FOSSIL LAKE WANNAGAN (PALEOCENE: TIFFANIAN) BILLINGS COUNTY, NORTH DAKOTA

by

Bruce R. Erickson

MISCELLANEOUS SERIES NO. 87 NORTH DAKOTA GEOLOGICAL SURVEY John P. Bluemle, State Geologist 1999 ~ 20 35 jUllUlllu., ....II,

~2

27 .. +18 ... "26

I. Trionyx/Aspideretes (soft shell turtle) 19. Presbyornis isoni (waterfowl) 2. Protoche/ydra zangerli (snapping turtle) 20. Dakotornis cooperi (shore bird) 3. Undetermined turtle 21. Owl 4. Plostomenus (soft shell turtle) 22. Plesiadapis (primate) 5. Champsosaurus gigas 23. Phenacodus (condylarth) 6. Palaeophid snake 24. Protietis (carnivore) 7. Varanid lizard 25. Pt.i/odus (multituberculate) 8. Leidyosuchus (ormidabilis (crocodile preying on 26. Troeodendron (with bark beetle borings) turtle) 27. Sabal (palm) 9. Leidyosuchus (ormidabilis (crocoeile near den 28. Zlzyphus (cycad) entrance) 29. Platanus (sycamore) 10. Anuran (frog) 30. Ginkgo (maidenhair tree) I I. Piceoerpeton wi/lwoodense (giant salamander) 31. Cercdiphy/lum (katsura tree) 12. Amia fragosa (dogfish or mudfish) 32. Taxodium (cypress tree) 13. Joffrichthyes (bony fish) 33. Cyrpess knees 14. Lepisosteus (garfis h) 34. Vitis olriki (grape vine) 15. Myliobatis (freshwater ray) 35. Metasequoia (dawn redwood) 16. Gomphaeschna schrank,i (drangonny) 36. Equisetum (horsetail) 17. Ephemeropteran (may ny) 37. Ne/umbium (waterlily) 18. Plover-like shorebird 38. Magnolia ISSN 0078·1576

FOSSIL LAKE WANNAGAN (PALEOCENE: TIFFANIAN) BILLINGS COUNTY, NORTH DAKOTA

by

Bruce R. Erickson Department of Paleontology The Science Museum of Minnesota St. Paul, Minnesota 5510 I

MISCELLANEOUS SERIES NO. 87 NORTH DAKOTA GEOLOGICAL SURVEY John P. Bluemle, State Geologist 1999 TABLE OF CONTENTS

ABSTRACT...... iv

ACKNOWLEDGMENTS iv

INTRODUCTION .

LOCATION 2

STRATIGRAPHY. 2

DEPOSITIONAL ENVIRONMENT 3

BIOTA 4

DISCUSSION 7

REFERENCES...... 7

ILLUSTRATIONS AND TABLES

Cover picture. Paleoenvironmental reconstruction of Fossil Lake Wannagan.

Figure I. Panoramic view of Fossil Lake Wannagan area looking north I

Figure 2. Wannagan Creek Quarry looking southeast toward working face of quarry 2

Table I. Wannagan Creek Flora , 5

Table 2. Wannagan Creek Fauna 6

iii ABSTRACT

Fossil Lake Wannagan is a new name for a local freshwater lake of undetermined size that existed as part of a floodplain system during the Late Paleocene. It is located in the upper breaks of the badlands of the Little Missouri River in western North Dakota. Fossil Lake Wannagan is recognized from: sediments of fluvial. paludal and lacustrine character; a section of shoreline with well-defined beach cusps; and an exceptionally well-preserved freshwater assemblage of fossils. A sequence of stratified sediments records the brief history of its development and termination by crevasse splay deposition. Limnogeological and paleoenvironmental aspects of this ancient lake are presented along with its age and correlations. The name "Fossil Lake Wannagan" is, herein, introduced for the first time.

KEY WORDS: "Fossil Lake Wannagan"; Paleocene lake/fJoodbasin; limnogeology and paleoecology; Wannagan Creek Quarry.

