MACNBR   00242
MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
artículos
Título:
Reconstruction of the dentition of Propyrotherium Ameghino, 1901 (Mammalia, Pyrotheria). Taxonomic and phylogenetic implications
Autor/es:
KRAMARZ, ALEJANDRO; BOND, MARIANO
Revista:
JOURNAL OF VERTEBRATE PALEONTOLOGY
Editorial:
SOC VERTEBRATE PALEONTOLOGY
Referencias:
Lugar: Lawrence; Año: 2014 p. 434 - 443
ISSN:
0272-4634
Resumen:
Propyrotherium saxeum is one the least known members of Pyrotheria, an
enigmatic group of extinct, giant, endemic South American ?ungulates.? The species was
originally described based upon two isolated cheek teeth and two tusk
fragments. Later authors assigned additional isolated teeth to this taxon, but
the position within the tooth row of all these teeth remained uncertain,
preventing an accurate dental characterization and taxonomic distinction from
other related species. Here we reexamine the type specimens of P. saxeum and
additional materials previously reported as belonging to this species, and
analyze several lots of still undescribed specimens, in order to reconstruct
the cheek tooth series. Based on comparisons with better known pyrotheres, we
conclude that the most probable cheek teeth formula is P2?M3/p2?m3. The cheek
teeth gradually increase in size from front to back, and the upper cheek teeth
have a gradual increase in loph curvature, as in Pyrotherium. All cheek
teeth are bilophodont, but in premolars the anterior loph/id is transversely
shorter than the posterior. All have lingual/labial cingulum/id; P3?M3 are
subquadratic and three-rooted; p4?m3 are longer than wide, two-rooted, and bear
a variably developed vestige of cristid obliqua. Propyrotherium is
distinguishable from Griphodon and Baguatherium, but the
distinction between these latter two taxa is uncertain with the current
evidence. A revised cladistic analysis confirms that Propyrotherium is
one of the earliest diverging pyrotheriids, but the resolution of its
relationship with Griphodon and Baguatherium requires further
evidence.