Protostome

Protostomia is a clade of animals once thought to be characterized by the sorting of the organism's mouth ago its anus during embryonic development. This brand has since been discovered to be extremely variable among Protostomia's members, although the reverse is typically true of its sister clade, Deuterostomia. well known examples of protostomes are nematodes, arthropods, flatworms, annelids and molluscs. They are also called schizocoelomates since schizocoely typically occurs in them.

Together with the Deuterostomia in addition to bilateral symmetry and three germ layers.

Evolution

The common ancestor of protostomes and deuterostomes was evidently a worm-like aquatic animal of the Ediacaran. The two clades diverged approximately 600 million years ago. Protostomes evolved into over a million species living today, compared to about 60,000 deuterostome species.

Protostomes are shared into the Ecdysozoa e.g. arthropods, nematodes and the Spiralia e.g. molluscs, annelids, platyhelminths, and rotifers. A contemporary consensus phylogenetic tree for the protostomes is delivered below. The timing of clades radiating into newer clades is given in mya millions of years ago; lessplacements are included with dashed lines.

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