ACKNOWLEDGMENTS

The writer thanks J. Bluemle and J. Hoganson of the North Dakota Geological Survey and R. Benson of the University of Minnesota for critically reading the manuscript and offering suggestions for its improvement. For the detailed paleoenvironmental painting of Fossil Lake Wannagan (cover) , am grateful to J. Martinez of the Science Museum of Minnesota. For proofreading and word-processing I thank E. Holt of the Science Museum of Minnesota. R. Spading of the Science Museum of Minnesota did the photography (Figures I and 2). I am further indebted to A Kihm of Minot State University; R. Melchior of Bemidji State University; K. Johnson of the Denver Museum of Natural History; J. Hartman of the University of North Dakota and M. Newbrey of the University of Wisconsin for assistance in compiling the floral and faunal lists. Support for paleoenvironmental reconstructions of Fossil Lake Wannagan was prOVided by the Hawkinson Paleontology Research Fund; Theodore Rooselvelt Na­ tional Park; United States Forest Service and NSF Grant ESI 9705453.

iv INTRODUCTION

Initial investigation of the fossil deposits in These are unquestionably fluvial and lacustrine the Wannagan Creek drainage of Billings County, rather than eolian deposits. Unlike freshwater North Dakota, began in mid-1970 after a small lakes known elsewhere, such as Paleocene Lake sample of crocodilian remains was reported to the Flagstaff in Utah, which gave rise to the well-known author (Figure /). Early examination of the site Green River lakes and the intermontane basins they where the major concentration of bones had been later occupied (Schaeffer and Mangus, 1965), Lake found produced a number of additional specimens Wannagan began as a swamp or embayment asso­ and resulted in the decision to further investigate. ciated with a major river system and its accompa­ More intensive efforts during the following year nying meandering streams and natural levees. revealed that a rich fossiliferous layer could be Jacob (1972) describes such a lake/floodbasin as a accessed by removal of the top of a small butte to subenvironment of an alluvial-plain. a depth of about 10 meters. After two seasons of digging, the existence of a local basin was appar­ Paleontologically, Lake Wannagan and its ent. This proved to be the margin of a shallow environs supported a rich and diverse biota com­ floodbasin, which held a sizable body of fresh wa­ prising an array of all major vertebrate groups, in­ ter during Bullion Creek time. vertebrate taxa, and a large assemblage of aquatic and forest plants (Erickson, 199\). A few Evidence of abrupt lithofacies changes; a ichnofossils are also included in this biota. This mappable shoreline with beach cusps; shallow­ report describes the type locality of several new water shale and lignite zones; and a bottom marl taxa. horizon characterize Wannagan Creek Quarry.

Figure I. Panoramic view of Fossil Lake Wannagan area looking north. Wannagan Creek Quarry (large arrow); contact between the Bullion Creek and Sentinel Butte Formations (long arrow). LOCATION area. The Bullion Creek (Tongue River) Forma­ tion and the overlying Sentinel Butte Formation Wannagan Creek Quarry was annually op­ are flat-lying with the basal part of the Bullion erated by the Department of Paleontology of the Creek in the subsurface. The two formations are Science Museum of Minnesota from 1970 to 1996 easily distinguished from one another by the overall (Figure 2). The quarry occupies the margin of what buff, yellow and tan color, and numerous has been determined to be the remnant of a fossil interstratified lignitic layers of the Bullion Creek lake or floodbasin. It is located in the upper breaks Formation and the general "somber" gray color ofthe Little Missouri River in Billings County, North of the Sentinel Butte Formation. They are sepa­ Dakota: Sec.18, TI41N, RI02W (Figure I). Six­ rated by a prominent lignite or clinker zone (HT teen readings were taken by one GPS instrument Butte Bed). There is considerable lithological di­ at various positions within the limits of the 40 by verSity in each formation, but a few layers such as 56 square meter excavation site. A mean value of the HT boundary bed and somewhat higher blue these readings is N47° 02', WI 03° 39' and is pro­ strata, locally called the "Blue Beds", are continu­ vided here merely for comparison with scaled-map ous over considerable distances. For broader and locations as recommended by Brew et al. (1993) more detailed accounts of these strata, see Royse as a check on precision or reproducibility of posi­ (1967; 1972), Jacob (1972) and Murphy et al. tions determined by low-cost GPS units. Topo­ (1993). graphically, the quarry is situated on a low wedge­ shaped ridge formed by the confluence of two The stratigraphic position of the quarry site small coulees which trend in a northwest direc­ is in the Bullion Creek Formation 20 meters be­ tion. The immediate area is an uneven grassy table low the Sentinel Butte contact. Although the of washes and erosion surfaces with re-entrant quarry is limited in size, measuring approximately slopes. 40 by 54 meters, it provides a remarkable variety of lithologies. At the bottom of the sequence, a STRATIGRAPHY clay and silt marl defines an initial influx of sedi­ ments into adeveloping backswamp environment. Two stratigraphic units are exposed in the Above this is a lignitic zone a few millimeters thick,

