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Based on data from analyses on previously-reported carbon stable isotope data from dental enamel and dentine from tusks reported in the literature, diets were inferred for the gomphothere genera Amebelodon, Cuvieronius, Gomphotherium, Rhynchotherium, Serbelodon, and Stegomastodon (Proboscidea, Gomphotheriidae) that inhabited the Americas during the Cenozoic. Amebelodon, Gomphotherium, and Serbelodon specimens of the Barstovian and Clarendonian faunal stages fed on C plants; while the same Hemphillian genera consumed a mixed C/C diet. Hemphillian Rhynchotherium were mixed-diet feeders while Blancan specimens of the same genus fed on C plants. Stegomastodon from the same Blancan period consumed a mixed C/C diet, similar to Rancholabrean animals, although Lujanian specimens ate C plants. As for the genus Cuvieronius, Irvingtonian, Rancholabrean, and Lujanian specimens consumed a mixed C/C diet. These results suggested that American gomphotheres displayed generalist feeding habits, allowing them to inhabit different environments in extensive areas of the continents, and survive to the end of the Pleistocene., To PAPIIT (IA#104017 and IA#102719), for providing financial support for this project to Víctor Adrian Perez Crespo. Research Project ANPCYT PICT 20151512 and Grant UNICEN, Argentina were awarded to Jose Luis Prado; DGICYT CGL2016-79334-P from Spain granted to Maria Teresa Alberdi contributed to funding this investigation.

Studies on South American Gomphotheriidae started around 210 years ago and, 150 years later, the classic study “The mastodonts of Brazil” by Simpson and Paula Couto (1957) attempted to clarify the complex issues related to our understanding of these proboscideans. Here, we update state of knowledge regarding proboscideans in South America subsequent to the publication of Simpson and Paula Couto (1957). The taxonomy of South American proboscideans is now stable and two species are recognized, Notiomastodon platensis and Cuvieronius hyodon. The former had a wide distribution in South America (from lowlands to highlands and from east to west coasts), while the latter was restricted to Ecuador, Peru and Bolivia. Although records of Notiomastodon are abundant and occur in almost overlapping geographic distribution with Cuvieronius, they have never been recorded in the same locality. Here, we evaluated over 500 South American localities with proboscidean remains, although only cranial and dental specimens show recognizable diagnostic features. As both proboscideans in South America had a generalist-opportunist alimentary strategy, a competitive exclusion probably precluded their sympatry. Their origin is most probably related to independent migrations from Central America during the Great American Biotic Interchange. They are not sister-taxa – Cuvieronius hyodon is sister-taxon of Rhynchotherium, and this clade is closer to Notiomastodon platensis than to the other proboscideans, supporting the hypothesis of independent origins. Notiomastodon platensis has a continuous record from the Early Pleistocene to Early Holocene, when it became extinct, probably due to synergy of human impact and climatic changes during the Pleistocene/Holocene transition. In contrast, extinction of Cuvieronius hyodon happened much earlier, and it was not related to the terminal Pleistocene event that lead the extinction of selected megafauna in South America, including Notiomastodon., Facultad de Ciencias Naturales y Museo

The South American gomphotheres were previously classified in three genera and three species. Two biogeographic corridors are recognized for the dispersion of gomphotheres in South America. Cuvieronius hyodon was found mainly in the highlands and west to the Andes, and Stegomastodon platensis and Haplomastodon chimborazi were found in lowlands. The aim of the present study is to review the taxonomy of South American lowland gomphotheres. A large sample of specimens was analyzed, which included crania, teeth and postcrania from several localities in Brazil, Ecuador, Colombia, Venezuela, Argentina, and Uruguay. A review of the diagnostic characters proposed in previous taxonomic studies of South American lowland gomphotheres found that they are variable in both reputed species if large samples are considered. There is no support for more than one South American lowland gomphothere species, and it shows a significant morphological variation in some characteristics. The name for this taxon, after a taxonomic review, must be Notiomastodon platensis (Ameghino, 1888) new combination. This reduces the number of gomphothere species in South America to two genera and species. The lowland gomphothere is closely related to Cuvieronius and Rhynchotherium, and not closely related to Stegomastodon from North America, and Sinomastodon from Asia.

The purpose of this application, under Article 81.1 of the Code, is to conserve the long and widely used name Rhynchotherium Falconer, 1868, applied to proboscidean fossils from North America, by designating Rhynchotherium falconeri Osborn, 1923 as the type species. It has long been agreed that the cast of the holotype of R. tlascalae Osborn, 1918, the type species of Rhynchotherium, belongs to the genus Gomphotherium Burmeister, 1837, so preservation of the present usage of the genus name Rhynchotherium requires a type species that fits the current concept of the genus. It is proposed that Rhynchotherium falconeri Osborn, 1923 be designated the type species.

