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Un placodermo maxilar silúrico ilumina la evolución de la mandíbula
Min Zhu1,2, Per E Ahlberg3, Zhaohui Pan4,2
1Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, PO Box 643, Beijing 100044, China. zhumin@ivpp.ac.cn per.ahlberg@ebc.uu.se.
Science (New York, N.Y.)
|November 16, 2016
Resumen
Un nuevo descubrimiento de placodermo siluriano aclara la evolución de los huesos de la mandíbula. El maxilar, el premaxilar y los huesos dentales en los placodermos son homólogos a las placas gnatales, lo que revela un origen dental compartido.
Área de la Ciencia:
- Paleontología
- Evolución de los vertebrados
- Anatomía comparada
Sus antecedentes:
- El descubrimiento de Entelognathus en los estratos silurianos presentó maxilares, premaxilares y huesos dentales en un placodermo, desafiando las clasificaciones anteriores.
- La homología entre estos huesos marginales de la mandíbula y las placas gnatales de otros placodermos, tradicionalmente consideradas la arcada dental interna, permaneció sin resolver.
- Comprender esta relación es crucial para rastrear los orígenes evolutivos de las estructuras de la mandíbula en los vertebrados.
Objetivo del estudio:
- Investigar el vínculo evolutivo entre las placas gnatales de los placodermos y los huesos marginales de la mandíbula (máxilla, premaxilla, dentaria) que se encuentran en algunos placodermos silurianos.
- Para aclarar la homología de estos elementos de la mandíbula y su contribución a la arcada dental temprana.
- Para reconstruir el proceso de transformación de las estructuras de la mandíbula durante la evolución de los vertebrados.
Principales métodos:
- Análisis de un espécimen de placodermo maxilar silúrico recién descubierto.
- Análisis morfológico comparativo de los elementos de la mandíbula entre diferentes grupos de placodermos y osteictianos tempranos.
- Entre paréntesis filogenéticas para inferir la homología y las relaciones evolutivas.
Principales resultados:
- El placodermo recién descrito exhibe características de mandíbula intermedias, cerrando la brecha entre las placas gnatales típicas del placodermo y las estructuras de la mandíbula maxilar.
- La evidencia sugiere que el maxilar, el premaxilar y el dentario en estos placodermos silurianos son homólogos a las placas gnáticas de otros placodermos.
- El estudio indica que la transformación de las placas gnaciales a los huesos maxilares se produjo simultáneamente en la mandíbula superior e inferior.
Conclusiones:
- El maxilar, el premaxilar y el dental están integrados en la arcada dental del placodermo, lo que sugiere un origen evolutivo compartido con las placas gnatales.
- Esta transformación gnatal-maxilar es anterior a la evolución de los huesos infradentarios en la mandíbula inferior.
- Los hallazgos proporcionan información crítica sobre la evolución temprana del aparato de la mandíbula en los vertebrados, particularmente la transición hacia estructuras de la mandíbula similares a las de los osteictianos.
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