squamate reptiles from the middle eocene of lissieu (france). a landmark in the middle eocene of...

Original article

Squamate reptiles from the middle Eocene of Lissieu (France).A landmark in the middle Eocene of Europe§

Les squamates (reptiles) de l’Eocène moyen de Lissieu (France).Un repère dans l’Eocène moyen d’Europe

Jean-Claude Rage *, Marc AugéCentre de recherches sur la paléobiodiversité et les paléoenvironnements, UMR-CNRS 7207,

département histoire de la Terre, Muséum national d’histoire naturelle, CP 38,8, rue Buffon, 75231 Paris cedex 05, France

Received 21 April 2009; accepted 7 August 2009

Available online 1 February 2010

Abstract

In Europe, faunas of squamates (lizards and snakes) from the middle Eocene are very poorly known, with the exception of those from thelevel MP 16 (latest middle Eocene). From the MP 11–MP 15 interval, squamates were previously reported only from Messel (MP 11, earliestmiddle Eocene) and from the untere and obere Mittelkohle of Geiseltal (MP 12 and MP 13 respectively) in Germany. The present reportdescribes the middle Eocene assemblage of squamates from Lissieu (France), the first fauna reported from the level MP 14. Whereas fossilsfrom Messel and Geiseltal are mostly articulated skeletons, fossils from Lissieu are represented by disarticulated bones; such fossils may bemore easily compared to those from other Cenozoic localities, in which bones are almost always disarticulated. The fauna from Lissieu is morediverse than those from the Geiseltal sites and approximately as diverse as that from Messel as they are presently known; it is comprised of 17distinct taxa. These taxa cannot be all identified to the species or genus level. They belong to iguanids, gekkonids, lacertids, anguids,thecoglossan platynotans, ophidians incertae sedis, boids, ?tropidophiines, ‘‘tropidophiids’’ incertae sedis, booids incertae sedis, and perhapsrussellophiids. The fauna includes several new taxa but only a presumed tropidophiine snake may be named on the basis of the availablematerial. The fauna from Lissieu is a mixture of taxa restricted to the middle Eocene and taxa known from older or younger levels. Taxa sharedby Lissieu and the few other localities from the middle Eocene of Europe are rare. This fauna from Lissieu represents a stratigraphicallandmark for the middle Eocene.# 2009 Elsevier Masson SAS. All rights reserved.

Keywords: Squamata; Lacertilia; Ophidia; Eocene; France

Résumé

En Europe, les faunes de squamates (lézards et serpents) de l’Eocène moyen sont très mal connues, à l’exception de celles du niveau MP 16(Eocène moyen terminal). Jusqu’à présent, les seuls squamates signalés pour l’intervalle MP 11–MP 15 venaient des gisements allemands deMessel (MP 11) et des « untere » et « obere Mittelkohle » du Geiseltal (respectivement MP 12 et MP 13). Dans le présent article, sont étudiés lessquamates de l’Eocène moyen de Lissieu (France) qui représentent la première faune décrite du niveau MP 14. Alors que les fossiles de Messel etdu Geiseltal correspondent généralement à des squelettes articulés, ceux de Lissieu sont représentés par des os isolés ; ils peuvent être plusfacilement comparés aux fossiles des autres gisements tertiaires dans lesquels on trouve le plus souvent des os désarticulés. La faune de Lissieucomprend 17 taxons ; elle est plus diversifiée que celles du Geiseltal et approximativement aussi diversifiée que celle de Messel, telles que cesfaunes sont actuellement connues. Les taxons de Lissieu ne peuvent pas être tous identifiés au niveau de l’espèce ou du genre. Ils appartiennent auxiguanidés, gekkonidés, lacertidés, anguidés, thecoglosses (platynotes), ophidiens incertae sedis, boïdés, ? tropidophiinés, « tropidophiidés »incertae sedis, booides incertae sedis et peut-être aux russellophiidés. La faune comprend plusieurs taxons nouveaux mais un seul, untropidophiiné présumé, peut être nommé sur la base du matériel disponible. La faune de Lissieu inclut des taxons restreints à l’Eocène moyen

Geobios 43 (2010) 253–268

§ Corresponding editor: Gilles Escarguel.* Corresponding author.

E-mail address: [email protected] (J.-C. Rage).

0016-6995/$ – see front matter # 2009 Elsevier Masson SAS. All rights reserved.doi:10.1016/j.geobios.2009.08.002

mailto:[email protected]

http://dx.doi.org/10.1016/j.geobios.2009.08.002

ainsi que des taxons connus dans des niveaux plus anciens et/ou plus récents. Les formes communes à Lissieu et aux autres gisements de l’Eocènemoyen d’Europe sont rares. La faune de Lissieu représente un repère stratigraphique pour l’Eocène moyen.# 2009 Elsevier Masson SAS. Tous droits réservés.

