Fossil lobsters from Seymour Island, Antarctica
Fossil lobsters from Seymour Island, Antarctica
RODNEY
M. FELDMANN
Department of Geology Kent State University Kent, Ohio 44242
Examination of the decapod crustacean fauna of Seymour Island, Antarctic Peninsula, has been in progress during the past 4 years. During the field season of 1983-1984, several specimens of fossil lobsters were collected from the Late Cretaceous Lopez de Bertodano Formation. Examination of these organisms has resulted in the refinement of the description of Hoploparia stokesi Weller, a species previously described from sites on James Ross Island (Ball 1960) and noted on Seymour Island (del Valle and Rinaldi 1975). Additionally, a single lobster specimen was collected and referred to Linuparus, a genus previously reported from the Southern Hemisphere at a single site in Africa (Tshudy and Feldmann in press). As a result of these preliminary investigations, it was recognized that there was a strong potential for further enhancement of our understanding of decapods in the Antarctic. Therefore, during the 1986-1987 field season, extensive collections of fossil decapods were made. More than 440 specimens were collected from sites on Seymour Island and adjacent James Ross, Vega, Humps, Cockburn, and Snow Hill islands (figure 1). Comments regarding the significance of specimens collected from the adjacent islands are premature, except to note that decapods previously have not been reported from Vega, Humps, Cockburn, or Snow Hill islands. However, several general conclusions can be drawn based upon specimens collected from Seymour Island. Whereas brachyuran decapods—crabs--have been noted to be abundant and diverse in the Eocene La Meseta Formation of Seymour Island (Feldmann and Zinsmeister 1984; Feldmann 1985), none has been collected in the subjacent units. Instead, the decapod fauna in the Cretaceous and Paleocene rocks consists entirely of macrurans—lobsters. Decapod crustaceans are generally common throughout the upper units, units 7 through 10, of the Lopez de Bertodano Formation. These units are known as the molluscan units (Macellari 1986). Invariably, the specimens are found in concretions. Diversity and numerical abundance of lobsters seems to increase upward in the section. At the lowermost localities, in unit 7, Hoploparia stokesi (figure 2) is the only species represented. Above that, however, Linuparus n. sp. and a second new species, possibly referable to the genus Metanephrops, occur in association with H. stokesi. The rocks of the Lopez de Bertodano Formation range in age from Campanian to Paleocene (Macellari 1986). The boundary between the Cretaceous and Tertiary occurs within unit 10, the uppermost unit of the formation, and has been considered to occur within a sequence containing several glauconite beds (Macellari 1986). Nearly 100 fossil lobsters have been collected 1987 REVIEW
from 20 sites spanning this boundary, thus providing an excellent opportunity to examine the effects of the presumed Cretaceous/Tertiary (K/T) boundary event. Furthermore, numerous lobsters were collected for the first time from the overlying, Paleocene age, Sobral Formation. Although final analysis of the specimens has not been undertaken, preliminary field observations suggest that the decapods did not experience a major extinction at this time. Instead, the new species, tentatively referred to Mefanephrops, appears near the base of unit 10, in association with a diverse assemblage of ammonite cephalopods, and continues into the Sobral Formation. Hoploparia stokesi has also been identified above, as well as below, the KIT boundary. During the examination of decapods from the Lopez de Bertodano Formation, it was noted that different regions of lobster skeletons were selectively preserved (Feldmann and Tshudy 1987). Approximately 45 percent of the specimens, collected in 1983-1984, were anatomically incomplete; invariably the abdominal region was absent. Feldmann and Tshudy (1987) speculated that selective scavenging by cephalopods may have been responsible for this phenomenon. These results will be retested by detailed examination of the large sample of fossil lobsters collected during 1986-1987; however, preliminary results seem to suggest that the same general relationships will be observed. Thus, the collection of numerous macrurous decapod crustaceans from sites within the James Ross Basin has extended the geographic range of decapods throughout the basin and has extended their stratigraphic range into the Paleocene as well. Diversity of decapods seems to increase near the K/T boundary. Taxa occurring in uppermost Cretaceous rocks also occur in overlying Paleocene rocks. The lobsters appear to be unaffected by the presumed K/i boundary event. Although processes of selective predation and scavenging seem to affect the preservation potential of different anatomical parts of lobsters, preserved on Seymour Island, the area stands as one in which decapods are unusually abundant. The field work for this study was supported by a National Science Foundation grant to William J. Zinsmeister and laboratory work was supported by National Science Foundation grant DPP 84-11842 to Feldmann. (This article is Contribution 358, Department of Geology, Kent State University, Kent, Ohio 44242.)
