Lampropeltis, Fitzinger, 1843

Jacisin Iii, John J. & Lawing, A. Michelle, 2024, Fossil snakes of the Penny Creek Local Fauna from Webster County, Nebraska, USA, and the first record of snakes from the Early Clarendonian (12.5 - 12 Ma) of North America, Palaeontologia Electronica (a 2) 27 (1), pp. 1-42 : 12

Genus LAMPROPELTIS Fitzinger, 1843

Diagnosis. Lampropeltis vertebrae are somewhat robust, relatively short, and wide for a colubrine (centrum about as wide as long; Parmley, 1987), with long neural spines that are moderate to low in height, overhang posteriorly, and are either straight or overhanging anteriorly ( Auffenberg, 1963; Meylan, 1982; Parmley, 1988; Parmley, 1990). The neural spines may also be thickened dorsally ( LaDuke, 1991). The neural arches are depressed and wide ( Auffenberg, 1963; Meylan, 1982; LaDuke, 1991; Holman, 2000). The hemal keel is well-developed and usually widened posteriorly, with well-developed subcentral ridges that curve inward near the cotyle ( Auffenberg, 1963; Meylan, 1982; Parmley, 1988), and may be bordered laterally by fossae ( LaDuke, 1991). The cotyle is round ( Auffenberg, 1963), the condyle is round and sometimes obliquely tilted upwards ( Parmley, 1990), the zygosphenes are flat anteriorly ( LaDuke, 1991) and epizygapophyseal spines are absent ( Auffenberg, 1963; Holman, 2000).

Remarks. Lampropeltis vertebrae differ from those of Pantherophis and Pituophis in exhibiting more pronounced subcentral ridges, less vaulted neural arches, and relatively lower neural spines ( Parmley, 1990). They may additionally differ from Pantherophis and Arizona in being relatively longer and more robust ( LaDuke, 1991). Lampropeltis vertebrae differ from those of Rhinocheilus in being relatively longer, with relatively thinner and taller neural spines that do not project anteriorly beyond the zygosphene, narrower hemal keels, relatively wider cotyles, larger zygapophyses, and more developed subcentral ridges ( Van Devender and Mead, 1978; LaDuke, 1991).

Holman (2000) suggested that Lampropeltis vertebrae are more easily diagnosed on a speciesby-species basis, as there are greater differences among some species of Lampropeltis than there are among some other colubrine genera (such as Coluber and Masticophis ). This idea was reexamined and discussed in Parmley and Hunter (2010), who found that Lampropeltis alterna and the Lampropeltis pyromelana-zonata grouping have diagnostic vertebral characters distinct from each other and from the rest of the genus, while Lampropeltis getula , Lampropeltis calligaster , and Lampropeltis triangulum form a discernable L. getula complex. Furthermore, Auffenberg (1963) noted that smaller species appeared to have neural spines that are relatively shorter in height compared to larger species and that the hemal keel showed variation in development between species and age groups. Where exactly the known fossil species of Lampropeltis fall within the genus could therefore be dependent on the ability to discern between these three main morphospaces on a case-by-case basis. A better understanding of these morphospaces and the morphology of fossil species could also help determine when the genus started exploring the various morphologies associated with these groupings.