Psychocidaridae
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| Psychocidaridae Temporal range: | |
|---|---|
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| Fossil of Balanocidaris marginata | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Echinoidea |
| Order: | Cidaroida |
| Superfamily: | Histocidaroidea |
| Family: | Psychocidaridae Ikeda, 1936 [1] |
| Genera | |
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See text | |
Psychocidaridae is a family of sea urchins in the order Cidaroida. The genus Psychocidaris is extant while the other genera are only known from fossils. The family has been in existence since the Lower Jurassic (Toarcian) and the range includes Europe, Ukraine, North America, North Africa and the West Pacific.[2]
All Cidaroids are regular and have the test composed of twenty columns of plates with two ambulacral columns alternating with two interambulacral columns. The pedicellariae are exclusively globiferous or tridentate. In addition, Psychocidarids are characterized by having no plates between the ambulacra. Instead they have a single primary tubercle with a large mamelon, the ball-like surface that articulates with the spine. In most genera this is imperforate and non-crenulate. The pores are in pairs that are not connected by grooves. The spines are broad and either spindle, gland or club-shaped.[2]