Holothuroidea, Blainville, 1834

Hausmann, Imelda M., Nützel, Alexander, Roden, Vanessa Julie & Reich, Mike, 2021, Palaeoecology of tropical marine invertebrate assemblages from the Late Triassic of Misurina, Dolomites, Italy, Acta Palaeontologica Polonica 66 (1), pp. 143-192 : 179

Holothuroidea

Sea cucumbers are represented by calcareous ring (CR) elements and body-wall ossicles of Apodida (Fig. 31A–C, E, F) and Synallactida (Fig. 31D, G, H) only.

Class Holothuroidea Blainville, 1834

Subclass Paractinopoda Ludwig, 1891

Order Apodida Brandt, 1835

“Stem group chiridotids”

Gen. et sp. indet. 1

Fig. 31A, B.

Material.—Four calcareous ring elements (PZO 12784, 12785) from Misurina Landslide bulk samples, Italy, Carnian, Triassic.

Description and remarks.—Radial (Fig. 31A) and interradial (Fig. 31B) calcareous ring elements of a medium-sized apodid sea cucumber, probably with?15 tentacles. Radial and interradial nearly squarish in shape and with a deep posterior indent, radial with two unequal medium long anterior processes, the shorter one notched for the passage of the radial nerve (Fig. 31A 1, A 2, A 4; here filled with sediment). The additional anterior process is longer and pointed like that of the interradial (Fig. 31B). On the external face of radial a tongue-shaped insertion area for the tentacle ampullae. The stereom of radial resembles that of the interradial. Interradial with a single well-developed pointed anterior process and associated frontal excavations.

Both types of elements are closely comparable with the calcareous ring elements found in modern chiridotids (and myriotrochids), but presenting apparently a stem group chiridotid, with respect to the stout morphology in combination with medium-sized anterior processes.

Definitely associated body-wall ossicles missing, but probably represented by Theelia cf. multiplex (Fig. 31E).