Lepidosauria E. Haeckel 1866 [K. de Queiroz and J. A. Gauthier], converted clade name

Registration Number: 61 least 35 apomorphies relative to other extant amniotes (only some of which are diagnostic De!nition: !e smallest crown clade contain- relative to di#erent stem lepidosaurs). !ese ing Lacerta agilis Linnaeus 1758 (Squamata) and apomorphies derive from disparate anatomical Sphenodon (originally Hatteria) punctatus (Gray systems, are apparently unrelated functionally 1842) (Rhynchocephalia). !is is a minimum- and developmentally, and have persisted for crown-clade de"nition. Abbreviated de"nition: hundreds of millions of years among lepido- min crown ∇ (Lacerta agilis Linnaeus 1758 & saurs with remarkably divergent ecologies. !ey Sphenodon punctatus (Gray 1842)). include the following apomorphies (those lack- ing citations are from Gauthier et al., 1988a): Etymology: Derived from the Greek lepidos, (1) transversely oriented external opening of scale, plus sauros, lizard, reptile. cloaca and loss of amniote penis (hemipenes of squamatans are neomorphic); (2) kidney in tail Reference Phylogeny: Gauthier et al. base and adrenal gland suspended in gonadal (1988a: Fig. 13), where Lacerta agilis is part of mesentery (Gabe, 1970); (3) lingual prey pre- Squamata and Sphenodon punctatus is part of hension; (4) sagittal crest of scales projecting Rhynchocephalia. See also Gauthier (1984: Figs. from neck, body and tail; (5) scales composed 32–33), Evans (1984: Fig. 2, 1988: Figs. 6.1– of superimposed, rather than juxtaposed, amni- 6.2), Rest et al. (2003: Fig. 3), Hill (2005: Fig. 3), ote alpha keratin and reptilian phi keratin layers Evans and Jones (2010: Fig. 2.1), Crawford et al. (Maderson, 1985); (6) skin shed regularly in its (2012: Fig. 2), Jones et al. (2013: Figs. 3–4), and entirety; (7) prefrontal braces skull roof on pal- Simões et al. (2018: Fig. 2). ate (Gauthier, 1994); (8) lacrimal bone largely con"ned to orbital rim; (9) maxilla broadly Composition: Lepidosauria is composed of contributes to ventral orbital margin (Gauthier, two primary crown clades: the New Zealand 1994); (10) marginal teeth attached super"cially endemic Sphenodon with one currently recog- to lingual surface of jaw (rather than in shal- nized extant species (Hay et al., 2010) and the low sockets; further modi"ed to more apical globally distributed Squamata with approxi- attachment in some taxa); (11) teeth lost from mately 10,078 currently recognized extant transverse process of pterygoid and from sphe- species (Uetz, 2016). See Squamata and Pan- noid bones (Gauthier et al., 1988b); (12) zygos- Squamata (this volume) for references regarding phene-zygantrum accessory intervertebral joints extinct species in those clades. Reviews of dis- formed from dorsal extensions of zygapophysial parate and diverse fossil rhynchocephalians can surfaces (see Petermann and Gauthier, 2018); be found in Jones et al. (2013), Apesteguía et al. (13) autotomic and regenerable tail (autotomy, (2014), and Bever and Norell (2017). but not regeneration, has also been reported in some captorhinids; LeBlanc et al., 2018); (14) all Diagnostic Apomorphies: According to non-ossifying cartilaginous parts of skeleton cal- Gauthier et al. (1988a), Lepidosauria has at cify during postnatal ontogeny; (15) neomorphic Lepidosauria

