RESUMO
The skull of the polydolopimorphian marsupialiform Epidolops ameghinoi is described in detail for the first time, based on a single well-preserved cranium and associated left and right dentaries plus additional craniodental fragments, all from the early Eocene (53-50 million year old) Itaboraí fauna in southeastern Brazil. Notable craniodental features of E. ameghinoi include absence of a masseteric process, very small maxillopalatine fenestrae, a prominent pterygoid fossa enclosed laterally by a prominent ectopterygoid crest, an absent or tiny transverse canal foramen, a simple, planar glenoid fossa, and a postglenoid foramen that is immediately posterior to the postglenoid process. Most strikingly, the floor of the hypotympanic sinus was apparently unossified, a feature found in several stem marsupials but absent in all known crown marsupials. "Type II" marsupialiform petrosals previously described from Itaboraí plausibly belong to E. ameghinoi; in published phylogenetic analyses, these petrosals fell outside (crown-clade) Marsupialia. "IMG VII" tarsals previously referred to E. ameghinoi do not share obvious synapomorphies with any crown marsupial clade, nor do they resemble those of the only other putative polydolopimorphians represented by tarsal remains, namely the argyrolagids. Most studies have placed Polydolopimorphia within Marsupialia, related to either Paucituberculata, or to Microbiotheria and Diprotodontia. However, diprotodonty almost certainly evolved independently in polydolopimorphians, paucituberculatans and diprotodontians, and Epidolops does not share obvious synapomorphies with any marsupial order. Epidolops is dentally specialized, but several morphological features appear to be more plesiomorphic than any crown marsupial. It seems likely Epidolops that falls outside Marsupialia, as do morphologically similar forms such as Bonapartherium and polydolopids. Argyrolagids differ markedly in their known morphology from Epidolops but share some potential apomorphies with paucituberculatans. It is proposed that Polydolopimorphia as currently recognised is polyphyletic, and that argyrolagids (and possibly other taxa currently included in Argyrolagoidea, such as groeberiids and patagoniids) are members of Paucituberculata. This hypothesis is supported by Bayesian non-clock phylogenetic analyses of a total evidence matrix comprising DNA sequence data from five nuclear protein-coding genes, indels, retroposon insertions, and morphological characters: Epidolops falls outside Marsupialia, whereas argyrolagids form a clade with the paucituberculatans Caenolestes and Palaeothentes, regardless of whether the Type II petrosals and IMG VII tarsals are used to score characters for Epidolops or not. There is no clear evidence for the presence of crown marsupials at Itaboraí, and it is possible that the origin and early evolution of Marsupialia was restricted to the "Austral Kingdom" (southern South America, Antarctica, and Australia).
RESUMO
With less than 3 g of estimated body mass, the early Eocene Minusculodelphis minimus Paula Couto (Mammalia, Metatheria, Jaskhadelphyidae) is one of the smallest mammals, living or extinct. It has alternatively been regarded as a didelphid or a derorhynchid "ameridelphian," or even as an eometatherian marsupial. Here, we describe a new species of Minusculodelphis coming from the same locality (Itaboraí Quarry, Brazil) and age (Itaboraian age) of the type species of the genus. It differs from M. minimus in its larger size and several dental characters. The new species offers data on the upper dentition and femur, which are unknown in the type species. Compared to other Paleogene metatherians, Minusculodelphis shows closer relationships with Jaskhadelphys, from the early Paleocene of Tiupampa, Bolivia, as well as with Kiruwamaq, from the late Eocene-early Oligocene of Perú. A cladistic analysis places all three genera within the family Jaskhadelphyidae (Metatheria, Order indet.), which includes small to tiny, insectivorous-like metatherians. We argue that insectivory (soft insects) is the best-supported diet for both species of Minusculodelphis, and that the most probable microhabitat for them was the understorey or leaf litter of tropical, rain forested environments.
