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Un nuevo mamífero eutriconodonte y el desarrollo evolutivo en los primeros mamíferos
Zhe-Xi Luo1, Peiji Chen, Gang Li
1Carnegie Museum of Natural History, Pittsburgh, Pennysylvania 15213, USA. luoz@carnegiemnh.org
Nature
|March 16, 2007
Resumen
Un mamífero del Mesozoico recién descubierto revela una estructura de oreja-mandíbula de transición, que conecta los huesos del oído medio con la mandíbula a través del cartílago de Meckel osificado. Esta característica pedomorfa ofrece información sobre la evolución temprana de los mamíferos y el tiempo de desarrollo.
Área de la Ciencia:
- Paleontología Paleontología.
- Biología del desarrollo Biología del desarrollo.
- Biología evolutiva Biología evolutiva.
Sus antecedentes:
- Los huesos del oído medio de los mamíferos (malleus, incus) se desprenden de la mandíbula durante la evolución.
- Esta transición es una característica clave que distingue a los mamíferos modernos de sus antepasados reptiles.
Objetivo del estudio:
- Para describir un fósil de eutriconodonto del Mesozoico que exhibe una estructura de oreja media y mandíbula de transición.
- Investigar las implicaciones evolutivas y del desarrollo de este hallazgo para los primeros mamíferos.
Principales métodos:
- Análisis fósil de un espécimen de eutriconodonte del Mesozoico.
- Análisis comparativo con patrones de desarrollo embrionario y adulto en monotremas existentes y mamíferos placentarios.
Principales resultados:
- El fósil muestra huesos del oído medio conectados a la mandíbula a través del cartílago de Meckel osificado.
- Esta estructura representa una característica pedomorfa, conservada en los adultos, a diferencia de los mamíferos modernos.
- La evidencia sugiere heterocronia (tiempo de desarrollo alterado) en eutriconodonts.
Conclusiones:
- Este descubrimiento proporciona una clara ilustración de la transición del desprendimiento del oído medio de los mamíferos.
- Los hallazgos apoyan el papel de la pedomorfosis y la heterocronia en la evolución temprana de los mamíferos.
- El estudio también contribuye a la comprensión de la homoplasia del carácter vertebral en los primeros mamíferos, potencialmente vinculada al patrón del gen Hox.
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