Revision of the unusual Carboniferous ophiuroid Cholaster (Echinodermata) and remarks on skeletal differentiation within the Asterozoa

Newly discovered, relatively well-preserved specimens of Cholaster whitei n. sp. (Ophiuroidea, Echinodermata) are described from a small area of extensive outcrop of the Bangor Limestone (Mississippian, Chesterian) exposed on the edge of Cedar Creek Reservoir in northern Alabama, USA. The only other...

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Bibliographic Details
Published in:Journal of paleontology 2019-07, Vol.93 (4), p.753-763
Main Authors: Blake, Daniel B, Nestell, Merlynd K
Format: Article
Language:English
Subjects:
Alabama
Asterozoa
Bangor Limestone
Carboniferous
Cedar Creek Reservoir
Chesterian
Cholaster whitei
Delicaster
Echinodermata
Franklin County Alabama
invertebrate
Mississippian
morphology
new taxa
Ophiuridae
Ophiuroidea
Paleontology
Paleozoic
revision
Stelleroidea
taxonomy
United States
Upper Mississippian
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Description
Summary:Newly discovered, relatively well-preserved specimens of Cholaster whitei n. sp. (Ophiuroidea, Echinodermata) are described from a small area of extensive outcrop of the Bangor Limestone (Mississippian, Chesterian) exposed on the edge of Cedar Creek Reservoir in northern Alabama, USA. The only other known species of the genus, C. peculiaris Worthen and Miller, is based on a single specimen exposed in dorsal aspect and collected from strata of similar age from southwestern Illinois. Incomplete preservation of the single C. peculiaris specimen limits comparisons, but differences between the two occurrences support separation at the species level. Skeletal remains of both asteroids and ophiuroids are first recognized from Early Ordovician sediments, and representatives of the two classes have retained plesiomorphies or converged morphologically since that time, thereby suggesting important evolutionary potentials and limitations. Cholaster is asteroid-like and unusual among ophiuroids in that the arms are comparatively broad and strap-like, and lateral ossicles are similar to asteroid adambulacrals and marginals, whereas the “vertebrae” (i.e., fused axial pair) and oral frame configurations of C. whitei n. sp. are typical of the Ophiuroidea. The oral frame of C. peculiaris is unknown. A poorly preserved specimen of the asteroid Delicaster? also was recovered from nearby strata associated with the C. whitei n. sp.
ISSN:0022-3360
1937-2337
DOI:10.1017/jpa.2018.109