Chrispaulia spinosa sp. nov.

urn:lsid:zoobank.org:act: 4C003A9F-1F91-44BC-91AB-2910B8EA756A

Fig. 13D–E, H–O

Diagnosis

Chrispaulia in which distal inferomarginals bear an oblique row of large, bifid spine attachment sites, which carried long, flattened spines.

Etymology

Latin for ‘bearing spines’, in reference to the row of spine attachment sites on distal inferomarginals.

Material examined

A distal arm fragment (Nds LH 105.107), comprising five marginal pairs, with articulating spines preserved, is the holotype; it is from the lower Hauterivian ( Endemoceras amblygonium ammonite Zone) at Engelbostel near Hannover (northern Germany). Paratypes (NHMUK PI EE 17998–18004) are 35 marginal ossicles and a single oral ossicle from the upper 3 metres of the Tealby Clay (Hauterivian) at Nettleton, Lincolnshire (United Kingdom).

Description

Arms elongated, narrow, tapering slowly (Fig. 13D–E); proximal superomarginals tall, block-like, bearing a single, abactinally directed, crater-like spine base. Central region of external face narrow, poorly defined, lateral surfaces broad with small rugosities for attachment of tiny cribriform spines (Fig. 13H–I, N; spines still articulated in Fig. 13D). Distal superomarginals with or without an abactinally situated, distally directed large spine base (Fig. 13I–J), rugose (Fig. 13D) or smooth (Fig. 13I–J). Distal infero- and superomarginals thin, imbricating proximally; distal inferomarginals with oblique row of large, bifid spine bases, which bore flattened, lanceolate spines (Fig. 13D). Sharply defined grooves for cribriform organs between each infero-/superomarginal pair. Oral ossicle (Fig. 13O) with broad actinal face, bearing large rugosities for attachment of sos; large elongate oradm, low, broad apophyse.

Remarks

Chrispaulia spinosa sp. nov. differs from its congeners in its possession of 3–4 bifid spine pits on distal inferomarginals.