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Extinciones de tetrápodos del Triásico-Jurásico: ¿son reales?
Science (New York, N.Y.)
|September 2, 1977
Resumen
Los fósiles de vertebrados terrestres del Jurásico temprano de América del Norte y África revelan nuevas correlaciones. Este hallazgo desafía la idea de un importante evento de extinción de tetrápodos en el límite Triásico-Jurásico.
Área de la Ciencia:
- Paleontología Paleontología.
- La estratigrafía es la estratigrafía.
- Evolución de los vertebrados.
Sus antecedentes:
- El límite Triásico-Jurásico se considera tradicionalmente un período de extinción significativa de tetrápodos.
- Correlaciones anteriores de estratos rocosos a través de los continentes se han utilizado para definir este límite.
- El supergrupo de Newark (este de Estados Unidos), el grupo de Glen Canyon (suroeste de Estados Unidos) y el grupo de Stormberg (sur de África) son las principales formaciones que contienen fósiles.
Objetivo del estudio:
- Reevaluar la edad de los principales conjuntos de fósiles de vertebrados terrestres del supergrupo de Newark, el grupo de Glen Canyon y el grupo de Stormberg.
- Para establecer una correlación cronostratigráfica más precisa entre estas formaciones del hemisferio sur y el hemisferio norte.
- Para probar la hipótesis de un evento de extinción generalizada de tetrápodos en el límite Triásico-Jurásico.
Principales métodos:
- Análisis de las ocurrencias fósiles de vertebrados terrestres dentro de los grupos geológicos especificados.
- Datamiento biostratigráfico basado en rangos fósiles establecidos.
- Correlación de estratos geológicos a través de diferentes continentes usando evidencia fósil.
Principales resultados:
- Los fósiles de vertebrados terrestres indican que partes del Supergrupo Newark y la totalidad del Grupo Glen Canyon son del Jurásico Temprano en edad.
- El Grupo Superior Stormberg del sur de África también se confirma como del Jurásico Temprano.
- Estos hallazgos establecen un nuevo marco cronostratigráfico para estas unidades rocosas.
Conclusiones:
- La extinción generalizada de tetrápodos inferida anteriormente en el límite Triásico-Jurásico es un artefacto de una correlación inexacta.
- El registro fósil indica una transición más gradual para los vertebrados terrestres a través de la frontera Triásico-Jurásico.
- Esta correlación revisada proporciona una comprensión más robusta de la evolución de los vertebrados durante este período crítico.
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