Pedinoida is an
order of
sea urchins, containing the single living genus ''
Caenopedina''. The group was much more diverse during the
Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...
, and represents the oldest surviving order of
euechinoid sea urchins.
They are distinguished from other sea urchins by the presence of a rigid test with
tessellated plates. While their primary spines are solid, the smaller ones may be hollow, further distinguishing them from the closely related orders
Diadematoida and
Echinothurioida
The Echinothurioida are an order of sea urchins in the class Echinoidea. Echinothurioids are distinguished from other sea urchins by the combination of a flexible test and hollow spines. The membrane around the mouth contains only simple plat ...
, which possess only hollow spines.
References
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Extant Early Triassic first appearances
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