References Ball, H.W. 1960. Upper Cretaceous Decapoda and Serpulidae from James Ross Island, Graham Land. Falkland Islands Dependencies Survey Scientific Reports, 24,1-30. del Valle, R., and C.A. Rinaldi. 1975. Sobre la presencia de Hoploparia stokes, (Weller) en las "Snow Hill Island Series," de la Isla Vice-
comodoro Marambio, Antartida. (Contribucion del Instituto Antartico Argentino, Contribucion No. 190.) Feldmann, R.M. 1985. Decapod crustaceans from the Late Cretaceous and the Eocene of Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 19(5),4-5. Feldmann, R.M., and D. Tshudy. 1987. Ultrastructure in cuticle from Hoploparia stokesi (Decapoda: Nephropidae) from the Lopez de Bertodano Formation (Late Cretaceous-Paleocene) of Seymour Island, Antarctica. Journal of Paleontology, 61(6);1194-1203. 11
Surf icial Deposits ;en Telm&7 fe LA MESETA 1dm 1r5 FORMATION 1dm 3 (EOCENE)
::.:.:..
Tel 1-2
Tpcv 1-5 CROSS VALLEY FORMATION Tps 4 • E PALEOCENE) 13 AL FORMATION ______ rpss 3 l-2 ALEOCENE)
LOPEZ DE BE RIO 0 AND FORMATION ETACEoue-. lLEOCENE) M. Cs
• DECAPOD SITE
Figure 1. Location maps showing the position of sites from which macrurous decapod crustaceans have been collected in the Lopez de Bertodano and Sobral formations. The geological map and stratigraphic section are adapted from Sadler (in press) and are reproduced with his permission. ("KIT" denotes "Cretaceous/Tertiary.") 12
ANTARCTIC JOURNAL
Feldmann, R.M., and W.J. Zinsmeister. 1984. Fossil crabs (Decapoda: Brachyura) from the La Meseta Formation (Eocene) of Antarctica: Paleoecological and biogeographic implications. Journal of Paleontology, 58(4), 1046-1061. Macellari, C.E. 1986. Late Campanian-Maastrichtian ammonite fauna from Seymour Island (Antarctic Peninsula). Journal of Paleontology, Vol. 60, (The Paleontological Society Memoir 18, Part 2.) Sadler, P.M. In press. Geometry and stratification of Paleogene and latest Cretaceous units on Seymour Island, northern Antarctic Peninsula. In R.M. Feldmann and M.O. Woodburne, (Eds.), Geology and paleontology of Seymour island, Antarctica. (Geological Society of America Memoir 169.) Tshudy, D., and R.M. Feldmann. In press. Macrurous decapod crustaceans, and their epibionts, from the Lopez de Bertodano Formation (Late Cretaceous), Seymour Island, Antarctica. In R.M. Feldmann and M . O. Woodburne, (Eds.), Geology and paleontology of Seymour Island, Antarctica. (Geological Society of America Memoir 169.)
-j
Figure 2. Hoploparia stokesi Weller. Latex cast of a specimen from the Lopez de Bertodano Formation, preserved as a molted, but complete, carapace and abdomen. (Bar scale equals 1 centimeter.)
