Shankouclava

Shankouclava is an extinct genus of tunicates. It represents the oldest candidate member of this group, dating to. It has been found in the Lower Cambrian Maotianshan Shale at Shankou village, Anning, near Kunming (South China). Each of the eight specimens found and used for description were isolated, suggesting that the genus was solitary and not colonial.

Morphology
Shankouclava had a soft, sac-like body that was elongated and pointed proximally. The body lengths of individuals vary from 2 cm (0.8 in) to 4 cm (1.6 in).

Degan Shu asserts that some fossil specimens exhibit tentacles, which would make the genus similar to the deuterostome Phlogites. Expanding on this idea, Shu and colleagues argue against a tunicate affinity for Shankouclava.

Etymology
The generic name is composed of the fossil locality, Shankou, and the Latin word clava (club-shaped).

Classification
A stem group tunicate affinity for Shankouclava has been broadly accepted, though some authors have expressed reservations that the evidence in favour of this affinity is not conclusive.

Another Cambrian tunicate, Megasiphon, known from a single specimen, resembles more closely the morphology of surviving tunicates.