Skip to main content
×
×
Home

Left behind – delayed extinction and a relict trilobite fauna in the Cambrian–Ordovician boundary succession (east Laurentian platform, New York)

  • ED LANDING (a1), STEPHEN R. WESTROP (a2), BJÖRN KRÖGER (a3) and ADAM M. ENGLISH (a4)
Abstract
Abstract

Two completely dissimilar faunal changes occur between the Sunwaptan and Skullrockian Stages (Ptychaspid and Symphysurid ‘Biomeres’) in the uppermost Cambrian on the east Laurentian craton. An undolomitized section in the Little Falls Formation in Washington County, New York, shows a typical ‘biomere’ extinction, with highest Sunwaptan trilobites followed by the abrupt appearance of Cordylodus proavus Zone conodonts and the lowest post-extinction trilobites (Parakoldinioidia Endo) 5.0 m higher. This stage boundary interval is very condensed by comparison with coeval Great Basin and Texas sections. Approximately 70 km southwest, typical pre-extinction taxa (the catillicephalid Acheilops Ulrich and several dikelocephalid species) are shown for the first time to persist well beyond the extinction as they occur with middle C. proavus Zone conodonts (Clavohamulus elongatus or, more likely, Hirsutodontus simplex Subzone). The Ritchie Limestone member of the uppermost Little Falls Formation yields a succession of conodont faunas that spans the C. elongatusH. simplexClavohamulus hintzei Subzones (middle–upper C. proavus Zone). These data prove that the trilobites are a relict fauna that persisted into the Symphysurina Zone of the Skullrockian Stage. The massive (burrow-churned), mollusc-dominated Ritchie Limestone, with the second Upper Cambrian cephalopod locality in east Laurentia, represents an inner-shelf refugium for Sunwaptan trilobites that has not been previously encountered. Final extinction of typical Sunwaptan clades is at least locally diachronous, and a simple, genus-based approach to trilobite biostratigraphy in the Cambrian–Ordovician boundary interval is untenable. The relict fauna appears to be distinct at the species level, so it is likely that a viable, species-based biostratigraphy can be developed. Teridontus gallicus Serpagli et al. 2008 is a synonym of T. nakamurai (Nogami, 1967), and T.? francisi Landing sp. nov., with a large base and tiny cusp, is a lower C. proavus Zone form. New trilobites are Acheilops olbermanni Westrop sp. nov. and Parakoldinioidia maddowae Westrop sp. nov. The lowest Ordovician ‘Gailor Dolomite’ is a junior synonym of the Tribes Hill Formation, and the Ritchie Limestone is assigned to the top of the terminal Cambrian Little Falls Formation.

Copyright
Corresponding author
Author for correspondence: elanding@mail.nysed.gov
References
Hide All
Adrain J. M. & Westrop S. R. 2004. A Late Cambrian (Sunwaptan) silicified trilobite fauna from Nevada. Bulletins of American Paleontology 365, 156.
Adrain J. M. & Westrop S. R. 2006. New earliest Ordovician trilobite genus Milardicurus: the oldest known hystricurid. Journal of Paleontology 80, 650–71.
Bradley J. H. 1925. Trilobites of the Beekmantown in the Phillipsburg region of Quebec. Canadian Field Naturalist 39, 59.
Bridge J. 1931. Geology of the Eminence and Cardareva quadrangles. Missouri Bureau of Geology and Mines, 2nd Series 24, 1228.
Brook B. W., Sodhi N. S. & Bradshaw C. A. J. 2008. Synergies among extinction drivers under global change. Trends in Ecology and Evolution 23, 453–60.
Chen J.-Y. & Gong W.-L. 1986. Conodonts. In Aspects of Cambrian–Ordovician Boundary in Dayangcha, China (ed. Chen J.-Y.), pp. 93223. Beijing: China Prospect Publishing House.
Chen J.-Y. & Teichert C. 1983. Cambrian Cephalopoda of China. Palaeontographica Abteilung A 181, 1102.
Chen J.-Y., Tsou S.-P., Chen T.-E. & Qi D.-L. 1979. Late Cambrian cephalopods of North China. Plectronocerida, Proactinocerida (ord. nov.) and Yanhecerida (ord. nov.) Acta Palaeontologica Sinica 18, 124.