Palynological investigations of the James Ross Island basin, Antarctica ROSEMARY
A. ASKIN
Department of Earth Sciences University of California Riverside, California 92521
During December 1986 and January 1987, additional sampling of Campanian to Eocene sediments was carried out for palynological study in the James Ross Island basin (figure), northeastern Antarctic Peninsula. The 300 samples collected are mainly from Seymour Island and cover certain intervals of interest in more detail than was previously available. Data from these samples will refine and extend the palynomorph zonation proposed for the upper Campanian to Paleocene part of the succession (Askin in press). Parts of the upper Lopez de Bertodano Formation, including the glauconitic interval that spans the Cretaceous/Tertiary boundary, and parts of the Eocene La Meseta Formation were sampled. Short helicopter-supported visits also were made to three nearby islands to collect from ?Campanian sections. The three sampled localities are Cockburn Island, Humps Island, and Ula Point on eastern James Ross Island (figure). Fossil palynomorphs are ubiquitous in the Seymour and nearby island sedimentary succession and occur, often abundantly, in all 935 samples processed to date. It is expected that the newly collected samples also will be productive, bringing the samples available for this study to a total of over 1,200. The present phase of this project includes taxonomic description of nonmarine (spores, pollen) and marine (dinoflagellate 1987 REVIEW
cysts, acritarchs) palynomorphs and documentation of their distribution patterns. The dinocyst assemblages have proved particularly useful for biostratigraphy (Askin in press), and the land plant-derived spores and pollen should add useful information on climatic evolution of the area. Unlike terrestrial sediments, which can contain palynomorphs of relatively local derivation, the mainly nearshore marine sediments of Seymour Island contain spores and pollen transported from a wide range of terrestrial habitats and microclimates. Thus these as-
Vega Island
(J c::;
AAfarctica
Naze
640
Island
9
5 10 15 20
VUIO Point
I)
I James Ross Island
(
Km
Cockburn
Island
Hamilton
Seymour Island EPateogene sediments []
Cretaceous sediments
Snow Hill
Island
Locality map for the James Ross Island basin. ("Km" denotes "kilometer?")
13
RODNEY
M. FELDMANN
Department of Geology Kent State University Kent, Ohio 44242
Examination of the decapod crustacean fauna of Seymour Island, Antarctic Peninsula, has been in progress during the past 4 years. During the field season of 1983-1984, several specimens of fossil lobsters were collected from the Late Cretaceous Lopez de Bertodano Formation. Examination of these organisms has resulted in the refinement of the description of Hoploparia stokesi Weller, a species previously described from sites on James Ross Island (Ball 1960) and noted on Seymour Island (del Valle and Rinaldi 1975). Additionally, a single lobster specimen was collected and referred to Linuparus, a genus previously reported from the Southern Hemisphere at a single site in Africa (Tshudy and Feldmann in press). As a result of these preliminary investigations, it was recognized that there was a strong potential for further enhancement of our understanding of decapods in the Antarctic. Therefore, during the 1986-1987 field season, extensive collections of fossil decapods were made. More than 440 specimens were collected from sites on Seymour Island and adjacent James Ross, Vega, Humps, Cockburn, and Snow Hill islands (figure 1). Comments regarding the significance of specimens collected from the adjacent islands are premature, except to note that decapods previously have not been reported from Vega, Humps, Cockburn, or Snow Hill islands. However, several general conclusions can be drawn based upon specimens collected from Seymour Island. Whereas brachyuran decapods—crabs--have been noted to be abundant and diverse in the Eocene La Meseta Formation of Seymour Island (Feldmann and Zinsmeister 1984; Feldmann 1985), none has been collected in the subjacent units. Instead, the decapod fauna in the Cretaceous and Paleocene rocks consists entirely of macrurans—lobsters. Decapod crustaceans are