| Convergent dental adaptations in pseudo-tribosphenic and tribosphenic mammals. | |
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MedLine Citation:
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PMID: 17972884 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Tribosphenic molars of basal marsupials and placentals are a major adaptation, with the protocone (pestle) of the upper molar crushing and grinding in the talonid basin (mortar) on the lower molar. The extinct pseudo-tribosphenic mammals have a reversed tribosphenic molar in which a pseudo-talonid is anterior to the trigonid, to receive the pseudo-protocone of the upper molar. The pseudo-protocone is analogous to the protocone, but the anteriorly placed pseudo-talonid is opposite to the posterior talonid basin of true tribosphenic mammals. Here we describe a mammal of the Middle Jurassic period with highly derived pseudo-tribosphenic molars but predominantly primitive mandibular and skeletal features, and place it in a basal position in mammal phylogeny. Its shoulder girdle and limbs show fossorial features similar to those of mammaliaforms and monotremes, but different compared with those of the earliest-known Laurasian tribosphenic (boreosphenid) mammals. The find reveals a much greater range of dental evolution in Mesozoic mammals than in their extant descendants, and strengthens the hypothesis of homoplasy of 'tribosphenic-like' molars among mammals. |
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Authors:
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Zhe-Xi Luo; Qiang Ji; Chong-Xi Yuan |
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Publication Detail:
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Type: Historical Article; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. |
Journal Detail:
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Title: Nature Volume: 450 ISSN: 1476-4687 ISO Abbreviation: Nature Publication Date: 2007 Nov |
Date Detail:
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Created Date: 2007-11-01 Completed Date: 2007-11-28 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0410462 Medline TA: Nature Country: England |
Other Details:
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Languages: eng Pagination: 93-7 Citation Subset: IM |
Affiliation:
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Carnegie Museum of Natural History, Pittsburgh, Pennsylvania 15213, USA. luoz@carnegiemnh.org |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals China Evolution* Fossils* History, Ancient Mammals / anatomy & histology* Mandible / anatomy & histology Molar / anatomy & histology* Phylogeny Skeleton |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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