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Home , Cuvieronius, Gomphothere, Mammutidae, Mastodon, Proboscidea, Quaternary extinction

The () from : diversity, habitats and feeding ecology

J.L. Prado1, M.T. Alberdi2, B. Azanza3, B. Sánchez2, D. Frassinetti4 1INCUAPA-Facultad de CC. Sociales, UNC. Olavaria, Argentina [email protected] 2Museo Nacional de Ciencias Naturales, CSIC, Madrid, [email protected] - and [email protected] 3Universidad de Zaragoza, Zaragoza, Spain - [email protected] 4Museo Nacional de Historia Natural, Santiago, - [email protected]

SUMMARY: Gomphotheres were recorded in South America from the early-middle Pleistocene (Ensenadan Land- Age) to the ( Land-mammal Age). They arrived in South America during the “Great American Biotic Interchange”. Only two genera are recognised: , which has only one , Cuvieronius hyodon; and , which has two species, Stegomastodon waringi and Stegomastodon platensis. The small Cuvieronius utilised the Andean corridor and it was almost exclu- sively mixed-feeder. The large Stegomastodon dispersed through the east route and the coastal area, where Stegomastodon waringi shows an adaptive trend from mixed-feeder to grazer, and Stegomastodon platensis shows a trend from mixed to browser feeding. Cuvieronius seems to have been adapted to a temperate-cold climate conditions, while Stegomastodon seems to have predominated in lower latitudes, and was better adapted to warm or temperate climatic conditions.

1. INTRODUCTION photheres into the subfamily Cuvieroniinae. In any case, the problem of nomenclature is a The proboscidea gomphotheres (family complex one. Cuvieronius hyodon is geograph- Gomphotheriidae) are known in South America ically restricted to the Andine Region of from the (Ensenadan Land- , Peru, Bolivia, Chile and Northwest mammal Age) to the late Pleistocene (Lujanian Argentina. Stegomastodon waringi has been Land-mammal Age). They were descendants of recorded in Brazil and Ecuador (on the Santa the stock that originated in North Elena peninsula and in the Quebrada Pistud America and arrived in South America during locality, near Bolivar province of Carchi). the “Great American Biotic Interchange” Stegomastodon platensis has been recorded in (Webb 1991). Only two genera are recognized: Argentina from the middle to the latest Cuvieronius, which has only one species, Pleistocene, principally in the Pampean Cuvieronius hyodon; and Stegomastodon, Region, and also in Uruguay and Paraguay dur- which has two species, Stegomastodon waringi ing the late Pleistocene. and Stegomastodon platensis (Alberdi & Prado During the Pleistocene, two corridors devel- 1995; Alberdi et al. in press). Recently, oped in South America. These two corridors Casamiquela et al. (1996) presented a simpli- shaped the paleobiogeographic history of most fied classification modified after Simpson & North American in South America. Paula Couto (1957), and Shoshani (1996) sug- The most viable model postulated for the gom- gested including all South American gom- phothere dispersal process seems to indicate

337 The World of - International Congress, Rome 2001

that the small Cuvieronius utilised the in widely spaced lophs. This dental morpholo- corridor, whereas the large Stegomastodon dis- gy led to the recognition of as persed through the East route and some coastal browsers (Webb et al. 1992). areas. (Mammuthus) have high-crowned molars with closely spaced enamel lophs coated with 2. FEEDING AND HABITAT cement, which identifies them as grazers (Davis et al. 1985). Isotopic analyses confirm Generally, it is considered that the habitat of this hypothesis (MacFadden & Cerling 1996). Cuvieronius would have been high grassland By contrast, the gomphotheres from West Palm with cold to temperate climatic conditions, Beach, , USA, and from South America while Stegomastodon would have been adapted have a δ13C values which are intermediate to more open grassland with warm to temperate between browsers and grazers (Koch et al. climatic conditions. By means of isotopic 1998; Sánchez et al. in press). Both Mammut analyses, Sánchez et al. (in press) have and Mammuthus were more specialised feeders analysed the diet of different gomphothere than Cuvieronius, which was a mixed-feeder, species from Pleistocene deposits of South and Stegomastodon which was a mixed-feeder America, and have reconstructed the diet of with tendencies toward browser-feeding or Cuvieronius hyodon, Stegomastodon waringi grazer-feeding (see above). These observations and Stegomastodon platensis. do not match the predictions of Vrba’s (1992) The carbon isotopic results for Cuvieronius model, who indicated that forms that would and Stegomastodon from the middle have tended to disperse from north to south Pleistocene indicate different feeding ecologies would have been more adapted to open envi- for these two genera. Cuvieronius from Tarija ronments, and consequently would have been has isotopic values that are more homogeneous. predominantly grazers. These values agree with those previously described by MacFadden & Sockey (1997), and 3. GOMPHOTHERE IN SOUTH AMERICA indicate that this was predominan- tly a mixed-feeder. On the other hand, There are many causes for Pleistocene mam- Stegomastodon platensis from middle and late mal extinction, which make it difficult to con- Pleistocene of Argentina exhibits more nega- sider and evaluate all of the complex phenome- tive isotopic values, suggesting an adaptive na that produced the disappearance of an trend from mixed-feeding to browser-feeding important part of the Pleistocene fauna. Two (Sánchez et al., in press). In addition, isotopic types of theories have been offered for this composition in S. waringi from the late extinction: the direct impact of man through Pleistocene of Santa Elena Peninsula, Ecuador, hunting activities and climate and ecological suggests that this species was a mixed-feeder changes. with grazer tendencies. This may be related to Martin (1984) proposed that the extinction of the altitudinal and latitudinal distribution of large mammals from America and are this species. related to various, sudden impacts. The There appears to be no biological explanation overkill hypothesis is supported by the syn- why Mammuthus () and Mammut chrony of extinction with the arrival of large (), recorded in Florida and numbers of in these continents. It Honduras during the Pleistocene, and which seems that human activities, such as hunting might have been expected to cross the pressure or habitat disturbance, affected the Panamanian land bridge, did not reach South Pleistocene population of gomphotheres America (Koch et al. 1998). The reasons may (Politis et al. 1995). The archaeological record be found in the diet and habitat preferences of from South America shows that gomphotheres these genera. Mastodons (Mammut) have rela- were common in Paleo-Indian sites (Montané, tively low-crowned molars with cusps arrayed 1968; Bryan et al. 1978; Correal Urrego 1981; 338 The Pleistocene Gomphotheres (Proboscidea) from South America: Diversity, Habitats and Feeding Ecology

