''Erjiecaris'' Is an extinct genus of bivalved

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

arthropod, known from the

Chengjiang Biota The Maotianshan Shales () are a series of Early Cambrian sedimentary deposits in the Chiungchussu Formation or Heilinpu Formation, famous for their '' Konservat Lagerstätten'', deposits known for the exceptional preservation of fossilized orga ...

of Yunnan, China. It is only known from a single species ''Erjiecaris minisculo''. Around long, It has an unusual flattened head-shield, with an elongate body with at least 19 segments and a forked tail similar to ''

Waptia ''Waptia'' is an extinct genus of marine arthropod from the Middle Cambrian of North America. It grew to a length of , and had a large bivalved carapace and a segmented body terminating into a pair of tail flaps. It was an active swimmer and like ...

''. Unlike most bivalved arthropods, its simple, unstalked eyes are placed on top of the headshield. It was likely a nektobenthic (swimming above ocean floor) deposit feeder. The relationship of ''Erjiecaris'' to other arthropods was considered uncertain in its original description. A later study suggested it was a member of

Hymenocarina Hymenocarina is an Order (biology), order of extinct marine arthropods known from the Cambrian. They possess bivalved carapaces, typically with exposed posteriors. Members of the group are morphologically diverse and had a variety of ecologies, i ...

. Despite the head shield being portrayed as flattened in most specimens, this is likely a preservational artifact from the valves being “butterflied” out, and ''Erjiecaris'' likely looked more similar to other hymenocarines.

References

{{Taxobar, from1=Q113858939 Cambrian arthropods Fossil taxa described in 2014 Cambrian genera