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El más antiguo osteichthyan articulado revela mosaico caracteres gnathostome mosaico
Min Zhu1, Wenjin Zhao, Liantao Jia
1Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, PO Box 643, Beijing 100044, China. zhumin@ivpp.ac.cn
Nature
|March 28, 2009
Resumen
Un nuevo fósil casi completo de peces del período silúrico revela características inesperadas, arrojando luz sobre la evolución temprana de los peces óseos (osteictianos) y los vertebrados con mandíbula (gnatostomas). Este descubrimiento retrasa la línea de tiempo para las divisiones evolutivas clave.
Área de la Ciencia:
- Paleontología Paleontología.
- Biología evolutiva Biología evolutiva.
- Zoología de los vertebrados Zoología de los vertebrados.
Sus antecedentes:
- La evolución de los osteictianos (peces óseos y tetrápodos) se remonta al período silúrico, pero la evidencia se ha limitado a fósiles fragmentados.
- Comprender la evolución temprana de los gnathostomes requiere registros fósiles más completos.
Objetivo del estudio:
- Para describir un pez primitivo recién descubierto y excepcionalmente conservado de la época Ludlow del período silúrico.
- Para analizar el esqueleto postcraneal del fósil para obtener información sobre la evolución temprana de los osteictios y sarcopterigios.
- Establecer una fecha mínima para la división actinopterigiano-sarcopterigiano.
Principales métodos:
- Descubrimiento y excavación de fósiles en Yunnan, China.
- Análisis morfológico detallado del pez fósil excepcionalmente conservado.
- Estudio anatómico comparativo con sarcopterygians basales conocidos y gnathostomes no-osteichthyan.
Principales resultados:
- Descubrimiento del más antiguo gnathostome casi completo, un pez primitivo del Ludlow de Yunnan, China.
- El fósil exhibe una mezcla de características primitivas (cinturón pectoral, columna vertebral de aleta mediana) y derivadas (escamación macromérica).
- Esta combinación apoya los hallazgos anteriores sobre sarcopterygians basales como Psarolepis.
Conclusiones:
- El nuevo taxón representa el sarcopterygian articulado más antiguo, proporcionando datos cruciales sobre los orígenes osteichthyan.
- Los hallazgos indican que la división actinopterigiana-sarcopterigiana ocurrió no más tarde de hace 419 millones de años.
- Este descubrimiento pone de relieve la naturaleza de mosaico de la evolución temprana de los vertebrados.
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