ossi"cation centers in limb bone epiphyses that described as an agamid “lizard” (Gray, 1831, fuse to diaphyses near maximum adult size; 1842), S. punctatus was later separated from aga- (16) medial centrale larger than lateral central mids as Hatteriidae (Cope, 1864), and later still in wrist (Gauthier et al., 1988b); (17) radiale from “lizards” (and snakes) as Rhynchocephalia contacts 1st distal carpal or 1st metacarpal in within Squamata (Günther, 1867). Cope (1875) hand (Gauthier et al., 2012); (18) 4th metacar- furthered the separation, "rst, by not recog- pal shorter than 3rd (symmetrical metacarpals); nizing Squamata, second, by including the (19) fenestrate pelvic girdle; (20) posterodorsally extinct protorosaurs (i.e., Protorosaurus speneri) sloping ilium; (21) embryonic fusion between and rhynchosaurs (i.e., Rhynchosaurus articeps) anlage of lateral centrale and astragalus in tar- along with extant Sphenodon punctatus in his sus; (22) astragalus and calcaneum fused in Rhynchocephalia, and third, by interposing tur- adult (and lack a perforating foramen between tles (Testudines) between Rhynchocephalia and them as neurovascular system passes between “lizards” (and snakes) in his taxonomy. Cope tibia and "bula proximal to tarsus; Rieppel and (1889) later continued this trend by separating Reisz, 1999); (23) absence of separate 1st distal Rhynchocephalia and Squamata as taxa of equal tarsal in foot; (24) hooked 5th metatarsal—and rank (although the taxa were adjacent in his absence of discrete 5th distal tarsal presumably list). Distancing them further still, Cope (1900) incorporated into it—modi"ed to act as both a placed Rhynchocephalia and Squamata in sepa- ‘heel’ and a grasping ‘thumb’ enabling the 5th rate higher taxa, Archosauria and Streptostylica, toe to rotate 90° with respect to rest of the foot respectively, although his phylogenetic diagram according to Robinson (1975). (p. 160) had them closely related. In general, many late nineteenth and early to mid twen- Synonyms: All synonyms are approximate (not tieth century authors treated Sphenodon and phylogenetically de"ned). !e names that fol- Squamata (not always using that name) as rel- low were used after Sphenodon punctatus was atively distantly related among reptiles (e.g., "rst recognized (Gray, 1831, 1842) for taxa that Cope, 1875; Haeckel, 1895; Williston, 1917, explicitly included Sphenodon (sometimes as 1925), or at least considered Sphenodon closer Hatteria or Rhynchocephalus) and squamatans: to rhynchosaurs (and sometimes also to choris- Squamata of Gray (1845), partial (amphisbae- toderans) than to Squamata (e.g., Gadow, 1898, nians excluded); Saura of Gray (1845), partial 1901; Jaekel, 1911; Nopcsa, 1923; Romer, 1933, (amphisbaenians and snakes excluded); Lacertia 1945, 1956, 1966; Underwood, 1957; Kuhn, of Owen (1845), partial (snakes excluded); 1966). Dissolution of Cope’s idea that rhyn- Squamata of Cope (1864) and Günther (1867); chosaurs and “protorosaurs” are closely related Lacertilia of Cope (1864) and Huxley (1886), to Sphenodon began with Hughes’ (1968) study partial (snakes excluded); Saurii of Gegenbaur of the rhynchocephalian tarsus and culminated (1874, 1878), partial (snakes excluded). In in Carroll’s (1975) argument that characters most of these cases (except for Günther, 1867), traditionally used to unite Sphenodon punc- Sphenodon punctatus was considered nested tatus (and its legitimate fossil relatives) with within the taxon corresponding to Squamata. rhynchosaurs and “protorosaurs” are erroneous. Subsequent authors working in an explicitly Comments: Changing ideas about the rela- phylogenetic framework (Benton, 1982; Evans, tionship between Sphenodon punctatus and 1984; Gauthier, 1984; Carroll, 1985) presented Squamata have come nearly full circle. Originally evidence that rhynchosaurs and “protorosaurs”

