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Los núcleos fosilizados y las estructuras de germinación identifican a los "embriones animales" de Ediacaran como
Therese Huldtgren1, John A Cunningham, Chongyu Yin
1Department of Palaeozoology, Swedish Museum of Natural History, Stockholm, Sweden.
Science (New York, N.Y.)
|December 24, 2011
Resumen
Los fósiles ediacaranos que anteriormente se pensaba que eran embriones de animales primitivos exhiben patrones de desarrollo no metazoarios. Estos fósiles globulares se reclasifican como holozoos no metazoos, no embriones animales.
Área de la Ciencia:
- Paleontología Paleontología.
- Biología del desarrollo Biología del desarrollo.
- Biología evolutiva Biología evolutiva.
Sus antecedentes:
- Los fósiles globulares de la Formación Ediacaran Doushantuo se interpretan comúnmente como los primeros embriones de metazoos.
- Esta interpretación se ve cuestionada por la ausencia de sinapomorfías metazoarias, diferenciación tisular y formas adultas o juveniles asociadas.
Objetivo del estudio:
- Reevaluar el estado filogenético y de desarrollo de los fósiles globulares de Doushantuo.
- Para determinar si estos fósiles representan embriones de animales primitivos o un linaje evolutivo alternativo.
Principales métodos:
- Se empleó microscopía tomográfica de rayos X basada en sincrotrón para analizar la morfología y las características de desarrollo de los fósiles.
- Se realizó un análisis comparativo del desarrollo con organismos holozoos existentes.
Principales resultados:
- Los fósiles muestran patrones de desarrollo inconsistentes con los embriones de metazoos multicelulares.
- Se identificaron las etapas de germinación, excluyendo la característica embriología post-clivado de los metazoos.
- Las características son comparables a las de los holozoos no metazoos, como los choanoflagelados y los mesomycetozoea.
Conclusiones:
- Los fósiles globulares de Doushantuo no son ni animales ni embriones.
- Representan un grado evolutivo dentro del grupo total de Holozoos o eucariotas potencialmente más distantes.
- La escisión palintómica en estos fósiles probablemente sirvió para la producción de propágulos para la dispersión.
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