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Spiniferites nux
Plate 25, Figures 13-15, 17, 18
Holotype: Plate 25, Figures 13, 14.
Type Locality: Speeton Clay Formation, Bed C7C, early Hauterivian, inversum ammonite Zone. Holotype: Slide Lr.C7C(4), E.F. L38.4
Derivation of Name: From the Latin nux, a nut - in reference to the ovoidal shape and thick endophragm of this species.
Diagnosis: A species with a thick-walled, ovoidal, microreticulate endocyst and a closely attached, smooth pericyst. The periphragm forms short, evenly-spaced, distally rounded to rarely capitate denticles, proximally connected by crests of varying height. A ventral pericoel is invariably present, associated with a prominent claustrum. A cingulum with zig-zag margins is clearly seen, and a low, apical prominence is present. The archeopyle is single plate precingular (3").
Dimensions: Holotype: 61 × 61 μm
All measured specimens: Overall 68 (61) 58 μm × 61 (60) 56 μm.
Specimens Measured: 7.
Remarks: The main characteristic feature of this species is its short, evenly-spaced crestal denticles, which do not furcate and which often resemble the cogs of a gear wheel. Crestal height varies and can be particularly low where associated with the ventral pericoel; in this case, denticles are shorter and more numerous but still evenly spaced.
This species has a very short range at Speeton, occurring only between Beds C7G and C7C (early Hauterivian, inversum ammonite Zone), although rare occurrences offshore appear to range slightly older.
Holotype: Plate 25, Figures 13, 14.
Type Locality: Speeton Clay Formation, Bed C7C, early Hauterivian, inversum ammonite Zone. Holotype: Slide Lr.C7C(4), E.F. L38.4
Derivation of Name: From the Latin nux, a nut - in reference to the ovoidal shape and thick endophragm of this species.
Diagnosis: A species with a thick-walled, ovoidal, microreticulate endocyst and a closely attached, smooth pericyst. The periphragm forms short, evenly-spaced, distally rounded to rarely capitate denticles, proximally connected by crests of varying height. A ventral pericoel is invariably present, associated with a prominent claustrum. A cingulum with zig-zag margins is clearly seen, and a low, apical prominence is present. The archeopyle is single plate precingular (3").
Dimensions: Holotype: 61 × 61 μm
All measured specimens: Overall 68 (61) 58 μm × 61 (60) 56 μm.
Specimens Measured: 7.
Remarks: The main characteristic feature of this species is its short, evenly-spaced crestal denticles, which do not furcate and which often resemble the cogs of a gear wheel. Crestal height varies and can be particularly low where associated with the ventral pericoel; in this case, denticles are shorter and more numerous but still evenly spaced.
This species has a very short range at Speeton, occurring only between Beds C7G and C7C (early Hauterivian, inversum ammonite Zone), although rare occurrences offshore appear to range slightly older.