Mots clés : Squamata ; Lacertilia ; Ophidia ; Eocène ; France

J.-C. Rage, M. Augé / Geobios 43 (2010) 253–268254

1. Introduction

Squamates (i.e., lizards and snakes) are common in Eocenelocalities of Europe. However, although the early (MP 7–MP10, i.e., Ypresian) and late (MP 17–MP 20, i.e., Priabonian)Eocene are represented by numerous localities that haveproduced rich and diverse faunas, fossiliferous localities fromthe middle Eocene (MP 11–MP 16, see below) are rare, with theexception of those from MP 16. Faunas of squamates from theMP 11–MP 15 interval were previously described from onlytwo localities or group of localities: Messel and the Geiseltalsites (Germany). Messel is equated with the level MP 11, andthe Geiseltal sites bracket the levels MP 11 to MP 14 (Haubold,1989); however, as far as Geiseltal is concerned, squamateswere reported only from the Mittelkohle beds, that is from theMP 12 and MP 13 levels (Haubold and Krumbiegel, 1984).Aside from the faunas of Messel and Geiseltal, only onesquamate was previously reported from the MP 11–MP 15interval in Europe. This fossil is the gekkonid lizardRhodanogekko vireti, which is based on a single bone andwas described by Hoffstetter (1946); it comes from Lissieu(France), which is referred to the level MP 14. The fossils fromMessel and Geiseltal are mostly represented by articulatedskeletons. Comparisons of such faunas with those of otherEocene localities are somewhat difficult because the latter havealmost always yielded disarticulated bones.

Lissieu yielded squamates apart from Rhodanogekko viretithat were not studied; they are described in the present article.The fauna is not rich but it is approximately as diverse as thatfrom Messel and more diverse than those from the Geiseltalsites. Seventeen taxa have been identified from Lissieu. Thefauna from Lissieu is the only known assemblage of squamatesfrom the level MP 14. In addition, Lissieu is the only localityfrom the MP 11–MP 15 interval that produced fossilsrepresented by isolated bones, i.e., fossils that may be easilycompared to those from other Eocene localities. As far assquamates are concerned, the fauna from Lissieu represents animportant landmark within the Eocene.

The fossils are curated in the Musée des Confluences(MHNL), Lyon (France).

Remark about the notion of middle Eocene: For years, themiddle Eocene was understood as equivalent to the Lutetianstage by paleontologists studying terrestrial vertebrates inEurope (e.g., Hartenberger et al., 1974; Sudre, 1978; Rage andRocek, 2003). From this perspective, the middle Eocene isequated with the levels MP 11 to MP 14 of the Europeancontinental stratigraphy (Schmidt-Kittler, 1987). However,Franzen and Haubold (1987) restricted the middle Eocene tothe levels MP 11–MP 13, thus classifying Lissieu (MP 14) asearliest late Eocene. In contrast, other experts have extended the

middle Eocene up to the Bartonian (e.g., Milner, 1986; Jenkinsand Luterbacher, 1994). In a review of the Eocene stratigraphy,Cavelier and Pomerol (1983) suggested that the Bartonian beincluded in the middle Eocene. Here, we follow the lastsuggestion and therefore regard the middle Eocene as spanningthe levels MP 11 to MP 16.

2. The locality

The locality no longer exists. It was located in a westernextension of the Mont d’Or lyonnais, a small limestone mountlocated 10 km north-northwest of Lyon, central eastern France(‘‘département’’, or administrative region, of Rhône). Thefossils were recovered from a fissure-fill situated close to thehamlet of La Clôtre, near the village of Lissieu. The enclosingrocks, and therefore the fissure disappeared (mined out) by theend of the nineteenth century. The fauna was listed by Mein(1969) and Hartenberger (1969); it includes mainly mammals,the list of which was subsequently updated by Sudre (1972).The geological age of the fauna does not appear to be in doubt.Mein (1969) noted that it is coeval to that of the classicallocality of Egerkingen (Switzerland) whereas Hartenberger(1969) and Sudre (1972) regarded it as close to, but slightlyyounger than the Swiss one. In terms of standard levels, Lissieuis assigned to the level MP 14 (Schmidt-Kittler, 1987;BiochroM’97, 1997).

3. Systematic paleontology

Remark: Binominal nomenclature should be retained fromtraditional classifications because it is necessary, but above thegenus level categorical hierarchy raises difficulties. Forexample, within squamates, ‘‘lizards’’ and snakes were longregarded as taxa of equivalent taxonomic levels. However, it isestablished that snakes are nested within ‘‘lizards’’, whatevertheir precise relationships. In addition, the higher-levelrelationships within squamates are highly disputed (e.g., Esteset al., 1988; Conrad, 2008; Hedges and Vidal, 2009) andconsequently there is no generally accepted classification.Therefore, we prefer not to attach hierarchical ranks tosuprageneric taxa (Table 1).

SQUAMATA Oppel, 1811

Remarks on anatomical terminology: As far as squamatesare concerned, various characters of the dentary and maxilla areoften used for purposes of identification. Unfortunately, animportant element was ambiguously defined: the subdentalshelf of the dentary (sometimes named lamina horizontalis). Assuggested by its name, the subdental shelf may be understood asthe part of the bone on which rest the bases of the teeth (Gao and

Table 1Adopted phylogenetic hierarchy of squamates (only taxa recovered fromLissieu are mentioned).