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.

A mandible and partial skeleton of Rhynchotherium falconeri is described from late Pliocene deposits of the 111 Ranch Locality in southeastern Arizona. The morphology of the mandible and m3 of the 111 Ranch individual is consistent with other specimens of Rhynchotherium and compares closely with previously reported R. falconeri from Arizona, as well as R. simpsoni from Florida. The 111 Ranch specimen is the basis for only the second description of postcranial material for the genus Rhynchotherium, and adds important morphological and ontogenetic attributes to this taxon. A morphometric analysis of specimens including the genotype indicates several junior synonyms are represented and the type specimen for the genus is no longer valid. A suggestion is made to raise F:AM 18225 to type status.

Two new records of gomphotheriid proboscideans, one identified as Rhynchotherium and the other as Cuvieronius, are reported in Mexico. Both records are in the southwesternmost points of their known distributional range. The remains of both genera consist of molars and tusks. Their measurements were compared with data available from the literature and collection specimens. The molar index of Rhynchotherium shows statistical differences between m2 and M2, and m3 and M3. However, differences between the m3 from both genera are not statistically significant, despite slight morphological differences. This suggests that metric and morphological information should be included for a reliable identification of isolated molars and, if available, any other data of the associated tusk. All known records relating to both genera suggest that they found southwestern Mexico favorable for use as a dispersal corridor to South America, likely due to the region's tropical or subtropical climate. However, some distri...

A partial left and right manus of a gomphotheriid are described from earliest Pleistocene deposits of 111 Ranch in southeastern Arizona, USA. The discovery of these well preserved manuses provides a rare opportunity to describe these elements of a gomphotheriid in North America. I provide detailed descriptions and measurements as well as comparisons of the manuses with those of other extant and extinct proboscideans. Analyses of the manuses indicate it was a small gomphotheriid, possibly a small female, having morphological attributes more similar to other gomphotheriids, then elephantids and mammutids. The gomphotheriids Stegomastodon and Rhynchotherium have both been previously reported from 111 Ranch. Michael R. Pasenko. Environmental Planning Group, 4141 North 32nd Street, Suite 102, Phoenix, Arizona, 85018, USA, mammut501@yahoo.com, Mpasenko@epgaz.com

The diet of a gomphothere (Proboscidea, Gomphotheriidae, Rhynchotherium species) from the Mexican Pliocene was determined using carbon and oxygen stable isotopes relationships in dental enamel. The analyses demonstrated that this individual exclusively fed on C3 plants, similar to some specimens found in Florida, United States.

Remains of juvenile individuals of Rhynchotherium blicki (Frick 1933) mastodon have been collected from sediments of the Upper Miocene (Late Hemphillian) locality of San Gerardo de Limoncito, corresponding with the top of Curré Formation. The recovered material, includes two second left upper deciduous molars and three frag- ments of tusks that were associated to the false gavial Gavialosuchus americanus (Sellards, 1915), remains of a soft shelled turtle Apalone sp., teeth of selachians (sharks and rays) and other icthyolites. The ecological requirements of the taxa suggest the existence of different environmental conditions from open grassland habitats to more closed marine environments like estuaries. Restos de individuos inmaduros del mastodonte Rhynchotherium blicki (Frick 1933) fueron colectados en sedimentos de la localidad de San Gerardo de Limoncito de edad Mioceno superior (Hemphilliano tardío), correspondiente al tope la Formación Curré. El material se compone de dos segundos molares deciduos, superiores, izquierdos y tres fragmentos de defensas asociados con restos del falso gavial Gavialosuchus americanus (Sellards, 1915), la tortuga de caparazón blando Apalone sp., dientes de seláceos (tiburones y rayas) y otros ictiolitos. Esta asociación de taxa, sugieren la existencia de diferentes condiciones ambientales que van desde hábitats de sabanas abiertas a ambientes marinos limitados tipo estuario.

