New well-preserved craniodental remains of<i>Simomylodon uccasamamensis</i>(Xenarthra: Mylodontidae) from the Pliocene of the Bolivian Altiplano: phylogenetic, chronostratigraphic and palaeobiogeographical implications

Boscaini, Alberto; Gaudin, Timothy J.; Quispe, Bernardino Mamaní; Münch, Philippe; Antoine, Pierre‐Olivier; Pujos, François

doi:10.1093/zoolinnean/zly075

Cited by 24 publications

(49 citation statements)

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“…The palate is subtriangular with the tooth rows diverging anteriorly. The palatine surface is rugose with numerous vascular foramina, as in Pleurolestodon Rovereto, 1914 (Kraglievich, 1923) and Simomylodon (Saint-André et al, 2010; Boscaini et al, 2019).…”

Section: Systematic Paleontologymentioning

confidence: 99%

New records of Neogene Xenarthra (Mammalia) from eastern Puna (Argentina): diversity and biochronology

et al. 2019

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Xenarthra is an endemic South American lineage of mammals, probably the sister clade of the other placental mammals. The oldest records of Xenarthra are from the latest Paleocene, although its current diversity is much lower than that recorded in some intervals of the Cenozoic Era. A new Neogene Xenarthra (Pilosa and Cingulata) assemblage from two localities of the Argentine Eastern Puna (Calahoyo and Casira) is described. The newly recorded taxa—Cingulata, Dasypodidae, Eutatini: Stenotatus sp. indet. and Eutatini indet., Euphractini: Macrochorobates scalabrinii (Moreno and Mercerat, 1891), and Tardigrada, Mylodontinae: cf. Simomylodon sp. indet. and Simomylodon cf. S. uccasamamensis Saint-André et al., 2010—and those already published from Calahoyo—Cingulata: Macrochorobates chapadmalensis (Ameghino, 1908), Eosclerocalyptus sp. indet., and Tardigrada, Megatheriidae: Pyramiodontherium bergi (Moreno and Mercerat, 1891)—suggest a middle–late Miocene age for the fossil-bearing levels. In Calahoyo, the presence of Stenotatus sp. indet., in addition to some rodents currently under study in the lower levels, suggest a closer similarity with the palaeofauna of Cerdas (southern Bolivia), probably involving the last part of the Miocene Climatic Optimum. The Xenarthra recorded in the middle and upper levels of Calahoyo and Casira suggest a late Miocene–Pliocene age. A comparative analysis between Calahoyo and Casira highlights the absence of Cingulata in the latter and a high diversity in the former. This situation probably indicates different paleoenvironmental conditions. Finally, we present the first certain record of the genus Simomylodon Saint-André et al., 2010 in Argentina, which includes the oldest record of dermal ossicles for sloths in South America.

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Section: Systematic Paleontologymentioning

confidence: 99%

New records of Neogene Xenarthra (Mammalia) from eastern Puna (Argentina): diversity and biochronology

et al. 2019

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“…This idea is confirmed in subsequent phylogenetic studies based mainly on craniodental features, such as those of Gaudin (), Esteban (), Boscaini, Gaudin, Mamani Quispe, et al () and Brambilla and Ibarra (). In these studies, lestodontines are considered the most derived subgroup of Mylodontinae, thus constituting the tribe Lestodontini (sensu Gaudin, ).…”

Section: Introductionmentioning

confidence: 55%

“…Glossotheridium chapadmalense (southeastern Argentina, early Pliocene; Kraglievich, ) and S. uccasamamensis (Bolivian Altiplano, late Miocene–Pliocene; Boscaini, Gaudin, Mamani Quispe, et al, ; Saint‐André et al, ) together form a well‐supported monophyletic group (Figure : node 28). The relationship of these two species is corroborated by four unambiguous synapomorphies: condyloid process of mandible oriented posterodorsally in lateral view (52:1 → 0), mandibular symphysis anteroposteriorly short (62:2 → 1), descending process of jugal strongly tapering towards the tip (151:0 → 1) and greatly elongate zygomatic process of squamosal relative to total cranial length (168:2 → 3).…”

Section: Resultsmentioning

confidence: 99%

“…In Haro et al (, ), Lestodontini is not even retrieved as a monophyletic group, a probable consequence of the lack of phylogenetic signal in their matrices, the analyses of which provide an extremely high number of most parsimonious trees (MPTs). In Varela et al () and Cartelle et al (), Lestodontini constitutes a monophyletic group, but does not occupy the same position as in Gaudin (, ), Esteban () and Boscaini, Gaudin, Mamani Quispe, et al (). Varela et al () position the lestodontine sloths as the sister group of a clade that includes Pleurolestodon , Simomylodon , Glossotherium and Paramylodon , with Mylodon as an external taxon to this clade and the lestodontines.…”