Figure 2. Wannagan Creek Quarry looking southeast toward working face of quarry. Field party excavating above clay and silt layers at the base of fossiliferous zone (arrow).

2 which increases to over 30 centimeters to the floodplain system. Clays and silts were introduced south-southwest. Its interstratified structure of by streams, followed by a thick build-up of organic matted plant remains and mudstone indicates a material that resulted in the development of swamp environment. The local dip within the ex­ swampy conditions. Jacob (1972) found no bar­ cavation is about 3-4 degrees to the southwest. rier or shoreline sands in the Tongue River and The regional dip is north toward the center of concluded that marshes or swamps probably did Williston Basin. The thin Iignitic margin follows not have a lagoonal origin. The lenticular shore­ rather closely the contour of the lenticular shore­ line sands identified in the excavation (Erickson, line sand, and represents what may be referred to /982; 1991) are limited in extent to some 18 as a wave-base. The lignitic material grades up­ meters and may represent splay features. WeI/­ ward into a gray shale some 30-40 centimeters developed sand cusps having asymmetrical form thick. This, in turn, grades upward into a lighter indicate a local embayment with shallow water cur­ colored shale and clayey sand that is terminated rents. The presence of these features offers an by an erosional unconformity. The total thickness insight into the depositional setting (Erickson, ofthe sediments of Lake Wannagan , as excavated, 1982). is approximately 0.8 meters. A massive overlying cross-bedded crevasse splay sand reaches a thick­ Above the basal marl, a lignitic zone and ness of 8 meters. Crevasse splay sand ofthis thick­ an overlying gray shale provide the setting for the ness indicates proximity to a large stream as the origin of Fossil Lake Wannagan. The lignitic mate­ source ofthe sand that terminated Lake Wannagan. rial indicates settling in relatively quiet shallow water. Plant debris at this level becomes denser Sediments of Wannagan Creek Quarry away from the shoreline where many identifiable have yielded a number of specimens of the pri­ plant taxa are preserved. Among these are vari­ mate Plesiadapis churchill; (Kihm, 1993). Biochrons ous trees and shrubs represented by leaves, fruit­ for land mammal ages indicate an age of Tiffanian ing bodies and coalified stems (Table I). Some of 4 for P churchilti (Butler et aI., 1980). Wannagan these stems are logs 30 centimeters in breadth and Creek Quarry dates to early Tiffanian 4, with an over 10 meters long. The shallow water at this age of about 60 million years (Benson, in press, time was choked with branches from overhang­ and references cited therein). ing trees along the lake margin. Bottom condi­ tions were somewhat mobile, allOWing branches DEPOSITIONAL ENVIRONMENT as well as some of the long bones to assume the more or less vertical positions in which they were Sediments encountered in the excavation found in situ. Subsequent deposition and a con­ of the quarry show a sequence of layers that indi­ tinuous buildup of organic debriS resulted in cate paludal and fluvial conditions followed by a eutrophic conditions. It is suspected that accu­ lacustrine environment. The origin of these sedi­ mulation was gradual, occurring over a span of ments was mainly from streams flowing into the considerable time which represented the period basin, as well as from the accumulation of organic of greatest stability in the duration of Fossil Lake debris derived from extensive aquatic plant growth Wannagan. The sediments are uniformly fine­ and trees in the basin and on nearby levees. Royse grained and show graded bedding. (1970) and Jacob (1972) discuss the overall origin and source of sediments of the Tongue River For­ Duration and size of the lake are problem­ mation from highlands to the west. atical and can be inferred from several bits of evi­ dence. A subtropical setting demonstrated by The basin occupied by Fossil Lake ample plant fOSSils suggests only moderate season­ Wannagan was part of a local floodbasin of unde­ ality. No convincing record of varves or any other termined size. It existed as part of a much larger annual bloom or crop was detected nor is there

