Unusual occurrence of nautilids from the Upper Eocene La Meseta ...
Alvarez, W., L.W. Alvarez, F. Asaro, and H.V. Michel. 1984. The end of the Cretaceous: Sharp boundary or gradual transition? Science, 223, 1183-1186. Bohor, B.F., E.E. Foord, P.J. Modreski, and D.M. Triplehorn. 1984. Mineralogic evidence for an impact event at the Cretaceous-Tertiary boundary. Science, 224, 867 - 868. Ganapathy, R. 1980. A major meteorite impact on the earth 65 million years ago: Evidence from the Cretaceous-Tertiary boundary clay. Science, 209, 921 - 923. Huber, B.T., D.M. Harwood, and P.N. Webb. 1983. Upper Cretaceous microfossil biostratigraphy of Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 18(5), 72 - 74. Huber, B.T., D.M. Harwood, and P.N. Webb. 1985. Microfossil distribution data and diagenetic features of the Cretaceous/Tertiary boundary on Seymour Island (Antarctic Peninsula). (Abstract) GWATT Conference on Rare Events in Geology. (IGcP No. 199.) Zurich, Switzerland.
Unusual occurrence of nautilids from the Upper Eocene La Meseta Formation, Seymour Island W.J. ZINSMEISTER
Department of Geosciences Purdue University West Lafayette, Indiana 47907
Although fossil nautilids are normally encountered in most early Cenozoic deposits throughout the world, they are generally represented by only a few specimens at any given locality. On Seymour Island, most of the fossil localities in the La Meseta Formatiop contain the odd nautilid, except for one locality where they occur in large numbers. This unusual occurrence takes on unexpected importance because it is the same locality where the marsupial remains of Antarctodolops dailyi were discovered (Woodburne and Zinsmeister 1982, 1984). The apparent beach stranding of large numbers of nautilids at the mainal locality provides additional data to support the hypothesis hat the marsupial remains were preserved in a beach facies. The nautilid fauna from the La Meseta Formation is repreented by two genera (Eutrephoceras and Aturia) with Eurephoceras being the most frequently encountered at most loalities while specimens of Aturia are exceedingly rare. During lour seasons of intense sampling of the Upper Eocene sequence On Seymour Island in which approximately 15,000 specimens of molluscs were collected, only three specimens of Aturia have been found. At the mammal site with an exposure of approximately 15 square meters, 35 nautilid phragmocones were collected with 85 percent of the nautilids being small phragmocones of Aturia. All the phragmocones display some degree of breakage and abrasion. Based on specimens of Aturia collected prior to the discovery of the occurrence at the mammal site locality, it was believed that the size of an adult individual was approximately 50 millimeters. Of the 25 phragmocones of 1985 REVIEW
Kyte, F.T., and J . Smit. 1985. Cretaceous-Tertiary spinels: High-temperature relicts from a major accretionary event. Lunar and Planetary Science, 16(1), 473 - 474. Luck, J.M., and K.K. Turekian. 1983. Osmium-187/Osmium-186 in manganese nodules and the Cretaceous-Tertiary boundary. Science, 222, 613 - 615. Montanan, A., R.L. Hay, W. Alvarez, F. Asaro, H.V. Michel, L.W. Alvarez, and J . Smit. 1983. Spheroids at the Cretaceous-Tertiary boundary are altered impact droplets of basaltic composition. Geology, 11, 668 - 671. Zinsmeister, W.J. 1985. 1985 Seymour Island expedition. Antarctic Journal of the U. S., 20(5). Zinsmeister, W.J., and C.E. Macellari. 1983. Changes in the macrofossil faunas at the end of the Cretaceous on Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 18(5), 68 - 69.