generally common throughout the upper units, units 7 through 10, of the Lopez de Bertodano Formation. These units are known as the molluscan units (Macellari 1986). Invariably, the specimens are found in concretions. Diversity and numerical abundance of lobsters seems to increase upward in the section. At the lowermost localities, in unit 7, Hoploparia stokesi (figure 2) is the only species represented. Above that, however, Linuparus n. sp. and a second new species, possibly referable to the genus Metanephrops, occur in association with H. stokesi. The rocks of the Lopez de Bertodano Formation range in age from Campanian to Paleocene (Macellari 1986). The boundary between the Cretaceous and Tertiary occurs within unit 10, the uppermost unit of the formation, and has been considered to occur within a sequence containing several glauconite beds (Macellari 1986). Nearly 100 fossil lobsters have been collected 1987 REVIEW
from 20 sites spanning this boundary, thus providing an excellent opportunity to examine the effects of the presumed Cretaceous/Tertiary (K/T) boundary event. Furthermore, numerous lobsters were collected for the first time from the overlying, Paleocene age, Sobral Formation. Although final analysis of the specimens has not been undertaken, preliminary field observations suggest that the decapods did not experience a major extinction at this time. Instead, the new species, tentatively referred to Mefanephrops, appears near the base of unit 10, in association with a diverse assemblage of ammonite cephalopods, and continues into the Sobral Formation. Hoploparia stokesi has also been identified above, as well as below, the KIT boundary. During the examination of decapods from the Lopez de Bertodano Formation, it was noted that different regions of lobster skeletons were selectively preserved (Feldmann and Tshudy 1987). Approximately 45 percent of the specimens, collected in 1983-1984, were anatomically incomplete; invariably the abdominal region was absent. Feldmann and Tshudy (1987) speculated that selective scavenging by cephalopods may have been responsible for this phenomenon. These results will be retested by detailed examination of the large sample of fossil lobsters collected during 1986-1987; however, preliminary results seem to suggest that the same general relationships will be observed. Thus, the collection of numerous macrurous decapod crustaceans from sites within the James Ross Basin has extended the geographic range of decapods throughout the basin and has extended their stratigraphic range into the Paleocene as well. Diversity of decapods seems to increase near the K/T boundary. Taxa occurring in uppermost Cretaceous rocks also occur in overlying Paleocene rocks. The lobsters appear to be unaffected by the presumed K/i boundary event. Although processes of selective predation and scavenging seem to affect the preservation potential of different anatomical parts of lobsters, preserved on Seymour Island, the area stands as one in which decapods are unusually abundant. The field work for this study was supported by a National Science Foundation grant to William J. Zinsmeister and laboratory work was supported by National Science Foundation grant DPP 84-11842 to Feldmann. (This article is Contribution 358, Department of Geology, Kent State University, Kent, Ohio 44242.)
References Ball, H.W. 1960. Upper Cretaceous Decapoda and Serpulidae from James Ross Island, Graham Land. Falkland Islands Dependencies Survey Scientific Reports, 24,1-30. del Valle, R., and C.A. Rinaldi. 1975. Sobre la presencia de Hoploparia stokes, (Weller) en las "Snow Hill Island Series," de la Isla Vice-
comodoro Marambio, Antartida. (Contribucion del Instituto Antartico Argentino, Contribucion No. 190.) Feldmann, R.M. 1985. Decapod crustaceans from the Late Cretaceous and the Eocene of Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 19(5),4-5. Feldmann, R.M., and D. Tshudy. 1987. Ultrastructure in cuticle from Hoploparia stokesi (Decapoda: Nephropidae) from the Lopez de Bertodano Formation (Late Cretaceous-Paleocene) of Seymour Island, Antarctica. Journal of Paleontology, 61(6);1194-1203. 11
Surf icial Deposits ;en Telm&7 fe LA MESETA 1dm 1r5 FORMATION 1dm 3 (EOCENE)
::.:.:..