In 1858, American geologist Joseph LeConte published the first scientific report of vertebrate fossils (mastodon, bison and horse) from Central America a brief record of a "mastodon bed" near the old village of Tambla in Honduras. In 1859, American archaeologist Ephraim George Squier also mentioned these fossils, illustrating a lower jaw fragment with a molar and providing specific clues to the location of the bonebed. J. M. Dow subsequently gave a gomphothere molar from the locality to Joseph Leidy at the Academy of Natural Sciences in Philadelphia, USA. Leidy published on the fossil, which still remains in the collection of the Academy, as ?Mastodon ohioticus? or as M. andium, and it was later referred to Rhynchotherium by Osborn and others. This molar is best identified as Cuvieronius hyodon, and the bonebed from which it was derived is near the modern village of Humuya (Tambla in the 1800s), not near the village currently called Tambla. The Tambla ?mastodon bed? has never been relocated, though data provided here should make that possible. Its discovery in the 1850s did not encourage further exploration for vertebrate fossils in Honduras, probably because ?mastodon? fossils were already commonplace in the USA, so the Tambla bonebed did not constitute a remarkable discovery. .

Los fósiles de proboscideos de América Central se asignan a cuatro géneros: Gomphotherium, Cuvieronius, Mammut y Mammuthus. Los trabajos previos de Stegomastodon, Rhynchotherium y Haplomastodon para la región se basaron en identificaciones taxonómicas desactualizadas o en fósiles no diagnósticos para estos géneros. El proboscidio más antiguo para Centroamérica (Guatemala, El Salvador, Honduras y Costa Rica) es el registro de Gomphotherium del Mioceno (Hemphiliano, ~ 7 Ma), sugiriendo que los gonfoterios se dispersaron desde Norteamérica a Centroamérica aproximadamente hace 9 millones de años después de que ellos se dispersaran desde Asia a Norteamérica. Sin embargo, no existe evidencia de que se dispersaran a Sudamérica, donde no existen registros de Gomphotherium, así que el canal interoceánico panameño del Mioceno debió de haber representado una barrera para su dispersión. Durante el Plioceno Tardío, el Cuvieronius evolucionó de un ancestro del Gomphotherium norteamericano y subsecuentemente se dispersó hacia el sur a través de América Central a Sudamérica (Plioceno Tardío). El Mammut posee un único registro en América Central (Honduras), posiblemente del Pleistoceno Tardío. Se conoce dos especies de Mammuthus, una del Pleistoceno Temprano (M. meridionalis) y una más abundante del Pleistoceno Tardío (M. columbi). Significativamente, ni el Mammut o el Mammuthus poseen registros en Sudamérica. América Central no funcionó como un centro de evolución u origen de algún nuevo taxón de proboscidio durante el Cenozoico Tardío, pese a ello, si fue un lugar de paso o tránsito migratorio. El Gomphotherium arribó a Centroamérica durante el Mioceno Tardío, el Cuvieronius durante el Plioceno Tardío, Mammuthus durante el Pleistoceno Temprano y el Mammut hasta el Pleistoceno Tardío. Existió una única emigración de Cuvieronius desde América Central a Sudamérica durante el Plioceno Tardío (~ 2,5 Ma). Todos los proboscídeos sudamericanos son Cuvieronius, o sus descendientes directos Notiomastodon y Haplomastodon durante el Plio-Pleistoceno. .

The genus Rhynchotherium has been described as a fossil for the Upper Miocene of Guatemala and volcanic deposits of Nicaragua, the Upper Miocene and Pliocene fluvial sediments of El Salvador and Honduras, but this is the first time it is recorded from Costa Rica. The material described includes a partially preserved skull with three upper molars. The material has been collected from a single locality, Santa Rita, near San Vito Town in the Puntarenas Province.

The subhumid Pacific slopes of El Salvador and Honduras contain a valuable record of late Cenozoic terrestrial vertebrates. Vast ignimbrite flows, mainly of mid-Miocene age, and subsequent block-faulting and basin-filling provide a substantial sequence of late Cenozoic tuffaceous sediments. This paper discusses the geological setting and faunal content of six local faunas ranging from the late Miocene through the late Pleistocene. Many other more limited late Pleistocene sites are known throughout Honduras and El Salvador. The late Miocene fauna includes no families not already known from North America at temperate latitudes, but does indicate an endemic turtle genus, Rhinoclemmys, and endemic mammal species Pliohippus hondurensis and Rhynchotherium blicki, and a much earlier record of brevirostrine proboscideans than in temperate North America. Although no Pliocene faunas are known, substantial numbers of previously South American taxa appear in the early Pleistocene. By the late Pleistocene, in...

The vertebrate fauna from deposits at the Holloman gravel pit, Frederick, Oklahoma, is described and compared with other Pleistocene faunas. The Frederick fauna lacks the early Pleistocene (Nebraskan) genera Nannippus, Hippotigris, Borophagus, and Rhynchotherium but contains Equus and Archidiskodon, which first appear in North America at this time, and Stegomastodon and Gigantocamelus, which are not known to survive into middle Pleistocene Kansan time. This fauna indicates an Aftonian age for the deposit.