An Occurrence of the Protocetid Whale" Eocetus" wardii in the Middle Eocene Piney Point Formation of Virginia by Jason Osborne | Papers by Jason

Journal of Paleontology, 85(2), 2011, p. 271–278 Copyright ’ 2011, The Paleontological Society 0022-3360/11/0085-0271$03.00 AN OCCURRENCE OF THE PROTOCETID WHALE ‘‘EOCETUS’’ WARDII IN THE MIDDLE EOCENE PINEY POINT FORMATION OF VIRGINIA ROBERT E. WEEMS,1 LUCY E. EDWARDS,1 JASON E. OSBORNE,2 1 AND AARON A. ALFORD2 926A National Center, United States Geological Survey, Reston, Virginia 20192, USA, ,rweems@usgs.gov., ,leedward@usgs.gov.; and 2Paleo Quest, 14243 Murphy Terrace, Gainesville, Virginia 20155, USA, ,osbornej@paleoquest.org., ,alforda@paleoquest.org. ABSTRACT—Two protocetid whale vertebrae, here referred to ‘‘Eocetus’’ wardii, have been recovered from the riverbed of the Pamunkey River in east-central Virginia. Neither bone was found in situ, but both were found with lumps of lithified matrix cemented to their surfaces. Most of this matrix was removed and processed for microfossils. Specimens of dinoflagellates were successfully recovered and this flora clearly demonstrates that both vertebrae came from the middle Eocene Piney Point Formation, which crops out above and below river level in the area where the bones were discovered. These vertebrae are the oldest whale remains reported from Virginia and are as old as any cetacean remains known from the western hemisphere. INTRODUCTION T record of whale evolution in North America is not well documented. The oldest fossil material from anywhere within the Atlantic and Gulf coastal plains is middle Eocene in age and is from the Blue Bluff unit of Georgia (Hulbert et al., 1998; Hulbert, 1998), the Santee Limestone of South Carolina (Albright, 1996; McLeod and Barnes, 2008), and the Castle Hayne Limestone of North Carolina (McLeod and Barnes, 1990, 1991, 1996, 2008; Uhen, 1999, 2001) (Fig. 1, Table 1). Slightly younger material, still of middle Eocene age, has been reported in South Carolina from the Cross Member of the Tupelo Bay Formation of Geisler et al. (2005), in Alabama from the upper Lisbon Formation (Uhen, 2008), in Mississippi from the Potterchitto Member of the Cook Mountain Formation (Uhen, 2008), and in Louisiana from the Milams Member of the Cook Mountain Formation (Uhen, 1998). Late Eocene whale fossils have been reported from the Atlantic Coastal Plain in the Harleyville Formation of South Carolina (Sanders, 1974), and Oligocene whale fossils have been reported from the Ashley and Chandler Bridge formations of South Carolina (Sanders et al., 1982; Weems and Sanders, 1986; Sanders and Barnes, 2002a, 2002b). Farther north, in eastern Virginia, remains of Miocene and Pliocene fossil whales have been reported in the scientific literature since early in the nineteenth century (Mitchill, 1818; Lyell, 1842; Wyman, 1850; and numerous papers thereafter). No older material from this region has been reported until now, probably due to the very limited outcrops of appropriately aged sediments. Available evidence suggests that whales evolved in the India-Pakistan region and did not become sufficiently seaworthy to reach North America until sometime during the middle Eocene (Uhen, 1999; Geisler et al., 2005). Although early Eocene deposits of the Nanjemoy Formation are widespread in Virginia and Maryland, these deposits almost certainly are too old to contain cetacean remains. The only strata of an appropriate middle Eocene through Oligocene age that crop out in Virginia occur along a limited stretch of the lower, tidal portion of the Pamunkey River, where middle Eocene strata (Piney Point Formation) and lower Oligocene strata (Old Church Formation) are exposed, and on the south side of the upper tidal portion of the James River east of Hopewell, where the middle Eocene Piney Point Formation occurs (Ward, 1984). Upper Eocene deposits (the Chickahominy Formation) are known from Virginia (Powars and Bruce, 1999; Edwards et al., 2005), but they are deeply HE EARLY buried and therefore virtually inaccessible to exploration for cetacean remains. North of Virginia, beds of middle Eocene through late Oligocene age are known almost entirely from the subsurface of the coastal plain, except for a few middle Eocene outcrops along the Shark River in New Jersey (Self-Trail and Bybell, 1995). This void in the early cetacean fossil record of the Virginia coastal plain now has been partly filled by the recovery of an anterior thoracic and a posterior lumbar cetacean vertebra of primitive aspect from the bottom of the Pamunkey River near Putneys Mill, about one mile north-northeast of Tunstall, Virginia. Although isolated bones and teeth have been recovered in this region by a number of divers in the past, nearly all of this material has been washed clean of its surrounding sediment, leaving no direct evidence of its stratigraphic context. In both vertebrae described here, however, indurated calcite-cemented quartz-glauconite