SQUAMATAIGUANIA

‘‘Iguanids’’SCLEROGLOSSA

GekkonidaeAUTARCHOGLOSSA

LacertidaeANGUIMORPHA

AnguidaeAnguinaeGlyptosaurinae

PLATYNOTAVARANOIDEATHECOGLOSSAOPHIDIA

Stem SerpentesSerpentesAlethinophidiaBooid grade snakesBoidae‘‘Tropidophiids’’Tropidophiinae

ColubroideaRussellophiidae

J.-C. Rage, M. Augé / Geobios 43 (2010) 253–268 255

Fox, 1996). Such a subdental shelf cannot be absent. However,the term subdental shelf was more often applied to a medialextension of the shelf that projects medially to the teeth andtherefore does not support them; such a subdental shelf may bepresent or absent (e.g., Estes et al., 1988; Smith, 2006; Conrad,2008). Here, we name ‘‘subdental table’’ the area that supportsthe bases of the teeth; it cannot be absent and it is generally, butnot always, more or less horizontal. Following the morefrequent use, we term ‘‘subdental shelf’’ the medial extensionof the table; the bases of the teeth do not extend on it. Thesubdental shelf may be present or absent. The sulcus dentalis isa groove that runs on the subdental shelf, along the tooth rowand close to the bases of the teeth. The sulcus dentalis may bepresent or absent; obviously, it is lacking where the subdentalshelf is absent. The parapet is the lateral wall of the dentary thatrises above the subdental table; we name ‘‘alveolar surface’’ itsmedial face against which are attached the shafts of the teeth.The alveolar surface is generally subvertical, but not always.The same terms may be used for description of the maxilla,subdental table and subdental shelf being replaced bysupradental table and supradental shelf, respectively.

3.1. Iguania Cuvier, 1807

According to phylogenies based on morphology, theiguanids are possibly paraphyletic (Frost and Etheridge,1989), certainly paraphyletic (Conrad, 2008), or monophyletic(Smith, 2009). Molecular phylogenies generally show mono-phyletic Iguanidae (e.g., Schulte et al., 2003; Hedges and Vidal,2009). In view of this uncertainty, iguanians that do not belongto the monophyletic Acrodonta are here referred to as‘‘iguanids’’.

‘‘IGUANIDS’’

Genus and species indeterminateFig. 1(1)Material: One fragmentary dentary (MHNL, Li 301).Description: The alveolar surface and the subdental table

meet at a marked angle. The subdental shelf little protrudesmedially and apparently lacks a sulcus dentalis. Meckel’sgroove is relatively wide and opens medioventrally; it beginsnarrowing in a comparatively posterior portion of the bone. Thepreserved teeth are tall, slender, deeply pleurodont, and closelyspaced. Slightly more than one-fourth of the tooth heightprojects above the parapet. The crowns are tricuspid; the cuspsare aligned anteroposteriorly, the central one being the largest.In each tooth, the two small cusps are similar in size. The maincusp bears poorly marked striae.

Comments: The observable features are consistent withGeiseltaliellus from the European Eocene; more specifically,the tooth morphology and Meckel’s groove recall G. long-icaudus from the early and middle Eocene. However, such aprecise assignment cannot be made on the basis of the availablematerial.

Today, the iguanids inhabit the Americas, Madagascar, andFiji and Tonga islands. In Europe, they were reported from thelate Cretaceous (Rage, 1999) to the late Eocene (Augé, 2005).Geiseltaliellus, to which Li 301 may belong, occurs in Europefrom the earliest to the late Eocene (MP 7-19; Augé, 2007).Rossmann (1993, 1999) referred Geiseltaliellus to thesubfamily Messelosaurinae that also includes North Americanand other European taxa from the Paleogene, but Sullivan andHolman (1996) and Smith (2009) questioned this referral.

3.2. Scleroglossa Estes, de Queiroz and Gauthier, 1988

GEKKONIDAE Gray, 1825Genus Rhodanogekko Hoffstetter, 1946Rhodanogekko vireti Hoffstetter, 19461946. Rhodnogekko Vireti gen. and sp. nov. - Hoffstetter,

pp. 237–238, Fig. 1.1969. Rhodnogekko Vireti - Mein, p. 400.1969. Rhodnogekko Vireti - Hartenberger, p. 30.1983. Rhodnogekko Vireti - Estes, p. 72, fig. 14D.2005. Rhodnogekko Vireti - Augé, p. 95.Material: One frontal, holotype (MHNL, Li 300).Comments: The frontal is characterized by its narrow

interorbital area and by the presence of pustular, irregularrugosities on the dorsal face. As noted by Estes (1983), othergekkonids with dermal rugosities have a clearly widerinterorbital area. However, R. vireti remains poorly diagnosed.This frontal from Lissieu is the only known specimen belongingto Rhodanogekko.

