Ammodiscus pennyi Cushman & Jarvis, 1928

Fig. 17. Paratype specimen of A. pennyi, from Cushman & Jarvis (1928)

ORIGINAL DESIGNATION: Ammodiscus pennyi Cushman & Jarvis, 1928.

TYPE REFERENCE: Cushman, J.A., & Jarvis, P.W., 1928. Cretaceous foraminifera from Trinidad. Contributions from the Cushman Laboratory for Foraminiferal Research, 4, p. 87, pl. 12, figs 4-5.

TYPE SPECIMEN: Paratypes are housed in the Cushman Collection, U.S. Natural History Museum, Smithsonian Institution. The specimen figured by Cushman & Jarvis in pl. 12, fig. 4 and another unfigured specimen are in Slide CC 9670. There is no holotype slide in the Cushman Collection. Many additional metatype specimens are also preserved in the collection.

TYPE LEVEL: Late Paleocene, Lizard Springs Formation.

TYPE LOCALITY: Pit at Lizard Springs, Trinidad.

DIAGNOSTIC FEATURES: Test free, robust, discoidal, comprised of a thick evolute planispiral coil of up to six whorls, without a coil suture. Megalospheric forms have about four whorls, microspheric forms have around six whorls. The diameter of the coiled chamber increases in size slowly, and the test maintains a relatively constant thickness. The wall is thick, and made up of coarse agglutinated particles. Some specimens display irregular coiling in the last one or two whorls.

SIZE: Larger than other ammodiscids.

SYNONYMS: None verified.

OBSERVED OCCURRENCES: Ammodiscus pennyi was first described by Cushman & Jarvis (1928) from the Upper Paleocene of the lower Lizard Springs Formation of Trinidad. Dylążanka (1923) reported it as A. latus from the Upper Cretaceous Inoceramus beds of the Magura Unit of the Polish Carpathians. Cushman (1947) subsequently reported A. pennyi from the Santa Anita Fm. (Colon Shale) of Venezuela and from the Velasco Shale of Mexico. Beckmann (1994) listed it from the Lower Maastrichtian to Lower Eocene of Trinidad. Hanzlíková (1972) illustrated a similar variety as Ammodiscus sp. from the Campanian to Maastrichtian Frydek Formation of Moravia. Ammodiscus pennyi was also reported by Huss (1966) from Campanian marls of the Subsilesian Unit of the Polish Carpathians, and was illustrated by Webb (1975) from the Paleocene of DSDP Site 283 in the Tasman Sea. Krasheninnikov & Pflaumann illustrated a similar specimen (as Ammodiscus cretaceous rugosus) from the Upper Cretaceous of DSDP Site 367 in the Eastern North Atlantic. Milner (1997) illustrated specimens from the Paleocene Moogli Mudstone of Papua New Guinea.
We observed Ammodiscus pennyi from Danian flysch sediments outcropping in Zumaya, Spain, from the upper Campanian to Maastrichtian (C. gigantea Zone) of DSDP Sites 137, 141, and 368 in the Eastern Atlantic, in the Maastrichtian flysch sediments of the Moroccan Rif, and in the Upper Campanian to Lower Maastrichtian of the Bottacione section in Italy.

KNOWN STRATIGRAPHIC RANGE: Campanian to Paleocene.

BATHYMETRY: Bathyal to Abyssal.

REMARKS: This species is similar to Ammodiscus latus in size and thickness of the wall, but differs in having a coiled chamber which increases in size somewhat more rapidly, and in lacking a depressed umbilicus as well as the tendency to uncoil. In the type specimens of Ammodiscus pennyi the proloculus may protrude from the plane of coiling and is often broken open. Specimens from the Upper Cretaceous of Poland and from Atlantic DSDP sites are smaller than the type specimens and display more irregular coiling.
Beckmann (1994) noted that the morphology of A. pennyi varies with respect to both size and the regularity of coiling. He illustrated a large, slightly irregular specimen from the Maastrichtian of Trinidad as "Ammodiscus pennyi type A", and a smaller, more regularly coiled specimen from the Paleocene as "Ammodiscus pennyi type B". A species that resembles A. pennyi in the coarse nature of the wall was described as "Glomospira sp. 5" from the Paleocene of the Moroccan Rif by Kaminski et al., (1996; pl. 1, figs. 5-8). This form differs in its more irregular outline and mode of coiling, which varies from planispiral to distinctly glomospiral at different stages during its ontogeny.

ILLUSTRATIONS: Plate 17 - Ammodiscus pennyi Cushman & Jarvis
Fig. 1-2. Upper Paleocene, Lizard Springs Formation, Trinidad, Ravine Ampelu, Trinidad (Topotypes); Fig. 3-4. Paleocene, Lizard Springs Formation, Trinidad, Well G-287, 3248'; Fig. 5. Paleocene, Lizard Springs Formation, Well G-287, 3248'; Fig. 6. Paleocene, Rif-Betic flysch, Morocco.