Choi D. K., Kim D. H., Sohn J. W, & Lee S-B. 2003. Trilobite faunal successions across the Cambrian-Ordovician boundary intervals in Korea and their correlation with China and Australia. Journal of Asian Earth Sciences 21, 781–93.
Clark T. H. 1948. Theodenisia, new name, replacing Denisia Clark. Journal of Paleontology 22, 643.
Cuvier G. 1797. Tableau élémentaire de l'historie naturelle des animaux. Publisher or printer not recorded, Paris, 710 pp.
Dean W. T. 1977. The early Ordovician trilobite genus Missisquoia Shaw, 1951, in the southern Canadian Rockies of Alberta and British Columbia. Geological Survey of Canada Paper 76–33, 1–7.
Dean W. T. 1989. Trilobites of the Survey Peak, Outram and Skoki Formations (Upper Cambrian–Lower Ordovician) at Wilcox Pass, Jasper National Park. Alberta. Geological Survey of Canada Bulletin 389, 1141.
Didham R. K., Tylianikis J. M., Gemmell N. J., Rand T. A. & Ewers R. M. 2007. Interactive effects of habitat modification and species invasion on native species decline. Trends in Ecology and Evolution 22, 489–96.
Druce E. C. & Jones P. J. 1971. Cambro-Ordovician conodonts from the Burke River structural belt, Queensland. Bureau of Mineral Resources, Geology and Geophysics, Canberra, A. C. T. Bulletin 110, 1159.
Drygant D. M. 1974. Prostyle konodonty Silura I nizov Devona Volyno-Podolya. Paleontologishe Siborny Lvov Universitaet 10, 6470.
Eichenberg W. 1930. Conodonten aus dem Culm des Harzes. Paläontologisches Zeitschrift 12, 177–82.
Endo R. 1937. Addenda to Parts 1 and 2. Manchurian Science Museum Bulletin 1, 302–69, 435–61.
Epstein A. G., Epstein J. B. & Harris L. D. 1977. Conodont color alteration—an index to organic metamorphism. United States Geological Survey Professional Paper 995, 127.
Erdtmann B.-D. 1986. Early Ordovician eustatic cycles and their bearing on punctuations in early nematophorid (planktic) graptolite evolution. Lectures in Earth Sciences 8, 139–52.
Ergaliev G. K. 1980. Middle and Upper Cambrian trilobites from Maly Karatau. Kazakhstan SSR Academy of Sciences, 211 pp. [in Russian]
Ethington R. L. & Clark D. L. 1971. Lower Ordovician conodonts in North America. In Symposium on Conodont Biostratigraphy (eds Sweet W. C. and Bergström S. M.), pp. 6382. Geological Society of America Memoir no. 127.
Fåhraeus L. E. & Roy K. 1993. Conodonts from the Cambro-Ordovician Cooks Brook and Middle Arm Formations, Bay of Islands, western Newfoundland. Geologica et Palaeontologica 27, 135.
Fisher D. W. 1954. Lower Ordovician (Canadian) stratigraphy of the Mohawk valley. Bulletin of the Geological Society of America 65, 7196.
Fisher D. W. 1977. Correlation of Hadrynian, Cambrian, and Ordovician rocks in New York State. New York State Museum Map and Chart Series 25, 175.
Fisher D. W. 1984. Bedrock geology of the Glens Falls–Whitehall region, New York. New York State Museum, Map and Chart Series 35, 165.
Fisher D. W. & Hanson G. F. 1951. Revisions in the geology of Saratoga Springs, New York, and vicinity. American Journal of Science 249, 795814.
Fisher D. W. & Mazzullo S. J. 1976. Lower Ordovician (Gasconadian) Great Meadows Formation in eastern New York. Geological Society of America Bulletin 87, 1443–8.
Flower R. H. 1954. Cambrian cephalopods. New Mexico Institute of Mining and Technology Bulletin 40, 151.
Flower R. H. 1964. The nautiloid order Ellesmeroceratida (Cephalopoda). New Mexico Institute of Mining and Technology Memoir 12, 1164.
