The fossil record of the asteroid (Echinodermata) family Chaetasteridae Sladen 1889 and subfamily Hyalothricinae Fisher, 1911 Author Gale, Andrew S. School of the Environment, Geography and Geological Sciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth PO 13 QL U. K. & Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW 75 BD U. K. text Zootaxa 2020 2020-09-29 4858 1 144 150 journal article 10.11646/zootaxa.4858.1.11 1175-5326 4411478 93DB37F6-2564-4E3A-AA25-4A842994BE68 Chaetasterina gracilis Hess, 1970 Figure 2 C–I 1970 Chaetasterina Hess : p. 1082, figs 9–14, pl. 3: fig. 5. Diagnosis. As for genus. Type. The unique holotype is from the Upper Hauterivian of Neuchâtel , Switzerland ( NMB Hess A 94) . Remarks. The sole specimen is small (R approximately 12 mm ) and probably juvenile, but well-preserved, and parts of the specimen are covered in tiny, dense spines, similar to those on Hyalinothrix . The abactinal ossicles ( Fig. 2C ) of the arm are arranged in transverse rows diverging from mid-radius, very different from situation in Chaetaster in which the abactinals form well-defined columns extending from the disc to the arm tip ( Fig. 1F ). The abactinals of C. gracilis ( Fig. 2 E-I) are small and paxillose, with flanged, imbricating bases, like those in Hyalinothrix ( Fig. 2M ) and unlike the robust, block-like ossicles of Chaetaster ( Fig. 1D, F ). The inferomarginals of C. gracilis ( Fig. 2H, I ) are small and similar to those of Hyalinothrix ( Fig. 2I ). The body shape of C. gracilis , with short, straplike arms ( Fig. 2C, D ) and broad disc, is unlike those of Hyalothrix specimens, which have long, cylindrical arms and a small disc. However, the unique specimen of C. gracilis is probably a juvenile, and many asteroid juveniles have proportionately short arms.