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Contrastando las trayectorias de desarrollo en las primeras extremidades delanteras de tetrápodos conocidas
Viviane Callier1, Jennifer A Clack, Per E Ahlberg
1University Museum of Zoology Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
Science (New York, N.Y.)
|April 18, 2009
Resumen
Los primeros tetrápodos Ichthyostega y Acanthostega muestran un desarrollo distinto de las extremidades. Ichthyostega, por ejemplo.
Área de la Ciencia:
- Paleontología Paleontología.
- Biología evolutiva Biología evolutiva.
- Anatomía comparada y anatomía comparada.
Sus antecedentes:
- Ichthyostega y Acanthostega son las claves de los primeros tetrápodos.
- Acanthostega es típicamente visto como más primitivo.
- Comprender el desarrollo de sus extremidades ofrece información sobre la evolución de los tetrápodos.
Objetivo del estudio:
- Investigar las trayectorias ontogenéticas del desarrollo de las extremidades delanteras en Ichthyostega y Acanthostega.
- Para comparar los patrones de fijación muscular en el húmero entre estos primeros tetrápodos y los tetrápodos del tallo.
- Para inferir diferencias en la locomoción terrestre y las relaciones filogenéticas.
Principales métodos:
- Análisis de nuevo material esquelético de Ichthyostega y Acanthostega.
- Examen comparativo de los sitios de fijación muscular en humeri a través de diferentes etapas ontogenéticas.
- Análisis filogenético que incorpora características primitivas recientemente identificadas.
Principales resultados:
- Ichthyostega humeri muestra un cambio en el desarrollo de los patrones de fijación muscular de los peces a los tetrápodos.
- Acanthostega humeri muestra constantemente patrones de fijación muscular de tipo tetrápodo durante todo el desarrollo.
- Los rasgos primitivos recién identificados sugieren que Ichthyostega puede ser filogenéticamente más basal que Acanthostega.
Conclusiones:
- Ichthyostega probablemente exhibió una mayor terrestrización locomotora durante su desarrollo.
- La posición filogenética de Ichthyostega puede necesitar una reevaluación, siendo potencialmente más basal de lo que se pensaba anteriormente.
- Los datos ontogenéticos proporcionan evidencia crucial para comprender la evolución temprana de los tetrápodos y la adaptación terrestre.
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