Friedman G. M. 1980. Dolomite is an evaporate mineral: evidence from the rock record and from sea-marginal ponds of the Red Sea. In Concepts and Models of Dolomitization (eds Zenger D. H., Dunham J. B. & Ethington R. L.), pp. 6980. SEPM Special Publication no. 28.
Fortey R. A. 1983. Cambrian–Ordovician trilobites from the boundary beds in western Newfoundland and their phylogenetic significance. Special Papers in Palaeontology 30, 179211.
Fortey R. A., Landing E., & Skevington D. 1982. Cambrian-Ordovician boundary sections in the Cow Head Group, western Newfoundland. In The Cambrian–Ordovician boundary: sections, fossil distributions and correlations (eds Bassett M. G. & Dean W. T.), pp. 95129. National Museum of Wales, Geological Series 3.
Furnish W. M. 1938. Conodonts from the Prairie du Chien (Lower Ordovician) beds of the upper Mississippi valley. Journal of Paleontology 12, 318–40.
Geyer G. & Shergold J. H. 2000. The quest for internationally recognized divisions of Cambrian time. Episodes 23, 188–95.
Hall J. 1863. Preliminary notice of the fauna of the Potsdam sandstone, with remarks on previously known species of fossils and descriptions of some new ones from the sandstones of the Upper Mississippi Valley. Report of the New York State Cabinet of Natural History 16, 119222.
Hanski I., Koivulehto H., Cameron A., & Rahagalala P. 2007. Deforestation and apparent extinctions of endemic forest beetles in Madagascar. Biology Letters 3, 344–7.
Haq B. U. & Schutter S. R. 2008. A chronology of Paleozoic sea-level changes. Science 322, 64–8.
Harris G. & Pimm S. L. 2008. Range size and extinction risk in birds. Conservation Biology 22, 163–71.
Hupé P. 1955. Classification des trilobites. Annales de Paléontologie 41, 91325.
Jablonski D. 1986. Causes and consequences of mass extinction: a comparative approach. In Dynamics of Extinction (ed. Elliot D.K.), pp. 183229. New York: Wiley & Sons.
Ji Z. & Barnes C. R. 1994. Lower Ordovician conodonts of the St. George Group, Port au Port Peninsula, western Newfoundland, Canada. Palaeontographica Canadiana 11, 1149.
Kaljo D., Borovko N., Heinsalu H., Khasanovich K., Mens K., Popov L., Sergeeva S., Sobolevskaya R. & Viira V. 1986. The Cambrian–Ordovician boundary in the Baltic Lagoda Clint area (north Estonia and Leningrad region), USSR). Proceedings of the Academy of Sciences of the Estonian SSR, Geology 35, 97108.
Kobayashi T. 1955. The Ordovician fossils of the McKay Group in British Columbia, western Canada, with a note on the Early Ordovician palaeogeography. Journal of the Faculty of Science, University of Tokyo, Section 2 – Geology 9, 355493.
Kröger B. & Landing E. 2007. The earliest Ordovician cephalopods of eastern Laurentia—ellesmeroceroids of the Tribes Hill Formation, eastern New York. Journal of Paleontology 81, 841–56.
Kröger B. & Landing E. 2008. Onset of the Ordovician cephalopod radiation – evidence from the Rochdale Formation (middle Early Ordovician, Stairsian) in eastern New York. Geological Magazine 145, 490520.
Kröger B. & Landing E. 2009. Cephalopods and paleoenvironments of the Fort Cassin Formation (upper Lower Ordovician), eastern New York and adjacent Vermont. Journal of Paleontology 83, 664–93.
Landing E. 1979. Conodonts and biostratigraphy of the Hoyt Limestone (Late Cambrian, Trempealeauan), eastern New York. Journal of Paleontology 53, 1023–29.
Landing E. 1988. Cambrian–Ordovician boundary in North America: revised Tremadocian correlations, unconformities, and “glacioeustasy”. In The Canadian Paleontology and Biostratigraphy Seminar, Proceedings (ed. Landing E.), pp. 4858. New York State Museum Bulletin 462.
Landing E. 1993. Cambrian–Ordovician boundary in the Taconic allochthon, eastern New York, and its interregional correlation. Journal of Paleontology 67, 119.
