Origin of the tooth-replacement pattern in therian mammals: evidence from a 110 Myr old fossil.
Proc Biol Sci
; 269(1489): 369-73, 2002 Feb 22.
Article
en En
| MEDLINE
| ID: mdl-11886624
ABSTRACT
Living placental and marsupial mammals (therians) use distinctive tooth-replacement patterns that have not yet been traced back fully to their time of divergence in the Early Cretaceous (>100 Myr ago). Slaughteria eruptens, a small 110 Myr old fossil mammal from Texas, USA, is near the base of that divergence. Using ultra-high-resolution X-ray CT analysis we demonstrate that Slaughteria preserves an unrecognized pattern of tooth replacement with simple posterior premolars replacing molariform precursors. Differing from both placentals that have a more complex posterior adult premolar, and from marsupials, in which only one premolar is replaced, Slaughteria provides the first direct evidence of a tooth-replacement pattern that is plausible for the common ancestor of all therians. By our interpretation Slaughteria has only one adult molar in place and contains two mental foramina in the jaw, thus changing characters that are critical to reconstruction of mammalian relationships and to species discrimination and interpretations of diversity for Early Cretaceous mammals.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Erupción Dental
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Dentición
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Evolución Biológica
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Fósiles
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Mamíferos
Límite:
Animals
Idioma:
En
Revista:
Proc Biol Sci
Asunto de la revista:
BIOLOGIA
Año:
2002
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
ENGLAND
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ESCOCIA
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GB
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GREAT BRITAIN
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INGLATERRA
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REINO UNIDO
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SCOTLAND
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UK
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UNITED KINGDOM