Tel 1-2
Tpcv 1-5 CROSS VALLEY FORMATION Tps 4 • E PALEOCENE) 13 AL FORMATION ______ rpss 3 l-2 ALEOCENE)
LOPEZ DE BE RIO 0 AND FORMATION ETACEoue-. lLEOCENE) M. Cs
• DECAPOD SITE
Figure 1. Location maps showing the position of sites from which macrurous decapod crustaceans have been collected in the Lopez de Bertodano and Sobral formations. The geological map and stratigraphic section are adapted from Sadler (in press) and are reproduced with his permission. ("KIT" denotes "Cretaceous/Tertiary.") 12
ANTARCTIC JOURNAL
Feldmann, R.M., and W.J. Zinsmeister. 1984. Fossil crabs (Decapoda: Brachyura) from the La Meseta Formation (Eocene) of Antarctica: Paleoecological and biogeographic implications. Journal of Paleontology, 58(4), 1046-1061. Macellari, C.E. 1986. Late Campanian-Maastrichtian ammonite fauna from Seymour Island (Antarctic Peninsula). Journal of Paleontology, Vol. 60, (The Paleontological Society Memoir 18, Part 2.) Sadler, P.M. In press. Geometry and stratification of Paleogene and latest Cretaceous units on Seymour Island, northern Antarctic Peninsula. In R.M. Feldmann and M.O. Woodburne, (Eds.), Geology and paleontology of Seymour island, Antarctica. (Geological Society of America Memoir 169.) Tshudy, D., and R.M. Feldmann. In press. Macrurous decapod crustaceans, and their epibionts, from the Lopez de Bertodano Formation (Late Cretaceous), Seymour Island, Antarctica. In R.M. Feldmann and M . O. Woodburne, (Eds.), Geology and paleontology of Seymour Island, Antarctica. (Geological Society of America Memoir 169.)
-j
Figure 2. Hoploparia stokesi Weller. Latex cast of a specimen from the Lopez de Bertodano Formation, preserved as a molted, but complete, carapace and abdomen. (Bar scale equals 1 centimeter.)
Palynological investigations of the James Ross Island basin, Antarctica ROSEMARY
A. ASKIN
Department of Earth Sciences University of California Riverside, California 92521
During December 1986 and January 1987, additional sampling of Campanian to Eocene sediments was carried out for palynological study in the James Ross Island basin (figure), northeastern Antarctic Peninsula. The 300 samples collected are mainly from Seymour Island and cover certain intervals of interest in more detail than was previously available. Data from these samples will refine and extend the palynomorph zonation proposed for the upper Campanian to Paleocene part of the succession (Askin in press). Parts of the upper Lopez de Bertodano Formation, including the glauconitic interval that spans the Cretaceous/Tertiary boundary, and parts of the Eocene La Meseta Formation were sampled. Short helicopter-supported visits also were made to three nearby islands to collect from ?Campanian sections. The three sampled localities are Cockburn Island, Humps Island, and Ula Point on eastern James Ross Island (figure). Fossil palynomorphs are ubiquitous in the Seymour and nearby island sedimentary succession and occur, often abundantly, in all 935 samples processed to date. It is expected that the newly collected samples also will be productive, bringing the samples available for this study to a total of over 1,200. The present phase of this project includes taxonomic description of nonmarine (spores, pollen) and marine (dinoflagellate 1987 REVIEW
cysts, acritarchs) palynomorphs and documentation of their distribution patterns. The dinocyst assemblages have proved particularly useful for biostratigraphy (Askin in press), and the land plant-derived spores and pollen should add useful information on climatic evolution of the area. Unlike terrestrial sediments, which can contain palynomorphs of relatively local derivation, the mainly nearshore marine sediments of Seymour Island contain spores and pollen transported from a wide range of terrestrial habitats and microclimates. Thus these as-
Vega Island
(J c::;
AAfarctica
Naze
640
Island
9
5 10 15 20
VUIO Point
I)
I James Ross Island
(
Km
Cockburn
Island
Hamilton
Seymour Island EPateogene sediments []
Cretaceous sediments
Snow Hill
Island
Locality map for the James Ross Island basin. ("Km" denotes "kilometer?")
13