sand matrix was attached to and partially encased the bones. This matrix, while complicating fossil preparation, was invaluable for microfossil study. In the Pamunkey River valley, calcitecemented nodules can occur in the Nanjemoy, Piney Point, Old Church, and basal Calvert Formations, so it was important to try to ascertain precisely which stratigraphic unit yielded each specimen through microfossil recovery and analysis. To this end, matrix was removed from each vertebra and processed separately both for calcareous nannofossils and for dinoflagellates. MICROFOSSIL RESULTS Paleogene stratigraphic units in the Pamunkey River valley often yield abundant nannofossil floras (e.g., DiMarzio, 1984; Bybell and Gibson, 1994), but none were recovered from either sample discussed here. In all probability, the chemical processes that induced calcite-cementation in this material also resulted in recrystallization of any nannofossils that originally may have been present. In contrast, dinoflagellates were unharmed by the cementation process and yielded floras that, while not extremely abundant or diverse, nevertheless were stratigraphically diagnostic for each specimen. The flora recovered from each sample is shown in Table 2. The sample from the posterior lumbar vertebra was more abundant and diverse than the sample recovered from the anterior thoracic vertebra, but both were adequate to show that their contained flora is middle Eocene (late Lutetian to Bartonian) in age. In eastern Virginia, the only outcropping 271 272 JOURNAL OF PALEONTOLOGY, V. 85, NO. 2, 2011 TABLE 2—Species of dinoflagellates recovered from matrix surrounding the protocetid vertebrae found on the bed of the Pamunkey River. Sample: R6669, from posterior lumbar vertebra of Eocetus wardii Age: middle Eocene (within upper half) Preservation: fair to good. Diversity: Diverse, no single species dominates. Other fossils present: pollen, foram linings Flora identified: Achilleodinium biformoides (Eisenack 1954) Eaton 1976 Cleistosphaeridium placacanthum (Deflandre & Cookson 1955) Eaton et al. 2001 Corrudinium sp. I of Edwards 1984 Cribroperidinium Neale & Sarjeant 1962 sp. Deflandrea phosphoritica Eisenack 1938 Elytrocysta Stover & Evitt 1978 sp. or spp. Heteraulacacysta Drugg & Loeblich 1967 sp. Hystrichokolpoma Deflandre & Cookson 1955 sp. Lingulodinium machaerophorum (Deflandre & Cookson 1955) Wall 1967 Lophocysta ? Manum 1979 sp. Operculodinium Wall 1967 sp. Palaeocystodinium golzowense Alberti 1961 Pentadinium goniferum Edwards 1982 Pentadinium laticinctum Gerlach 1961 subsp. laticinctum Samlandia Eisenack 1954 sp. Spiniferites Mantell 1850 spp. Tectatodinium pellitum Wall 1967 Thalassiphora pelagica (Eisenack 1954) Eisenack & Gocht 1960 Turbiosphaera ? Archangelsky 1969 sp. Wetzeliella-group spp. miscellaneous areoligeracean forms (Glaphyrocysta group) small peridiniacean forms Sample: R6669 B, from anterior thoracic vertebra of Eocetus wardii Age: middle Eocene (within upper half) Preservation: Poor. Diversity: Only a few specimens recovered. Other fossils present: Rare pollen. Flora identified: Deflandrea phosphoritica Eisenack 1938 Elytrocysta Stover & Evitt 1978 sp. or spp. Lingulodinium machaerophorum (Deflandre & Cookson 1955) Wall 1967 Pentadinium goniferum Edwards 1982 Pentadinium laticinctum Gerlach 1961 subsp. laticinctum Spiniferites pseudofurcatus (Klumpp 1953) Sarjeant 1970 Thalassiphora pelagica (Eisenack 1954) Eisenack & Gocht 1960 Wetzeliella-group sp. miscellaneous areoligeracean forms (Glaphyrocysta group) FIGURE 1—Regional map of the southeastern United States showing the location of Piney Point Formation outcrops along the Pamunkey River in Virginia, and the locations of other middle Eocene protocetidbearing strata in North Carolina, South Carolina, and Georgia. In North Carolina, the southern star marks the type area of ‘‘Eocetus’’ wardii and the northern star marks the type area of Crenatocetus rayi. Dashed line approximates the southernmost known range of ‘‘Eocetus’’ wardii. STRATIGRAPHIC CONTEXT unit known to fall within this age range is the Piney Point Formation. The Piney Point is the same age as the Comfort Member of the Castle Hayne Formation in North Carolina, the Santee Limestone in South Carolina, and the Blue Bluff unit in Georgia (Weems et al., 2004). These age-equivalent units have yielded the oldest reported remains of protocetid whales from anywhere within the Atlantic and Gulf coastal plains (Albright, 1996; Hulbert et al., 1998; Uhen, 1999, 2001; McLeod and Barnes, 2008) (Table 2). Based on the age of the associated dinoflagellate flora, the only unit in this region from which these specimens could have come is the middle Eocene (upper Lutetian to lower Bartonian) Piney Point Formation. A core hole drilled at Putneys Mill, Virginia (Fig. 2), which is within a mile of where these bones were found, recovered a 38-foot section of the Piney Point between the lower Eocene Nanjemoy Formation and the