Rectifacies, A Rare Chengjiang Arthropod with Patterned Shell

Description: This rare arthropod is known as Rectifacies abnormalis. The species was one of the larger arthropods found in the Chngjiang Biota, with examples 12 cm in overall length known.. The diversity of soft-tissue fossils is astonishing: algae, medusiforms, sponges, priapulids, annelid like worms, echinoderms, arthropods (including trilobites), hemichordates, chordates, and the first agnathan fish make up just a small fraction of the total. Numerous problematic forms are known as well, some of which may have represented failed attempts at diversity that did not persist to the present day.

The taxon has a distinctive polygonally-ornamented surficial detail not known from any other arthropod from the region. This trilobite-like form is thought most closely related to Emeraldella and Sidneyia from the younger Burgess Shale. While missing the head, it is quite detailed, and comes from the site of the discovery of the Chengjiang Biota, Mao Tian Shan.

Also see: Chengjiang Biota Fauna List Chengjiang Fossils