Abstract
The Early Devonian Hunsrück Slate of Germany provides a unique glimpse of the composition and diversity of the marine biota of the mid-Paleozoic, but understanding long has been hindered by problematic preservation. Exemplifying both the unique nature of the Hunsrück fauna and the limitations of preservation, the three genera and three species of the family Erinaceasteridae (class Stenuroidea, subphylum Asterozoa ,) are discussed: Erinaceaster tenuispinosus Lehmann; Maxaster , new generic name for Erinaceaster giganteus Lehmann; and Bartelsaster lineatus , gen. et sp. nov. Erinaceasterids are difficult to study because thickened bodies, delicate body wall ossicles, and abundant elongate spines yield a construction readily obscured by burial and diagenesis. Diagnostic characters undergirding recognition of four classes of the subphylum Asterozoa are reviewed. An earlier interpretation of ambulacral column configuration of Maxaster giganteus offered a major departure from the accepted pattern of asterozoan ambulacral ossicular addition and growth: this interpretation is rebutted. Two aboral skeletal surfaces in erinaceasterids that served to enclose a supradorsal chamber are delineated. A comparable chamber is found in the extant asteroid family Pterasteridae, the occurrences homoplastic. Although tentative, some data support homoplastic emergence of both the calcified madreporite and the terminal ossicle within the subphylum Asterozoa .