Tuesday, October 22, 2013

Alalcomenaeus: Unusual Cambrian Animal with Spider-Like Brain

''Collected from the famous Chengjiang formation near Kunming in southwest China, the four-eyed, 3-cm-long Alalcomenaeus belongs to an extinct group of marine arthropods known as megacheirans (large claws in Greek).
These animals had an elongated, segmented body equipped with about a dozen pairs of body appendages enabling the animal to swim or crawl or both. All featured a pair of long, scissor-like appendages attached to the head, most likely for grasping or sensory purposes.
Alalcomenaeus solves the long-standing mystery of where this group fits in the tree of life. It suggests that the ancestors of spiders, scorpions and their kin (chelicerates) branched off from the family tree of other arthropods – including insects, crustaceans and millipedes – more than half a billion years ago..''

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