, slightly dilated sacral diapophyses, and a long
scapular shaft precludes referral to an archeobatrachian taxon and,
conversely, is consistent with neobatrachian affinity. The overall morphology
of the skull recalls that of other broad-headed hyperossified frogs, such as
the extant ceratophryines, Calyptocephalella, and Pyxicephalus,
and several fossil taxa including the Late Cretaceous Baurubatrachus
from Brazil and Beelzebufo from Madagascar, and the Paleogene Thaumastosaurus
from Europe. However, the ornamentation pattern and different cranial and
postcranial characters readily differentiate the anuran from RP from the
aforementioned taxa. These taxa share many features, such as cranial exostosis
and squamosal with extensive otic plate and zygomatic ramus, which have been
widely used in morphology-based phylogenetic analyses. Notwithstanding, results
of recent molecular analyses have made evident that this suite of characters
may produce a misleading phylogenetic signal, calling for a more critical use
of such characters; some of them may have developed in association with a
broad, highly ossified skull. In order to assess the systematic position of the
new taxon from Patagonia, we conducted several parsimony analyses based on a
matrix of 42 taxa and 75 morphological characters, and preliminarly explored
the impact of some of the characters that a priori might reflect
hyperossification rather than phylogeny.
