Re-evaluation of the Devonian family Helianthasteridae Gregory, 1899 (Asteroidea: Echinodermata) |
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Authors: | Daniel B Blake |
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Institution: | (1) Department of Geology, University of Illinois, 1301 W. Green Street, Urbana, IL 61801, USA |
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Abstract: | Because of their taxonomic and morphologic diversity, the asteroids of the Lower Devonian Hunsrück Slate of Germany are important
to both an understanding of the history of the class Asteroidea and to the interpretation of community evolution during the
Paleozoic. Helianthaster Roemer, 1863, a large multiarmed Hunsrück asteroid, is redescribed. The Helianthasteridae Gregory is restricted to Helianthaster and Arkonaster Kesling, 1982 (Middle Devonian, Canada); Lepidasterella Schuchert is similar to the other two genera but known specimens are of poor quality and as a result the status of the genus
is uncertain. Helianthaster is noteworthy in part because its size, multiarmed state, and presence of pedicellariae suggest certain crown-group genera,
yet aspects of the arrangement of the ambulacral column are characteristic of the Paleozoic asteroid evolutionary grade. Neither
Helianthaster nor other Hunsrück asteroids appear closely linked to the crown group; instead, functional patterns apparently re-emerged
through time, although identification of specific behavior of ancient asteroids is difficult to impossible.
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Keywords: | Echinodermata Asteroidea Hunsrück Slate Devonian Paleoecology Phylogeny |
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