Dillehay & Collins 1988). Prado et al. (2001) 5. ACKNOWLEDGEMENTS show that large mammal were cor- related with climate change, a process that We thank Dr. E. Cerdeño and an anonymous began prior to the arrival of humans in the reviewer for their critical revision of the manu- Pampean Region. script, and the valuable comments. The present Climatic and ecological changes produced work was made possible through a joint rapid change in communities. The nutri- Research Project from AECI, Spain - Argentina tional stress induced by these changes is identi- (2000). fied as the main cause of extinction by Graham & Lundelius (1984) and King & Saunders 6. REFERENCES (1984). This models implies that gomphotheres died off because they were specialised feeders, Alberdi, M.T., Cartelle, C. & Prado, J.L. (in adapted to a kind of plant that disappeared dur- press). El registro de Stegomastodon ing the times. With this in mind, (Mammalia, Gomphotheriidae) en el Guthrie (1984) hypothesised that plant diversi- Pleistoceno superior de Brasil. ty was greater and the growing season was Ameghiniana. longer in the Pleistocene than in the Holocene. Alberdi, M.T. & Prado, J.L. 1995. Los mastodontes de América del Sur. In M. T. 4. FINAL REMARKS Alberdi, G. Leone & E. P. Tonni (eds.), Evolución biológica y climática de la The South American gomphotheres must be Región Pampeana durante los últimos 5 included in only one subfamily. We recognise millones de años. Un ensayo de correlación two genera, Cuvieronius and Stegomastodon; con el Mediterráneo occidental. and three species, Cuvieronius hyodon, Monografías, MNCN, CSIC, 12: 277-292. Stegomastodon waringi, and Stegomastodon Madrid. platensis. Bryan, A., Casamiquela, J., Cruxent, J., Gruhn, Cuvieronius genus arrived in South America R. & Ochsenius, C. 1978. An El Jobo during the Great American Biotic Interchange, Kill at Taima-Taima, Venezuela. and was recorded from the early Pleistocene to Science, 200: 1275-1277. the late Pleistocene utilising the Andes corridor Correal Urrego, G. 1981. Evidencias culturales for its dispersal. The genus Stegomastodon y pleistocénica en Colombia, appeared later, during the middle Pleistocene 12: 1-148. Bogotá: Fundación de and dispersed through the East route and some Investigaciones Arqueológicas Nacionales. coastal areas. Casamiquela, R.M., Shoshani, J. & Dillehay, Cuvieronius was a mixed feeder, and T.D. 1996. South American proboscidean: Stegomastodon was a mixed-feeder with ten- general introduction and reflections on dencies toward browser-feeding or grazer-feed- Pleistocene extinctions. In J. Shoshani & P. ing. These differences in diet preferences could Tassy (eds.), The Proboscidea. Evolution explain why only the bunodont forms reached and Palaeoecology of Elephants and their South America when both types, lophodont and relatives: 316-320. Oxford, New York, bunodont, lived together in Tokyo: Oxford University Press. prior to the emergence of the Isthmus of Davis, O.K., Mead, J.I., Martin, P.S. & Panama. Agenbroad, L.D. 1985. Riparian Cuvieronius hyodon would have inhabited were a major component of the diet of high grasslands with cold to temperate climatic mammoths of Southern Utah. Current conditions, and Stegomastodon would have Research in the Pleistocene, 2: 81-82. been adapted to more open grasslands with Dillehay, T.D. & Collins, M.B. 1988. Early cul- warm to temperate conditions. tural evidence from in Chile. Nature, 332: 150-152 339 The World of Elephants - International Congress, Rome 2001

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