Assuntos
Fósseis , Marsupiais/anatomia & histologia , Marsupiais/classificação , Filogenia , Animais , Dieta , Ecossistema , Fêmur/anatomia & histologia , Marsupiais/fisiologia , América do Sul , Especificidade da Espécie , Dente/anatomia & histologiaRESUMO
The limestones of Itaboraí Basin (Middle Paleocene), Rio de Janeiro, Brazil, harbor a rich fossil molluscan fauna consisting exclusively of pulmonate snails, both terrestrial and freshwater. An extensive taxonomic revision of this paleofauna is conducted here. A new genus, Cortana, is described as well as two new species, Eoborus fusiforme and Gastrocopta itaboraiensis. The revised classification is as follows: Austrodiscus lopesi (Charopidae); Biomphalaria itaboraiensis (Planorbidae); "Brachypodella" britoi (Urocoptidae); Brasilennea arethusae, Brasilennea guttula, Brasilennea minor (Cerionidae); Bulimulus fazendicus, Bulimulus trindadeae, Cortana carvalhoi, Cyclodontina coelhoi, Itaborahia lamegoi, Leiostracus ferreirai, Plagiodontes aff. dentatus (Orthalicidae); Cecilioides sommeri (Ferussaciidae); Eoborus rotundus, Eoborus sanctijosephi, Eoborus fusiforme (Strophocheilidae); Gastrocopta mezzalirai, Gastrocopta itaboraiensis (Gastrocoptidae); Temesa magalhaesi (Clausiliidae). The species Strobilopsis mauryae was considered a synonym of Brasilennea arethusae; Bulimulus sommeri a synonym of Itaborahia lamegoi; and Vorticifex fluminensis a synonym of Eoborus sanctijosephi. Itaboraí Basin has the most ancient records of the families Orthalicidae, Gastrocoptidae, Ferussaciidae and Strophocheilidae. Moreover, the basin's records of Charopidae, Clausiliidae, Cerionidae, and Urocoptidae are among the most ancient in the world and, among these, those of Cerionidae, Clausiliidae and Urocoptidae deserve special attention since they are greatly removed from these families' current distribution. Additionally, Itaboraí has the most ancient records for the genera Austrodiscus, Brachypodella, Bulimulus, Cecilioides, Cyclodontina, Eoborus, Gastrocopta, Leiostracus, Plagiodontes and Temesa. There are three endemic genera in the basin: Brasilennea, Cortana and Itaborahia. Further discussion on paleobiogeography and evolution of this paleofauna is also provided.
Os calcários da Bacia de Itaboraí (Paleoceno Médio), Rio de Janeiro, Brasil, abrigam uma rica fauna de gastrópodes pulmonados do Paleoceno Médio, tanto terrestres quanto dulciaquícolas. No presente trabalho realiza-se uma extensiva revisão taxonômica dessa paleofauna. Duas novas espécies, Eoborus fusiforme e Gastrocopta itaboraiensis, são descritas, assim como um novo gênero, Cortana. A classificação revisada encontra-se do seguinte modo: Austrodiscus lopesi (Charopidae); Biomphalaria itaboraiensis (Planorbidae); "Brachypodella" britoi (Urocoptidae); Brasilennea arethusae, Brasilennea guttula, Brasilennea minor (Cerionidae); Bulimulus fazendicus, Bulimulus trindadeae, Cortana carvalhoi, Cyclodontina coelhoi, Itaborahia lamegoi, Leiostracus ferreirai, Plagiodontes aff. dentatus (Orthalicidae); Cecilioides sommeri (Ferussaciidae); Eoborus rotundus, Eoborus sanctijosephi, Eoborus fusiforme (Strophocheilidae); Gastrocopta mezzalirai, Gastrocopta itaboraiensis (Gastrocoptidae); Temesa magalhaesi (Clausiliidae). A espécie Strobilopsis mauryae foi considerada sinônimo de Brasilennea arethusae; Bulimulus sommeri sinônimo de Itaborahia lamegoi; e Vorticifex fluminensis sinônimo de Eoborus sanctijosephi. A bacia conta com os registros fósseis mais antigos das famílias Orthalicidae, Gastrocoptidae, Ferussaciidae e Strophocheilidae. Além disso, os registros de Itaboraí das famílias Charopidae, Clausiliidae, Cerionidae, e Urocoptidae estão entre os mais antigos do mundo e, dentre esses, os de Cerionidae, Clausiliidae e Urocoptidae merecem destaque por estarem bem afastados das distribuições atuais das famílias. Ademais, os registros de Itaboraí são os mais antigos para os gêneros Austrodiscus, Brachypodella, Bulimulus, Cecilioides, Cyclodontina, Eoborus, Gastrocopta, Leiostracus, Plagiodontes e Temesa. Há três gêneros endêmicos na bacia: Brasilennea, Cortana e Itaborahia. Discussões adicionais sobre paleobiogeografia e evolução dessa paleofauna são oferecidas.