1080 Lepidosauria

(including Protorosaurus speneri and Prolacerta were considered most closely related among broomi) are related to archosaurs while Sphenodon extant taxa. !erefore, when rhynchosaurs punctatus is closer to squamatans. Gauthier were allied to Archosauria and evidence was et al. (1988a) provided extensive morphologi- presented for an exclusive relationship between cal evidence for a close relationship between Rhynchocephalia and Squamata, the name Sphenodon punctatus and Squamata based on a Lepidosauria was applied to the group includ- computer-assisted analysis of 171 characters in ing the latter two taxa (e.g., Benton, 1982, 1983, 13 taxa, and this result has been corroborated by 1985; Gardiner, 1982; Evans, 1984; Gauthier, subsequent studies based on morphology (e.g., 1984; Gauthier et al., 1988a; Pritchard and Evans, 1988; Hill, 2005; Evans and Jones, 2010; Nesbitt, 2017). Gauthier et al., 2012), molecules (e.g., Rest et al., Selection of the name Lepidosauria for the 2003; Crawford et al., 2012; Pyron et al., 2013), Sphenodon + Squamata clade is relatively straight- and combined morphological and molecular forward. Other names that have been applied data (e.g., Jones et al., 2013; Reeder et al., 2015; to a taxon composed of Sphenodon and squa- Simões et al., 2018). matans (see Synonyms) either have been little !e name Lepidosauria was proposed by used (Saura, Lacertia, Saurii) or have been more Haeckel (1866) for what is now known as commonly associated with a less inclusive clade Squamata—that is, “lizards” (a paraphyletic (Squamata) or a paraphyletic group originating group) and snakes. Although Sphenodon punc- in the same ancestor (Lacertilia as well as the tatus was not explicitly included, members of seldom-used names Saura, Lacertia, and Saurii). this taxon were originally thought to be “liz- !e name Lepidosauria was "rst de"ned ards” (e.g., Gray, 1831, 1842). After Günther’s phylogenetically by Gauthier et al. (1988a: (1867) study demonstrating major anatomical 34) as “the most recent common ancestor of di#erences between Sphenodon (as Hatteria) Sphenodon and squamates and all of its descen- and “lizards”, and the subsequent increas- dants.” We have updated that de"nition by ing taxonomic separation of these groups (see using species as speci"ers. In the context of phy- previous paragraph), the name Lepidosauria logenies in which Sphenodon punctatus is more was seldom used, or it was used for the taxon closely related to turtles, crocodilians, and birds now called Squamata (e.g., Zittel, 1887–1890; than to Squamata (e.g., Hedges and Polling, Williston, 1904; Jaekel, 1911). Romer (1933) 1999; Zardoya and Meyer, 2000), the names resurrected the name Lepidosauria for a taxon Lepidosauria and Reptilia (this volume) are syn- designated “validity doubtful” composed of onyms, and Reptilia is to be granted precedence. Eosuchia (also considered of doubtful valid- Until very recently, the earliest known ity), Rhynchocephalia (choristoderans, rhyn- unambiguous crown lepidosaurs were extinct chosaurs, and sphenodontians), and Squamata. relatives of Sphenodon punctatus extending !is arrangement became more solidly estab- back at least ~220 Ma (late Carnian; early Late lished in Romer’s subsequent publications Triassic; e.g., Pritchard and Nesbitt, 2017, and (e.g., 1945, 1956, 1966), although choristoder- references therein). Simões et al. (2018) have, ans (= champsosaurids) were transferred from however, recently concluded that Megachirella Rhynchocephalia to Eosuchia. Despite Sphenodon wachtleri represents a stem squamatan (~240 having been considered more closely related to Ma; Anisian; Middle Triassic), making it the (extinct) rhynchosaurs than to squamatans, it only pan-squamatan currently known from should be noted that Sphenodon and Squamata the Triassic or Early Jurassic (Evans, 2003; see

