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Lophocyrtis tanythorax (Sanfilippo and Riedel, 1970)

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Cyclampterium ? tanythorax Sanfilippo and Riedel. n. sp.
Plate 2. figures 13 - 14


Description: Shell robust, subspherical to subellipsoidal in general form. Cephalis subspherical. poreless or with a few small pores, commonly with a short apical horn. Collar stricture pronounced. Thorax inflated, thickwalled, with rather regular circular pores increasing in size away from the collar stricture, and a thorny surface. Abdomen thick-walled, with subcircular pores less regular than those of the thorax, always closed distally. ranging in form from a slightly convex cap to inflated, more than hemispherical. There are no feet, but in some specimens a few short, irregularly scattered subterminal spines.


Measurements: Based on 15 specimens from cores CHUB 24; DODO 39P. 184 - 186 cm., 214 -216 cm. and 323 - 325 cm. Total length 290 - 380 Ám. Length of thorax 185 - 235 Ám, its maximum breadth 240-290 Ám.


Remarks: This species is distinguished from C. ? leptetrum by the greater dimensions of the thorax, thorny rather than nodose surface of the thorax, and more regular lattice-work of the abdomen, which is closed in all specimens in which it is preserved. The thorax is not
compressed as it is in C. ? brachythorax. It is practically impossible to distinguish between this species and C. ? brachythorax unless specimens can be viewed perpendicularly to the axis of the shell. In the cases of some of the samples examined, insufficient material was available to permit making special preparations to orient the specimens, and this accounts for the doubtful occurrences of these two species indicated in the tables. The specific name is derived from the Greek tany=long. and thorax.
Sanfilippo and Riedel 1970
Lophocyrtis ( Cyclampterium ) tanythorax (Plate IV, 7-10)


Remarks: Lophocyrtis ( Cyclampterium ) tanythorax has an inflated, thick-walled thorax. In some specimens the thickened wall is tuberose proximally (Plate IV, 7). The closed abdomen ranges from a small cap to inflated, more than hemispherical (Plate IV, 7-9). The abdominal pores vary in size from small, irregularly arranged, up to four times as large as the thoracic pores. Irregularly scattered subterminal spines are present in some specimens (Plate IV, 8).


New observations on 30 specimens from DSDP Site 77B Cores 23-26; Site 217 Core 4; Site 289 Cores 43-54 and Site 315A Core 5 have made it easier to distinguish this species from its ancestor and descendant. A short apical horn or a thickened cap is commonly present. Total length (excluding horn and subterminal spines) 290-380 Ám, length of thorax 185-235 Ám, of abdomen 60-245 Ám. Maximum width of thorax 235-315 Ám, of abdomen 170-345 Ám. Number of pores around the maximum circumference of thorax 44-54 Ám, of abdomen 24-30 Ám. L. (C.) tanythorax occurs in moderate abundance from its evolutionary origin near the middle of the Calocycletta costata Zone to its transition into L. (C.) brachythorax near the boundary between the Dorcadospyris alata and Diartus petterssoni Zones, early to middle Miocene.
Sanfilippo 1990


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