mid-Oligocene Old Church Formation (Edwards, 1982, 1984; Bybell and Gibson, 1994). Throughout the Pamunkey River valley region the Piney Point has been subdivided into three beds by Ward (1984, 1985), which he designated as A, B, and C from oldest to youngest. Morrell (1984) assigned all of these beds to the middle Eocene (Claibornian) Cubitostrea sellaeformis zone, which can be TABLE 1—Occurrences of middle Eocene protocetid whales in the southeastern Atlantic Coastal Plain of the United States. Stage Bartonian (NP 17) Upper Lutetian to lower Bartonian (NP 16) Georgiacetus vogtelensis Blue Bluff unit Georgia South Carolina Carolinacetus gingerichi Cross Member, Tupelo Bay Fm. Georgiacetus aff. G. vogtelensis Santee Limestone North Carolina Virginia ‘‘Eocetus’’ wardii Crenatocetus rayi Comfort Member, Castle Hayne Fm. ‘‘Eocetus’’ wardii Piney Point Formation WEEMS ET AL.—PROTOCETID WHALE FROM VIRGINIA recognized as far south and west as Texas. Beds A and B can be confidently assigned to nannofossil Zone NP16, but bed C (the uppermost three feet of the unit) probably was deposited during nannofossil zone NP 17 (Bybell and Gibson, 1994). The dinoflagellate flora from the Putneys Mill core also supports an early Bartonian age for bed C (Edwards, 1984; Ward, 1984). Ward (1984) described calcite-cemented nodules in bed A and calcite-cemented oyster layers in bed B, but no one has reported any calcite cementation in bed C. This suggests that the specimens described here in all likelihood come from bed A or B, though this cannot be rigorously demonstrated. The depositional environment of the Piney Point was a shallow, open marine shelf environment at about 60 to 120 ft water depth based on foraminifera (Bybell and Gibson, 1994), mollusks (Strickland, 1984; Ward, 1984), and ostracodes (Deck, 1984). Muller (1999) has documented 19 species of ¨ sharks, 9 species of rays, and 57 otolith species of bony fish from the Piney Point. These vertebrates also indicate deposition in a shallow neritic environment. The molluscan fauna indicates a mild to warm temperate marine environment during the middle Eocene in the eastern Virginia region (Ward, 1984). The palynomorph assemblage reported from this unit by Frederiksen (1984) is dominated by extinct genera and species of the Fagaceae (which today includes oaks, beech, and chestnuts) with lesser amounts of pollen produced by extinct species of the Juglandaceae (which today includes walnuts, pecans, and hickories). Ferns, palms and tupelo (Nyssa) are also present. Together, these and other palynomorphs indicate a winter-dry tropical climate onshore in this region during the middle Eocene (Frederiksen, 1984). The sediments of the middle Eocene are clastic-poor throughout the southeastern United States, indicating that inland areas in this region had very low relief at that time, were well vegetated, and provided very little sediment input into the tropical to subtropical Atlantic and Gulf coastal plain regions (Weems et al., 2004). MATERIAL 273 Specimens include two vertebrae, an anterior thoracic (CMM-V-4334) and a posterior lumbar (CMM-V-4335), both lacking epiphyses and the greater part of their transverse processes and neural arches. Both specimens were collected on 18 July 2009 (by Jason Osborne and Aaron Alford) on the riverbed of the Pamunkey River in the vicinity of Putneys Mill (37.604 N, 77.092 W), north-northeast of Tunstall, Virginia. In this region, the Pamunkey River is the boundary line between New Kent and King William counties, Virginia. Specimens are from the Piney Point Formation and are probably late Lutetian but possibly early Bartonian in age. Both specimens are now held at the Calvert Marine Museum, Solomons, Calvert County, Maryland. TAXONOMIC ASSIGNMENT the lumbar vertebra can be confidently assigned to ‘‘E.’’ wardii. The mid-thoracic vertebra is quite different in its overall length (Fig. 4), but in ‘‘Eocetus’’ wardii there is an exceptional elongation of the vertebral series starting in the thoracic region and continuing back toward the lumbar region. This degree of vertebral elongation in the lumbar region is greater than that found in any other known protocetid whale. In the type specimen of ‘‘E.’’ wardii, a far anterior thoracic vertebra has a ventral centrum length of 59.5 mm, whereas a far posterior lumbar vertebra has a ventral centrum length of 183 mm (Uhen, 1998, 2001). This is slightly greater than the difference in values for the specimens at hand, which have a preserved ventral centrum length of 63 mm and 143 mm, respectively. Neither Piney Point vertebra has epiphyses attached to its centrum, so each is from a subadult animal and both of these centra would have been slightly but comparably longer when complete. Both bones have a size relative to each other that is comparable to correlative bones in the vertebral series of ‘‘Eocetus’’ wardii, and the thoracic vertebra also has the distinctive pock-marked surface texture found in ‘‘E.’’ wardii. Therefore, the thoracic vertebra also can be referred confidently to this taxon. As both bones were found along the same stretch of riverbed, have a comparable relative size, and show a similar degree of maturity, it seems quite possible that they came from a single individual. Uhen (1998, 2001) assigned ‘‘E.’’ wardii to the genus Eocetus, which was originally described from Egypt. The type species (E. schweinfurthi) is based on a somewhat damaged skull, with two vertebrae assigned to it that were inferred to belong to this form but were not directly associated with the type material. Geisler et al. (2005), noting the lack of direct association of the type skull with the referred vertebrae and the poor preservation of the posterior portion of the type skull, have questioned the assignment of ‘‘E.’’ wardii to the genus Eocetus and recommended that this species be designated as ‘‘Eocetus’’ wardii until such time as more complete material of Eocetus schweinfurthi can clarify just how closely related these two species are. We follow this recommended designation, but note that even if future discoveries of better material of E. schweinfurthi prove that the American material is distinctive enough to belong in its own genus, referral of our material to the species wardii remains firm. DISCUSSION The lumbar vertebra illustrated here (Fig. 3) is exceptionally large for a protocetid whale, and only ‘‘Eocetus’’ wardii Uhen is known to reach a comparable or somewhat larger size (Hulbert et al., 1998; Uhen, 1999, 2001; Geisler et al., 2005). Additionally, the distinctive pock-marked external texture of the bone, the presence of dense layered cortical bone, and the exceptional elongation of the centrum and basal transverse processes are all features unique to material assigned to Eocetus among protocetid whales (Uhen, 1999, 2001). Thus, based on size, bone texture, and the exceptional anteroposterior elongation of its centrum and transverse processes, The lower Eocene Nanjemoy Formation, which spans calcareous nannofossil Zones NP 10 and NP 13, is extensively exposed in both Virginia and Maryland. These outcrops have been searched extensively for fossils for well over one hundred years (e.g., Clark, 1896), and a considerable vertebrate fauna has been recovered from this unit (e.g., Weems and Grimsley, 1999), but not one tooth or scrap of bone referable to a cetacean has been found. A scapula of a putative primitive whale (Anglocetus beatsoni) was reported from the ageequivalent lower Eocene London Clay of England by Tarlo (1964), but that specimen later was referred to the primitive leatherback sea turtle Eosphargis gigas (Halstead, 1984). Except for this one now refuted claim, no whale material ever has been reported from the London Clay despite more than two hundred years of intensive collecting. As neither the lower Eocene Nanjemoy Formation nor the lower Eocene London Clay has yielded any whale remains, it seems virtually certain that cetaceans were not present either in the northern Atlantic 274 JOURNAL OF PALEONTOLOGY, V. 85, NO. 2, 2011 WEEMS ET AL.—PROTOCETID WHALE FROM VIRGINIA 275 FIGURE 3—Lumbar vertebra of ‘‘Eocetus’’ wardii Uhen, found in the bed of the Pamunkey River. A is ventral view with anterior end down; B is dorsal view with anterior end up; C is right lateral view; D is posterior view. Scale bar 5 5 cm. Coastal Plain or in the London Basin region during early Eocene time. The oldest and most primitive remains of whales found anywhere occur in lower Eocene to lower middle Eocene sediments in Pakistan and western India, and are referable to the families Pakicetidae, Ambulocetidae, and Remingtonocetidae. (Sahni and Mishra, 1975; Gingerich et al., 1995). These were all rather small animals that were only partly adapted to an aquatic existence. This stock gave rise to the family Protocetidae, which was much better adapted to marine life and spread throughout the Tethys Sea region and then to eastern North America during the middle Eocene (Uhen, 1999; Geisler et al., 2005). The occurrence of whale remains in the Piney Point Formation, the Comfort Member of the Castle Hayne Formation, and the Santee Limestone, all of which contain middle Eocene (upper Zone NP16) calcareous nannofossils, demonstrates that whales had reached eastern North America by late Lutetian time. The material from the Santee Limestone additionally indicates that at least two and perhaps three different species were present (Albright, 1996; Geisler et al., 2005, p. 52). Therefore, the time of the earliest r cetacean dispersal to eastern North America was no earlier than the latest early Eocene (early Zone NP14) and no later than late middle Eocene (early Zone NP16). This is a firm but fairly large window of time within which protocetid whales spread from the Tethys region to southeastern North America (approximately 49 to 42 million years ago, or latest Ypresian through early Lutetian time; Gradstein et al., 2004). The