April 10, 2008

The first animal on Earth was probably significantly more complex than thought

A new study mapping the evolutionary history of animals indicates that Earth's first animal - a mysterious creature whose characteristics can only be inferred from fossils and studies of living animals - was probably significantly more complex than previously believed.


Among the study's surprising findings is that the comb jelly split off from other animals and diverged onto its own evolutionary path before the sponge. This finding challenges the traditional view of the base of the tree of life, which honoured the lowly sponge as the earliest diverging animal. 'This was a complete shocker,' says Dunn. 'So shocking that we initially thought something had gone very wrong.'

But even after Dunn's team checked and rechecked their results and added more data to their study, their results still suggested that the comb jelly, which has tissues and a nervous system, split off from other animals before the tissue-less, nerve-less sponge.

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