recovered at the mammal locality, most specimens, except for one very large individual, were 50 millimeters or smaller with the smallest individual being less than 20 millimeters in diameter. Although the large phragmocone was incomplete, it was approximately 110 millimeters in diameter. It would appear, except for the single large specimen, the entire collection from the mammal locality represents juvenile individuals. During the last 10 years, a number of investigators have been studying the biology and ecology of the modern species of Nautilus from the central Pacific. As a consequence of these studies, a considerable body of knowledge exists concerning the biology and ecology of Nautilus. These data are now providing insight into the environmental significance and life habits of Late Mesozoic and Cenozoic nautilids. Saunders (1985), based on photosequence study of Nautilus belauensis on the forereef slopes in Palau, has shown that although N. belauensis has total depth range of 70 to 500 meters, the preferred depth range is about 150 to 300 meters. Based on his observations of feeding and reproductive tactics of N. belauensis, Saunders suggested that Nautilus typifies an organism well adapted to deep-water conditions. He further suggested that, contrary to current belief, modern deep-water representatives of the nautilids are Late Cretaceous shallow-water refugees that have always been adapted to deep-water conditions. The rare occurrence of nautilids in most shallow-water deposits would seem to support his hypothesis. From my own personal experience, the only time one finds more than the odd specimen of nautilid is in deep-water deposits, and even then they are not common. The unusual occurrence of large numbers of nautilids in the beach facies at the mammal locality on Seymour Island suggests that the nautilids were transported from their normal deep habitat and stranded on the beach. The breakage and abrasion of most of the phragmocones tends to support the hypothesis of a high-energy (i.e., big waves and strong current) beach environment. Whether the occurrence on Seymour Island represents a single mass stranding event or an accumulation of shells over a period of time is difficult to determine. The presence of a large number of phragmocones at one small locality suggests a single Aturia
stranding event. The only published accounts of extensive accumulations are limited to (1) Iredale (1944) who reported observing over 100 broken shells on a beach near Cape Bedford, North Queensland; (2) Hamada (1964) in which he reported collecting 47 drifted Nautilus shells from a small beach on Phe Tra Island, off the coast of Thailand; and (3) Glaessner (in Stenzel 1957) in which he reported "large numbers (perhaps up to 1/2 dozen on a suitable day along the half-mile stretch of beach in front of our house) of empty shells arriving on the south or south-facing beaches during wind season (April to September)." These accounts indicate that the shells were broken and encrusted with epifaunal invertebrates which suggests that the drifted shells accumulated over a period of time and do not represent a single stranding event. The presence of large numbers of nautilid phragmocones in an Upper Eocene beach deposit from the La Meseta Formation on Seymour Island is the first report of beach-drifted accumulations of nautilid shells in the fossil record and may also represent the report of a mass stranding event. This work was supported by National Science Foundation grant DPP 82-13985.
Palynological studies in the James Ross Island basin, Antarctic Peninsula: A progress report R.A. ASKIN Geology Department Colorado School of Mines Golden, Colorado 80401
Six informal palynological zones are recognized in the uppermost Cretaceous of southern Seymour Island and surrounding region in the James Ross Island basin, northeastern Antarctic Peninsula. These zones are, at present, based mainly on dinoflagellate cyst species. Zones 4 through 6 are defined primarily on an apparent evolutionary lineage of Isabelidinium species, therefore the zonal boundaries are somewhat transitional. Key angiosperm pollen species, although sometimes rare, permit additional resolution in the zonation. The diagnostic species, distribution, correlation, and age of these zones are noted briefly. • Zone 1 is the lowest zone recognized in this study, although older Cretaceous rocks occur in northwestern James Ross Island. Key species include the dinoflagellates Odontochitina operculata (0. Wetzel) Deflandre (last occurrence), 0. spinosa Wilson, 0. porifera Cookson, Cribroperidinium sp., cf.Canningiopsis sp., cf.Alterbia sp., and Palaeocystodinium spp. Represented by two samples of the Lopez de Bertodano Forma tion from The Naze, northeastern James Ross Island. • Zone 2 includes the same species as zone 1 except that 0. porifera is more frequent, 0. operculata is absent, and Isabelidinium cretaceum (Cookson) Lentin and Williams is present.
References
Hamada, T. 1964. Notes on drifted Nautilus in Thailand. University of Tokyo, College of General Education, Science Papers, 14, 255 - 277.
Iredale, T. 1944. Australian pearly Nautilus. Australian Zoologist, 10(3), 294-298.
Saunders, W.B. 1985. The role and status of Nautilus in its natural habitat: Evidence from weed-water remote camera photosequences. Paleobiology, 10(4), 469 - 486.
