New York: The first animal on Earth, a mysterious creature whose characteristics can only be inferred from fossils, was probably more complex than earlier thought, a new study has revealed.

Using high-powered technologies, researchers in the United States have defined the earliest splits at the base of the animal tree of life -- a hierarchical representation of the evolutionary relationships between species, introduced by Charles Darwin.

According to the study, the comb jelly split off from other animals and diverged onto its own evolutionary path before the sponge, a finding that challenges the traditional view of the base of the tree of life.

"This was a complete shocker. So shocking that we initially thought something had gone very wrong. The presence of the relatively complex comb jelly at the base of the tree of life suggests that the first animal was probably more complex than believed," lead researcher Casey Dunn said.

According to her, the comb jelly could have achieved its apparent seniority over the simpler sponge via one of two new evolutionary scenarios -- either it evolved its complexity independently of other animals, after it branched off onto its own evolutionary path or the sponge evolved its simple form from more complex creatures.

"The second scenario is a possibility that underscores the fact that evolution isn't necessarily just a march towards increased complexity.

This scenario would provide a dramatic example of that principle," Dunn said.

Source : PTI