Congaree and Warley Hill Formations in South Carolina are among the few outcropping strata in the southeastern United States that are referable to the lower or middle Lutetian (calcareous nannofossil Zones upper NP14, NP 15, and lower NP 16), and no whale remains have been reported from either unit. Because outcrops are sparse, however, there is no way to be sure if protocetid whales are absent from these strata or if insufficient time has been spent prospecting them to provide a reasonable chance for finding whale remains. Thus, for now, it is not certain exactly when within this time interval protocetid whales first arrived offshore of North America. However, it is interesting to note that there was a major change in the depositional regime throughout the Atlantic and Gulf coastal plains of the FIGURE 2—Stratigraphic column of the Putneys Mill core (after Bybell and Gibson, 1994), which shows representative stratigraphy of the Eocene and Oligocene section exposed along the Pamunkey River in Virginia. Bed designations are from Ward (1984, 1985) except for the Woodstock, which is divided here into bed A and bed B. Age of Marlboro Clay is from Gibson and Bybell (1994). Calcareous nannofossil zones are from Martini (1971). 276 JOURNAL OF PALEONTOLOGY, V. 85, NO. 2, 2011 FIGURE 4—Thoracic vertebra of ‘‘Eocetus’’ wardii Uhen, found in the bed of the Pamunkey River. A is dorsal view with anterior end down; B is ventral view with anterior end down; C is anterior view; D is left lateral view. Scale bar 5 5 cm. southeastern United States around the lower-middle Eocene boundary, which was the basis for establishing the boundary between the Ancora and Trent Supergroups (Weems et al., 2004). Deposition regionally changed from a clastic-dominated regime in the Ancora Supergroup to a carbonatedominated regime in the Trent Supergroup, and this corresponds to the time at which the climate within the northern North Atlantic basin (and elsewhere) changed from exceptionally warm and stable in the early Eocene to relatively cooler and much more unstable in the middle and late Eocene (Wade and Kroon, 2002, 2003). Because these strong shifts in climate, depositional regime, and oceanic circulation pattern occurred in the North Atlantic region at or close to the earlymiddle Eocene boundary, we suggest that this change in climate and circulation pattern may have been the event that provided the initial opportunity for whales to cross the Atlantic Ocean and become established in the southeastern United States. Feldmann et al. (1998) noted that there was an extensive dispersal of decapod crustaceans from the Tethys region to North Carolina in the middle Eocene, and they suggested that this occurred due to a major change in ocean currents at the beginning of the middle Eocene that created a strong westward flowing north-equatorial current. Uhen (1999), citing their work, suggested that the initial cetacean colonization of North America occurred by coastal migration along the northern coast of Africa and then by riding across the Atlantic to northeastern South America on this north-equatorial current into the Caribbean region and then to the southeastern United States. However, Geisler et al. (2005) have disputed the likelihood of this scenario on the grounds that protocetid whales were still poorly adapted to marine life at that time and probably could not have survived a direct trans-Atlantic crossing between Africa and South America, even considering the much narrower breadth of the Atlantic between these continents in the middle Eocene (Smith et al., 1994). Instead, they argued strongly that the more likely path of migration was by way of shallow marine shelf waters around the rim of the North Atlantic, hopping across short stretches of deep water between Britain and Greenland and between Greenland and North America, then migrating down the coast of eastern North America. This route would have required much shorter WEEMS ET AL.—PROTOCETID WHALE FROM VIRGINIA hops across deep water than a southern dispersal across a single long trans-Atlantic gap. Both routes have their appeal. However, in view of the fact that the Piney Point, Castle Hayne, Santee, and Blue Bluff whale remains are of late Lutetian to perhaps early Bartonian age, both routes for now suffer from a complete absence of evidence for fossil whales of Lutetian age in either northwestern Europe or northeastern South America. In Europe the oldest known whale remains are from the upper middle Eocene Bartonian stage, above the Lutetian. In Germany a protocetid whale has been reported from the Stockletten Formation of Bavaria (Uhen and Berndt, 2008), and in England two relatively advanced species of basilosaurids have been reported (Prozeuglodon (now Dorudon) and Basilosaurus) (Seeley, 1876; Andrews, 1907; Halstead and Middleton, 1972; McLeod and Barnes, 2008). This does not suggest an abundance of archaeocetes in this region during the middle Eocene, even after the