Dimila Mothé

The South American Gomphotheres (Mammalia, Proboscidea, Gomphotheriidae): Taxonomy, Phylogeny, and Biogeography

The taxonomic history of South American Gomphotheriidae is very complex and controversial. Three species are currently recognized: Amahuacatherium peruvium, Cuvieronius hyodon, and Notiomastodon platensis. The former is a late Miocene gomphothere whose validity has been 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 distributions, respectively. South American gomphotheres became extinct at the end of the Pleistocene. We conducted a phylogenetic analysis of Proboscidea including the South American Quaternary gomphotheres, which resulted in two most parsimonious trees. Our results support a paraphyletic Gomphotheriidae and a monophyletic South American gomphothere lineage: C. hyodon and N. platensis. The late Miocene gomphothere record in Peru, Amahuacatherium peruvium, seems to be a crucial part of the biogeography and evolution of the South American gomphotheres.

The Systematics of South American Quaternary Mammals with Holarctic Origins – an Introduction to the I FOGEMI Proceedings Volume

This special issue of the Journal of Mammalian Evolution represents the proceedings from a meeting held in conjunction with the VII Brazilian Symposium on Vertebrate Paleontology, entitled “First Forum of the Group of Specialists on Immigrant Mammals” (I FOGEMI). This meeting gathered researchers on the systematics of South American Quaternary mammals with holarctic origins. In this brief introduction to the meeting proceedings, we discuss the justification for the meeting, quote its main results, and introduce the contents of the present volume. The intent of the First Forum of the Group of Specialists on Immigrant Mammals (I FOGEMI, I Fórum do Grupo de Especialistas em Mamíferos Invasores) was to join scientists conducting research on the systematics of South American Quaternary mammals with holarctic origins. Most of these studies were theses and dissertations, mainly conducted by Brazilian paleontologists. Therefore, the I FOGEMI was one of the special events of the VII Simpósio Brasileiro de Paleontologia de Vertebrados (VII SBPV, Seventh Brazilian Symposium on Vertebrate Paleontology), which occurred from the 18th to 23rd July of 2010, at the Universidade Federal do Estado do Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil. All researchers invited for the I FOGEMI attended the event (Fig. 1), and we gathered during three days, from the 19th to 21st of July, 2010. The I FOGEMI was an open event for the participants of the VII SBPV, and it was composed of a series of oral presentations. At the end of the third day, all participants (including the audience) were invited to debate about the main issues highlighted during the event. The oral presentations of the I FOGEMI became the papers in this special volume. These papers present taxonomic revisions and biogeographical inferences, mostly based on new phylogenetic studies for Gomphotheriidae (Proboscidea), Camelidae, Tayssuidae (Artiodactyla), and Tapiridae (Perissodactyla). Furthermore, another paper demonstrates new ideas about the controversial issue on the ecological displacement and consecutive extinction of the Sparassodonta (Metatheria), a South American native carnivorous group, by the holarctic Carnivora. Moreover, there is a paper on new absolute datings for Brazilian Pleistocene mammals. The main results of these papers suggest that the ingression of holarctic mammals in South America occurred in several independent pulses on each of the lineages. Also, probably, these ingressions happened from the upper Miocene on, and not only after the imposition of the Panamanian Isthmus. The ingression of holarctic Carnivora is not related to the extinction of the South American native mammalian carnivores, the Sparassodonta. The southern Brazilian Pleistocene mammals were represented by a mixture of “Brazilian” and Pampean Quaternary mammals, and they occurred throughout the Pleistocene. However, some Pampean faunal elements apparently went extinct earlier in Argentina and Uruguay. Apart from the papers present here, the main conclusions of the I FOGEMI were: 1) some other groups of South American Pleistocenemammals with holarctic origins, such as Cervidae, Equidae, and Sigmodontinae, require taxonomic revisions; in consequence, this would stimulate phylogenetical and L. dos Santos Avilla (*) Departamento de Zoologia, Instituto de Biociências, Laboratório de Mastozoologia, Universidade Federal do Estado do Rio de Janeiro, Avenida Pasteur, 458, Urca, 22290-240, Rio de Janeiro, Brazil e-mail: leonardo.avilla@gmail.com

The Dance of Tusks: Rediscovery of Lower Incisors in the Pan-American Proboscidean Cuvieronius hyodon Revises Incisor Evolution in Elephantimorpha.

The incisors of proboscideans (tusks and tushes) are one of the most important feature in conservation, ecology and evolutionary history of these mammals. Although the absence of upper incisors is rare in proboscideans (occurring only in deinotheres), the independent losses of lower incisors are recognized for most of its lineages (dibelodont condition). The presence of lower incisors in the Pan-American gomphothere Cuvieronius hyodon was reported a few times in literature, but it was neglected in systematic studies. We analyzed several specimens of Cuvieronius hyodon from the Americas and recognized that immature individuals had lower incisors during very early post-natal developmental stages. Subsequently, these are lost and lower incisors alveoli close during later developmental stages, before maturity. Moreover, for the first time in a formal cladistic analysis of non-amebelodontine trilophodont gomphotheres, Rhynchotherium and Cuvieronius were recovered as sister-taxa. Among several non-ambiguous synapomorphies, the presence of lower incisors diagnoses this clade. We recognize that the presence of lower incisors in Cuvieronius and Rhynchotherium is an unique case of taxic atavism among the Elephantimorpha, since these structures are lost at the origin of the ingroup. The rediscovery of the lower incisors in Cuvieronius hyodon, their ontogenetic interpretation and the inclusion of this feature in a revised phylogenetic analysis of trilophodont gomphotheres brought a better understanding for the evolutionary history of these proboscideans.