3.3. Autarchoglossa Wagler, 1830

LACERTIDAE Bonaparte, 1831Genus Plesiolacerta Hoffstetter, 1942Plesiolacerta lydekkeri Hoffstetter, 19421888. Iguanaeuropaea,Filhol -Lydekker,1888,p.277,fig.61.

Fig. 1. ‘‘Iguanid’’, genus and species indeterminate, left dentary (MHNL, Li 301), medial view. 2. Anguinae, genus and species indeterminate, trunk vertebra(MHNL, Li 304) in anterior (a), lateral (l) and ventral (v) views. 3, 4. Glyptosaurinae, genus and species indeterminate; 3, left maxilla (MHNL, Li 307), lateral view; 4,left dentary (MHNL, Li 308), medial view. Scale bars = 5 mm.


1893. Proiguana europaeana - Zittel, 1893, p. 597, fig. 537.1942. Plesiolacerta Lydekkeri gen. and sp. nov. - Hoffstetter,

p. 238.1983. Plesiolacerta lydekkeri - Estes, p. 103, fig. 24B.2005. Plesiolacerta lydekkeri - Augé, pp. 109–114, figs. 70–

76.2006. Plesiolacerta lydekkeri - Rage, p. 166, table 3.Material: One trunk vertebra (MHNL, Li 302) and perhaps

one incomplete humerus (MHNL, Li 303).Comments: The presence of P. lydekkeri at Lissieu was

reported by Augé (2005). The vertebra shows the lacertidmorphology (Rage, 1988). In addition, a well-developedpseudozygosphene is present. It approaches the morphologyof true zygosphenes in having a roof which connects the twoarticular facets; however, the extent of the roof is stronglyreduced by a large notch. This vertebra stands as the oldestrepresentative of P. lydekkeri. The proximal portion of a humerusis consistent with the presence of a lacertid. Based on itscompatibility in size with the vertebra, it is tentatively referred toP. lydekkeri, which is the only lacertid known in the locality.

P. lydekkeri is known from the middle Eocene to the earliestOligocene (MP 14–MP 21; Augé, 2005).

3.4. Anguimorpha Fürbringer, 1900

Remark: The absence of an angle between the alveolarsurface and the subdental table is a characteristic of bonesbearing teeth of various anguimorphs; in these forms, there is asingle, inclined surface. In addition, the subdental shelf doesnot markedly project medially.

ANGUIDAE Gray, 1825ANGUINAE Gray, 1825

Genus Anguis Linnaeus, 1758Anguis sp.Material: One left dentary (MHNL, Li 350).Description: This small dentary (length: 8.2 mm) bore ten

teeth, of which five are preserved (Augé, 2005: fig. 161). Theteeth are shallowly pleurodont (subpleurodont sensu Gao andFox, 1996), unicuspid, conical and recurved, and they haverelatively large bases. Lingually, a tall medial swelling thatlacks a sharp dorsomedial edge may represent a weaklydeveloped subdental shelf; its dorsal face is depressed andforms a wide groove that may be a poorly defined sulcusdentalis. The anterior inferior alveolar foramen is locatedbeneath the penultimate tooth. Meckel’s groove opens ventrallyfrom the symphysis to the level of the anterior inferior alveolarforamen. An intramandibular septum is present; its ventralborder is free. The surangular notch is shallow.

Comments: The small size, reduced number of teeth, andpronounced reduction of the tooth row posterior to the anteriorinferior alveolar foramen point to Anguis (Augé, 2005). A fewcharacters suggest that this dentary may represent a distinctspecies. The tooth bases appear to be somewhat wider than inliving Anguis. Posteriorly, the coronoid and surangular processesreach the same transverse level, whereas the surangular one isslightly longer in extant forms. The intramandibular septum isshorter than in living forms. The longitudinal lingual swelling(subdental shelf?) and depression (sulcus dentalis?) are absent inextant Anguis. Despite these features, on the basis of this singlespecimen no clear conclusion can be reached as to the taxonomicstatus of this fossil within Anguis.

Today, Anguis inhabits Europe, southwestern Asia andnorthern Africa. Fossils have been reported only from Europe;in the Eocene, they are known from MP 8 + 9 to MP 19 (Augé,2005). No extinct species has been named from the Paleogene.


Genus and species indeterminateFig. 1(2)Material: Three trunk (MHNL, Li 304, 305) and three

caudal (MHNL, Li 306) vertebrae.Description and comments: The vertebrae show the typical

morphology of anguine lizards. They are elongate and stronglydepressed, their cotyle and condyle are enlarged transversely, aneural spine is present, and their centrum is narrow with well-marked lateral margins. The presence at Lissieu of a dentaryreferred to Anguis may suggest that these vertebrae belong tothat genus (see below). However, the vertebrae cannot beassigned to Anguis. Their centrum slightly, but unquestionablywidens anteriorly and its ventral face is slightly convex. InAnguis, the subcentral ridges that limit the centrum laterally areparallel; they are even weakly laterally concave and thecentrum is thus constricted in its middle part. Moreover, theventral face is practically flat in Anguis. In addition, theparadiapophyses of Anguis are almost vertical whereas they areoblique on the fossils from Lissieu. An assignment moreprecise than Anguinae is not possible.