Lutetian. In northeastern South America, no whale remains have been reported from any part of the middle Eocene. This could be due to lack of outcrop and/or collecting, however, because middle Eocene protocetids recently have been reported from southern Peru (Uhen et al., 2008). For now, the exact path of migration to eastern North America by protocetid whales remains undocumented, and it is by no means impossible that the earliest whales came to North America around the rim of the North Pacific and through the then-open Central American seaway. In any case, by the late Lutetian protocetid whales were well established along the eastern seaboard of the present United States and even then were represented by several immigrant species. Uhen (2001) has noted that, despite intensive searching in South Carolina, Georgia, Alabama, and Mississippi, no remains of ‘‘Eocetus’’ wardii have been found. One could argue that ‘‘E.’’ wardii became extinct by the end of middle Eocene calcareous nannofossil Zone NP16, and that this would explain why its remains are not found among the relatively common whale remains recovered in strata that were deposited during the time of late middle Eocene Zone NP17. This, however, still would not explain why ‘‘E.’’ wardii has not been reported from the demonstrably age equivalent and whale bone-bearing Santee Limestone in South Carolina (Geisler et al., 2005) and the Blue Bluff unit in Georgia (Hulbert et al., 1998). The fact that ‘‘E.’’ wardii now has been recovered much farther north from age-equivalent strata in Virginia shows that this species is not endemic to only a small region in southeastern North Carolina, but rather seems to have been a species with a broad but more northerly range than other known North American protocetids. This suggests that, even at this early date in whale evolution, there already was a latitudinal division between mild- to warm-temperate whale faunas versus subtropical to tropical whale faunas along the east coast of North America, comparable to differences documented for the molluscan fauna in those two areas (Ward, 1984). If the ancestor of ‘‘E.’’ wardii perhaps reached North America via a counterclockwise northern route, while Georgiacetus and Carolinacetus came via a clockwise southern route on a west-flowing equatorial current, then such a latitudinal boundary also might reflect the point at which two different but concurrent waves of migration met. Obviously, more complete and geographically more widespread material will be needed to answer these intriguing questions concerning the biogeography of the earliest cetacean inhabitants of the western North Atlantic and Caribbean regions. ACKNOWLEDGMENTS 277 The authors thank E. Seefelt and C. Durand for their careful preparation of the matrix from these specimens in search of calcareous nannofossils and dinoflagellate specimens; L. B. Albright III (University of North Florida), S. Godfrey (Calvert Marine Museum), A. E. Sanders (Charleston Museum), J. M. Self-Trail (USGS), and M. D. Uhen (George Mason University) for their careful and thoughtful reviews of the manuscript versions of this paper; and H. Starns, Jr. of AmericanWater Sports for providing important contributions of equipment and technical advice that aided greatly in the successful recovery of the specimens described here. REFERENCES ALBRIGHT, L. B. III. 1996. A protocetid cetacean from the Eocene of South Carolina. Journal of Paleontology, 70:519–523. ANDREWS, C. W. 1907. Note on the cervical vertebra of a Zeuglodon from the Barton Clay of Barton Cliff (Hampshire). Quarterly Journal of the Geological Society of London, 63:124–127. BYBELL, L. M. AND T. G. GIBSON. 1994. Paleogene stratigraphy of the Putneys Mill, New Kent County, Virginia, corehole. U. S. Geological Survey Open-File Report, 94–217:1–38. CLARK, W. B. 1896. The Eocene deposits of the Middle Atlantic slope in Delaware, Maryland, and Virginia. U. S. Geological Survey Bulletin, 141:1–167. DECK, L. T. 1984. Ostracodes of the Piney Point Formation, Pamunkey River, Virginia, p. 186–191. In L. W. Ward and K. Krafft (eds.), Stratigraphy and paleontology of the outcropping Tertiary beds in the Pamunkey River region, central Virginia Coastal Plain. Guidebook for the Atlantic Coastal Plain Geological Association 1984 field trip. DIMARZIO, J. A. 1984. Calcareous nannofossils from the Piney Point Formation, Pamunkey River, Virginia, p. 111–118. In L. W. Ward and K. Krafft (eds.), Stratigraphy and paleontology of the outcropping Tertiary beds in the Pamunkey River region, central Virginia Coastal Plain. Guidebook for the Atlantic Coastal Plain Geological Association 1984 field trip. EDWARDS, L. E. 1982. Early Tertiary dinoflagellates in the in the Putneys Mill Core, Virginia Coastal Plain, U.S.A. Palynology, 6:279. EDWARDS, L. E. 1984. Dinocysts of the Tertiary Piney Point and Old Church formations, Pamunkey River area, Virginia, p. 124–134. In L. W. Ward and K. Krafft (eds.), Stratigraphy and paleontology of the outcropping Tertiary beds in the Pamunkey River region, central Virginia Coastal Plain. Guidebook for the Atlantic Coastal Plain Geological Association 1984 field trip. EDWARDS, L. E., J. A. BARRON, D. BUKRY, L. M. BYBELL, T. M. CRONIN, C. W. POAG, R. E. WEEMS, AND G. L. WINGARD. 