Ophiogaleus, Thuy, 2013

Thuy, Ben, 2013, Temporary expansion to shelf depths rather than an onshore-offshore trend: the shallow-water rise and demise of the modern deep-sea brittle star family Ophiacanthidae (Echinodermata: Ophiuroidea), European Journal of Taxonomy 48, pp. 1-242 : 118-119

Ophiogaleus sp.

Fig. 21 : 2

Material examined

GZG.INV.78632 and GZG.INV.78633 (2 dissociated LAPs) from the lower Kimmeridgian Lacunosa Marls of Geisingen, Germany; GZG.INV.78634 (3 dissociated LAPs) from the upper Oxfordian Bimammatum Zone of the Plettenberg, Germany.

Description

Small, fragmentary proximal to distal LAPs; edges poorly preserved, outline and presence of spurs cannot be assessed; outer surface with moderately finely meshed stereom. Five (distal LAPs) to at least seven (proximal LAPs) large, ear-shaped spine articulations freestanding on strongly elevated distal portion of LAP; dorsal and ventral lobes merged into continuous volute; spine articulations proximally sharply delimited by very narrow, weakly prominent dorsally very slightly undulose ridge; gap between spine articulations and distal edge of LAP narrower than one spine articulation; very weak dorsalward increase in size of spine articulations; row of spine articulations strongly protruding ventralwards.

Inner side of LAPs with large, conspicuous, sharply defined, prominent ridge composed of narrow ventral part and strongly widened, vertically elongate, triangular dorsal part with pointed dorsal and ventro-proximal angles; very short ventro-proximalward extension of ventralpart of ridge; inner side of distal edge of LAP with up to three moderately large, weakly defined, non-prominent spurs composed of slightly more densely meshed stereom; inner side of tentacle notch relatively small. No perforations or furrow discernible.

Remarks

This material unambiguously belongs to Ophiogaleus gen. nov. Its fragmentary nature, however, precludes a detailed identification at the specific level. Closest similarities are shared with the LAPs of Ophiogaleus constrictus comb. nov. and it is more than likely that the above-described material, indeed, belongs to that species. In the absence of more complete specimens, however, this assignment remains elusive.

Figures

Fig. 21. Fossil lateral arm plates (LAPs) of ophiacanthid brittle stars in external (a) and internal (b) views and articulated arm fragment in ventral (a) and dorsal (b) views. 1. Ophiogaleus constrictus (Hess, 1966) comb. nov. from the late Oxfordian (Late Jurassic) of Savigna, France; GZG.INV.78627 distal arm fragment. 2. Ophiogaleus sp. from the early Kimmeridgian (Late Jurassic) of Geisingen, Germany; GZG.INV.78632, proximal LAP. 3-4. Ophiogaleus danicus (Rasmussen, 1952) comb. nov. from the early Maastrichtian (Late Cretaceous) of Rügen, Germany. 3. GZG.INV.78635, proximal LAP. 4. GZG. INV.78636, distal LAP. 5-6. Hanshessia sp. nov. innom. 1 from the late Sinemurian to early Pliensbachian (Early Jurassic) of the Glasenbach Gorge, Austria. 5. NHMW 2012/0137/0021, proximal LAP. 6. NHMW 2012/0137/0022, proximal LAP. 7-9. Hanshessia sp. nov. innom. 2 from the early Bathonian (Middle Jurassic) of La Pouza, France. 7. GZG.INV.78637, proximal LAP. 8. GZG.INV.78638, proximal LAP. 9. GZG.INV.78639, distal to median LAP. One common scale bar per species except for 1.