Helmetiidae / Skioldidae
Time: Early Cambrian (~525 million years ago)
is 26 mm long
Site: Chengjiang Maotianshan Shales - Quiongzhusi Section, Yu’anshan
Member, Heilinpu Formation, Haiyi Village, Anning, Kunming County, Yunnan
Helmetid arthropod is known as Skioldia aldna. The species is
from only a few examples as of 2004, some of which are as much
as 100 mm in length. HelmetidaeThe
taxon has some resemblance to the younger Burgess Shale arthropod
Hemetia expansa that has led some to place them in the Helmetidae
along with several other similar arthropods from Chengjiang
the Burgess Shale. Other scientists have suggested that the Helmetidae
are the closest sister taxon to trilobites in the Cambrian fossil
record. Skioldia has currently, however, been assigned its own
family, Skioldidae. The body shape suggests that, like the similar
Kuamaia, it was a benthic animal that also was possibly carnivorous.
Unlike Kuamaia, Skioldia has considerably less distinct segmentation.
The central digestive system is the most distinct feature seen
on this exceptionally rare specimen. The species is only known
the Chengjiang Biota.
see: Chengjiang Biota Relatives
and Ancestors of Trilobites Chengjiang
Fossils Cambrian Explosion