The youngest species of the aquatic sloth<i>Thalassocnus</i>and a reassessment of the relationships of the nothrothere sloths (Mammalia: Xenarthra)

Muizon, Christian de; McDonald, H. Gregory; Salas, Rodolfo; Urbina, Mario

doi:10.1671/2429a

Cited by 55 publications

(62 citation statements)

References 13 publications

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“…Moreover, the microanatomical data presented herein corroborate a posteriori this hypothesis: T. natans features microanatomical parameters closer to those of the late species than to those of T. antiquus or of the outgroups used in the phylogenetic analysis. The only specimen of the latest species, T. yaucensis, available for measurement (MUSM 37, the holotype) is interpreted as a pregnant female deceased near parturition [13] and is hence not included in the comparisons of compactness. See the electronic supplementary material, tables S1 and S2 for details on this consideration and on other parameters having a possible effect on bone compactness.…”

Section: Materials and Methods (A) Systematic Frameworkmentioning

confidence: 99%

“…The incipient stages of bone transformation in these groups and the mechanisms involved in this process remain to be documented. The model on which we focus here is the aquatic sloth, Thalassocnus, known in the Pisco Formation (Peru) by five species spanning from Late Miocene to Late Pliocene [13]. Its fossil record provides the most detailed data available about the gradual acquisition of osteosclerosis among tetrapods.…”

Section: Introductionmentioning

confidence: 99%

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Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru

et al. 2014

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Non-pathological densification (osteosclerosis) and swelling ( pachyostosis) of bones are the main modifications affecting the skeleton of land vertebrates (tetrapods) that returned to water. However, a precise temporal calibration of the acquisition of such adaptations is still wanting. Here, we assess the timing of such acquisition using the aquatic sloth Thalassocnus, from the Neogene of the Pisco Formation, Peru. This genus is represented by five species occurring in successive vertebrate-bearing horizons of distinct ages. It yields the most detailed data about the gradual acquisition of aquatic adaptations among tetrapods, in displaying increasing osteosclerosis and pachyostosis through time. Such modifications, reflecting a shift in the habitat from terrestrial to aquatic, occurred over a short geological time span (ca 4 Myr). Otherwise, the bones of terrestrial pilosans (sloths and anteaters) are much more compact than the mean mammalian condition, which suggests that the osteosclerosis of Thalassocnus may represent an exaptation.

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Section: Materials and Methods (A) Systematic Frameworkmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru

et al. 2014

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“…Hence, we place the Nothrotheriinae here identified in the family Nothrotheriidae (cf. Gaudin & De Iullis, 1999;Muizon et al, 2004).This is the first record of a nothrothere for Central BrazilBrazilian nothrotheres were previously known only for the states of São Paulo, Minas Gerais, Bahia and Ceará (Lund, 1839;Cartelle & Fonseca, 1983;Cartelle, 2000;Ghilardi et al, 2011). In South America, Quaternary nothrotheres are included in two genera: Nothrotherium (found mainly in Brazil) and Nothropus (Argentina).The genus Nothrotheriops is unknown for South American Quaternary deposits, being recorded only in North America (Brandoni & McDonald, 2015).…”

Section: Oliveira Et Al -Quaternary Mammals From Central Brazilmentioning

confidence: 99%

Quaternary mammals from central Brazil (Serra da Bodoquena, Mato Grosso do Sul) and comments on paleobiogeography and paleoenvironments

Oliveira

Becker-Kerber²,

Cordeiro

et al. 2017

Rev. bras. paleontol.

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-Studies regarding Quaternary mammals from the Serra da Bodoquena (South-western Brazil, state of Mato Grosso do Sul) are scarce. In the region, the Fadas Cave has been an important paleontological site. Remnants of Pleistocene fauna were collected along a river channel inside the cave. It is the first record of Arctotherium, Scelidotheriinae and Nothrotheriinae in the Serra da Bodoquena. Smilodon populator, Eremotherium laurillardi, Gomphotheriidae and Glyptodontinae, already known for the region, were also identified. These new occurrences allow us to redefine the paleozoogeographical distribution of some of the aforementioned taxa. Herein we propose the expansion of the range of the Brazilian Intertropical Region, which should include Mato Grosso do Sul and São Paulo. The state of Rio Grande do Sul keeps a greater paleozoogeographical affinity to others temperate zones from Argentina and Uruguay. Taxa associated to open environments indicate the existence of large areas of savannas during the late Pleistocene in the Serra da Bodoquena.Key words: Brazilian Intertropical Region, Pampean Region, paleozoogeographical zones, Fadas Cave, Quaternary mammals, Serra da Bodoquena.RESUMO -Os estudos sobre mamíferos quaternários da Serra da Bodoquena (Mato Grosso do Sul) são escassos. Na região, a Gruta das Fadas tem sido um importante sítio paleontológico. Os restos da fauna do Pleistoceno foram coletados ao longo de um canal do rio dentro da caverna. É o primeiro registro de Arctotherium, Scelidotheriinae e Nothrotheriinae na Serra da Bodoquena. Smilodon populator, Eremotherium laurillardi, Gomphotheriidae e Glyptodontinae, já conhecidos pela região, também foram identificados. Estas novas ocorrências nos permitem redefinir a distribuição paleozoogeográfica de alguns dos táxons acima mencionados. Aqui propomos a ampliação da faixa da Região Intertropical Brasileira, que deve incluir Mato Grosso do Sul e São Paulo. O Estado do Rio Grande do Sul mantém uma maior afinidade paleozoogeográfica com outras zonas temperadas da Argentina e do Uruguai. Táxons associados a ambientes abertos indicam a existência de grandes áreas de savanas durante o Pleistoceno final na Serra da Bodoquena. Palavras-chave:Região Intertropical Brasileira, Região Pampeana, zonas paleozoogeográficas, Gruta das Fadas, mamíferos quaternários, Serra da Bodoquena.

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“…Stratigraphic correlation of the Portland fossil marine mammal-bearing formations with selected major late Neogene marine mammalbearing units. Stratigraphy and geochronology are from Barnes (1973Barnes ( , 1977Barnes ( , 1984Barnes ( , 1998, Muizon and DeVries (1985), Muizon and Bellon (1986), Gottfried et al (1994), , Prothero (1998), Fordyce (2002a), Fordyce et al (2002), Fitzgerald (2004b), Muizon et al (2004), Barnes et al (2005) and Gradstein et al (2004) Fordyce, 2002b), although the record only becomes reasonably well known from the Mio-Pliocene boundary onwards (McLeod et al, 1993;Bisconti, 2003 Lacépède, 1818(e.g., Cummings, 1985Reeves and Leatherwood, 1985;Bannister, 2002). Note that Rice (1998) included all extant balaenids in the genus Balaena and recognised only two species, B. mysticetus and B. glacialis.…”

Section: Genus and Species Indeterminatementioning

confidence: 99%

Pliocene marine mammals from the Whalers Bluff Formation of Portland, Victoria, Australia

Fitzgerald¹

2005

MMV

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The youngest species of the aquatic slothThalassocnusand a reassessment of the relationships of the nothrothere sloths (Mammalia: Xenarthra)

Cited by 55 publications

References 13 publications

Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru

Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru

Quaternary mammals from central Brazil (Serra da Bodoquena, Mato Grosso do Sul) and comments on paleobiogeography and paleoenvironments

Pliocene marine mammals from the Whalers Bluff Formation of Portland, Victoria, Australia

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