3 any cyclicity present in these deposits, as occurs in Sediments laid down during the final stages the Eocene Green River lakes (Selley, 1978). A of lake deposition are light-colored fine sands and calculated rate of sedimentation would have ques­ clays with relatively few fossils. The fossil speci­ tionable reliability. mens that are found in these sediments display signs of considerable oxidation. Jacob (1972) com­ Shoreline sands, which yielded remains of ments on the oxidiZing conditions that prevailed hatchling crocodiles and provided likely nesting en­ in the light-colored beds of the Bullion Creek For­ vironment (Erickson, 1982), imply an established mation. behavior for the eighty individuals of Leidyosuchus (=Borealosuchus) that were recovered. These in­ Crevasse splay sands lie unconformably dividuals exhibit a size range that includes several over the uppermost limits of lake deposits. These unusually large individuals. Three exceptionally sands are heaVily cross-bedded and reach a thick­ large skulls some 12-15 percent larger than aver­ ness of 8 meters. Splay sand in this amount must age-size specimens are taken as the oldest and have had a large stream as its source. Further­ most dominant males in this population. Among more, the unconformity at the contact is an ero­ living species, the largest forms are the oldest sional surface attributed directly to scouring by a males. These individuals have established breed­ large volume of water released through a rupture ing territories (Cott, 1960). The ratio of three in the nearby levee system, which produced the exceptionally large individuals, among the popula­ sand. This is not unlike recent examples of alluvial tion of some eighty individuals, is not unlike ratios sub-facies deposition (Selley, 1978). found in living populations (Cott. 1960). The ratio for the fossil crocodile suggests arather stable habi­ BIOTA tat. The largest skulls are estimated to represent individuals 35 years of age or more. It is therefore A flora of over 100 plant taxa has been re­ reasonable to presume that these individuals oc­ corded from Wannagan Creek (Melchior, 1976; cupied Lake Wannagan for at least this long. 1977; Melchoir and Hall, 1983) (Table I). Plant distribution is calculated primarily based on rela­ A modern analogue to the Paleocene Fos­ tive abundance of specific taxa in the swamp and sil Lake Wannagan might be found along the Mis­ lake deposits and the known habitat preference sissippi River in the states of Mississippi and Ten­ of related living species. Large trees such as nessee. Here, flood-plain lakes along the mean­ Taxodium (Bald Cypress) as well as avariety ofsmall dering river course are often several miles across. aquatic plants grew in the waters of the f1oodbasin. The origin of lakes, such as these, is attributed to The margins of the lake, including the levees, were flooding when the river breaks its banks (Selley, flush with Magnolia, Platanus, Cercidiphyllum and 1978). Further evidence that addresses the ques­ many shrubs. Some large trees including Metase­ tion of size of the lake includes the presence of quoia (Dawn Redwood) were found at a distance large fishes such as 1-1.5 meter-long specimens of from the lake's edge on higher ground (see cover). Amia and abundant remains of Lepisosteus. Each of these predaceous forms would require large ex­ Lake Wannagan and its surroundings were panses of open water with appreciable depth and a haven for the many species that constitute the a good supply of prey species. In the description Wannagan Creek Fauna (Table 2). Most conspicu­ of the shoreline features discussed above under ous of the riparian taxa were the crocodile Stratigraphy, note was made of a lignitic layer mar­ Leidyosuchus (=BoreaJosuchus), the snapping turtle gin that was likely wave-base. Depth of the water Protochelydra and the fish-eating Champsosaurus at this point is judged to have been at least one (Erickson, 1982; 1991). Other reptiles include a meter (Sawyer, 1981). This in turn implies a con­ small altigatorine, other turtles, several lizards, and siderable fetch, further suggesting that a large body a palaeophid snake. Piceoerpeton. a "Hell-bender"­ of water was present. sized amphibian, and some smaller species are rep­

4 TABLE 1. WANNAGAN CREEK FLORA

The following list includes all plant fossil taxa from Fossil Lake Wannagan and bordering areas. Amended from Erickson (/991).