Stenzel, H.B. 1957. Nautilus. Treatise of marine ecology and paleoecology. Geological Society of America, (Memoir 67), Vol. 1, 1135 1142.
Woodburne, MO., and W.J. Zinsmeister. 1982. Fossil land mammal from Antarctica. Science, 218, 284 - 286. Woodburne, M.0., and W.J. Zinsmeister. 1984. The first land mammal from Antarctica and its biogeographic implications. Journal of Paleontology, 58(4), 913 - 948.
Represented by Lopez de Bertodano Formation from Cape Lamb, southwestern Vega Island. • Zone 3 includes I. cretaceum, Alterbia acutula (Wilson) Lentin and Williams, the last rare specimens of Cribroperidinium sp., cf.Canningiopsis sp. and cf.Alterbia sp.; and among the pollen the first Tricolporites lilliei (Couper) Stover and Evans. Represented by Lopez de Bertodano Formation on the exposed northern part of Snow Hill Island and approximately the "lower 150 meters on Seymour Island at the southern point (also known as Cape Lamb). • Zone 4 is characterized by Isabelidinium n.sp.3 (cf.I. haumuriense of Wilson 1984-b), A. acutula, and various angiosperm pollen species. Represented by approximately 800 meters of Lopez de Bertodano Formation on Seymour Island. • Zone 5 is characterized by the Isabelidinium n. sp. 1-n.sp.2 complex, Dinogymnium digitus (Deflandre) Evitt et al.; and, among pollen, the first Liliacidites kaitangataensis Couper. Frequent Palaeocystodiniurn spp. and Exochosphaeridium bifidum (Clarke and Verdier) Clarke et al. Represented by approximately 100 meters of Lopez de Bertodano Formation on Seymour Island. • Zone 6 is a "transition zone" which spans the Cretaceous/ Tertiary boundary (Askin 1984, 1985). Characterized by the Isabelidinium druggii (Stover) Lentin and Williams-I. seelandicum (Lange) Lentin and Williams complex. Frequent Palaeocystodinium spp. and Exochosphaeridium bifidum. First occurrences of Phelodinium sp.cf.P. magnificum (Stanley) Stover and Evitt and Deflandrea sp. cf. D. med caifli Stover. Represented by approximately 40 meters of Lopez de Bertodano Formation on Seymour Island (overlain by remaining 30 to 90 meters, depending on location, of uppermost Lopez de Bertodano Formation). In terms of dinoflagellate distribution these six zones may be correlated with three dinoflagellate zones described by Wilson (1984-a) from the Piripauan and Haumurian (Campanian and ANTARCTIC JOURNAL
Unusual occurrence of nautilids from the Upper Eocene La Meseta Formation, Seymour Island W.J. ZINSMEISTER
Department of Geosciences Purdue University West Lafayette, Indiana 47907
Although fossil nautilids are normally encountered in most early Cenozoic deposits throughout the world, they are generally represented by only a few specimens at any given locality. On Seymour Island, most of the fossil localities in the La Meseta Formatiop contain the odd nautilid, except for one locality where they occur in large numbers. This unusual occurrence takes on unexpected importance because it is the same locality where the marsupial remains of Antarctodolops dailyi were discovered (Woodburne and Zinsmeister 1982, 1984). The apparent beach stranding of large numbers of nautilids at the mainal locality provides additional data to support the hypothesis hat the marsupial remains were preserved in a beach facies. The nautilid fauna from the La Meseta Formation is repreented by two genera (Eutrephoceras and Aturia) with Eurephoceras being the most frequently encountered at most loalities while specimens of Aturia are exceedingly rare. During lour seasons of intense sampling of the Upper Eocene sequence On Seymour Island in which approximately 15,000 specimens of molluscs were collected, only three specimens of Aturia have been found. At the mammal site with an exposure of approximately 15 square meters, 35 nautilid phragmocones were collected with 85 percent of the nautilids being small phragmocones of Aturia. All the phragmocones display some degree of breakage and abrasion. Based on specimens of Aturia collected prior to the discovery of the occurrence at the mammal site locality, it was believed that the size of an adult individual was approximately 50 millimeters. Of the 25 phragmocones of 1985 REVIEW
Kyte, F.T., and J . Smit. 1985. Cretaceous-Tertiary spinels: High-temperature relicts from a major accretionary event. Lunar and Planetary Science, 16(1), 473 - 474. Luck, J.M., and K.K. Turekian. 1983. Osmium-187/Osmium-186 in manganese nodules and the Cretaceous-Tertiary boundary. Science, 222, 613 - 615. Montanan, A., R.L. Hay, W. Alvarez, F. Asaro, H.V. Michel, L.W. Alvarez, and J . Smit. 1983. Spheroids at the Cretaceous-Tertiary boundary are altered impact droplets of basaltic composition. Geology, 11, 668 - 671. Zinsmeister, W.J. 1985. 1985 Seymour Island expedition. Antarctic Journal of the U. S., 20(5). Zinsmeister, W.J., and C.E. Macellari. 1983. Changes in the macrofossil faunas at the end of the Cretaceous on Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 18(5), 68 - 69.