Section: Introductionmentioning

confidence: 96%

“…Some of these studies using postcranial features were recently included in an enlarged matrix by Varela et al (), with the aim of exploring sloth relationships using Bayesian methods. Finally, Boscaini, Gaudin, Mamani Quispe, et al (), Brambilla and Ibarra () and Cartelle, De Iuliis, Boscaini, and Pujos () analysed the phylogenetic positions of Simomylodon uccasamamensis (Bolivian Altiplano, late Miocene–Pliocene; Saint‐André et al, ), Archaeomylodon sampedrinensis (middle Pleistocene of Argentina; Brambilla & Ibarra, ) and Glossotherium phoenesis (late Pleistocene of intertropical Brazil; Cartelle et al, ), performing phylogenetic analyses largely based on the craniodental data set of Gaudin ().…”

Section: Introductionmentioning

confidence: 99%

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A reappraisal of the phylogeny of Mylodontidae (Mammalia, Xenarthra) and the divergence of mylodontine and lestodontine sloths

2019

Self Cite

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The phylogeny of mylodontid sloths has recently been the subject of multiple studies. Contrasting hypotheses have been proposed, especially for the relationships among late Miocene–Pleistocene mylodontines and lestodontines. In this paper, a new and detailed phylogenetic analysis is conducted, after adding new characters and taxa previously unexplored from a phylogenetic point of view. New features derived from postcranial skeletal anatomy are added to previous studies based on craniodental evidence. In this way, the current reappraisal represents the first exhaustive phylogenetic study on the Mylodontidae that incorporates features coded for the entire skeleton. When available, multiple specimens of each bony element are observed for each operational taxonomic unit, in order to take into account intraspecific variation. The taxonomic sample of this study considers Mylodontinae at the specific level. However, many other Mylodontidae are considered, and their phylogenetic relationships tested. The taxonomic sample of this study is enriched with new taxa from central and northern South America, with the aim of compensating for the knowledge bias in favour of austral mylodontids, which have historically been more extensively studied than those from tropical latitudes. Special emphasis is given to the phylogenetic relationships of Mylodontinae, and particularly to the mylodontine and lestodontine sloths, that are recovered in the present study as monophyletic clades, and together form a larger monophyletic group. According to the present results, the Mylodontini–Lestodontini split occurred at the middle–late Miocene transition, giving rise to independent adaptive radiations across South and North America.

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Cranial osteology of a juvenile specimen of Acratocnus ye (Mammalia, Xenarthra, Folivora) and its ontogenetic and phylogenetic implications

Gaudin

Scaife

2022

The Anatomical Record

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The present study comprises a description of the skull and jaw anatomy of a juvenile specimen of the Antillean sloth Acratocnus ye, from the Holocene of Haiti. Detailed descriptions and illustrations are provided of the skull bones and their sutural connections, which normally fuse in adults. Descriptions are also provided for the mandible and ear ossicles, as well as endocranial surfaces and sinuses exposed by breaks. The anatomy of our juvenile A. ye is compared to that of adult A. ye to assess ontogenetic changes in the skull. Several of these ontogenetic features are significant new observations that impact the relationships within Xenarthra as a whole, or between Xenarthrans and other placental mammals, most notably, the presence of a separate mesethmoid element, the presence of alveoli for a lower deciduous canine and anterior incisor, and the presence of separate rostral and caudal entotympanic elements. A full list of such changes are provided. In addition, the specimen provides information on phylogenetically relevant characters, including features unique to the genus Acratocnus, and features of the clade Choloepodini, including Acratocnus, the smaller extinct Antillean sloth Neocnus, and the extant two-toed sloth Choloepus. Contrary to previous studies, Acratocnus shares as many features with Choloepus as it does with its fellow Antillean form Neocnus in the present study, which is consistent with current morphology-based phylogenetic hypotheses regarding the relationships within Choloepodini. The current study highlights the need for further anatomical and phylogenetic investigations of Antillean sloths (Megalocnidae/Megalonychidae), and juvenile sloths in general.

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New well-preserved craniodental remains ofSimomylodon uccasamamensis(Xenarthra: Mylodontidae) from the Pliocene of the Bolivian Altiplano: phylogenetic, chronostratigraphic and palaeobiogeographical implications

Cited by 24 publications

References 50 publications

New records of Neogene Xenarthra (Mammalia) from eastern Puna (Argentina): diversity and biochronology

New records of Neogene Xenarthra (Mammalia) from eastern Puna (Argentina): diversity and biochronology

A reappraisal of the phylogeny of Mylodontidae (Mammalia, Xenarthra) and the divergence of mylodontine and lestodontine sloths

Cranial osteology of a juvenile specimen of Acratocnus ye (Mammalia, Xenarthra, Folivora) and its ontogenetic and phylogenetic implications

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