Remarks on the Anguinae from Lissieu: Two taxa areidentified within the Anguinae from Lissieu. It is somewhatsurprising that one of them is represented by one skull bone butno vertebrae, whereas only vertebrae are assigned to the otherone. Aside from their sizes that are compatible, there is no goodbasis for associating them in the same taxon, but this cannotdefinitely be rejected. The vertebrae from Lissieu display thegeneralized anguine morphology while those of Anguis appearto be derived (centrum with parallel borders and flat ventralface). If the dentary and vertebrae belong to a single taxon, thensuch a taxon might be a primitive member of the Anguis clade.However, on current evidence we regard the dentary andvertebrae as belonging to two distinct taxa.

GLYPTOSAURINAE Marsh, 1872Genus and species indeterminateFig. 1(3, 4)Material: One fragment of maxilla (MHNL, Li 307), one

fragment of dentary (MHNL, Li 308), and four fragments ofbone bearing teeth (MHNL, Li 309).

Description and comments: The single surface formed bythe subdental table and alveolar surface is more steeply inclinedthan in Anguis. The specimens lack sub- or supradental shelvesand consequently there can be no sulcus dentalis. Anintramandibular septum is present. The maxilla bears atubercular ornamentation which is continuous, without limitsbetween osteoderms. The teeth are neither conical nor recurvedbut almost vertical, and they are somewhat swollen medially;their apex forms a more or less straight, horizontal cutting edge.The resorption pits are not shifted posterolingually. The toothmorphology suggests assignment to Glyptosaurinae. Thisreferral is supported by the tubercular ornamentation of themaxillary osteoderms. The absence of limits betweenosteoderms might perhaps point to Melanosaurini rather thanGlyptosaurini (Sullivan, 1979). However, this material is toofragmentary for a reliable assignment within Glyptosaurinae.

Glyptosaurinae are known in North America and Eurasia.They range from the Paleocene to Oligocene in North America

but are restricted to the Eocene in Europe (earliest to lateEocene; Augé, 2005) and Asia.

3.5. Platynota Duméril and Bibron, 1839

VARANOIDEA Boulenger, 1891THECOGLOSSA Cope, 1900Thecoglossa is a clade that includes the extant Varanidae,

Lanthanotidae and Pythonomorpha (i.e., Ophidiomorpha andMosasauroidea; Palci and Caldwell, 2007); it was resurrectedby Lee who provided new definition and diagnosis (Lee, 1997:78 and fig. 15). Although Conrad (2008) did not recognize thistaxon, we maintain it here.

3.5.1. Family IndeterminateGenus and species indeterminateFig. 2Material: One parietal (MHNL, Li 351), one posterior

extremity of mandible (MHNL, Li 311), one fragment of bonebearing the bases of two teeth (MHNL, Li 310), the centrum ofan axis (MHNL, Li 312), one incomplete cervical vertebra(MHNL, Li 313), one dorsal vertebra (MHNL, Li 314), fourfragmentary dorsal vertebrae (MHNL, Li 315), two caudalvertebrae (MHNL, Li 316), and perhaps one incomplete pelvis(MHNL, Li 317) and one fragment of humerus (MHNL, Li318).

Description: The parietal was described by Augé (2005).This is a large and unusually thick bone that comprises a broad,nearly flat, very weakly concave table and two strongsupratemporal processes (Fig. 2(1)). It is constricted and thetable bears some irregular dermal rugosities, but no trueosteoderms. The parietal foramen is broad and it opens at aboutthe anterior third of the table length. The cross section of thesupratemporal processes appears as an inverted T. The lateralborders of the table and of the supratemporal processes arethick and concave in transverse section; descending flangesventrolateral to the table are lacking. On the ventral face,posterior to the parietal foramen, is a shallow and narrowparietal fossa. It is limited laterally by two weak ridges (cristaepostfoveales; Fejérváry-Lángh, 1923) that are the continuationsof the medial borders of the supratemporal processes.

The posterior extremity of the mandible has a broad articularfacet that is almost as long as wide. The dorsal face of theincomplete retroarticular process is slightly concave and slopesmedially (Fig. 2(2)). On Li 310, the tooth-bearing surface is ofthe anguimorphan type and the bone lacks a subdental shelf. Onthe bases of teeth, some weak striae show that plicidentine ispresent and, although the bases are damaged lingually,resorption pits appear to be absent.

