Journal of Paleontology, 90(1), 2016, p. 147–153 Copyright © 2016, The Paleontological Society 0022-3360/16/0088-0906 doi: 10.1017/jpa.2016.16


Late Paleocene glyptosaur (Reptilia: Anguidae) osteoderms from South Carolina, USA


David J. Cicimurri,1 James L. Knight,1 Jean M. Self-Trail,2 and Sandy M. Ebersole3


1South Carolina State Museum, 301 Gervais Street, Columbia, SC 29201, USA ⟨dave.cicimurri@scmuseum.org⟩, ⟨karin@gforcecable.com⟩ 2United States Geological Survey, 926A National Center, Reston, VA 20192, USA ⟨jstrail@usgs.gov⟩ 3Alabama Geological Survey, P.O. Box 869999, Tuscaloosa, AL 35486, USA ⟨sebersole@gsa.state.al.us⟩


Abstract.—Heavily tuberculated glyptosaur osteoderms were collected in an active limestone quarry in northern Berkeley County, South Carolina. The osteoderms are part of a highly diverse late Paleocene vertebrate assemblage that consists of marine, terrestrial, fluvial, and/or brackish water taxa, including chondrichthyan and osteichthyan fish, turtles (chelonioid, trionychid, pelomedusid, emydid), crocodilians, palaeopheid snakes, and a mammal. Calcareous nannofossils indicate that the fossiliferous deposit accumulated within subzone NP9a of the Thanetian Stage (late Paleocene, upper part of Clarkforkian North American Land Mammal Age [NALMA]) and is therefore temporally equivalent to the Chicora Member of the Williamsburg Formation. The composition of the paleofauna indicates that the fossiliferous deposit accumulated in a marginal marine setting that was influenced by fluvial processes (estuarine or deltaic). The discovery of South Carolina osteoderms is significant because they expand the late Paleocene geographic range


of glyptosaurines eastward from the US midcontinent to the Atlantic Coastal Plain and provide one of the few North American records of these lizards inhabiting coastal habitats. This discovery also brings to light a possibility that post-Paleocene expansion of this group into Europe occurred via northeastward migration along the Atlantic coast of North America.


Introduction


The earliest record of glyptosaurines, an extinct group of armored lizards, is from the middle Paleocene (Torrejonian NALMA) of the United States, but the family achieved holarctic distribution during the Eocene (Meszoely et al., 1978; Sullivan, 1979; Estes, 1983; Holman,1998; Augé, 2005; Smith, 2009) and ultimately became extinct in the Oligocene (Augé and Smith, 2009; Rage and Augé, 2010). Purported post-Oligocene glyptosaur remains (Estes, 1963; Holman, 1976; Albright, 1994) are considered to have been misidentified or reworked from older deposits (Wellstead, 1982; Sullivan and Holman, 1996). Outside of the United States, glyptosaur fossils have been found on Ellesmere Island in the Canadian high arctic (Estes and Hutchinson, 1980) and in Belgium (Sullivan et al., 2012), England (Holman, 1998; Klembara and Green, 2010), France (Holman, 1998; Augé, 2003; Augé and Sullivan, 2006), Germany (Sullivan, 1979; Augé and Sullivan, 2006), Spain (Bolet and Evans, 2013), Portugal (Rage and Augé, 2003), Switzerland (Hoffstetter, 1962), and Mongolia (Sullivan, 1979). In the United States, the fossil record shows that


glyptosaurs were taxonomically diverse and geographically widespread west of the Missouri River. These lizards have been reported from Colorado (Sullivan, 1989),Montana (Estes, 1976), Nebraska (Sullivan, 1974), North Dakota (Smith, 2006), South Dakota (Lillegraven, 1970; Maddox and Wall, 1998), New Mexico (Sullivan, 1981; Lucas et al., 1983; Sullivan and Lucas, 1988), Texas (Westgate, 1989), and especially Wyoming


(Gauthier, 1982; Sullivan, 1982; Bartels, 1983; Gunnell et al., 1992; Zonneveld et al., 2000; Smith, 2009). To our knowledge, only one definitive glyptosaur occurrence has been reported from east of the Missouri River (Westgate, 1989; Estes, 1963 vs. Sullivan and Holman, 1996). Herein, we describe isolated glypto- saur osteoderms that were collected from an active limestone quarry inBerkeleyCounty, SouthCarolina (Fig. 1). In addition,we comment on the age and paleoenvironment of the fossil deposit and discuss the paleobiogeographical significance of the fossils.


Methods


The osteoderms were recovered from unconsolidated clay-rich, glauconitic, fine- to medium-grained quartz sand occurring in a Martin Marietta Aggregates limestone quarry located to the southeast of Jamestown in northern Berkeley County, South Carolina (Fig. 1). The fossiliferous deposit, which underlies the middle Eocene Santee Limestone, is below water level in the quarry and so is not directly available for observation. However, sediment is occasionally brought to the surface from the water-filled, actively mined portion of the quarry.We collected bulk matrix from spoil piles located directly adjacent to their excavation site and recovered vertebrate fossils by screen washing sediment in the laboratory down to 0.25mm(#60 USA Standard Testing Sieve). A calcareous nannofossil smear slide was made from some


of this bulk matrix by spreading a thin veneer of raw material onto a coverslip and affixing this to a glass slide using Norland


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