Cidaroida Claus, 1880

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 : 178-179

Order Cidaroida Claus, 1880

Isolated spines and partly articulated test fragments (gen. et spp. indet.)

Fig. 30E, I, K, N .

Material.—More than 90 spines, ambulacral plates, and other ossicles (teeth, rotulae, etc.) (including PZO 12777– 12780) from Misurina Landslide bulk samples and few other remains from Lago Antorno bulk samples, Italy, Carnian, Triassic.

Remarks.—In addition to the stem group echinoid taxon, we have found well preserved and partly articulated test fragments ( Fig. 30E ) and spines (a few types; e.g., Fig. 30I, K, N ) of cidaroid echinoids (including “ Cidaris ” cf. decoratissima Wöhrmann, 1889, and “ Cidaris ” cf. flexuosa Münster, 1841) at Misurina Landslide, which represent the majority of sea urchin material from the Ladinian/Carnian Cassian Formation (see also Kier 1984; Vadet 1999a, b; Kroh 2011). However, as more than 40% of the worldwide reported Triassic echinoid “species” are spine-based taxa ( Kroh 2011), disarticulated material remain often indeterminate to species or genus level. Spines (and other ossicles) can be distinct and recognizable, but more studies combining isolated spines and test material, like ambulacral plates, are needed to validate different single species.

Regular echinoids, like in our material, are vagile benthos, moving by means of their spines over the sea floor and using their tube-feet to climb and grip hard substrata ( Smith 2004b). The proterocidarid species described and figured here is presumably a deposit feeder, using its enlarged oral tube-feet for detritus gathering (cf. Thompson and Bottjer 2019).

Figures

Fig. 30. Echinoderm plates, ossicles, and elements from Misurina Landslide, northern Italy, Cassian Formation; Carnian, Upper Triassic. A. PZO 12765, isocrinid? (sediment encrusted) columnal. B. PZO 12878, asteroid?/asterozoan spine. C, D, H. Ophiuroids. C. PZO 12879, lateral arm plate, external view, showing the articulation for the attachment of spines.D. PZO 12880, arm vertebra, distal view, showing the muscle attachment area. E. PZO 12885, part of ambulacrum of unknown cidaroid? species. H. PZO 12881, distal lateral arm plate, in external view. F. PZO 11827, ophiocistioid goniodont Linguaserra triassica Reich in Reich et al., 2018, abaxial face, in outer view. G. Pronechinus? sp., PZO 12777, ambulacral plate. I. PZO 12884, broken hollow cidaroid? spine fragment, showing the microstructure at the inner side of the cylinder.J, L, M.Ambulacral plates of Pronechinus? sp. with slightly developed peripodial rim surrounding pore pairs (J, PZO 12780; L, PZO 12778; M, PZO 12779). K, N. Cidaroid? spines (partially broken) of unknown species (K, PZO 12882; N, PZO 12883).