1081 Lepidosauria

Pan-Squamata, this volume). Moreover, some Literature Cited of their analyses placed Sophineta cracoviensis on the squamatan stem as well, which would Apesteguía, S., R. O. Gómez, and G. W. Rougier. extend the lepidosaurian crown into the Late 2014. !e youngest South American rhyncho- cephalian, a survivor of the K/Pg extinction. Permian (see Pan-Lepidosauria this volume). Proc. R. Soc. Lond. B Biol. Sci. 281:20140811. Early and Middle Triassic terrestrial sediments Benton, M. J. 1982. !e Diapsida: a revolution in are rare, and small fossil vertebrates are di$- reptile relationships. Nature 296:306–307. cult to "nd; these factors doubtless contribute Benton, M. J. 1983. !e Triassic reptile to a poor early lepidosaurian record (Jones et Hyperodapedon from Elgin: functional mor- al., 2013). Nevertheless, rhynchocephalian phology and relationships. Philos. Trans. R. fossils from the Late Triassic are reasonably Soc. Lond. B Biol. Sci. 302:605–717. common and already well-diversi"ed phylo- Benton, M. J. 1985. Classi"cation and phylog- eny of the diapsid reptiles. Zool. J. Linn. Soc. genetically (e.g., Whiteside, 1986; Bever and 84:97–164. Norell, 2017). Rhynchocephalians had spread Bever, G. S., and M. A. Norell. 2017. A new rhyn- across Pangaea by the early Mesozoic, and have chocephalian (Reptilia: Lepidosauria) from the been in Gondwana since the Triassic, persisting Late Jurassic Solnhofen (Germany) and the in South America until at least the Palaeocene origin of the marine Pleurosauridae. R. Soc. (Apesteguía et al., 2014). !ey remain common Open Sci. 4(11):170570. well into the Jurassic of Laurasia (e.g., Cocude- Carroll, R. L. 1975. !e early di#erentiation of Michel, 1963), but are rare thereafter, with the diapsid reptiles. Colloq. Internat. CNRS last known occurrence a single species from the 218:433–449. Carroll, R. L. 1985. A pleurosaur from the Lower Early Cretaceous of southern Mexico (Reynoso, Jurassic and the taxonomic position of the 2000). Extinct taxa closer to Sphenodon punc- Sphenodontida. Palaeontographica 189:1–28. tatus have been on New Zealand since at least Cocude-Michel, M. 1963. Les rhynchocephales the Early Miocene (Jones et al., 2009). Subfossil et les sauriens des calcaires lithographiques Quaternary remains of an extinct relative closely (Jurassique superieur) d’Europe occidentale. resembling Sphenodon were named S. diversum Nouv. Arch. Mus. Hist. Nat. Lyon 7:1–187. by Colenso (1886). Colenso, W. 1886. Notes on the bones of a spe- Clevosaur rhynchocephalians are distributed cies of Sphenodon, (S. diversum, Col.,) appar- ently distinct from the species already known. worldwide by the Late Triassic and are relatively Trans. Proc. R. Soc. NZ 18:118–128. abundant in early Mesozoic localities that have Cope, E. D. 1864. On the characters of the higher yet to produce any representatives of the squa- groups of Reptilia Squamata—and especially matan total clade (e.g., Hsiou et al., 2015). Even of the Diploglossa. Proc. Acad. Nat. Sci. Phila. granting the inadequacies of the early lepidosaur 16:224–231. record, stem squamatans must have been pres- Cope, E. D. 1875. Check-list of North American ent, which suggests a disparity in relative abun- Batrachia and Reptilia with a systematic list dance between the two primary lepidosaurian of the higher groups and an essay on geo- subclades during the Triassic and Jurassic that graphical distribution. Bull. U.S. Natl. Mus. 1:1–104. is exactly the opposite of today. Squamatans Cope, E. D. 1889. Synopsis of the families of do not appear to surpass rhynchocephalians in Vertebrata. Am. Nat. 23:849–877. relative abundance until the Early Cretaceous Cope, E. D. 1900. !e crocodilians, lizards, and (e.g., Evans and Matsumoto, 2015; and refer- snakes of North America. Ann. Rep. U. S. ences therein). Natl. Mus. 1898:155–1270 + 36 plates.

