Aysheaia

Reconstruction of Aysheaia

• North America ( Burgess Shale, Canada; Wheeler Formation, USA )

• A. pedunculata Walcott, 1911
• A. prolata Robison, 1985

Aysheaia is a genus of extinct molting animals from the group of Lobopoden known, each with a type from the middle Cambrian Burgess Shale in Canada and the Wheeler Formation in Utah. Similar forms have been identified in about 10 million years older than Chengjiang Faunengemeinschaft of Maotianshan Shale in the western Chinese province of Yunnan.

The term Aysheaia derives from the mountain " Ayesha " north of Mount Wapta.

Physique

The 1-6 cm long organism possessed an elongated worm-like body consisting of at least 12 body segments, joined at the laterally ten pairs of conical, provided with small claws stubby legs. Aysheaia also had a fine, not matching with the body segmentation, superficial curl ring.

The forward facing mouth was lined with six finger-like papillae, which helped the animal to eat. Aysheaia possessed in addition to the 10 leg extensions a pair of spiny antennae in the front part of the fuselage, which was not separated from the rest of the body as a head. Presumably supporting said forward the animal also when gripping and seizing the prey.

Ecology

Due to the fact that many copies were together with the fossil remains of sponges ( sclerites ) found, it is assumed that Aysheaia lived on these and fed on them. Probably used Aysheaia the claws on its leg extensions, to cling to the sponges. It is believed that the unarmored animals in the sponge colonies also sought protection from predators.

19 specimens of A. pedunculata are known from the Burgess Shale in Canada. Thus, A. pedunculata is one of the rarer fossils of the Burgess Shale. A. prolata is known with an individual from the Wheeler Formation.

System

Aysheaia shows striking similarities with extant representatives of the velvet worms ( Onychophora ) and the water bears ( tardigrades ) and is therefore regarded by some as their precursors, but belongs to none of these groups. Instead Aysheaia is counted among the representatives of the Cambrian Lobopoden.