Landing E. 2002. Early Paleozoic sea levels and climates: new evidence from the east Laurentian shelf and slope. In Guidebook for Fieldtrips in New York and Vermont (eds McLelland J. & Karabinos P.), pp. C61C622. New England Intercollegiate Geological Conference 94th Annual Meeting and New York State Geological Association 74th Annual Meeting, Lake George, NY.
Landing E. 2007. Ediacaran–Ordovician of east Laurentia―geologic setting and controls on deposition along the New York Promontory. In Ediacaran–Ordovician of East Laurentia―S. W. Ford Memorial Volume (ed. Landing E.), pp. 524. New York State Museum Bulletin 510.
Landing E. In press. The lives and deaths of the Great American Carbonate Bank in eastern Laurentia. In The Great American Carbonate Bank: The Geology and Petroleum Potential of the Cambrian–Ordovician Sauk Sequence of Laurentia (eds Derby J., Fritz R., Morgan W. A., Sternbach C., Kupecz J., Kuykendall M., Longacre S. A., & Medlock P.). American Association of Petroleum Geologists Memoir.
Landing E., Bowring S. A., Davidek K., Westrop S. R., Geyer G. & Heldmaier W. 1998. Duration of the Early Cambrian: U-Pb ages of volcanic ashes from Avalon and Gondwana. Canadian Journal of Earth Sciences 35, 329–38.
Landing E., Franzi D. A., Hagadorn J. W., Westrop S. R., Kröger B. & Dawson J. 2007. Cambrian of east Laurentia: field workshop in eastern New York and western Vermont. In Ediacaran–Ordovician of East Laurentia―S. W. Ford Memorial Volume (ed. Landing E.), pp. 2580. New York State Museum Bulletin 510.
Landing E. & Kröger B. 2009. The oldest cephalopods from east Laurentia. Journal of Paleontology 83, 8993.
Landing E., Ludvigsen R & von Bitter P. H. 1980. Upper Cambrian to Lower Ordovician conodont biostratigraphy and biofacies, Rabbitkettle Formation, District of Mackenzie. Royal Ontario Museum, Life Sciences Contributions 126, 142.
Landing E. & Murphy J. B. 1991. Uppermost Precambrian(?)–Lower Cambrian of mainland Nova Scotia: faunas, depositional environment, and stratigraphic revision. Journal of Paleontology 65, 382–96.
Landing E. & Westrop S. R. 2006. Early Ordovician faunas, stratigraphy, and sea-level history of the middle Beekmantown Group, northeastern New York. Journal of Paleontology 80, 958–80.
Landing E., Westrop S. R. & Keppie J. D. 2007. Terminal Cambrian and lowest Ordovician succession of Mexican West Gondwana: biotas and sequence stratigraphy of the Tiñu Formation. Geological Magazine 144, 128.
Landing E., Westrop S. R. & Knox L. 1996. Conodonts, stratigraphy, and relative sea-level changes of the Tribes Hill Formation (Lower Ordovician), east-central New York. Journal of Paleontology 70, 652–76.
Landing E., Westrop S. R. & Miller J. F. 2010. Globally practical base for the uppermost Cambrian (Stage 10)—FAD of the conodont Eoconodontus notchpeakensis and the Housian Stage. In The 15th Field Conference of the Cambrian Stage Subdivision Working Group, International Commission on Cambrian Stratigraphy. Abstracts and Excursion Guide. (eds Fatka O. & Budil P.), p. 18. Prague: Czech Geological Survey.
Landing E., Westrop S. R. & Van Aller Hernick L. 2003. Uppermost Cambrian–Lower Ordovician faunas and Laurentian platform sequence stratigraphy, eastern New York and Vermont. Journal of Paleontology 77, 7898.
Lee S-B., Lee D-C. & Choi D. K. 2008. Cambrian–Ordovician family Missisquoiidae Hupé, 1955: systematic revision and palaeogeographical considerations based upon cladistic analysis. Palaeogeography, Palaeoclimatology, Palaeoecology 260, 315–41.
Loch J. D., Stitt J. H. & Derby J. R. 1993. Cambrian–Ordovician boundary interval extinctions: implications of revised trilobite and brachiopod data from Mount Wilson, Alberta, Canada. Journal of Paleontology 67, 497517.
Lochman-Balk C. 1970. Upper Cambrian faunal patterns on the craton. Geological Society of America Bulletin 81, 3197–224.