Alismaphyllites grandifo/ius Laurophyllum perseanum Amentotaxus campelli Magnolia berryi Ampelopsia acerifolia Magnolia magnifo/ia Azolla stanley;; Magnolia regaJis Canariophyllum ampla Melastomites montanensis Carpo/ithes arcticus Metasequoia occidenta/is Carpolithes sp. Minostites coloradensis Carya antiquorum Morus montanensis Castanea intermedia Nelumbium tenuifo/ium Celtis newberryi Oreopanax dakotensis Celtis peracuminata Pensophyllum cordatum Cercidiphyllum genetrix Persia brossiana Cissus marginata Planera microphylla Cocculus flabella Platanus nobilis Comus hyperborea Platanus reynoldsii Cory/us insignis cf. C. acutertiaria Po/areodoxites plicatus Cypericites sp. Porosia verrucosa Dictyophyllum anaomolum Prunus perita Dictyophyllum hebronensis Pterocarya hispida Equisetum Quercus sullyi Ficus artocarpoides d. Dietyophyllum Rhamnus c1ebumi Ficus minutidens cf. Dictyophyllum Sassafras thermate Ficus p/anistocata cf. Dictyophyllum sp. Sparganium stygium Ficus subtruncata d. Dietyophyllum sp. Taxodium o/riki Ginkgo adiantoides Ulmus rhamnifolia Glyptostrobus europaeus Viburnum antiquum Glyptostrobus nordenskioldi Viburnum asperum Hammamelites inaequalis Viburnum cupaneoides Hydrangea antica Vitis olriki Isoetites horridus Zamia c%radensis Juglans taurina Zelkova planeroides Zizyphus fibrillosus

5 TABLE 2. WANNAGAN CREEK FAUNA

Class GASTROPODA undet. genus Order Mesogastropoda undet. emydid Family Hydrobidae Order Squamata Hydrobia undet. varanid Family Viviparidae undet. palaeophid Viviparus Order Choristodera Family Pleuroceridae Champsosaurus gigas Liop/acodes Champsosaurus sp. Class PELECYPODA Order Crocodylia Family Unionidae Leidyosuchus undet. bivalves (=Borea/osuchus) formidabilis VVannaganosuchus Class INSECTA brachymanus Order Odonata Gomphaeschna schrankii Class AVES Order Coleoptera Order Charadriiformes undet. coleopteran Dakotornis coope,; Order Lepidoptera Presbyornis isoni undet. lepidopteran undet. plover-like shorebird

Class CHONDRICHTHYES Class MAM MALIA Order Batoidea Order Multituberculata My/iobatis sp. Neoplagiaulax hazeni Neoplagiau/ax d. N. hunteri Class OSTEICHTHYES Neoplagiau/ax mcldnnai Order Lepisosteiformes Ptilodus wyomingensis Lepisosteus sp. Ptilodus sp. Order Amiiformes Catopsa/is sp. Amia fragosa Order Polyprotodonta Order Osteoglossiformes Peradectes sp. Family Osteoglossidae Order Insectivora Joffrichthyes symmetropterus Leptictis sp. Family Hiodontidae cf. Pa/aeoryetes sp. d. Eohiodon Propalaeosinopa sp. Order Salmoniformes Labidolemur soricoides Family Esocidae Order Lipotyphla Esox d. E. tieman d. Leptacodon fnotomo/estes sp. Class AMPHIBIA Order Primates Order Urodela P/esiadapis churchilli Piceoerpeton willwoodense Plesiadapis sp. Scapherpeton sp. Ignacius sp. Order Anura d. Phenaco/emur sp. undet. anuran Order Carnivora Prot;et;s d. Micro/estes Class REPTI L1A Order Condylarthra Order Chelonia Thryptacodon cf. T australis Trionyx/Aspidere te s Thryptacodon sp. Plastomenus sp. fotocion sp. Protochelydra zangerli Phenacodus sp.

