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Fossils document evolutionary changes of jaw joint to mammalian middle ear.
- Source :
-
Nature [Nature] 2024 Apr; Vol. 628 (8008), pp. 576-581. Date of Electronic Publication: 2024 Apr 03. - Publication Year :
- 2024
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Abstract
- The dual jaw joint of Morganucodon <superscript>1,2</superscript> 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 evolution <superscript>1-5</superscript> . Here we report mandibular middle ears from two Jurassic mammaliaforms: a new morganucodontan-like species and a pseudotribosphenic shuotheriid species <superscript>6</superscript> . The morganucodontan-like species shows many previously unknown post-dentary bone morphologies <superscript>1,2</superscript> 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 dentary <superscript>7-12</superscript> and the eventual breakdown of the Meckel's cartilage <superscript>13-15</superscript> during the evolution of mammaliaforms.<br /> (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)
Details
- Language :
- English
- ISSN :
- 1476-4687
- Volume :
- 628
- Issue :
- 8008
- Database :
- MEDLINE
- Journal :
- Nature
- Publication Type :
- Academic Journal
- Accession number :
- 38570677
- Full Text :
- https://doi.org/10.1038/s41586-024-07235-0