2005. Paleontology of the upper Eocene to Quaternary postimpact section in the USGS-NASA Langley core, Hampton, Virginia. In J. W. Horton, Jr., D. S. Powars, and G. S. Gohn (eds.), U. S. Geological Survey Professional Paper, 1688:H1–H47. FELDMANN, R. M., B. L. BICE, C. S. HOPKINS, E. W. SALVA, AND K. PICKFORD. 1998. Decapod crustaceans from the Eocene Castle Hayne Limestone, North Carolina: paleoceanographic implications. Journal of Paleontology, Memoir, 48:1–28. FREDERIKSEN, N. O. 1984. Sporomorph correlation and paleoecology, Piney Point and Old Church formations, Pamunkey River, Virginia, p. 135–149. In L. W. Ward and L. Krafft (eds.), Stratigraphy and paleontology of the outcropping Tertiary beds in the Pamunkey River region, central Virginia Coastal Plain. Guidebook for the Atlantic Coastal Plain Geological Association 1984 field trip. GEISLER, J. H., A. E. SANDERS, AND Z.-X. LUO. 2005. A new protocetid whale (Cetacea: Archaeoceti) from the late middle Eocene of South Carolina. American Museum of Natural History, Novitates, 3480:1–65. GIBSON, T. G. AND L. M. BYBELL. 1994. Sedimentary patterns across the Paleocene-Eocene boundary in the Atlantic and Gulf Coastal Plains of the United States. Bulletin de la Societe belge de Geologie, 103:237–265. ´ ´ ´ GINGERICH, P. D., M. ARIF, AND W. C. CLYDE. 1995. New archaeocetes (Mammalia, Cetacea) from the middle Eocene Domanda Formation of the Sulaiman Range, Punjab (Pakistan). Contributions from the Museum of Paleontology, University of Michigan, 29:291–330. GRADSTEIN, F. M., J. G. OTT, AND A. G. SMITH. 2004. A geologic time scale 2004. Cambridge University Press, Cambridge, p. 1–610. HALSTEAD, L. B. 1984. The first whale (Anglocetus beatsoni) is a turtle. Tertiary Research, 6:1–4. 278 JOURNAL OF PALEONTOLOGY, V. 85, NO. 2, 2011 SELF-TRAIL, J. M. AND L. M. BYBELL. 1995. Cretaceous and Paleogene calcareous nannofossil biostratigraphy of New Jersey. Annual Field Conference, Geological Association of New Jersey, 12:102–139. SMITH, A. G., D. G. SMITH, AND B. M. FUNNELL. 1994. Atlas of Mesozoic and Cenozoic coastlines. Cambridge University Press, New York, 99 p., 31 maps. STRICKLAND, G. L. 1984. Molluscan biozones of the Piney Point Formation (middle Eocene, Claibornian Age) in the Pamunkey River valley, Virginia, p. 155–182. In L. W. Ward and K. Krafft, (eds.), Stratigraphy and paleontology of the outcropping Tertiary beds in the Pamunkey River region, central Virginia Coastal Plain. Guidebook for the Atlantic Coastal Plain Geological Association 1984 field trip. TARLO, L. B. H. 1964. A primitive whale from the London Clay of the Isle of Sheppey. Proceedings of the Geologists’ Association, 74:319–324. UHEN, M. D. 1998. New protocetid (Mammalia, Cetacea) from the late middle Eocene Cook Mountain Formation of Louisiana. Journal of Vertebrate Paleontology, 18:664–668. UHEN, M. D. 1999. New species of protocetid archaeocete whale, Eocetus wardii (Mammalia: Cetacea) from the middle Eocene of North Carolina. Journal of Paleontology, 73:512–528. UHEN, M. D. 2001. New material of Eocetus wardii (Mammalia: Cetacea) from the middle Eocene of North Carolina. Southeastern Geology, 40:135–148. UHEN, M. D. 2008. New protocetid whales from Alabama and Mississippi, and a new cetacean clade, Palagiceti. Journal of Vertebrate Paleontology, 28:589–593. UHEN, M. D. AND H.-J. BERNDT. 2008. First record of the archaeocete family Protocetidae from Europe. The Fossil Record, 11:57–60. UHEN, M. D., N. D. PYENSON, T. J. DEVRIES, M. URBINA-SCHMITT. 2008. The oldest cetaceans from the southern hemisphere: new archaeocetes from the Pisco Basin of Southern Peru. Journal of Vertebrate Paleontology, Program Abstracts, 28:154A–155A. WADE, B. S. AND D. KROON D. 2002. Middle Eocene regional climate instability; evidence from the western North Atlantic. Geology, 30:1011–1014. WADE, B. S. AND D. KROON D. 2003. Middle Eocene regional climate instability and palaeoceanography of the western North Atlantic: implications for the position of the proto Gulf Stream. American Association of Petroleum Geologists, Annual Meeting Expanded Abstracts, 12:177. WARD, L. W. 1984. Stratigraphy of outcropping Tertiary beds along the Pamunkey River – Central Virginia Coastal Plain, p. 11–78. In L. W. Ward and K. Krafft (eds.), Stratigraphy and paleontology of the outcropping Tertiary beds in the Pamunkey River region, central Virginia Coastal Plain. Guidebook for the Atlantic Coastal Plain Geological Association 1984 field trip. WARD, L. W. 1985. Stratigraphy and characteristic mollusks of the Pamunkey Group (Lower Tertiary) and the Old Church Formation of the Chesapeake Group – Virginia Coastal Plain. U. S. Geological Survey Professional Paper, 1346:1–78, 6 plates. WEEMS, R. E. AND G. J. GRIMSLEY. 