6 resented. Amia and Lepisosteus, mentioned ear­ and semi-aquatic plants occurring at all levels of lier. along with bony fishes such as Esox and the excavation site; 4) a shoreline habitat that was Joffrichthyes. were found at all levels within the lake. utilized by water-loving birds and water-seeking A browsing, sheep-sized mammal, Phenacodus, and land dwellers; and 5) comparison with present­ a badger-sized carnivore, Proticris, represent the day floodbasin lakes. largest land dwellers-collected. Tree-climbers such as the primates Plesiadapis and Phenacolemur, along Areas bordering Lake Wannagan have with multituberculates and insectivores, occupied yielded fewer fossils, and in several cases taxa the forest canopy and underbrush. Avian evidence poorly or not represented in the quarry. of water-loving birds Presbyornis and Dakotornis, Taphonomic differences between the two loca­ and a plover-like shorebird are also counted in the tions are also remarkable in that the majority of thanatocoenosis. Kihm and Hartman (1995) de­ bones in the swamp/lake deposits are disartiCU­ scribed footprints of probable shorebirds, which lated, presumably due to bioturbation, whereas inhabited a nearby floodplain. Insects were un­ completely articulated skeletons occur in doubtedly plentiful, but not found in significant stratigraphically equivalent, nearby layers. The numbers perhaps due to the vicissitudes of water three factors largely responsible for this are the currents and severe bioturbation. Ichnofossils in paucity of crocodiles and more importantly, the the form of burrows (Melchior and Erickson, 1979) existence of quiet backwaters and temporary shal­ established the presence of additional species. low pools, as well as interfluves beyond the pe­ rimeter of the lake. Some of these playas pro­ DISCUSSION vided unique habitats. The shore was also an esti­ mated gathering place for many species and the Lake Wannagan is an example of one eco­ abundance ofcrocodilian coprolites throughout the system which characterized the western interior deposits indicates that it was also a feeding place of North America during Late Paleocene time. for the large crocodile (Sawyer, 1981). Due to fortuitous circumstances of preservation, a freshwater lakeshore and its biota affords a In 1996, operations at Wannagan Creek unique opportunity to study its development and Quarry ended. Final inspection and location of all its local fauna. survey points were made and the entire excava­ tion was back-filled, sloped, subsequently seeded Certain fossil mammalian species indicate and fertilized as per requirements of the U.S. For­ an age of about 60 m.y.b.p. This estimate is de­ est Service. Plans call for continued investigation rived from Plesiadapis churchilli, an "index" taxon in the surrounding area. Surface collecting will con­ of Tiffanian 4 (Sloan, 1987). tinue in an effort to gather further scarce or new specimens, and to revisit earlier evaluations about Evidence inferring the durability of the lake the paleoenvironment of the area. over a long period oftime is: I) the stability im­ plied by a subtropical environment; 2) a thick mar/­ REFERNCES bottom bed with overlying accumulations of interstratified lignite and shale; and 3) the large Benson, RD. in press. Presbyornis isoni and other number of individuals of several taxa which had Late Paleocene Birds from North Dakota: well-established nesting regimens, including old Smithsonian Contributions to Paleobiology individuals. (conference volume of Society of Avian Pale­ ontology and Evolution). The large size of Lake Wannagan can be inferred from: I) a wave-base at a meter or more Brew, D.A., A.B. Ford, RD. Koch, M.F. Diggles, below the water's surface; 2) the presence of large J.L. Drinkwater, R.A. Loney, and J.G. Smith, predaceous fishes; 3) the large quantity of aquatic 1993, GPS versus template-simple field and 7 office experiments concerning GPS-deter­ Proceedings ofthe North Dakota Academy ofSci­ mined positions and template: Geological Sur­ ence, vol. 49, p. 65. vey Publication, p. 199-205. Melchior, R.C, 1976, Oreopanaxdakotensis, A new Butler, R.F., E.H. Lindsay, and P.D. Gingerich, 1980, species of the Araliacea from the Paleocene of Magnetic polarity stratigraphy and Paleocene­ North Dakota: SCientific Publications of the Eocene biostratigraphy of Polecat Bench, Science Museum of Minnesota, vol. 3, no. 3, p. northwestern Wyoming, in Early Cenozoic Pa­ 1-8. leontology and Stratigraphy of the Bighorn Ba­ sin, Wyoming: Gingerich, P.D. ed., University of ___' 1977, On the occurrence ofMinerisporites Michigan Papers on Paleontology, vol. 24, p. 95­ mirabilis in situ: Scientific Publications of the 98. Science Museum ofMinnesota, vol. 3, no. 4, p. I-I I. Cott, J.B., 1960, Scientific results of inquiry into the ecology and economic status of the Nile croco­ Melchoir, R.C, and B.R. Erickson, 1979, Paleonto­ dile (Crocodilusniloticus) in Uganda and north­ logical notes on the Wannagan Creek Quarry ern Rodesia: Transactions of the Zoological So­ site (Paleocene-North Dakota) Ichnofossils I: cietyof London, vol. 29, p. 211-356. SCientific Publications of The Science Museum ofMinnesota, vol. 4, no. 4, p. 1-/6. Erickson, B.R., 1982, The Wannagan Creek Quarry and its reptilian fauna (Bullion Creek Forma­ Melchior, R.C, and J.W. Hall, 1983, Some me­ tion, Paleocene) in Billings County, North Da­ gaspores and other small fossils from the kota: North Dakota Geological Survey Report of Wannagan Creek site (Paleocene) North Da­ Investigation Number 72, p. 1-17. kota: Palynology, vol. 7, p. 133-145.

