Spongilla purbeckensis Young, 1878

Pronzato, Roberto, Pisera, Andrzej & Manconi, Renata, 2017, Fossil freshwater sponges: Taxonomy, geographic distribution, and critical review, Acta Palaeontologica Polonica 62 (3), pp. 467-495 : 477

Spongilla purbeckensis Young, 1878

Fig. 12 .

Type horizon: Purbeck Limestone , Lower Cretaceous .

Type locality: Stare Cove , Dorset, England .

Refrences: Young 1878; Hinde 1883; Waldschmidt and Leroy 1944; Greensmith 1978; Clements 1967.

Description (emended from Young 1878 and Hinde 1883).— Oxeas (megascleres) abundant, fusiform, acerate, slightly curved, thickest in the centre (ca. 450 × 15–25.5 μm, Hinde 1883) and gradually diminishing to the tips. On the contrary, oxeas are minutely tubercled ( Young 1878).

Remarks. — Clements (1967) considered that the supposed sponge spicules of this species are not fossils at all but are actually silica pseudomorphs after lenticular crystals of gypsum. So, this species should be considered with caution. Attribution of this material to any Recent genera seems precarious due to its age. On the other hand, if we accept its sponge origin, the very few diagnostic characters (megascleres of similar type occur in several genera and families) allow only the attribution to the order Spongillida .

Figures

Fig. 12. Spongilla purbeckensis Young, 1878, Spongillida: Spongillidae; Purbeck Limestone, Lower Cretaceous, Stare Cove, Dorset, England.A. Spicules in the spiculite as illustrated by Hinde (1883). B. Spiny oxeas in the drawing of Young (1878). Originally not to scale; it may be inferred from the text that spicules are 450 μm long.