Longacre S. A. 1970. Trilobites of the Upper Cambrian Ptychaspid Biomere, Wilberns Formation, central Texas. Paleontological Society Memoir 4, 170.
Ludvigsen R. 1982. Upper Cambrian and Lower Ordovician trilobite biostratigraphy of the Rabbitkettle Formation, western District of Mackenzie. Life Sciences Contribution, Royal Ontario Museum 134, 1188.
Ludvigsen R. & Westrop S. R. 1983 a. Franconian trilobites of New York State. New York State Museum Memoir 23, 183.
Ludvigsen R. & Westrop S. R. 1983 b. Trilobite biofacies of the Cambrian–Ordovician boundary interval in northern North America. Alcheringa 7, 301–19.
Ludvigsen R. & Westrop S. R. 1985. Three new Upper Cambrian stages for North America. Geology 13, 139–43.
Ludvigsen R., Westrop S. R. & Kindle C. H. 1989. Sunwaptan (Upper Cambrian) trilobites of the Cow Head Group, western Newfoundland, Canada. Palaeontographica Canadiana 6, 1175.
Mazzulo S. J., Agostino P., Seitz N. & Fisher D. W. 1978. Stratigraphy and depositional environment of the Upper Cambrian–Lower Ordovician sequence, Saratoga Springs, New York. Journal of Sedimentary Petrology 48, 99116.
Miller J. F. 1969. Conodont faunas and biostratigraphy of the Upper Cambrian and lowest Ordovician, House Range, Utah. Journal of Paleontology 43, 413–39.
Miller J. F. 1980. Taxonomic revisions of some Upper Cambrian and lowest Ordovician conodonts with comments on their evolution. University of Kansas Paleontological Institute Paper 99, 139.
Miller J. F. 1984. Cambrian and earliest Ordovician conodont evolution, biofacies and provincialism. In Conodont biofacies and provincialism (ed. Clark D. L.), pp. 4368. Geological Society of America Special Paper 196.
Miller J. F., Evans K. R., Loch J. D., Ethington R. L., Stitt J. H., Holmer L. & Popov L. E. 2003. Stratigraphy of the Sauk III interval (Cambrian–Ordovician) in the Ibex area, western Millard County, Utah, and central Texas. Brigham Young University Geology Studies 47, 23118.
Miller S. A. 1899. North American Geology and Palaeontology for the Use of Amateurs, Students and Scientists. Publisher not listed, Cincinnati, Ohio, 718 pp.
Missarzhevsky V. V. 1969. Opisanie chioitov, gastropod, chiolitchelminthov, kamenid i form nizsnego sistematneskogo poloshenia. In Tommotski Yarus I Problemii Nizhneii Yaranish Kembriya (ed. Raaben A.) Trudy Leona Nict. AH CCCP, 206, pp. 93175.
Müller K. J. 1959. Kambrische Conodonten. Zeitschrift für Deutsche Geologische Gesellschaften 111, 434–85.
Müller K. J. 1964. Conodonten aus dem Unteren Ordovicium von Sudkorea. Neues Jahrbuch der Geologie und Paläontologie, Abhandlungen 119, 93102.
Müller K. J., Nogami Y. & Lenz H. 1974. Phosphatische Ringe als Mikrofossilien in Altpaläozoikum. Palaeontographica Abteilung A 146, 7999.
Nicoll R. S. 1994. Seximembrate apparatus of the Late Cambrian coniform conodont Teridontus nakamurai from the Chatsworth Limestone, Georgina Basin, Queensland. AGSO Journal of Australian Geology & Geophysics 15, 367–79.
Nielsen A. T. 2004. Ordovician sea level changes: a Baltoscandian perspective. In The Great Ordovician Biodiversification Event (eds Webby B. D., Paris F., Droser M. L. & Percival I. G.), pp. 8493. New York: Columbia University Press.
Nogami Y. 1967. Kambrische Conodonten von China, Teil 2, Conodonten aus den hoch obercambrischen Yencho-Schichten. Kyoto University College of Sciences, Memoir Series B 33, 211–19.
Palmer A. R. 1965. Biomere, a new kind of biostratigraphic unit. Journal of Paleontology 39, 149–53.
