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Desarrollo evolutivo del oído medio en los mamíferos terianos del Mesozoico
Qiang Ji1, Zhe-Xi Luo, Xingliao Zhang
1Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China.
Science (New York, N.Y.)
|October 10, 2009
Resumen
Un fósil de mamífero del Cretácico revela que el oído medio definitivo de los mamíferos (DMME) evolucionó independientemente en diferentes grupos de mamíferos. Este hallazgo pone de relieve la pedomorfosis y la heterocronia como mecanismos evolutivos clave.
Área de la Ciencia:
- Paleontología Paleontología.
- Biología evolutiva Biología evolutiva.
- Biología del desarrollo Biología del desarrollo.
Sus antecedentes:
- El oído medio mamífero definitivo (DMME) es un rasgo clave que distingue a los mamíferos, caracterizado por la pérdida del cartílago de Meckel y la separación de la mandíbula.
- El entendimiento previo atribuía la evolución de DMME a linajes específicos, principalmente eutriconodonts.
- Los procesos de desarrollo implican complejas redes genéticas y vías de señalización para la reabsorción del cartílago de Meckel.
Objetivo del estudio:
- Para investigar la historia evolutiva de la DMME en mamíferos del Cretácico.
- Para explorar ejemplos de evolución homoplástica de la DMME.
- Comprender los mecanismos de desarrollo subyacentes a la evolución de la DMME en un taxón fósil.
Principales métodos:
- Análisis de un fósil de mamífero trechnotherian del Cretácico.
- Estudio anatómico comparativo centrado en las estructuras de la mandíbula y el oído medio.
- Interpretación de los patrones de desarrollo, incluida la pedomorfosis y la heterocronia.
Principales resultados:
- Descubrimiento de un mamífero trechnotherian adulto del Cretácico que conserva un cartílago de Meckel osificado.
- Evidencia de la evolución homoplástica de la DMME en mamíferos derivados de los terios, más allá de los eutriconodontes.
- El cartílago de Meckel osificado sugiere una condición pedomorfa.
Conclusiones:
- La DMME ha evolucionado de forma independiente varias veces dentro de los mamíferos (homoplasia).
- La heterocronia del desarrollo y el patrón genético son mecanismos significativos que impulsan la evolución homoplástica de la DMME.
- Este fósil proporciona información crucial sobre la plasticidad de la evolución del oído medio de los mamíferos.
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