TAPHONOMY OF ECHINOCYAMUS PUSILLUS, A MINUTE CLYPEASTEROID FROM THE MEDITERRANEAN SEA (GIGLIO ISLAND)

Echinoid skeletons are often vulnerable to rapid disarticulation after death depending on several factors including skeletal or tissue connections as well as various environmental factors. Clypeasteroid echinoids are known to be relatively resistant to disarticulation since they feature rigid interplate connections and internal support structures. Echinocyamus is a minute clypeasteroid echinoid that is abundant in a wide variety of settings. High number of individuals within separate samples allows for statistical comparisons not only of size classes, but also predation rates and various taphonomic features of the test surface.

The present research is based on numerous specimens of Recent Echinocyamus pusillus from the Tuscan Island of Giglio in the Mediterranean Sea. The results are compared to published results on Echinocyamus crispus from the Red Sea with similar methods being used in order to make the results comparable. These methods include analyses on the abrasion of general surface characters such as tuberculation as well as that of the ambitus, peristome, and periproct. The presence of encrustation is also noted and, if available, drillhole outline and abrasion. Taphonomic features are categorized into five grades ranging from pristinely preserved to highly affected tests. The results are compared among different size classes, localities and depths. The ratios of drilled and undrilled tests along taphonomic gradients are also compared in order to detect possible influence of drilling predation on shell preservation. The results from Giglio indicate that most tests of Recent Echinocyamus pusillus can be assigned into taphonomic grades 1 and 2 with only few individuals showing higher levels of damage. These results are discussed with respect to variation in depositional environments and taphonomic processes between different samples from Giglio and to those from the Red Sea.