Evolution of Dental Replacement in Mammals

Luo, Zhe‐Xi; Kielan‐Jaworowska, Zofia; Cifelli, Richard L.

doi:10.2992/0145-9058(2004)36[159:eodrim]2.0.co;2

Cited by 104 publications

(135 citation statements)

References 54 publications

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“…This type of replacement is also present in other ictidosaurs (Gow 1980;Crompton and Luo 1993;Martinelli and Rougier 2007) and in most carnivorous nonmammaliaform cynodonts (e.g. Crompton 1963b; Luo et al 2004).…”

Section: Discussionmentioning

confidence: 92%

New information about Irajatherium hernandezi Martinelli, Bonaparte, Schultz & Rubert 2005 (Eucynodontia, Tritheledontidae) from the upper triassic (Caturrita Formation, Paraná Basin) of Brazil

Oliveira

Martinelli²,

Soares

2010

Paläontol Z

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In this contribution, new specimens of the tritheledontid eucynodont Irajatherium hernandezi, from the Late Triassic (Caturrita Formation) of southern Brazil, are analyzed. The new material provides significant information about incisor count, canine size and shape, basicranial morphology, and other previously unknown aspects of skull and dentition. A cladistic analysis with inclusion of the new data supports the assignment of Irajatherium to Tritheledontidae, basal to Chalimininae and Pachygenelinae. Previously unknown characters of Irajatherium revealed by the new material include: the presence of three lower incisors; the first lower incisor is enlarged; the presence of large upper and lower canines with deep paracanine fossa on the maxilla; almost complete upper and lower postcanine tooth row with a pattern similar to that of other tritheledontids (e.g. Pachygenelus and Chaliminia); there is a conspicuous crest on the inner surface of the maxilla for the attachment of the inferred maxillary turbinates; partially confluent jugular foramen and fenestra rotunda within the jugular fossa, separated by a finger-like projection of the posterolateral wall of the opisthotic; and hypoglossal foramina located outside the jugular fossa. Irajatherium is a key taxon for understanding the early evolution of ictidosaurs, a group of cynodonts closely related to mammaliaforms, during the cynodont-mammal transition from the Late Triassic to Early Jurassic.

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Section: Discussionmentioning

confidence: 92%

New information about Irajatherium hernandezi Martinelli, Bonaparte, Schultz & Rubert 2005 (Eucynodontia, Tritheledontidae) from the upper triassic (Caturrita Formation, Paraná Basin) of Brazil

Oliveira

Martinelli²,

Soares

2010

Paläontol Z

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“…As in other metatherians, only the third upper and lower premolars have deciduous precursors (Flower, 1867;Luckett, 1993;Luo et al, 2004;van Nievelt andSmith, 2005a, 2005b). Despite this prevailing consensus, marsupial tooth homologies have long been controversial, with the result that several alternative systems have been used to identify didelphid dental loci (table 7).…”

Section: Dentitionmentioning

confidence: 99%

Phylogenetic Relationships and Classification of Didelphid Marsupials, an Extant Radiation of New World Metatherian Mammals

Voss

Jansa

2009

Bulletin of the American Museum of Natural History

309

443

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“…15). It is very likely this tooth represents DP2 (Martin, 1997;Luo et al, 2004;Luo and Ji, 2005), though no successor has yet to be formed. The third premolar probably also has irregular roots, though it is less …”

Section: Sinobaatar Fuxinensismentioning

confidence: 95%

“…These are typical of the deciduous premolars of Mesozoic mammals (Martin, 1997;Luo et al, 2004;Luo and Ji, 2005). It is likely that these are also deciduous teeth although its successor has not yet formed.…”

Section: Measurements-seementioning

confidence: 97%

Two Eobaatarid (Multituberculata; Mammalia) genera from the Lower Cretaceous Shahai and Fuxin Formations, northeastern Chinau

Kusuhashi

Wang

et al. 2009

Journal of Vertebrate Paleontology

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Two eobaatarid multituberculate genera including three species from the Lower Cretaceous (AptianAlbian) Shahai and Fuxin formations in Liaoning Province, northeastern China are described here: Sinobaatar xiei sp. nov., S. fuxinensis sp. nov., and Liaobaatar changi gen. et sp. nov. Sinobaatar xiei is characterized by m1 with cusp formula 3:2 (labial:lingual), P4 with cusp formula 2:4, blade-like P5 with three cusps anteroposteriorly arranged, M1 with cusp formula 4:4, and M2 with cusp formula 3:4. P1 to P3 of S. xiei lack distinct posterior cingulum. Sinobaatar fuxinensis has a more distinct posterior cingulum on P1 to P3, and its M2 has cusp formula 3:3. Sinobaatar xiei is within the size range of most other eobaatarids, and S. fuxinensis is slightly larger than S. xiei. Liaobaatar changi is clearly larger than other eobaatarids. The ratio of p4 length and height of L. changi and S. xiei (L./S.) are 1.9 and 1.7, respectively. Liaobaatar changi is also characterized by m1 with cusp formula 3:3. A specimen of S. fuxinensis indicates that tooth replacement in eobaatarids occurred in the typical backward sequence seen in Late Cretaceous-Tertiary multituberculates.

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Evolution of Dental Replacement in Mammals

Cited by 104 publications

References 54 publications

New information about Irajatherium hernandezi Martinelli, Bonaparte, Schultz & Rubert 2005 (Eucynodontia, Tritheledontidae) from the upper triassic (Caturrita Formation, Paraná Basin) of Brazil

New information about Irajatherium hernandezi Martinelli, Bonaparte, Schultz & Rubert 2005 (Eucynodontia, Tritheledontidae) from the upper triassic (Caturrita Formation, Paraná Basin) of Brazil

Phylogenetic Relationships and Classification of Didelphid Marsupials, an Extant Radiation of New World Metatherian Mammals

Two Eobaatarid (Multituberculata; Mammalia) genera from the Lower Cretaceous Shahai and Fuxin Formations, northeastern Chinau

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