Late Hemphillian Colubrid Snakes (Serpentes, Colubridae) from the Gray Fossil Site of Northeastern Tennessee
The Gray Fossil Site (GFS) of northeastern Tennessee is a late Hemphillian fossil locality in the southern Appalachian mountain region of eastern North America with a diverse vertebrate fauna. Snakes make up a substantial microfossil portion of the GFS herpetofauna, particularly the Colubridae, comprised of members of the Colubrinae and Natricinae. Seven colubrid taxa have been identified from the site so far, including three natricines (cf. Neonatrix, Nerodia, Thamnophis) and at least four colubrines (Coluber/Masticophis, Pantherophis, Pituophis, gen. et sp. nov.). Indeed, cf. Neonatrix and the new genus (and species) are the only extinct genera identified. Although Neonatrix is tentatively identified for the first time east of Nebraska, the new species represents a distinct taxon. In addition, the oldest reported definitive occurrence of Masticophis is presented herein. Some of the snakes suggest a pond or other aquatic habitat at GFS, particularly cf. Neonatrix and Nerodia, whereas others, such as Masticophis and Pituophis, tend to prefer more open forested habitats. The GFS represents a poorly understood region of North America at a crucial time period in snake evolution, and its study may help us further understand the modern snake fauna present today in midcontinental and eastern North America.Abstract
Terminology of snake vertebrae used in this study, following Auffenberg (1963), LaDuke (1991), and Holman (2000). Thamnophis sp., ETMNH-11961, trunk vertebra in A, anterior view; B, dorsal view; C, left lateral view; D, ventral view; E, posterior view. Abbreviations: CD, condyle; CT, cotyle; D, diapophysis; HP, hypapophysis; NA, neural arch; NC, neural canal; NS, neural spine; P, parapophysis; PO, postzygapophysis; POA, postzygapophyseal articular facet; PR, prezygapophysis; PRA, prezygapophyseal articular facet; SG, subcentral groove (=subcentral paramedian lymphatic fossa); SR, subcentral ridge; ZY, zygosphene. Scale bar equals 1 mm.
Natricines from the late Hemphillian of eastern Tennessee. A–C, cf. Neonatrix sp., ETMNH-9262, caudal (=postcloacal) vertebra in A, anterior view; B, left lateral view; C, ventral view; D–F, Nerodia sp., ETMNH-9362, trunk vertebra in D, anterior view; E, left lateral view; F, ventral view; G–I, Thamnophis sp., ETMNH-9261, posterior trunk vertebra in G, anterior view; H, left lateral view; I, ventral view; J–L, Thamnophis sp., ETMNH-9448, trunk vertebra in J, anterior view; K, left lateral view; L, ventral view; M–O, Thamnophis sp., ETMNH-11961, trunk vertebra in M, anterior view; N, left lateral view; O, ventral view. Abbreviation: HM, hemapophyses. Scale bars equal 1 mm and each scale bar corresponds to the three consecutive images representing each individual specimen.
Colubrines from the late Hemphillian of eastern Tennessee. A–C, Coluber/Masticophis sp., ETMNH-9244, trunk vertebra in A, anterior view; B, left lateral view; C, ventral view; D–F, Coluber/Masticophis sp., ETMNH-9401, trunk vertebra in D, anterior view; E, left lateral view; F, ventral view; G–I, Masticophis sp., ETMNH-11115, axis (=second cervical) vertebra in G, anterior view; H, left lateral view; I, ventral view; J–L, Pantherophis sp., ETMNH-9510, trunk vertebra in J, anterior view; K, left lateral view; L, ventral view; M–O, Pituophis sp., ETMNH-9451, trunk vertebra in M, anterior view; N, left lateral view; O, ventral view. Abbreviations: ES, epizygapophyseal spine; HK, hemal keel; I2A, intercentrum 2 attachment area; OPA, odontoid process attachment area; SP, spinal process; TP, transverse process. Scale bars equal 1 mm and each scale bar corresponds to the three consecutive images representing each individual specimen.
Holotype vertebra of Zilantophis schuberti (ETMNH-9557), trunk vertebra in A–B, dorsal view; C–D, ventral view; E–F, left lateral view; G–H, anterior view; I–J, posterior view. Scale bar equals 1 mm.
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