Palmer A. R. 1998. A proposed nomenclature for stages and series for the Cambrian of Laurentia. Canadian Journal of Earth Sciences 35, 323–8.
Pander C. H. 1856. Monographie der fossilen Fische des silurischen Systems der Russisch-Baltischen Gouvernments. Akademie der Wissenschaft, St. Petersburg, 91 pp.
Peng S. 1992. Upper Cambrian biostratigraphy and trilobite faunas of the Cili-Taoyuan area, northwestern Hunan, China. Association of Australasian Palaeontologists Memoir 13, 1119.
Pimm S. L. & Askins R. A. 1995. Forest losses predict bird extinctions in eastern North America. Proceedings of the National Academy of Sciences, USA 92, 9343–7.
Rasetti F. 1959. Trempealeauian trilobites from the Conococheague, Frederick, and Grove Limestones of the central Appalachians. Journal of Paleontology 33, 575–98.
Raymond p. E. 1913. Notes on some new and old trilobites in the Victoria Memorial Museum, Canada Geological Survey. Bulletin of the Victoria Memorial Museum 1, 33–9.
Raymond P. E. 1937. Upper Cambrian and Lower Ordovician Trilobita and Ostracoda from Vermont. Geological Society of America Bulletin 48, 1079–146.
Robison R. A. & Pantoja-Alor J. 1968. Tremadocian trilobites from the Nochixtlán region, Oaxaca, Mexico. Journal of Paleontology 42, 767800.
Rowley E. B. 1951. Crystal collecting at Saratoga Springs, N.Y. Rocks and Minerals September–October 1951, 528–32.
Schulte P. E, Alegret L., Arenillas I., Arz J. A.Barton P. J., Bown P. R., Bralower T. J., Christeson G. L., Claeys P., Cockell C. S., Collins G. S., Deutsch Al., Goldin T. J., Goto K., Grajales-Nishimura J. M., Grieve R. A. F., Gulick S. P. S., Johnson K. R., Kiessling W., Koeberl C., Kring D. A., Macleod K. G., Matsui T., Melosh J., Montanari A., Morgan J. V., Neal C. R., Nichols D. J., Norris R. D., Pierazzo E., Ravizza G., Rebolledo-Vieyra M., Reimold W. U., Robin E., Salge T., Speijer R. P., Sweet A. R., Urrutia-Fucugauchi J., Vajda V., Whalen M. T. & Willumsen P. S. 2010. The Chicxulub asteroid impact crater and mass extinction at the Cretaceous–Paleogene boundary. Science 327, 1214–18.
Scotese C. R. & McKerrow W. S. 1990. Revised world maps and introduction. Geological Society of London Memoir 12, 121.
Serpagli E., Ferretti A., Nicoll R. S. & Serventi P. 2008. The conodont genus Teridontus (Miller, 1980) [sic., delete parentheses] from the Early Ordovician from the Montagne Noire, France. Journal of Paleontology 82, 612–20.
Shaw A. B. 1951. The paleontology of northwestern Vermont. I. New Late Cambrian trilobites. Journal of Paleontology 25, 97114.
Shergold J. H. 1971. Late Upper Cambrian trilobites from the Gola Beds, western Queensland. Australian Bureau of Mineral Resources, Geology and Geophysics Bulletin 112, 1127.
Shergold J. H. 1975. Late Cambrian and Early Ordovician trilobites from the Burke River Structural Belt, western Queensland, Australia. Australian Bureau of Mineral Resources, Geology and Geophysics Bulletin 153, 1251.
Sohn J. W. & Choi D. K. 2007. Furongian trilobites from the Asioptychaspis and Quadraticephalus Zones of the Hwajeol Formation, Taebaeksan Basin, Korea. Geosciences Journal 11, 297314.
Stitt J. H. 1971 a. Repeating evolutionary patterns in Late Cambrian biomeres. Journal of Paleontology 45, 178–81.
Stitt J. H. 1971 b. Late Cambrian and earliest Ordovician trilobites, Timbered Hills and lower Arbuckle Groups, western Arbuckle Mountains, Murray County, Oklahoma. Oklahoma Geologic Survey Bulletin 110, 183.