1082 Lepidosauria

Crawford, N. G., B. C. Faircloth, J. E. McCormack, Relationships of the Lizard Families (R. Estes R. T. Brum"eld, K. Winker, and T. C. Glenn. and G. Pregill, eds.). Stanford University 2012. More than 1000 ultraconserved ele- Press, Stanford, CA. ments provide evidence that turtles are the sis- Gauthier, J. A., M. Kearney, J. A. Maisano, O. ter group of archosaurs. Biol. Lett. 8:783–786. Rieppel, and A. Behlke. 2012. Assembling the Evans, S. E. 1984. !e classi"cation of the squamate tree of life: perspectives from the Lepidosauria. Zool. J. Linn. Soc. 82:87–100. phenotype and the fossil record. Peabody Mus. Evans, S. E. 1988. !e early history and relation- Nat. Hist. Bull. 53(1):3–308. ships of the Diapsida. Pp. 221–260 in !e Gauthier, J., A. Kluge, and T. Rowe. 1988b. Phylogeny and Classi"cation of the Tetrapods. Amniote phylogeny and the importance of fos- Vol. 1: Amphibians, Reptiles, Birds (M. J. sils. Cladistics 4(2):105–209. Benton, ed.). Systematics Association Special Gegenbaur, C. 1874. Grundriss der Vergleichenden Volume No. 35A. Clarendon Press, Oxford. Anatomie. Wilhelm Engelmann, Leipzig. Evans, S. E. 2003. At the feet of dinosaurs: the early Gegenbaur, C. 1878. Elements of Comparative history and radiation of lizards. Biol. Rev. Anatomy. 2nd edition, English translation. 78:513–551. MacMillan, London. Evans, S. E., and M. E. H. Jones. 2010. !e origin, Gray, J. E. 1831. Note on a peculiar structure in the early history and diversi"cation of lepidosau- head of an Agama. Zool. Misc. 1831:13–14. romorph reptiles. Pp. 27–44 in New Aspects of Gray, J. E. 1842. Descriptions of two hitherto unre- Mesozoic Biodiversity (S. Bandyopadhyay, ed.). corded species of reptiles fro New Zealand; Lecture Notes in Earth Sciences 132. presented to the British Museum by Dr. Evans, S. E., and R. Matsumoto. 2015. An assem- Die#enbach. Zool. Misc. 1842:72. blage of lizards from the Early Cretaceous of Gray, J. E. 1845. Catalogue of the Specimens Japan. Palaeontol. Electron. 18.2.36A:1–36. of Lizards in the Collection of the British Gabe, M. 1970. !e adrenal. Pp. 263–318 in Museum. Trustees [of the British Museum], Biology of the Reptilia (Morphology C). Vol. 3 London. (C. Gans and T. S. Parsons, eds.). Academic Günther, A. 1867. Contribution to the anatomy Press, London. of Hatteria (Rhynchocephalus, Owen). Philos. Gadow, H. 1898. A Classi"cation of Vertebrata Trans. R. Soc. Lond. B Biol. Sci. 157:595–629. Recent and Extinct. Adam and Charles Black, Haeckel, E. 1866. Generelle Morphologie der Organ- London. ismen. Band 2: Allgemeine Entwicklungsge- Gadow, H. 1901. Amphibia and Reptiles. !e schichte der Organismen. George Reimer, Cambridge Natural History, Vol. 8. Macmillan, Berlin. London. Haeckel, E. 1895. Systematicshe Phylogenie. Dritter Gardiner, B. G. 1982. Tetrapod classi"cation. Zool. !eil: Systematicshe Phylogenie der Wirbelthiere J. Linn. Soc. 74:207–232. (Vertebrata). Georg Reimer, Berlin. Gauthier, J. A. 1984. A Cladistic Analysis of the Hay, J. M., S. D. Sarre, D. M. Lambert, F. W. Higher Systematic Categories of the Diapsida. Allendorf, and C. H. Daugherty. 2010. Genetic PhD dissertation, University of California, diversity and taxonomy: a reassessment of Berkeley, CA. species designation in tuatara (Sphenodon: Gauthier, J. A. 1994. !e diversi"cation of the Reptilia). Conserv. Genet. 11:1063–1081. amniotes. Pp. 129–159 in Major Features Hedges, S. B., and L. L. Polling. 1999. A molecular of Vertebrate Evolution: Short Courses in phylogeny of reptiles. Science 283:998–1001. Paleontology (D. Prothero, ed.). Paleontological Hill, R. V. 2005. Integration of morphological data Society. sets for phylogenetic analysis of Amniota: the Gauthier, J. A., R. Estes, and K. de Queiroz. importance of integumentary characters and 1988a. A phylogenetic analysis of increased taxonomic sampling. Syst. Biol. Lepidosauromorpha. Pp. 15–98 in Phylogenetic 54:530–547.

