INVESTIGADORES
ZURITA Alfredo Eduardo
congresos y reuniones científicas
Título:
Evolución y paleobiogeografía de los Glyptodontidae Glyptodontinae (Mammalia, Xenarthra): una nueva interpretación
Autor/es:
CARLINI, A. A; ZURITA, A. E
Lugar:
Santa Cruz de la Sierra
Reunión:
Congreso; III Congreso de Mastozoología en Bolivia; 2007
Resumen:
Knowledge of the main
aspects of the Great American Biotic Interchange (GABI) concerning the glyptodontine
Glyptodontidae (Xenarthra) is very scarce. A bidirectional dispersal process
was recently proposed for this clade, with the presence of the North American
genus Glyptotherium Osborn recognized
in latest Pleistocene sediments of northern South America (Venezuela and Brazil).
However, the earliest stages of this paleobiogeographical process remain poorly
understood, mainly because of the limited fossil record on this clade in late
Pliocene sediments. The goals of this contribution are: a) to present and describe the first record of a glyptodontine
glyptodontid from the late Pliocene of northern South America, tentatively
assigned to a new species of Boreostemma
Carlini et al. (Boreostemma? sp. nov);
and b) to analyze its
paleobiogeographical implications with respect to the GABI. This new material
was recovered from the San Gregorio Formation (late Pliocene, prior the GABI)
in northern Venezuela,
where it is represented by several osteoderms of
the dorsal carapace. A comparison among the three known late Pliocene
glyptodontine glyptodontids of a)
southern
South America (Paraglyptodon), b) northern South America (Boreostemma), and c) southern North
America ("Glyptotherium"),
reveals a series of shared characters between (b) and (c), not present
in (a). The most important of these shared
characters in (b) and (c) are: all the osteoderms present a great development
of the central figure, which is always larger than the peripherals; the sulcus
that delimits the central and peripheral figures is narrower and shallower; and
all the osteoderms present are relatively thin. This evidence suggests that the
lineage of Glyptodontinae which participated in the GABI and subsequently
diversified in North America originated in northern South
America. Moreover,
the evident morphological differences between these glyptodontines with respect
to the southern South American forms show a significant separation of both
lineages since at least latest Miocene-early Pliocene.