Assuntos
Animais , Fauna/análise , Gastrópodes/anatomia & histologia , ClassificaçãoRESUMO
The limestones of Itaboraí Basin (Middle Paleocene), Rio de Janeiro, Brazil, harbor a rich fossil molluscan fauna consisting exclusively of pulmonate snails, both terrestrial and freshwater. An extensive taxonomic revision of this paleofauna is conducted here. A new genus, Cortana, is described as well as two new species, Eoborus fusiforme and Gastrocopta itaboraiensis. The revised classification is as follows: Austrodiscus lopesi (Charopidae); Biomphalaria itaboraiensis (Planorbidae); "Brachypodella" britoi (Urocoptidae); Brasilennea arethusae, Brasilennea guttula, Brasilennea minor (Cerionidae); Bulimulus fazendicus, Bulimulus trindadeae, Cortana carvalhoi, Cyclodontina coelhoi, Itaborahia lamegoi, Leiostracus ferreirai, Plagiodontes aff. dentatus (Orthalicidae); Cecilioides sommeri (Ferussaciidae); Eoborus rotundus, Eoborus sanctijosephi, Eoborus fusiforme (Strophocheilidae); Gastrocopta mezzalirai, Gastrocopta itaboraiensis (Gastrocoptidae); Temesa magalhaesi (Clausiliidae). The species Strobilopsis mauryae was considered a synonym of Brasilennea arethusae; Bulimulus sommeri a synonym of Itaborahia lamegoi; and Vorticifex fluminensis a synonym of Eoborus sanctijosephi. Itaboraí Basin has the most ancient records of the families Orthalicidae, Gastrocoptidae, Ferussaciidae and Strophocheilidae. Moreover, the basin's records of Charopidae, Clausiliidae, Cerionidae, and Urocoptidae are among the most ancient in the world and, among these, those of Cerionidae, Clausiliidae and Urocoptidae deserve special attention since they are greatly removed from these families' current distribution. Additionally, Itaboraí has the most ancient records for the genera Austrodiscus, Brachypodella, Bulimulus, Cecilioides, Cyclodontina, Eoborus, Gastrocopta, Leiostracus, Plagiodontes and Temesa. There are three endemic genera in the basin: Brasilennea, Cortana and Itaborahia. Further discussion on paleobiogeography and evolution of this paleofauna is also provided.(AU)
Os calcários da Bacia de Itaboraí (Paleoceno Médio), Rio de Janeiro, Brasil, abrigam uma rica fauna de gastrópodes pulmonados do Paleoceno Médio, tanto terrestres quanto dulciaquícolas. No presente trabalho realiza-se uma extensiva revisão taxonômica dessa paleofauna. Duas novas espécies, Eoborus fusiforme e Gastrocopta itaboraiensis, são descritas, assim como um novo gênero, Cortana. A classificação revisada encontra-se do seguinte modo: Austrodiscus lopesi (Charopidae); Biomphalaria itaboraiensis (Planorbidae); "Brachypodella" britoi (Urocoptidae); Brasilennea arethusae, Brasilennea guttula, Brasilennea minor (Cerionidae); Bulimulus fazendicus, Bulimulus trindadeae, Cortana carvalhoi, Cyclodontina coelhoi, Itaborahia lamegoi, Leiostracus ferreirai, Plagiodontes aff. dentatus (Orthalicidae); Cecilioides sommeri (Ferussaciidae); Eoborus rotundus, Eoborus sanctijosephi, Eoborus fusiforme (Strophocheilidae); Gastrocopta mezzalirai, Gastrocopta itaboraiensis (Gastrocoptidae); Temesa magalhaesi (Clausiliidae). A espécie Strobilopsis mauryae foi considerada sinônimo de Brasilennea arethusae; Bulimulus sommeri sinônimo de Itaborahia lamegoi; e Vorticifex fluminensis sinônimo de Eoborus sanctijosephi. A bacia conta com os registros fósseis mais antigos das famílias Orthalicidae, Gastrocoptidae, Ferussaciidae e Strophocheilidae. Além disso, os registros de Itaboraí das famílias Charopidae, Clausiliidae, Cerionidae, e Urocoptidae estão entre os mais antigos do mundo e, dentre esses, os de Cerionidae, Clausiliidae e Urocoptidae merecem destaque por estarem bem afastados das distribuições atuais das famílias. Ademais, os registros de Itaboraí são os mais antigos para os gêneros Austrodiscus, Brachypodella, Bulimulus, Cecilioides, Cyclodontina, Eoborus, Gastrocopta, Leiostracus, Plagiodontes e Temesa. Há três gêneros endêmicos na bacia: Brasilennea, Cortana e Itaborahia. Discussões adicionais sobre paleobiogeografia e evolução dessa paleofauna são oferecidas.(AU)