33 Taimanawa

A distantly relative of heart urchin Pericosmus is the genus Taimanawa, first recognized and described by Henderson and Fell in 1969. The type species for the genus is a well-preserved Geology Museum specimen, Taimanawa pulchella.

The holotype of Taimanawa pulchella (specimen OU 8590) was collected from the Caversham Sandstone, near Karitane xxxx. It is Otaian (Early Miocene) in age.

A closely related species, T. greyi (Hutton) is also represented by several handsome specimens in the collections. The figured specimen, OU8598, was collected from Earthquakes, North Otago, by Doug Campbell and others.

In the figure there is a large specimen showing the upper side of Taimanawa greyi, the shell is made of many small plates whose outlines are faintly visible. There are three different sizes of tubercle, indicating different sizes of spine that were attached  to the tubercles, and four double rows of pores for tube feet. The spines and tube feet would have had various functions of maintaining the water space within the sediment, digging the animal through the sediment and maintaining a channel to the surface for gas exchange (see Figure for Pericosmus). A second specimen shows the lower side with the mouth.

A small Recent heart urchin is also shown, still with all its spines attaches and the faint outlines of the petals can be seen. Underwater videos on youtube show small heart urchins living on the sediment surface or digging their way into soft sediment quite rapidly.

Spatangoids that are closely related to those in New Zealand occur in rocks of similar Oligocene – Miocene age in Australia when conditions were right for larvae to disperse across the Tasman Sea.

– Written by Jeffrey H Robinson and Daphne E Lee