1 research outputs found
Feeding ecology, dispersal, and extinction of South American Pleistocene gomphotheres (Gomphotheriidae, Proboscidea)
To reconstruct the paleodiet and habitat preference of gomphotheres, we measured the
carbon and oxygen isotope composition of 68 bone and tooth samples for three species of Gomphotheriidae
from 24 different localities (Argentina, Bolivia, Ecuador, Chile, and Brazil). Additionally,
we measured the isotopic oxygen in the phosphate of 30 samples to control diagenetic
alteration. We calculated the correlation between pairs of d18Op–d18Oc values for enamel, dentine,
and bone, taken from the same individual in order to verify whether the oxygen of structural apatite
carbonate was in equilibrium with body water. Because of the good correlation obtained
among pairs of the three skeletal components, we considered the d13C results of all components to
be equally representative of both gomphothere groups, and we used them collectively in the analysis
of the data.
To compare the different groups of specimens, we divided the samples into six groups, taking
into account their taxonomy as well as their geographic and stratigraphic distribution. Cuvieronius
specimens from Chile were exclusively C3 plants eaters, whereas specimens from Bolivia and Ecuador
had a mixed C3-C4 diet. Stegomastodon showed a wider range of dietary adaptations. Specimens
from Queque´n Salado in Buenos Aires Province were entirely C3 feeders, whereas the diet of
specimens from La Carolina Peninsula (Ecuador) was exclusively C4. The remaining South American
groups analyzed were C3-C4 mixed-feeders. Carbon isotope composition of bone and teeth
decreased as latitude increased. We found evidence of an exclusively C3-dominated diet at approximately
35–418S. This result confirms that ancient feeding ecology cannot always be inferred from
dental morphology or extant relatives. Data from middle and late Pleistocene indicated that, over
time, there was an adaptive change in paleodiet from predominantly mixed-feeders to more specialized
feeders. We propose that this dietary evolution was one of the causes that forced gomphotheres
to extinction in South America. In addition, the data presented in this paper suggest that
because of the different feeding preferences among mastodons, mammoths, and gomphotheres,
only the bunodont gomphotheres reached South America.This work was supported by an
European Community project CI1*-CT90–0862
(B. Sa´nchez Chillo´n contract no. ERBCHBICT930742
at the University of Trieste); a joint
Research Project from the Agencia EspanËœola de
Cooperacio´n Iberoamericana, Spain–Argentina
(1994–96 and 2001–2002); Projects PB94–0071
and PB97–1250 from the Direccio´n General de
Investigacio´n Cientı´fica y Te´cnica of Spain;
grants from the Universidad Nacional del Centro
and from the Project PID-CONICET, Argentina.Peer reviewe