Re-evaluation of the Palasteriscidae Gregory, 1900, and the early phylogeny of the Asteroidea (Echinodermata)

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Abstract
Foliaster transversusn. gen. and sp. (Echinodermata: Asteroidea) is assigned to the Ordovician through Devonian family Palasteriscidae; the other genera included in the family arePalasteriscusandPlatanaster. Platanasteris redescribed; both it andFoliasterare thought to have been suspension feeders that extended their arms into the water column. Ampullar basins in both were external; there are no podial pores. The strongly petaloid arm ofFoliasterwith widely separated podial basins is unique.Two competing phylogenies have been offered for the origin of stelleroids, one treating edrioasteroids as ancestral, the other favoring crinoids. In the latter hypothesis, the Palasteriscidae is the primitive asteroid family, andPlatanasteris an example of the first true asteroids. Both hypotheses are here considered to lack adequate support; stelleroid origins remain problematic.