Two new Carboniferous Asteroidea (Echinodermata) of the family Urasterellidae
Blake, Daniel B.
Two new genera and species of the Paleozoic asteroid (Echinodermata) family Urasterellidae, Anthroosasterias stibareus and Staurasterias elegans, are described from the Carboniferous of the central United States. A revised familial diagnosis is proposed. Compared with earlier Paleozoic urasterellids, the new genera differ in ambulacral and disk morphology, whereas overall form and arm abactinals are similar to corresponding expressions of earlier representatives. Because feeding tends to be generalized among extant asteroids, interpretation of life modes of ancient taxa is problematic; nevertheless, morphologic similarities between ancient urasterellids and the extant predatory Asteriidae, together with limited fossil evidence, favors similar habits, that of urasterellids surviving through much of the Paleozoic. Differences between earlier and later genera might suggest increasing predatory efficiency of urasterellids through time. Comparative morphology does not favor direct phylogenetic linkage between urasterellids and asteriids; similarities of form and any of behavior are convergent. Known later Paleozoic asteroids are diverse enough as to suggest significant representation and varied habits during that interval, although the later Paleozoic through earlier Mesozoic transition saw major taxonomic changes within asteroids. Known later Paleozoic asteroids are diverse enough as to suggest significant representation and varied habits during that interval, although the later Paleozoic through earlier Mesozoic transition saw major taxonomic changes within asteroids.
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