The axis is represented by a centrum, which is not elongate.Anterior and posterior ventral processes (hypapophyses) arebroken away. The cervical vertebra preserves the centrum andprezygapophyses (Fig. 2(3)). As the axis, it is not elongate. Thehypapophysis is broken off. The condyles and cotyles of theaxis and cervical vertebra are not depressed. The dorsalvertebrae are depressed and not elongate; their cotyles andcondyles are markedly depressed. The caudal vertebrae are

Fig. 2. Thecoglossa, genus and species indeterminate. 1. Parietal (MHNL, Li 351). 2. Posterior extremity of a mandible (MHNL, Li 311). 3. Cervical vertebra(MHNL, Li 313). Anterior (a), dorsal (d), lateral (l), medial (m), and ventral (v) views. Scale bars = 1 cm.


elongate, have non-depressed cotyles and condyles, and theyare characterized by the presence of two marked ventralpeduncles for articulation with chevrons. All vertebrae lack azygosphene-zygantrum system and have inclined cotyles andcondyles (cotyle facing anteroventrally, condyle facing poster-odorsally). A fragmentary pelvis and a fragment of humerus aretentatively referred to this taxon on the basis of consistency insize.

Comments: On the basis of consistency of size, we presumethat the specimens referred to platynotans all belong to the sametaxon. However, the shape of the vertebral condyles and cotylesmay suggest that two taxa are present. Cotyles and condyles arenot depressed, almost circular in cervical and caudal vertebrae,whereas they are clearly depressed in vertebrae from the dorsalregion. Nevertheless, they all share a marked inclination of theaxis of cotyle and condyle. In addition, it would be surprisingthat a taxon is represented by cervical and caudal vertebrae, butno dorsals, while only dorsal vertebrae, but no cervicals and

caudals, belong to another taxon. The changes in shape ofcotyles and condyles are likely an intracolumnar variation. Thistaxon is the largest lizard from the locality.

The absence of both a subdental shelf and resorption pits inthe teeth is characteristic of the platynotans (Lee, 1997). Thisreferral is supported by a combination of features of the parietal(dermal rugosities on the dorsal face, constriction of the bone,supratemporal processes strong, cristae postfoveales weak), themedial inclination of the retroarticular process of the mandible,and the presence of strong ventral processes on the axis andcervical vertebrae (Augé, 2005). Within platynotans, thepresence of plicidentine points to the Varanoidea and, withinthe latter, the presence of well-developed peduncles on thecaudal vertebrae argues for referral to the Thecoglossa.

A more precise assignment is not possible. The stronginclination of the cotyles and condyles is a characteristic of theVaranidae, Necrosaurus and alethinophidian snakes, but otherfeatures are not consistent with these taxa. The parietal from


Lissieu lacks descending flanges, which distinguishes it fromthe parietal of the varanids, Necrosaurus and snakes. Thisplatynotan further differs from varanids in having non-elongatecervical vertebrae, and from lanthanotids in having a parietalforamen and broad vertebral centra whose posterior portion isnot limited by parallel subcentral ridges. Pythonomorphs maybe also ruled out because the parietal in that taxon has extensivedescending flanges and their vertebrae have a zygosphene-zygantrum system.

Three varanoids, which might be thecoglossans, have beenreported from the Paleogene of Europe: Saniwa, Eosaniwa, andNecrosaurus. In Europe, Saniwa is known from two skeletonsassigned to S. feisti and from isolated elements referred to S.orsmaelensis and indeterminate species. S. feisti, from themiddle Eocene (MP 11) of Messel (Germany) has a parietalprovided with descending flanges and whose table is narrowerthan in Li 351. In addition, the anterior half of the table bears anornamentation made of small protuberances, whereas theposterior half is smooth (Stritzke, 1983). According to Stritzke,reduced zygosphenes (pseudozygosphenes?) are present on thevertebrae. Augé (2005) and Conrad (2008) questioned theassignment of this species to Saniwa and suggested possiblereferral to Necrosaurus. S. orsmaelensis is restricted to the earlyEocene of Europe (Augé, 2005); apart from a maxilla, ilia, anda femur, it is known from isolated vertebrae. In addition,vertebrae of indeterminate Saniwa were reported from the lateEocene (Augé, 2005). These vertebrae referred to Saniwa differfrom those of Lissieu by the presence of a well-developedpseudozygosphene. Eosaniwa koehni, the only species in thegenus, is represented by a single specimen whose parietal isunknown; it comes from the obere Mittelkohle of Geiseltal(Haubold, 1977), i.e, from the middle Eocene (MP 13) ofGermany. It differs from the taxon from Lissieu in having asubdental shelf and a twisted retroarticular process of the lowerjaw (Rieppel et al., 2007). Species referred to Necrosaurus, themost common platynotan in the European Paleogene (Paleo-cene-early Oligocene; Augé, 2005), clearly differ from thetaxon from Lissieu. The parietal in Necrosaurus has a triangulartable anteriorly and either a sagittal ridge (N. cayluxi) or anarrow extension of the table (N. eucarinatus) posteriorly. Inaddition, the cervical vertebrae of Necrosaurus are elongate.

