Echinoidea taxon details
original description
Mooi, R., Hilton, R. P. (2014). First record and phylogenetic significance of a Jurassic diadematacean sea urchin from California. <em>Journal of Paleontology.</em> 88(3): 421-433., available online at https://doi.org/10.1666/13-130 page(s): 421-423; figs 2.1-2, 3.1-3, 4, 5.1-3 [details] Available for editors
From editor or global species database
Diagnosis Being a basal member of a group that is itself not richly endowed with autapomorphies, Sierradiadema is largely characterized by a plesiomorphic combination of features that uniquely excludes it from other known genera. Therefore, the species diagnosis cannot consist solely of autapomorphies for the genus. Relevant characters distinguishing Sierradiadema kristini from all other taxa are summarized in Table 1, which acts as tabular key to Jurassic and other near-contemporary taxa in diadematacean groups. Sierradiadema kristini is unique among diadematacean urchins in possessing thin, non-verticillate primary spines approximately equal in length to test diameter. Primary spines of almost constant diameter, but filled with internal meshwork running almost their entire length. [details]
Etymology Named after Kristin Hilton, the discoverer of the fossil echinoid [details]
Stratigraphy Colfax sequence of the Mariposa Formation [details]
Type locality Middle Fork American River drainage of the northern Sierra Nevada, California [details]
Type material Holotype: CASG 72939 [details]
From editor or global species database
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