1083 Lepidosauria

Hsiou, A. S., M. A. G. De França, and J. of a new tribe or sub-order of Sauria. Trans. Ferigolo. 2015. New data on the Clevosaurus Geol. Soc. Lond. 7:59–84 + 4 plates. (Sphenodontia: Clevosauridae) from the Upper Petermann, H., and J. A. Gauthier. 2018. Triassic of Southern Brazil. PLOS ONE Fingerprinting snakes: paleontological and 10(9):e0137523. paleoecological implications of zygantral Hughes, B. 1968. !e tarsus of rhynchocephalian growth rings in Serpentes. Peer J. 6:e4819. reptiles. J. Zool. 156:457–481. doi:10.7717/peerj.481. Huxley, T. H. 1886. A Manual of the Anatomy of Pritchard, A. C., and S. J. Nesbitt. 2017. A bird- Vertebrated Animals. D. Appleton, New York. like skull in a Triassic diapsid reptile increases Jaekel, O. 1911. Die Wirbeltiere; Eine Übersicht Über heterogeneity of the morphological and phylo- Die Fossilen und Lebenden Formen. Gebrüder genetic radiation of Diapsida. R. Soc. Open Sci. Borntraeger, Berlin. 4:170499. Jones, M. E. H., C. L. Anderson, C. A. Hipsley, J. Pyron, R. A., F. T. Burbrink, and J. J. Wiens. Müller, S. E. Evans, and R. R. Schoch. 2013. 2013. A phylogeny and revised classi"cation Integration of molecules and new fossils sup- of Squamata, including 4161 species of lizards ports a Triassic origin for Lepidosauria (lizards, and snakes. BMC Evol. Biol. 13:93. snakes, and tuatara). BMC Evol. Biol. 13:208. Reeder, T. W., T. M. Townsend, D. G. Mulcahy, Jones, M. E. H., A. J. D. Tennyson, J. P. Worthy, S. B. P. Noonan, P. L. Wood, J. W. Sites, and E. Evans, and T. H. Worthy. 2009. A sphen- J. J. Wiens. 2015. Integrated analyses resolve odontine (Rhynchocephalia) from the Miocene con%icts over squamate reptile phylogeny and of New Zealand and palaeobiogeography of reveal unexpected placments for fossil taxa. the tuatara (Sphenodon). Proc. R. Soc. Lond. B PLOS ONE 10(3):e0118199. Biol. Sci. 276:1385–1390. Rest, J. S., J. C. Ast, C. C. Austin, P. J. Waddell, Kuhn, O. 1966. Die Reptilien. System und E. A. Tibbetts, J. M. Hay, and D. P. Mindell. Stammesgeschichte. Oeben, Krailling. 2003. Molecular systematics of primary rep- LeBlanc, A. R. H., M. J. MacDougall, Y. Haridy, tilian lineages and the tuatara mitochondrial D. Scott, and R. R. Reisz. 2018. Caudal autot- genome. Mol. Phylogenet. Evol. 29:289–297. omy as anti-predatory behaviour in Palaeozoic Reynoso, V.-H. 2000. An unusual aquatic sphen- reptiles. Sci. Rep. 8:3328. doi:10.1038/ odontian (Reptilia: Diapsida) from the Tlayua s41598-018-21526-3. Formation (Albian), Central Mexico. J. Linnaeus, C. 1758. Systema Naturae Per Regna Tria Paleontol. 74:133–148. Naturae, Secundum Classes, Ordines, Genera, Rieppel, O., and R. Reisz. 1999. !e origin and Species, cum Characteribus, Di#erentiis, early evolution of turtles. Annu. Rev. Ecol. Syst. Synonymis, Locis. 10th edition. Laurentii 30:1–22. Salvii, Holmiae (Stockholm). Robinson, P. L. 1975. !e functions of the hooked Maderson, P. F. A. 1985. Some developmental prob- "fth metatarsal in lepidosaurian reptiles. Coll. lems of the reptilian integument. Pp. 525–598 Internat. CNRS 218:461–83. in Biology of the Reptilia, Vol. 14. (P. F. A. Romer, A. S. 1933. Vertebrate Paleontology. Maderson, C. Gans, and F. Billett, eds.). John University of Chicago Press, Chicago, IL. Wiley & Sons, New York. Romer, A. S. 1945. Vertebrate Paleontology. 2nd edi- Nopcsa, F. 1923. Die Familien der Reptilien. tion. University of Chicago Press, Chicago, IL. Gebrüder Borntraeger, Berlin. Romer, A. S. 1956. Osteology of the Reptiles. Owen, R. 1845. Description of certain fossil crania, University of Chicago Press, Chicago, IL. discovered by A. G. Bain, Esq., in sandstone Romer, A. S. 1966. Vertebrate Paleontology. 3rd edi- rocks at the south-eastern extremity of Africa, tion. University of Chicago Press, Chicago, IL. referable to a di#erent species of an extinct Simões, T. R., M. W. Caldwell, M. Tałanda, genus of Reptilia (Dicynodon), and indicative M. Bernardi, A. Palci, O. Vernygora, F.

