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

Abstract

The current fossil record of squamates across the Eocene/Oligocene boundary in central North America is perplexing in that it shows a marked increase in species richness in response to climatic cooling and drying, which is contrary to both the European record and expectation. A diverse, new squamate assemblage from the late Eocene Chadron Formation of the Medicine Pole Hills, North Dakota, provides new insight into these changes. Nineteen squamate species are described, fourteen of which were previously unknown. The acrodontan, varanid, and diploglossine anguid are previously unreported holdovers from the early Eocene. The Medicine Pole Hills local fauna is one of the most species-rich squamate assemblages yet reported from the fossil record.Late Eocene iguanids are remarkable for both their species-level and higher taxonomic diversity: among their numbers are a phrynosomatine (fence lizards and relatives), a polychrotine (anoles and relatives), and a crotaphytine (collared and leopard lizards). The polychrotine, interpreted as the earliest-known representative of the Polychrus lineage, indicates that at least one subgroup of Iguanidae shows a historical biogeographic pattern similar to that of North American scincomorph and anguimorph lizards. The increasing numerical dominance of iguanid species has been considered a hallmark of herpetofaunal modernization in central North America, but this measure appears inadequate in light of these data.Including the new fauna, the record of central North American squamates, like the European record, shows a decrease in richness across the Eocene/Oligocene boundary. However, many uncorrected sampling biases remain that may distort our picture of the squamate response to Eocene/Oligocene climate change. Sampling-standardized studies are indicated.Krister T. Smith.

First fossil frog from Antarctica: implications for Eocene high latitude climate conditions and Gondwanan cosmopolitanism of Australobatrachia

“…( 5) Lacertilia; lizards also have skull bones and osteoderms covered with ornamentation patterns 44 . They all are characterized by a network of spines, grooves, ridges 45 and protuberances 46 , which differs from the morphology on NRM-PZ B281.…”

Taxonomy and biostratigraphy of the elasmobranchs and bony fishes (Chondrichthyes and Osteichthyes) of the lower-to-middle Eocene (Ypresian to Bartonian) Claiborne Group in Alabama, USA, including an analysis of otoliths

“…F. folmeri, with teeth (n = 6) collected from the basal Lisbon Formation at site ACov-11 and the basal Gosport Sand at site ACl-4. The type species, Fisherichthys folmeri Weems, 1999, was reported from the upper Paleocene Williamsburg Formation (Zone NP9a) of South Carolina (Cicimurri & Knight 2009;Cicimurri et al 2016), and it occurs within the lower Eocene Bashi Formation (Zone NP10) of Mississippi (Case 1994b), lower Eocene Nanjemoy Formation (Zone NP11) of Virginia (Weems 1999), and the Lutetian in Alabama (Clayton et al 2013). The six specimens in our sample from ACov-11 confirms the presence of Fisherichthys in the Lutetian Zone NP15 as reported by Clayton et al (2013).…”

Cenozoic vertebrate biostratigraphy of South Carolina, U.S.A., and additions to the fauna

“…AP and TR refer to antero-posterior (length) and transverse (width) measurements, respectively; P or M, upper premolars and molars, respectively; p or m, lower premolars and molars, respectively. 2008), Sanders et al (2009), Tsukui and Clyde (2012), May et al (2014), andMurphey et al (2018).A, Paleogene stratigraphic units; chronostratigraphic placement of formations based on Nystrom et al (1991), Fallaw and Price (1995), Edwards et al (2000), and Weems et al (2016); boundaries of chrons C21-C23 from Tsukui and Clyde (2012); inclusion of "Jamestown beds" in Chicora Member of Williamsburg Formation from Cicimurri et al (2016). B, Miocene stratigraphic units; DN zones based on recalibration of de Verteuil and Norris (1996) using Dybkjaer and Piasecki (2008); boundaries of chrons C4Ar-C5r from Evans et al (2007); placement of Upland unit in upper Serravallian follows Nystrom et al (1991), Huddlestun (1988), and Weems and Edwards (2007a).…”

“…For relatively recent discussions of fossil vertebrates from South Carolina, the reader is referred to Roth and Laerm (1980), Bentley et al (1994), Sanders (1998a), Sanders (2002), Geisler et al (2005Geisler et al ( , 2014Geisler et al ( , 2017Geisler et al ( , 2018, Kohn et al (2005), Chandler and Knight (2009), Fierstine and Weems (2009), Sanders et al (2009), Cicimurri and Knight (2009a, b, c;, Knight and Cicimurri (2010), Fields et al (2012), Weems and Knight (2013), Ksepka (2014), Weems and Sanders (2014), Vélez-Juarbe and Domning (2014a, b), Cicimurri et al (2016), Weems and Brown (2017), Babiarz et al (2018), , Domning and Beatty (2019), and others mentioned throughout the text. Important older references include Leidy (1859Leidy ( , 1860Leidy ( , 1869Leidy ( , 1876aLeidy ( , b, c, 1877Leidy ( , 1890, Hay (1923), and Allen (1926).…”