Weems and Brown—New Occurrences of Paleogene Sea Turtles in South Carolina Table 2. Sources used to establish the age ranges of the cheloniid taxa shown in Figure 11.
Argillochelys cuneiceps (Owen, 1849)—Lowest and highest occurrences are in the lower Eocene (Ypresian) London Clay, England (Moody, 1997). Ashleychelys palmeri Weems and Sanders, 2014—Lowest occurrences are in the lower Oligocene (upper Rupelian) Ashley Formation, South Carolina (Weems and Sanders, 2014) and Old Church Formation, Virginia (Weems, 2014); highest occurrences are in the upper Oligocene (mid-Chattian) Chandler Bridge Formation (Weems and Sanders, 2014; Weems et al., 2016).
Caretta caretta (Linnaeus, 1758)—No fossil record has been reported for this modern species, but other material assigned to this genus has been reported from the lower Pliocene Bone Valley Formation, Florida (Dodd and Morgan, 1992) and the lower Pliocene part of the Yorktown Formation, North Carolina (Zug, 2001).
Carolinochelys wilsoni Hay, 1923b—Lowest occurrences are in the lower Oligocene (upper Rupelian) Ashley Formation, South Carolina (Weems and Sanders, 2014) and the lower Oligocene (upper Rupelian) Old Church Formation, Virginia (Weems, 2014); highest occurrences are in the upper Oligocene (mid-Chattian) Chandler Bridge Formation, South Carolina (Weems and Sanders, 2014; Weems et al., 2016).
Chelonia mydas (Linnaeus, 1758)—No fossil record has been reported for this species, but specimens assigned to this genus without a species designation are reported from the lower Pliocene Bone Valley Formation, Florida (Dodd and Morgan, 1992).
Eochelone brabantica Dollo, 1903—Lowest and highest occurrences are in middle Eocene (Lutetian) strata at Saint Remy-Geest, Belgium (Casier, 1968).
Eretmochelys imbricata (Linnaeus, 1766)—No fossil record has been reported for this modern species, but specimens assigned to this genus without a species designation are reported from the lower Pliocene Bone Valley Formation, Florida (Dodd and Morgan, 1992). Erquelinnesia gosseleti (Dollo, 1886)—Lowest and highest occurrences are in lower Eocene (lower Ypresian) strata at Erquelinnes, Belgium (Zangerl, 1971).
Euclastes spp. (Eu. wielandi [Hay, 1908] + Eu. roundsi [Weems, 1988])—Lowest occurrence of Euclastes wielandi is in the Upper Cretaceous (middle Campanian) Coachman Formation, South Carolina (Schwimmer et al., 2015), highest occurrence is in the lower Paleocene (Danian) Brightseat Formation, Maryland (Weems, 2014); lowest and highest occurrences of Euclastes roundsi are in the upper Paleocene (Thanetian) Aquia Formation, Maryland and Virginia (Weems, 2014); genus ranges upward into upper Eocene (Priabonian) Parkers Ferry Formation, South Carolina (this paper).
Lepidochelys spp. (L. olivacea [Eschscholtz, 1829] + L. kempii [Garman, 1880])—No fossil record has been reported for these modern species, but specimens assigned to this genus without a species designation are reported from the lower Pliocene Bone Valley Formation, Florida (Dodd and Morgan, 1992) and the lower Pliocene part of the Yorktown Formation, North Carolina (Zug, 2001).
Lophochelyinae – Lowest occurrence of this subfamily is in the Upper Cretaceous (Santonian) lower Mooreville Chalk, Alabama (
http://fossilworks.org/bridge.pl? a=taxonInfo&taxon_no=127991); highest occurrences are in the lower Paleocene (Danian) Brightseat Formation, Maryland (Weems, 2014) and in Paleocene strata (stage unspecified), West Africa (Wood, 1973).
Mexichelys coahuilaensis (Brinkman et al., 2009)—Lowest and highest occurrences are in the Upper Cretaceous (upper Campanian) Cerro del Pueblo Formation, Mexico (Brinkman et al., 2009).
Natator depressus (Garman, 1880)—No fossil record has been reported for this modern species (Zangerl et al., 1988).
Pacifichelys spp. (P. urbinae Parham and Pyenson, 2010 + P. hutchisoni [Lynch and Parham, 2003])—Lowest and highest occurrences of these two species respectively are in the middle Miocene (stage not specified) Pisco Formation, Peru and the middle Miocene (Langhian) Round Mountain Silt Formation, California (Parham and Pyenson, 2010).
