J Mammal Evol DOI 10.1007/s10914-012-9192-3 ORIGINAL PAPER The South American Gomphotheres (Mammalia, Proboscidea, Gomphotheriidae): Taxonomy, Phylogeny, and Biogeography Dimila Mothé & Leonardo S. Avilla & Mario A. Cozzuol # Springer Science+Business Media, LLC 2012 Abstract The taxonomic history of South American Gom- peruvium, seems to be a crucial part of the biogeography photheriidae is very complex and controversial. Three species and evolution of the South American gomphotheres. are currently recognized: Amahuacatherium peruvium, Cuvieronius hyodon,andNotiomastodon platensis.Thefor- Keywords South American Gomphotheres . Systematic mer is a late Miocene gomphothere whose validity has been review. Taxonomy. Proboscidea questioned by several authors. The other two, C. hyodon and N. platensis, are Quaternary taxa in South America, and they have distinct biogeographic patterns: Andean and lowland Introduction distributions, respectively. South American gomphotheres be- came extinct at the end of the Pleistocene. We conducted a The family Gomphotheriidae is, so far, the only group of phylogenetic analysis of Proboscidea including the South Proboscidea recorded in South America. Together with the American Quaternary gomphotheres, which resulted in two megatheriid sloths Eremotherium laurillardi Lund, 1842, most parsimonious trees. Our results support a paraphyletic the Megatherium americanum Cuvier, 1796,andthe Gomphotheriidae and a monophyletic South American notoungulate Toxodon platensis Owen, 1840, they are the gomphothere lineage: C. hyodon and N. platensis. The late most common late Pleistocene representatives of the mega- Miocene gomphothere record in Peru, Amahuacatherium fauna in South America (Paula-Couto 1979). Similar to the Pleistocene and Holocene members of the family Elephan- tidae (e.g., extant elephants and extinct mammoths), the D. Mothé (*) South American gomphotheres are characterized by having Programa de Pós-graduação em Ciências Biológicas (Zoologia), a brachycephalic and brevirostrine skull, a short and curved Museu Nacional/UFRJ, mandibular symphysis, and specialized dentition, which Quinta da Boa Vista, 20940-040, Rio de Janeiro, RJ, Brazil consists of a pair of upper tusks (second incisors) and six e-mail: [email protected] pairs of upper and lower molars (Simpson and Paula-Couto 1957; Paula-Couto 1979; Prado et al. 2001; Ferretti 2008a). L. S. Avilla Departamento de Zoologia, Instituto de Biociências, Laboratório de Mastozoologia, Universidade Federal do Estado do Rio de Janeiro, Taxonomy and Diversity of South American Avenida Pasteur, 458, Urca, 22290-240, Gomphotheres Rio de Janeiro, RJ, Brazil e-mail: [email protected] The taxonomic history of the South American gompho- M. A. Cozzuol theres is long and complex. Most authors consider that they Departamento de Zoologia, Instituto de Ciências Biológicas, were represented by three genera: Cuvieronius Osborn, Universidade Federal de Minas Gerais, 1923, Haplomastodon Hoffstetter, 1950,andStegomastodon Avenida Antônio Carlos, 6627, Pampulha, 31270-910, Belo Horizonte, Minas Gerais, Brazil Pohlig, 1912 (Simpson and Paula-Couto 1957;Ficcarellietal. e-mail: [email protected] 1995;Ferretti2008a, 2010). Later, some authors (Alberdi and J Mammal Evol Prado 1995; Alberdi et al. 2002, 2004, 2007; Prado et al. proposed a new genus and species, Notiomastodon ornatus, 2005; Prado and Alberdi 2008) synonymized Haplomastodon based on a short, massive tusk and a dentary from Playa del with Stegomastodon, reducing the diversity of genera, but Barco, Argentina. Hoffstetter (1950) proposed Haplomasto- keeping three species: Cuvieronius hyodon (Fischer, 1814), don as a subgenus of Stegomastodon and, in 1952, elevated Stegomastodon platensis (Ameghino, 1888), and S. waringi Haplomastodon to full generic status, based on the absence (Holland, 1920). Very recently, Mothé et al. (in press) of transverse foramina in the atlas (1st cervical vertebra). He proposed to include the last two species in a single species, also included all Brazilian gomphotheres in a new species under the name Notiomastodon platensis, as first suggested by Stegomastodon brasiliensis Hoffstetter, 1952.Thetrans- Madden (1984). verse foramen of the axis was recognized as a variable The first report of gomphothere remains from South character by Simpson and Paula-Couto (1957), and they America was made by Cuvier (1806),whoanalyzedan placed all Brazilian gomphotheres in Haplomastodon war- isolated left M2 from Imbabura, northern Ecuador, and ingi (Holland, 1920). Ficcarelli et al. (1995), based on nameditasthe“Mastodonte des Cordilliéres.” In 1824, diagnostic gomphothere remains from northern Ecuador, Cuvier established the formal names Mastodon andium for synonymized all Haplomastodon