1084 Lepidosauria

Bernardini, L. Mancini, and R. L. Nydam. caecilians (Amphibia: Gymnophiona). Genetics 2018. !e origin of squamates revealed by a 155:765 –775. Middle Triassic lizard from the Italian Alps. Zittel, K. A. 1887–1890. Handbuch der Nature 557:706–709. Palæontologie. I Abtheilung. Palæozoologie. III Uetz, P. 2016. Species numbers (as of August 2016). Band. Vertebrata (Pices, Amphibia, Reptilia, !e reptile database. Available at http://www. Aves). R. Oldenbourg, Munich. reptile-database.org/. Underwood, G. 1957. On lizards of the family Pygopodidae: a contribution to the morphology Authors and phylogeny of the Squamata. J. Morphol. 100:207–268. Kevin de Queiroz; Department of Vertebrate Whiteside, D. 1986. !e head skeleton of the Zoology; National Museum of Natural Rhaetian sphenodontid Diphydontosaurus avo- History; Smithsonian Institution; Washington, nis gen. et sp. nov. and the modernizing of a DC 20560-0162, USA. Email: dequeirozk@ living fossil. Philos. Trans. R. Soc. Lond. B Biol. si.edu. Sci. 312:379–430. Jacques A. Gauthier; Department of Geology and Williston, S. W. 1904. !e relationships and habits Geophysics; Yale University; 210 Whitney of the mosasaurs. J. Geol. 12:43–51. Avenue, New Haven, CT 06511, USA. Email: Williston, S. W. 1917. !e phylogeny and classi"ca- [email protected]. tion of reptiles. J. Geol. 25:411–421. Williston, S. W. 1925. !e Osteology of the Reptiles. Date Accepted: 11 August 2018 Harvard University Press, Cambridge, MA. Zardoya, R., and A. Meyer. 2000. Mitochondrial evidence on the phylogenetic position of Primary Editor: Philip Cantino

1085