Stitt J. H. 1975. Adaptive radiation, trilobite paleoecology and extinction, Ptychaspid Biomere, Late Cambrian of Oklahoma. Fossils and Strata 4, 381–90.
Stitt J. H. 1977. Late Cambrian and earliest Ordovician trilobites, Wichita Mountains area, Oklahoma. Oklahoma Geological Survey Bulletin 124, 179.
Szaniawski H. & Bengtson S. 1998. Late Cambrian euconodonts from Sweden. Palaeontologica Polonica 58, 729.
Taylor M. E. & Halley R. B. 1974. Systematics, environment, and biogeography of some Late and Early Ordovician trilobites from eastern New York State. U. S. Geological Survey Professional Paper 834, 138.
Ulrich E. O. & Cushing H. P. 1910. Age and relations of the Little Falls Dolomite (Calciferous) of the Mohawk valley. New York State Museum Bulletin 140, 97140.
Ulrich E. O. & Resser C. E. 1930. The Cambrian of the upper Mississippi Valley. Part 1. Trilobita; Dikelocephalinae and Osceolinae. Bulletin of the Milwaukee Public Museum 12, 1122.
Ulrich E. O. & Resser C. E. 1933. The Cambrian of the Upper Mississippi Valley. Part 2. Trilobita; Saukiinae. Bulletin of the Milwaukee Public Museum 12, 123306.
Walch J. E. I. 1771. Die Naturgeschichte der Versteinerungen zur Erläuterung der Knorrischen Sammlung von Merkwürdigkeiten der Natur. Dritter Theil. Paul Jonathan Felstecker, Nürnburg, 235 pp.
Walcott C. D. 1912. New York Potsdam–Hoyt fauna. Smithsonian Museum Miscellaneous Collections 57, 251304.
Walcott C. D. 1914. Dikelocephalus and other genera of the Dikelocephalinae. Smithsonian Miscellaneous Collections 57, 345413.
Westrop S. R. 1986 a. New ptychaspidid trilobites from the Upper Cambrian Mistaya Formation of southern Alberta. Canadian Journal of Earth Sciences 23, 214–21.
Westrop S. R. 1986 b. Trilobites of the Upper Cambrian Sunwaptan Stage, southern Canadian Rocky Mountains, Alberta. Palaeontographica Canadiana 3, 1179.
Westrop S. R. 1995. Sunwaptan and Ibexian (Upper Cambrian and Lower Ordovician) trilobites of the Rabbitkettle Formation, Mountain River region, northern Mackenzie Mountains, northwest Canada. Palaeontographica Canadiana 12, 175.
Westrop S. R. & Cuggy M. B. 1999. Comparative paleoecology of Cambrian trilobite extinctions. Journal of Paleontology 73, 337–54.
Westrop S. R., Knox L. A. & Landing E. 1993. Lower Ordovician (Ibexian) trilobites from the Tribes Hill Formation, central Mohawk valley, New York State. Canadian Journal of Earth Sciences 30, 1618–33.
Westrop S. R. & Ludvigsen R. 1987. Biogeographic control of trilobite mass extinction at an Upper Cambrian ‘biomere’ boundary. Paleobiology 13, 8499.
Westrop S. R., Palmer A. R. & Runkel A. 2005. A new Sunwaptan (Late Cambrian) trilobite fauna from the upper Mississippi Valley. Journal of Paleontology 79, 7288.
Winston D. & Nicholls H. 1967. Late Cambrian and Early Ordovician faunas from the Wilberns Formation of central Texas. Journal of Paleontology 41, 6696.
Zenger D. H. 1971. Age and relationships of the Ritchie Limestone, New York. Geological Society of America Abstracts with Programs, Northeastern Section, p. 65.
Zhou Z. & Zhang J. 1978. Cambrian-Ordovician boundary of the Tangshan area with descriptions of the related trilobite fauna. Acta Palaeontologica Sinica 17, 128.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Geological Magazine
  • ISSN: 0016-7568
  • EISSN: 1469-5081
  • URL: /core/journals/geological-magazine
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×

Keywords:

Metrics

Full text views

Total number of HTML views: 2
Total number of PDF views: 12 *
Loading metrics...

Abstract views

Total abstract views: 86 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 18th January 2018. This data will be updated every 24 hours.