species with H. chimbor- the Imbabura (Ecuador) gomphotheres and M. humboldtii azi (Proaño, 1922). Alberdi and Prado (1995) included the for a molar from Concepción (Chile). Before this study, species S. superbus (Ameghino, 1888), and N. ornatus in S. Fischer (1814) analyzed the same specimen from Imbabura, platensis. The genus Haplomastodon was later synony- and named it as Mastotherium hyodon, which has priority mized with the genus Stegomastodon, generating the new over Mastodon andium (see Cabrera 1929). The genus combination S. waringi (Alberdi et al. 2002). Lucas and Cuvieronius was erected by Osborn (1923)andlater, Alvarado (2010) used the combinations Notiomastodon pla- Cabrera (1929), in a revision of the Argentine gompho- tensis, in replacement of S. platensis, which was previously theres, synonymized Mastodon argentinus Ameghino, 1888, suggested by Madden (1984) and Ferretti (2008a). Ferretti under the name Cuvieronius hyodon (Fischer, 1814). (2010) used the combination Haplomastodon chimborazi Ficcarelli et al. (1995), in a taxonomic revision of Cuvier- and employed quote marks for “Stegomastodon” platensis, onius, validated C. tarijensis (Ameghino, 1902), and pro- arguing that the South and North American species attribut- posed the material referred to C. tarijensis from Tarija, ed to this genus are not congeneric with S. mirificus (Leidy, Bolivia, as the topotype for the species. Recently, Lambert 1859), the type species of the genus, from North America. and Shoshani (1998) considered C. hyodon as the type Mothé et al. (in press) reviewed the Pleistocene South species of Cuvieronius, but Lucas (2009) argued that the American lowland gomphotheres and concluded that they genus is monospecific, considering C. tropicus Cope, 1884, belong to a single species for which the valid name is Notio- from Mexico, as a junior synonym of C. hyodon. Lucas mastodon platensis. Consequently, only two gomphothere (2009), in order to solve the taxonomic problem of the name species were present in the Quaternary of South America: Mastotherium hyodon, suggested to keep the name Cuvier- the Andean Cuvieronius hyodon, and the lowland Notiomas- onius and consider M. hyodon as its type species, by desig- todon platensis (Fig. 1). nating a neotype to M. hyodon (the skull and lower jaw from The holotype of Notiomastodon ornatus (Museo Argen- Tarija, Bolivia originally described and illustrated by Boule tino de Ciencias Naturales “Bernardino Rivadavia,” collec- and Thevenin (1920)). tion number MACN 2157) is described by Cabrera (1929), The diagnostic material of C. hyodon comes from Tarija, and it is a mandible with a short symphysis, without lower Bolivia, where several skulls and postcranial remains were incisors, bunolophodont molars with several accessory con- found (Marshall and Sempere 1991; Coltorti et al. 2007). ules (double trefoil wear pattern), and short, massive and Cuvieronius hyodon is a short-jawed gomphothere charac- upper curved tusk with lateral enamel band (Cabrera 1929: terized by having a depressed and elongated cranium, a pair Figs. 2-4). Furthermore, Stegomastodon platensis is de- of twisted upper tusks, which have a spiraled enamel band scribed as having a variable wear pattern on the molars, along their entire length, and lower deciduous incisors in more complex than Haplomastodon chimborazi,and some juveniles (Prado et al. 2005; Ferretti 2008a, b). straight to slightly upper curved tusks, without enamel band The first one to review the taxonomy of South American (Prado et al. 2005). Both genera show a similar tusk mor- lowland gomphotheres was Florentino Ameghino (1888, photype and should represent the same taxon, in which 1889, 1891), who defined four species that he placed in Notiomastodon has priority and Stegomastodon is not ap- the genus Mastodon. After that, the Argentinean fossils were plicable to the South American species (Mothé et al. in again reviewed by Cabrera (1929), who synonymized some press). A brachycephalic skull with a high parieto-occipital species described by Ameghino (1889) and transferred them region, a pair of straight or curved upper tusks with absence to the North American genus Stegomastodon, recognizing of spiraled torsion, complex molar teeth with double-trefoil only two species: S. platensis and S. superbus. He also and simple-trefoil wear patterns (Mothé et al. in press) J Mammal Evol presence of pre-Quaternary gomphotheres in South America remains an open issue and more studies are needed to eluci- date the evolutionary history of South American proboscideans. The only consensus about proboscidean history in South America is that they became extinct by the end of the Pleistocene (Ficcarelli et al. 1997; Prado et al. 2001; Alberdi et al. 2002; Sánchez-Chillón