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The Fossil Record of Condors
(Ciconiiformes: Vulturidae) in Argentina
Claudia P. Tambussi and Jorge I. Noriega
ABSTRACT
At present, the fossil record indicates that condors probably
originated in North America, and their fossil history in South
America has been traced to the early?-middle Pliocene
(Montehermosan?-Chapadmalalan Age) of the Pampean region
(Argentina). The great diversity of condors that occurred in the
late Cenozoic of this region comprises three genera and at least
four species, namely, Dryornis pampeanus Moreno and Mercerat,
Vultur gryphus Linnaeus, Geronogyps reliquus Campbell, and an
indeterminate vulturid probably belonging to a new genus and species.
The presence of Geronogyps reliquus (up to now restricted to
the Pleistocene of Peru) in the Pleistocene sediments of the Pampean
region extends considerably the geographic range of the species.
Introduction
New World vultures (Vulturidae=Cathartidae auct.) are
widely distributed in the Americas, ranging from Canada to
Tierra del Fuego in Argentina, and are most diverse in tropical
regions of South America. All species are adapted to feeding
on carrion, but they present different and exceptional specializations
in their habits of scavenging (Hertel, 1992, 1994).
New World vultures are closely related in habits and appearance
to the Old World vultures (Accipitridae: Aegypiinae and
Gypaetinae) due to convergent evolution. Vulturids show close
phylogenetic relationships with the ciconiid storks (Ligon,
1967; Rea, 1983; Olson, 1985; Emslie, 1988a; Sibley and Ahlquist,
1990), whereas the Old World Vultures show close affinities
to hawks and eagles (Brown and Amadon, 1968). Some
analyses, however, do not agree with moving the Vulturidae
Claudia P. Tambussi, CONICET, Departamento Cientifico Paleontologia
Vertebrados, Museo de La Plata, Paseo del Bosque s/nro,
1900 La Plata, Argentina. Jorge I. Noriega, CONICET, Centro de Investigaciones
Cientificas y de Transferencia Technologica a la Produccion,
Materi y Espaha, 3105 Diamante, Entre Rios, Argentina.
177
from the Falconiformes to the Ciconiiformes (Griffiths, 1994,
and the literature cited therein). We do not discuss this controversy
but instead adopt the view that condors are Ciconiiformes.
Vulturids are represented by seven living species (Sibley and
Monroe, 1990; nomenclature for species' binomials of modern
birds mentioned herein follows Sibley and Monroe, 1990). The
two largest species, the condors, are characterized by having
long, broad wings and short tails and by certain osteological
features of the cranium (Emslie, 1988a; Hertel, 1992) and include
the California Condor, Gymnogyps californianus, and the
Andean Condor, Vultur gryphus, from North America and
South America, respectively.
The earliest fossil vulture with affinities to condors is
Hadrogyps aigialeus Emslie from the middle Miocene of California.
Two other pre-Pleistocene unequivocal condors were
described from the late Miocene of Florida {Pliogyps charon
Becker) and the middle Pliocene of Kansas {Pliogyps fisheri
Tordoff). Based on the geographic distribution of recent and
fossil species, Emslie (1988a, 1988b) suggested that condors
probably originated in North America and may have participated
in the Great American Biotic Interchange in the early-middle
Pliocene. In accordance with the latter hypothesis,
condors in Argentina are restricted to the Pliocene to late
Pleistocene of the Pampean region, far from the modern area
of distribution of the recent species, with the earliest fossil history
being the early?-middle Pliocene (Montehermosan?-Chapamalalan
Age) of Argentina, with the presence of
Dryornis pampeanus Moreno and Mercerat.
The purpose of the present study is to summarize the diversity
of the previously described condors from Argentina and to
describe new specimens.
MATERIALS AND METHODS
Specimens of fossil and extant vultures were examinated at
the Division of Birds, Department of Vertebrate Zoology, National
Museum of Natural History, Smithsonian Institution,
Washington, D.C, U.S.; Department of Ornithology, American