Aside from comparisons with other European platynotans, afeature of the parietal from Lissieu may deserve specialattention. On the dorsal face of this parietal, there is no trace ofmuscle attachment. This, coupled with the thickness andconcavity of the lateral borders, suggests that the jaw adductormuscles inserted on these lateral borders and perhaps also onthe lateral margins of the ventral face. Conrad (2008) regardedthe insertion of adductor muscles on the dorsal face of theparietal as a diagnostic character of platynotans, which mightcast doubts on the referral of this lizard to this group. However,the attachment is ventral in helodermatids according to Pregillet al. (1986) and Conrad assigned to Platynota several extincttaxa whose adductor musculature did not insert onto the dorsalface of parietal. It is not always easy to assess the condition infossils, but it appears clear that in at least three taxa referred toPlatynota by Conrad (2008) the adductor muscles attached on

the ventral face of the parietal: Proplatynotia, Gobiderma(Borsuk-Bialynicka, 1984) and Telmasaurus (Estes, 1983), allfrom the late Cretaceous of Mongolia. Whatever the status(plesiomorphic or derived) of this character, it does not argueagainst assignment of the species from Lissieu to Platynota.

Ultimately, the platynotan from Lissieu cannot be referred toa named taxon. It is regarded as an indeterminate thecoglossan.

3.5.2. Ophidia Brongniart, 1800As conceived by Caldwell and Lee (1997) and Scanlon and

Lee (2000), Ophidia contains basal snakes (i.e., stem Serpentes;Table 1) and the modern radiation or crown-clade Serpentes.Stem Serpentes are represented by hindlimbed taxa, madtsoiidsand dinilysiids, but other, very poorly known extinct snakes(e.g., Coniophis) may be basal forms, although this cannot bedemonstrated.

OPHIDIA incertae sedisGenus Coniophis Marsh, 1892Coniophis sp.Material: One trunk vertebra (MHNL, Li 319).Description and comments: The vertebra is mainly

characterized by the posterior border of the neural arch thatforms a shallow concavity and lacks a median notch. The neuralspine is a low, hardly distinct keel that ends posteriorly as a lowmound. The ventral face of the centrum is triangular. All snakesthat lack a posterior median notch in the neural arch (aplesiomorphic state) but whose ventral surface of centrum is notlimited by parallel or subparallel subcentral ridges (a characterof scolecophidians and various uropeltids) have been referred toas Coniophis. Generally assigned to the Aniliidae s.l., this taxonis likely para- or polyphyletic and it likely includes basalalethinophidians and/or snakes antedating the scolecophidian-alethinophidian dichotomy, i.e., stem Serpentes. The nameConiophis is conservatively used for reference to thisassemblage of primitive snakes, but this ‘‘genus’’ is artificial.Snakes labelled Coniophis have been reported from the mid-Cretaceous (Gardner and Cifelli, 1999) to the late Eocene(Crochet et al., 1981), mainly from Europe and North America.

SERPENTES Linnaeus, 1758ALETHINOPHIDIA Nopcsa, 1923BOOID GRADE SNAKESBooid snakes are a paraphyletic assemblage (Lee and

Scanlon, 2002) that includes several extant taxa: Boidae,Xenopeltidae, Loxocemidae, Bolyeriidae and ‘‘tropidophiids’’.However, a part of the ‘‘tropidophiids’’, namely the Tropido-phiinae, were excluded from the booid grade and referred to theanilioid grade by Wilcox et al. (2002), thus rendering the taxonBooidea polyphyletic. Whatever the phylogenetic structure, theoverall vertebral morphology is homogenous within this grade,the Ungaliophiinae being an exception. Non-ungaliophiinebooids have short, wide, and massively built vertebrae, withshort and generally wide centra, small prezygapophysealprocesses (except the bolyeriid Bolyeria), and weakly toscarcely subdivided paradiapophyseal surfaces. Vertebrae ofungaliophiines are characterized by narrower, more elongatecentra.


BOIDAE Gray, 1825Genus Palaeopython Rochebrune, 1880Palaeopython sp.Material: 31 trunk vertebrae (MHNL, Li 320-Li 324).Description and comments: A large-sized boid is

represented by vertebrae that are all incomplete and worn. Inthe largest one, the centrum length reaches 9.5 mm. The size isapproximately consistent with that of Palaeopython (middleand late Eocene; Rage, 2006), Paleryx (late Eocene; Rage,1984) and Bavarioboa (Oligocene and Miocene; Szyndlar andRage, 2003), the only mid- to large-sized boids described fromthe European Paleogene.

As a result of poor preservation, comparisons are difficult.Nevertheless, it may be stated that the boid from Lissieu differsfrom Paleryx in having a zygosphene wider than the cotyle, andfrom Bavarioboa in having a markedly vaulted neural arch,inclined anterior and posterior borders of neural spine, and inlacking paracotylar foramina. It more favorably compares withPalaeopython, although the axis of its prezygapophyseal facetsis more oblique than in typical, i.e. large, vertebrae of the lattergenus. However, this feature is affected by ontogeneticvariation (Auffenberg, 1963) and this axis may be oblique insmaller vertebrae of Palaeopython.

Other mid- to large-sized boids are known from the earlyEocene of Eurasia. They all remain undescribed but none ofthem is similar to the fossil from Lissieu. A rather large boidwas reported from the early-middle Eocene of Pakistan, but itclearly differs from the European taxa (Rage, 1987). The rarelocalities from the middle Eocene of Europe have producedsome mid- to large-sized boids. Aside from Palaeopython andperhaps Paleryx from Messel and Geiseltal in Germany, theyremain unstudied. Only Laprade (MP 14, France), that is coevalwith Lissieu (Sudre et al., 1990), has yielded somedisarticulated vertebrae that appear to belong to the samespecies as the snake from Lissieu (pers. obs.).

