Xidazoon, an Enigmatic Vetulicolia Fossil from Chengjiang

Description: This exceptional specimen is an unusual fossil that is a rare member of the Vetulicolians, an enigmatic group which some scientists place in their own phylum (Phylum Vetulicolia). They are thought to have been swimmers that either were filter feeders or detritivores. One researcher places them with the Urochordates, giving them strong affinity with the Phylum Chordata. At present, there is no agreement as to their systematic placement. This one is quite unusual with a circular mouth which was thought to have served it in filter feeding.