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Un conjunto de dinosauromorfos del Triásico tardío de Nuevo México y el surgimiento de los dinosaurios
Randall B Irmis1, Sterling J Nesbitt, Kevin Padian
1Museum of Paleontology and Department of Integrative Biology, University of California, Berkeley, CA 94720-4780, USA. irmis@berkeley.edu
Science (New York, N.Y.)
|July 21, 2007
Resumen
La transición de la fauna arcaica del Triásico tardío a los primeros dinosaurios fue gradual, no una extinción repentina. Los fósiles sugieren que esta diversificación de los dinosaurios tomó de 15 a 20 millones de años y varió según la región.
Área de la Ciencia:
- Paleontología Paleontología.
- La estratigrafía es la estratigrafía.
- Biología evolutiva Biología evolutiva.
Sus antecedentes:
- La teoría prevaleciente sugiere que los primeros dinosaurios reemplazaron rápidamente a las faunas arcaicas del Triásico Tardío a través de la exclusión competitiva o eventos de extinción repentina.
- La evidencia fósil de la Formación Chinle del Triásico Superior proporciona una oportunidad para reevaluar esta transición.
Objetivo del estudio:
- Para investigar la naturaleza de la transición de la fauna durante el Triásico Tardío, específicamente el surgimiento de los dinosaurios.
- Para determinar si la sustitución de la fauna arcaica por los dinosaurios fue abrupta o gradual.
Principales métodos:
- Análisis de ensamblajes fósiles de la cantera Hayden en la Formación Chinle del Triásico Superior, Nuevo México.
- Análisis comparativo de los conjuntos de fósiles regionales del Triásico superior.
Principales resultados:
- Los fósiles de la Cantera Hayden y la Formación Chinle circundante indican una transición gradual, no un reemplazo rápido.
- Los parientes de dinosaurios encontrados en el conjunto de Chinle representan grupos previamente conocidos solo de estratos más antiguos fuera de América del Norte.
- El surgimiento de los dinosaurios puede haber durado de 15 a 20 millones de años.
Conclusiones:
- El surgimiento de los dinosaurios y el declive de la fauna arcaica del Triásico tardío fue un proceso prolongado y gradual.
- Esta transición fue probablemente diacrónica, ocurriendo en diferentes momentos a través de varias paleolatitudes.
- Los hallazgos desafían la noción de larga data de una rápida toma de posesión de los dinosaurios al final del Triásico.
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