Camptostroma

Not to be confused with Camptostoma.

Camptostroma roddyi is an extinct echinoderm from the Bonnia-Olenellus Zone of the Early Cambrian Kinzers Formation near York and Lancaster, Southeastern Pennsylvania.^[2] It is the only known species in the genus Camptostroma, as other species referred to this genus "do not appear to be cogeneric."^[3]

Camptostroma Temporal range: Early Cambrian
Artist's reconstruction
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	†Edrioasteroidea
Genus:	†Camptostroma
Species:	†C. roddyi
Binomial name
Camptostroma roddyi Ruedemann 1933[1]

Anatomy

In life, Camptostroma would have resembled a cupcake, with the mouth in the center of the upper surface, with ambulacra radiating from it in the 2-1-2 pattern common in early echinoderms. The ambulacra are straight in juveniles, but in larger adult specimens, ambulacra A, B, C, and E curve clockwise while ambulacrum D curves counter-clockwise. The anus is near the periphery between ambulacra C and D.^[4]

The ambulacra may have extended beyond the upper surface on stubby arms. While this diagnosis is tentative, ongoing work appears to support it.^[5]

Classification and relationships

Camptostroma roddyi fossil on display at the Smithsonian's National Museum of Natural History.

While initially considered to be a scyphozoan due to the fossil's medusoid shape, later investigation detected the presence of stereom plates with the calcitic cleavage pattern diagnostic of echinoderms.^[2]

The Treatise on Invertebrate Paleontology accepted Durham's 1966 assignment of Camptostroma to its own class, Camptostromatoidea.^[6] However, a later revision of the Treatise's classification omitted this class.^[7]

Camptostroma has since been placed in a class of basal echinoderms, the Edrioasteroids,^[8] although some recent authors only describe it as "edrioasteroid-like".^[5]

Recent research has found weak support for the recovery of Camptostroma as the sister group of the crinoids.^[9][10] However, other phylogenies are ambiguous regarding whether it is closer to the crinoids, eocrinoids, or eleutherozoans.^[11]