Fossils document evolutionary changes of jaw joint to mammalian middle ear.
Nature
; 628(8008): 576-581, 2024 Apr.
Article
em En
| MEDLINE
| ID: mdl-38570677
ABSTRACT
The dual jaw joint of Morganucodon1,2 consists of the dentary-squamosal joint laterally and the articular-quadrate one medially. The articular-quadrate joint and its associated post-dentary bones constitute the precursor of the mammalian middle ear. Fossils documenting the transition from such a precursor to the mammalian middle ear are poor, resulting in inconsistent interpretations of this hallmark apparatus in the earliest stage of mammaliaform evolution1-5. Here we report mandibular middle ears from two Jurassic mammaliaforms a new morganucodontan-like species and a pseudotribosphenic shuotheriid species6. The morganucodontan-like species shows many previously unknown post-dentary bone morphologies1,2 and exhibits features that suggest a loss of load-bearing function in its articular-quadrate joint. The middle ear of the shuotheriid approaches the mammalian condition in that it has features that are suitable for an exclusively auditory function, although the post-dentary bones are still attached to the dentary. With size reduction of the jaw-joint bones, the quadrate shifts medially at different degrees in relation to the articular in the two mammaliaforms. These changes provide evidence of a gradual loss of load-bearing function in the articular-quadrate jaw joint-a prerequisite for the detachment of the post-dentary bones from the dentary7-12 and the eventual breakdown of the Meckel's cartilage13-15 during the evolution of mammaliaforms.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Articulação Temporomandibular
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Orelha Média
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Evolução Biológica
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Fósseis
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Arcada Osseodentária
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Mamíferos
Limite:
Animals
Idioma:
En
Revista:
Nature
Ano de publicação:
2024
Tipo de documento:
Article
País de afiliação:
China