____, J991 , Flora and fauna of the Wannagan Murphy, E.C, J.W Hoganson, and N.F. Forsman, Creek Quarry: Late Paleocene of North 1993, The Chadron, Brule, and Arikaree For­ America: SCientific Publications of The Science mations in North America, the buttes ofsouth­ Museum of Minnesota, vol. 7, no. 3, p. 1-19. western North Dakota: North Dakota Geologi­ cal Survey Report of Investigation Number 96, p. Jacob, AC, 1972, Depositional environments of 1-144. parts of the Tongue River Formation, western North Dakota, in Depositional Environments Olson, S.L., 1994, A giant Presbyornis (Aves: of Lignite-Bearing Strata in Western North Da­ Anseriformes) and other birds from the Pale­ kota: North Dakota Geological Survey Miscella­ ocene Aquia Formation of Maryland and Vir­ neous Series 50, p. 43-62. ginia" Proceedings of the Biological Society of Washington. vol. 107, p. 429-435. Kihm, AJ., 1993, Late Paleocene mammalian biochronolgyofthe Fort Union Group in North Royse. CF., Jr., 1967, The Tongue River-Sentinel Dakota: Plesiadapis (Plesiadapiformes) from Butte contact in western North Dakota: North the Brisbane, Judson, and Wannagan Creek Dakota Geological Survey Report of Investiga­ Quarry local faunas, The Marshall Lambert Sym­ tion Number 45, p. I-53. posium, AJ. Kihm and J.H. Hartman, eds., Bis­ marck: North Dakota Geological Society, p. ___' 1970, A sedimentologic analysis of the 26-27. Tongue River-Sentinel Butte interval (Pale­ ocene) of the Williston Basin, western North Kihm, Aj., and J.H. Hartman, 1995, Bird tracks Dakota: Sedimentary Geology, vol. 4, no. I, p. from the Late Paleocene of North Dakota: 19-80. 8 ___' 1972, The Tongue River and Sentinel Selley, R.C, 1978, Ancient Sedimentary Environ­ Butte Formations of western North Dakota, a ments: Cornell University Press, Ithaca, NY. review. North Dakota Geological Survey 2nd Ed., 287 p. Miselfaneous Series 50, p. 31-42. Sloan, R.E., 1987, Paleocene and latest Cretaceous Sawyer, G.T., 1981, A study of crocodilian coproli­ mammal ages, biozones, magnetozones, rates tes from the Wannagan Creek Quarry (Pale­ of sedimentation, and evolution: Geological ocene-North Dakota) Ichnofossils II: Scientifrc Society of America, Special Paper 209, p. 165­ Publications of The Science Museum of Minne­ 200. sota, vol. 5. no. 2, p. 1-29.

Schaeffer, B., and M. Mangus, 1965, Fossil lakes from the Eocene: American Museum of Natu­ " ral History, vol. 74, no. 4, p. 11-21.

9