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Una nueva especie de yunnanozoan con implicaciones para la evolución de deuterostome
Degan Shu1, Simon Conway Morris, Z F Zhang
1Early Life Institute and Department of Geology, Northwest University, Xi'an 710069, China. elidgshu@nwu.edu.cn
Science (New York, N.Y.)
|March 1, 2003
Resumen
Los yunnanozoos, los primeros animales del Cámbrico, se reclasifican como deuteróstomos del grupo madre. Nuevas evidencias fósiles sugieren que sus estructuras branquiales evolucionaron independientemente de las características de los cordados.
Área de la Ciencia:
- Paleontología Paleontología.
- Biología evolutiva Biología evolutiva.
- La vida en el período cámbrico temprano.
Sus antecedentes:
- Los yunnanozoos son metazoos del Cámbrico temprano.
- Su clasificación como deuterostomos es objeto de debate.
- Estudios previos sugirieron características parecidas a las de los cordados en los yunnanozoos.
Objetivo del estudio:
- Describa una nueva especie, Haikouella jianshanensis, de la Lagerstätte de Chengjiang.
- Aclarar la posición filogenética de los yunnanozoos.
- Investigar los orígenes evolutivos de las estructuras faríngeas.
Principales métodos:
- Análisis morfológico detallado de fósiles excepcionalmente conservados.
- Anatomía comparada de ejemplares fósiles.
- Inferencia filogenética basada en datos morfológicos.
Principales resultados:
- La conservación excepcional reveló agallas externas en H. jianshanensis.
- Las hendiduras faríngeas parecen haber evolucionado independientemente de las branquias.
- No se identificaron estructuras parecidas a cordados en esta especie.
- Los arcos branquiales en los cordados pueden ser estructuras compuestas.
Conclusiones:
- Se propone que los yunnanozoos sean el grupo madre de los deuterostomos.
- Los yunnanozoos están aliados con los vetulicolianos.
- Este hallazgo refina la comprensión de la evolución temprana de los deuteróstomos.
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