Procolpochelys charlestonensis Weems and Sanders, 2014—Lowest occurrences are in the lower Oligocene (upper Rupelian) Ashley Formation, South Carolina (Weems and Sanders, 2014) and Old Church Formation, Virginia (Weems, 2014); highest occurrences are in the upper Oligocene (Chattian) Chandler Bridge Formation, South Carolina (Weems and Sanders, 2014; Weems et al., 2016).
Procolpochelys grandaeva (Leidy, 1851)—Lowest occurrences are in the lower Miocene (Burdigalian) Kirkwood Formation, New Jersey (Zangerl and Turnbull, 1955) and lower Calvert Formation, Maryland (Weems and Sanders, 2014); highest occurrences are in the upper Miocene (Tortonian) St. Marys Formation, Maryland (multiple unpublished specimens in the collection of the Calvert Marine Museum, including CMM-V-5913, CMM-V-3115, and CMM-V-2978).
Puppigerus camperi (Gray, 1831)—Lowest occurrences are in the lower Eocene (Ypresian) London Clay, England (Moody, 1974); highest occurrence is in the middle Eocene (Lutetian) Bracklesham Beds, England (Moody, 1997).
Tasbacka spp. (T. aldabergeni Nessov, 1987 + T. ruhoffi [Weems, 1988])—Lowest and highest occurrences for T. aldabergeni are in the upper Paleocene (Thanetian) Ouled Abdoun phosphate basin, Morocco; lowest and highest occurrences for T. ruhoffi are in the upper Paleocene (Thanetian) Aquia Formation, Maryland.
Toxochelys latiremis Cope, 1873—Lowest occurrences are in the Upper Cretaceous (upper Santonian-lower Campanian) Niobrara Formation, Kansas (Nicholls, 1988); the highest occurrences are in the Upper Cretaceous (lower Maastrichtian) Ripley Formation, Tennessee (Nicholls, 1988).
Trachyaspis lardyi Meyer, 1843—Lowest well documented occurrences are in the lower Miocene (Burdigalian) lower Calvert Formation, Maryland (multiple unpublished specimens in the collection of the Calvert Marine Museum, including CMM-V-243); the highest occurrence is in an unnamed upper Pliocene (lower Piacenzian) unit at La Farfanara, Salsomaggiore Terme (PR) Italy (Villa and Raineri, 2015).
Paleocene, early Oligocene, and late Miocene. Each of these radiations followed times of exceptional extinction within this group. The first radiation occurred in the Paleocene, and it is readily explained as the result of sea turtle survivors of the Cretaceous-Paleogene extinction event undergoing rapid evolutionary radiation to fill niches vacated by victims of that event. Similarly, the early Oligocene radiation of pancheloniid turtles likely resulted from the filling of niches vacated due to extinctions caused by the end-Eocene cooling event that accompanied the beginning of widespread Antarctic glaciation at the beginning of the Oligocene (e.g., Prothero et al., 2003). This extinction event affected pancheloniid turtles (e.g., Puppigerus and Euclastes) and caused extinction among many other groups of marine animals, including the paleophid sea snakes and most archaeocete whales. The cause of the late Miocene radiation of modern cheloniid sea turtles is less obvious, but it does coincide with the late Miocene global climatic deterioration that heralded the beginning of significant
northern hemisphere glaciation leading up to the Pleistocene ice ages (Maslin et al., 1996). An interesting result of this phylogeny is the close rela-
tionship indicated for Ashleychelys and Procolpochelys. This likely reflects the strong regional endemism that developed among pancheloniid turtles during the Oligocene (Weems and Sanders, 2014) and further supports their suggestion that the southeastern United States was an ecosystem somewhat isolated from other parts of the Oligocene coastal marine world. Although Carolinochelys is an Oligocene South Carolina taxon that shows close relationship to the living branch of cheloniid turtles, this taxon is a rather specialized form that has strongly bent humeral shafts and thus is an unlikely ancestor for any of the later or living cheloniid turtles. This conclusion is reinforced by the fact that no close
relatives of the living cheloniid lineages show up in the western Northern Atlantic region until the early Miocene with the abrupt appearance of Trachyaspis lardyi Meyer, 1843, a specialized
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