1999. Early Eocene vertebrates and plants from the Fisher/Sullivan site (Nanjemoy Formation) Stafford County, Virginia. Virginia Division of Mineral Resources Publication, 152:1–159. WEEMS, R. E. AND A. E. SANDERS. 1986. The Chandler Bridge Formation (upper Oligocene) in the Charleston region, South Carolina. Geological Society of America Centennial Field Guide, Southeastern Section, 6:323–326. WEEMS, R. E., J. M. SELF-TRAIL, AND L. E. EDWARDS. 2004. Supergroup stratigraphy of the Atlantic and Gulf Coastal Plains (Middle? Jurassic through Holocene, Eastern North America). Southeastern Geology, 42:191–216. WYMAN, J. 1850. Notice of remains of vertebrated animals found at Richmond, Virginia. American Journal of Science, ser. 2, 10:228–235. HALSTEAD, L. B. AND J. A. MIDDLETON. 1972. Notes on fossil whales from the upper Eocene of Barton, Hampshire. Proceedings of the Geologists’ Association, 83:185–190. HULBERT, R. C. 1998. Postcranial osteology of the North American middle Eocene protocetid Georgiacetus, p. 235–267. In J. G. M. Thewissen (ed.), The Emergence of Whales. Plenum Press, New York. HULBERT, R. C., R. M. PETKEWICH, G. A. BISHOP, D. BUKRY, AND D. P. ALESHIRE. 1998. A new middle Eocene protocetid whale (Mammalia: Cetacea: Archaeoceti) and associated biota from Georgia. Journal of Paleontology, 72:907–927. LYELL, C. 1842. On the Tertiary formations and their connexion with the Chalk in Virginia and other parts of the United States. Proceedings of the Geological Society of London, 3:735–742. MARTINI, E. 1971. Standard Tertiary and Quaternary calcareous nannoplankton zonation. Proceedings of the Second Planktonic Conference (Rome, 1969), p. 739–785. MCLEOD, S. A. AND L. G. BARNES. 1990. Archaeocete cetaceans from the Atlantic Coastal Plain of the United States, including a new protocetid. Journal of Vertebrate Paleontology, 9:35A. MCLEOD, S. A. AND L. G. BARNES. 1991. The most primitive cetacean from the western hemisphere and its relationships to other archaeocetes. Abstracts of the Ninth Biennial Conference on the Biology of Marine Mammals (Chicago, 1991), 46 p. MCLEOD, S. A. AND L. G. BARNES. 1996. The systematic position of Pappocetus lugardi and a new taxon from North America (Archaeoceti: Protocetidae). In Repetski, J. E. (ed.), Sixth North American Paleontological Convention, Abstracts of Papers, Paleontological Society Special Paper, 8:270. MCLEOD, S. A. AND L. G. BARNES. 2008. A new genus and species of Eocene protocetid archaeocete whale (Mammalia, Cetacea) from the Atlantic Coastal Plain. Science Series of the Natural History Museum of Los Angeles County, 41:73–98. MITCHILL, S. L. 1818. Observations on the geology of North America, illustrated by the description of various organic remains found in that part of the world, p. 319–424. In G. L. C. F. D. Cuvier, Theory of the Earth. Kirk and Mercein, New York. MORRELL, C. C., 1984. Cubitostrea from the Nanjemoy and Piney Point Formations, p. 183–185. In L. W. Ward and K. Krafft (eds.), Stratigraphy and paleontology of the outcropping Tertiary beds in the Pamunkey River region, central Virginia Coastal Plain. Guidebook for the Atlantic Coastal Plain Geological Association 1984 field trip. ¨ ¨ MULLER, A. 1999. Ichthyofaunen aus dem atlantischen Tertiar der USA. Leipziger Geowissenschaften, 9/10:1–360. POWARS, D. S. AND T. S. BRUCE. 1999. The effects of the Chesapeake Bay impact crater on the geologic framework and correlation of hydrogeologic units of the lower York-James Peninsula, Virginia. U. S. Geological Survey Professional Paper, 1612:1–82. SAHNI, A. AND V. P. MISHRA. 1975. Lower Tertiary vertebrates from western India. Monograph of the Palaeontological Society of India, 3:1–48. SANDERS, A. E. 1974. A paleontological survey of the Cooper Marl and Santee Limestone near Harleyville, South Carolina, preliminary report. Geologic Notes, South Carolina Geological Survey, 18:4–12. SANDERS, A. E. AND L. G. BARNES. 2002a. Paleontology of the Late Oligocene Ashley and Chandler Bridge Formations of South Carolina: 2, Micromysticetus rothauseni, a primitive cetotheriid mysticete (Mammalia: Cetacea). Smithsonian Contributions to Paleobiology, 93:271–293. SANDERS, A. E. AND L. G. BARNES. 2002b. Paleontology of the Late Oligocene Ashley and Chandler Bridge Formations of South Carolina: 3, Eomysticetidae, a new family of primitive mysticetes (Mammalia: Cetacea). Smithsonian Contributions to Paleobiology, 93:313–356. SANDERS, A. E., R. E. WEEMS, AND E. M. LEMON, JR. 1982. Chandler Bridge Formation—a new Oligocene stratigraphic unit in the lower coastal plain of South Carolina. U. S. Geological Survey Bulletin, 1529H:105–124. SEELEY, H. G. 1876. Notice of the occurrence of remains of a British fossil zeuglodon (Z. wanklyni, Seeley) in the Barton Clay of the Hampshire coast. Quarterly Journal of the Geological Society of London, 32:428–432. ACCEPTED 10 OCTOBER 2010