INVESTIGADORES
CARLINI Alfredo Armando
artículos
Título:
Paleogene Land Mammal Faunas of South America; a Response to Global Climatic Changes and Indigenous Floral Diversity
Autor/es:
WOODBURNE, MICHAEL; GOIN, F.; BOND M.; CARLINI A.A.; GELFO, J.; LÓPEZ, GUILLERMO; IGLESIAS A.; ZIMICZ N.
Revista:
JOURNAL OF MAMMALIAN EVOLUTION
Editorial:
SPRINGER
Referencias:
Lugar: Berlin; Año: 2013 vol. 2013 p. 1 - 73
ISSN:
1064-7554
Resumen:
Abstract An appraisal of Paleogene floral and land mammal
faunal dynamics in South America suggests that both
biotic elements responded at rate and extent generally comparable
to that portrayed by the global climate pattern of the
interval. A major difference in the South American record is
the initial as well as subsequent much greater diversity of
both Neotropical and Austral floras relative to North
American counterparts. Conversely, the concurrent mammal
faunas in South America did not match, much less exceed,
the diversity seen to the north. It appears unlikely that this
difference is solely due to the virtual absence of immigrants
subsequent to the initial dispersal of mammals to South
America, and cannot be explained solely by the different
collecting histories of the two regions. Possible roles played
by non-mammalian vertebrates in niche exploitation remain
to be explored.
The Paleogene floras of Patagonia and Chile show a climatic
pattern that approximates that of North America, with
an increase in both Mean Annual Temperature (MAT) and
Mean Annual Precipitation (MAP) from the Paleocene into
the Early Eocene Climatic Optimum (EECO), although the
Paleocene-Eocene Thermal Maximum (PETM) is not recognized
in the available data set. Post-EECO temperatures declined
in both regions, but more so in the north than the south,
which also retained a higher rate of precipitation.
The South American Paleogene mammal faunas developed
gradual, but distinct, changes in composition and diversity
as the EECO was approached, but actually declined
somewhat during its peak, contrary to the record in North
America. At about 40 Ma, a post-EECO decline was recovered
in both hemispheres, but the South American record
achieved its greatest diversity then, rather than at the peak of
the EECO as in the north. This post-EECO faunal turnover
apparently was a response to the changing conditions when
global climate was deteriorating toward the Oligocene.
Under the progressively more temperate to seasonally arid
conditions in South America, this turnover reflected a major
change from the more archaic, and more tropical to
subtropical-adapted mammals, to the beginning of the ultimately
modern South American fauna, achieved completely
by the Eocene-Oligocene transition. Interestingly, hypsodonty
was achieved by South American cursorial mammals
about 15?20 m.y. earlier than in North America. In addition
to being composed of essentially different groups of mammals,
those of the South American continent seem to have
responded to the climatic changes associated with the ECCO
and subsequent conditions in a pattern that was initially
comparable to, but subsequently different from, their North
American counterparts.