recovered at the mammal locality, most specimens, except for one very large individual, were 50 millimeters or smaller with the smallest individual being less than 20 millimeters in diameter. Although the large phragmocone was incomplete, it was approximately 110 millimeters in diameter. It would appear, except for the single large specimen, the entire collection from the mammal locality represents juvenile individuals. During the last 10 years, a number of investigators have been studying the biology and ecology of the modern species of Nautilus from the central Pacific. As a consequence of these studies, a considerable body of knowledge exists concerning the biology and ecology of Nautilus. These data are now providing insight into the environmental significance and life habits of Late Mesozoic and Cenozoic nautilids. Saunders (1985), based on photosequence study of Nautilus belauensis on the forereef slopes in Palau, has shown that although N. belauensis has total depth range of 70 to 500 meters, the preferred depth range is about 150 to 300 meters. Based on his observations of feeding and reproductive tactics of N. belauensis, Saunders suggested that Nautilus typifies an organism well adapted to deep-water conditions. He further suggested that, contrary to current belief, modern deep-water representatives of the nautilids are Late Cretaceous shallow-water refugees that have always been adapted to deep-water conditions. The rare occurrence of nautilids in most shallow-water deposits would seem to support his hypothesis. From my own personal experience, the only time one finds more than the odd specimen of nautilid is in deep-water deposits, and even then they are not common. The unusual occurrence of large numbers of nautilids in the beach facies at the mammal locality on Seymour Island suggests that the nautilids were transported from their normal deep habitat and stranded on the beach. The breakage and abrasion of most of the phragmocones tends to support the hypothesis of a high-energy (i.e., big waves and strong current) beach environment. Whether the occurrence on Seymour Island represents a single mass stranding event or an accumulation of shells over a period of time is difficult to determine. The presence of a large number of phragmocones at one small locality suggests a single Aturia
stranding event. The only published accounts of extensive accumulations are limited to (1) Iredale (1944) who reported observing over 100 broken shells on a beach near Cape Bedford, North Queensland; (2) Hamada (1964) in which he reported collecting 47 drifted Nautilus shells from a small beach on Phe Tra Island, off the coast of Thailand; and (3) Glaessner (in Stenzel 1957) in which he reported "large numbers (perhaps up to 1/2 dozen on a suitable day along the half-mile stretch of beach in front of our house) of empty shells arriving on the south or south-facing beaches during wind season (April to September)." These accounts indicate that the shells were broken and encrusted with epifaunal invertebrates which suggests that the drifted shells accumulated over a period of time and do not represent a single stranding event. The presence of large numbers of nautilid phragmocones in an Upper Eocene beach deposit from the La Meseta Formation on Seymour Island is the first report of beach-drifted accumulations of nautilid shells in the fossil record and may also represent the report of a mass stranding event. This work was supported by National Science Foundation grant DPP 82-13985.
