Plated Cambrian bilaterians reveal the earliest stages of echinoderm evolution.
PLoS One
; 7(6): e38296, 2012.
Article
em En
| MEDLINE
| ID: mdl-22701623
ABSTRACT
Echinoderms are unique in being pentaradiate, having diverged from the ancestral bilaterian body plan more radically than any other animal phylum. This transformation arises during ontogeny, as echinoderm larvae are initially bilateral, then pass through an asymmetric phase, before giving rise to the pentaradiate adult. Many fossil echinoderms are radial and a few are asymmetric, but until now none have been described that show the original bilaterian stage in echinoderm evolution. Here we report new fossils from the early middle Cambrian of southern Europe that are the first echinoderms with a fully bilaterian body plan as adults. Morphologically they are intermediate between two of the most basal classes, the Ctenocystoidea and Cincta. This provides a root for all echinoderms and confirms that the earliest members were deposit feeders not suspension feeders.
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1
Base de dados:
MEDLINE
Assunto principal:
Padronização Corporal
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Equinodermos
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Evolução Biológica
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Fósseis
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article