Palynological studies in the James Ross Island basin, Antarctic Peninsula: A progress report R.A. ASKIN Geology Department Colorado School of Mines Golden, Colorado 80401
Six informal palynological zones are recognized in the uppermost Cretaceous of southern Seymour Island and surrounding region in the James Ross Island basin, northeastern Antarctic Peninsula. These zones are, at present, based mainly on dinoflagellate cyst species. Zones 4 through 6 are defined primarily on an apparent evolutionary lineage of Isabelidinium species, therefore the zonal boundaries are somewhat transitional. Key angiosperm pollen species, although sometimes rare, permit additional resolution in the zonation. The diagnostic species, distribution, correlation, and age of these zones are noted briefly. • Zone 1 is the lowest zone recognized in this study, although older Cretaceous rocks occur in northwestern James Ross Island. Key species include the dinoflagellates Odontochitina operculata (0. Wetzel) Deflandre (last occurrence), 0. spinosa Wilson, 0. porifera Cookson, Cribroperidinium sp., cf.Canningiopsis sp., cf.Alterbia sp., and Palaeocystodinium spp. Represented by two samples of the Lopez de Bertodano Forma tion from The Naze, northeastern James Ross Island. • Zone 2 includes the same species as zone 1 except that 0. porifera is more frequent, 0. operculata is absent, and Isabelidinium cretaceum (Cookson) Lentin and Williams is present.
References
Hamada, T. 1964. Notes on drifted Nautilus in Thailand. University of Tokyo, College of General Education, Science Papers, 14, 255 - 277.
Iredale, T. 1944. Australian pearly Nautilus. Australian Zoologist, 10(3), 294-298.
Saunders, W.B. 1985. The role and status of Nautilus in its natural habitat: Evidence from weed-water remote camera photosequences. Paleobiology, 10(4), 469 - 486.
Stenzel, H.B. 1957. Nautilus. Treatise of marine ecology and paleoecology. Geological Society of America, (Memoir 67), Vol. 1, 1135 1142.
Woodburne, MO., and W.J. Zinsmeister. 1982. Fossil land mammal from Antarctica. Science, 218, 284 - 286. Woodburne, M.0., and W.J. Zinsmeister. 1984. The first land mammal from Antarctica and its biogeographic implications. Journal of Paleontology, 58(4), 913 - 948.
Represented by Lopez de Bertodano Formation from Cape Lamb, southwestern Vega Island. • Zone 3 includes I. cretaceum, Alterbia acutula (Wilson) Lentin and Williams, the last rare specimens of Cribroperidinium sp., cf.Canningiopsis sp. and cf.Alterbia sp.; and among the pollen the first Tricolporites lilliei (Couper) Stover and Evans. Represented by Lopez de Bertodano Formation on the exposed northern part of Snow Hill Island and approximately the "lower 150 meters on Seymour Island at the southern point (also known as Cape Lamb). • Zone 4 is characterized by Isabelidinium n.sp.3 (cf.I. haumuriense of Wilson 1984-b), A. acutula, and various angiosperm pollen species. Represented by approximately 800 meters of Lopez de Bertodano Formation on Seymour Island. • Zone 5 is characterized by the Isabelidinium n. sp. 1-n.sp.2 complex, Dinogymnium digitus (Deflandre) Evitt et al.; and, among pollen, the first Liliacidites kaitangataensis Couper. Frequent Palaeocystodiniurn spp. and Exochosphaeridium bifidum (Clarke and Verdier) Clarke et al. Represented by approximately 100 meters of Lopez de Bertodano Formation on Seymour Island. • Zone 6 is a "transition zone" which spans the Cretaceous/ Tertiary boundary (Askin 1984, 1985). Characterized by the Isabelidinium druggii (Stover) Lentin and Williams-I. seelandicum (Lange) Lentin and Williams complex. Frequent Palaeocystodinium spp. and Exochosphaeridium bifidum. First occurrences of Phelodinium sp.cf.P. magnificum (Stanley) Stover and Evitt and Deflandrea sp. cf. D. med caifli Stover. Represented by approximately 40 meters of Lopez de Bertodano Formation on Seymour Island (overlain by remaining 30 to 90 meters, depending on location, of uppermost Lopez de Bertodano Formation). In terms of dinoflagellate distribution these six zones may be correlated with three dinoflagellate zones described by Wilson (1984-a) from the Piripauan and Haumurian (Campanian and ANTARCTIC JOURNAL