Mid- to large-sized boids were also described from thePaleogene of the Americas, but they all differ from the taxonfrom Lissieu. The latter is clearly distinguished from Para-epicrates (early Eocene, USA; Hecht, 1959), Cheilophis (earlyEocene, USA; Rage, 1984), and Waincophis (middle Paleocene-middle Miocene, South America; Albino, 1996; Rage, 2001) inhaving a markedly more vaulted neural arch, and from Boavus(early Eocene-early Oligocene, USA; Holman, 2000) andSanjuanophis (early Eocene, USA; Sullivan and Lucas, 1988)by its less tall vertebrae. The boid from Lissieu cannot bedistinguished from the poorly known Tallahattaophis (earlyEocene, USA; Holman and Case, 1988); this genus is knownfrom a single, incomplete vertebra and no conclusion can bereached as to possible relationships between these two snakes.

Ultimately, only Palaeopython appears to be consistent withthe boid from Lissieu, but the latter differs from the four speciesreferred to this genus. Palaeopython fischeri (MP 11, middleEocene; Schaal, 2004) has a more depressed neural arch,apparently anteroposteriorly shorter neural spine, and a narrowercentrum. Comparison with the poorly known P. ceciliensis fromthe middle Eocene (MP 13, middle Eocene; Barnes, 1927) of theGeiseltal obere Mittelkohle is difficult; however, in the latter the

zygosphene is narrower and clearly thicker. P. filholi (MP 19-20,late Eocene; Rage, 1974, 2006) has a markedly depressed neuralarch. The vertebrae of P. cadurcensis (MP 16-19; Rage, 1988,2006) do not appear to be greatly different from those of Lissieu,but the anterior border of the neural spine of this species isbevelled whereas it is straight at Lissieu.

The boid from Lissieu may represent a distinct speciesbelonging to Palaeopython. It is absent from the rich localities ofearly (MP 7–MP 10), latest middle (MP 16), and late (MP 17–MP19) Eocene ages. It is known only from two coeval localities,namely Lissieu and Laprade, both from the level MP 14.

Genus and species indeterminateMaterial: Three trunk vertebrae (MHNL, Li 325, Li 326).Comments: Three incomplete vertebrae belong to a mid-

sized boid (centrum length reaching about 6 mm). Their neuralarch is clearly more vaulted than that of non-boid booids. Thevertebrae differ from all other booids from Lissieu in having azygosphene narrower than the cotyle. Two of the vertebrae haveparacotylar foramina. The sole preserved neural spine is tall andinclined posteriorly. The anterior face (mainly the ratio ofzygosphene to cotyle width) and the neural spine arereminiscent of the boid Paleryx rhombifer from the lateEocene (MP 17–MP 19) of England (Rage and Ford, 1980).However, the neural arch appears to be more vaulted than thatof the English species. Another species of Paleryx, P. spiniferwas described by Barnes (1927) from the Geiseltale obereMittelkohle (MP 13). Its referral to this genus was questionedby Rage (1984). Whatever its status, it differs from thevertebrae from Lissieu at least in having a wider zygosphene.

‘‘TROPIDOPHIIDS’’The ‘‘tropidophiids’’ (i.e., the dwarf boas) comprise the

extant Tropidophiinae and Ungaliophiinae. According to recentstudies, they appear to be either paraphyletic (Lee and Scanlon,2002) or even polyphyletic (Vidal and Hedges, 2002; Wilcoxet al., 2002). However, their precise relationships beingcontroversial, it is convenient to retain the name ‘‘tropido-phiids’’ (Szyndlar et al., 2008). Anyway, irrespective of thephylogenetic structure of the ‘‘tropidophiids’’, Tropidophiinaeand Ungaliophiinae are each monophyletic.

? TROPIDOPHIINAE Brongersma, 1951Genus Szyndlaria nov. gen.Etymology: After Zbigniew Szyndlar (Polish Academy of

Sciences, Cracow), for his contributions to herpetology.

Diagnosis: As for the type species and only known species.

Szyndlaria aureomontensis nov. gen., nov. sp.(Fig. 3)

Etymology: Latin aurum, gold, and mons, mount; inreference to the geographic place, the Mont d’Or (Gold Mount).

Holotype: One mid-trunk vertebra (MHNL, Li 331).Type locality and horizon: Lissieu, central eastern France;

MP 14, middle Eocene.Referred material: Three almost complete (Li 332-334),

one incomplete (MHNL, Li 335) and perhaps one damaged(MHNL, Li 336) trunk vertebrae.


Diagnosis: Very distinctive small booid snake sharplydistinguished by the following combination of characters that isunique within booids: neural arch depressed but neural spinerelatively high; paradiapophyses broad and strongly projecting,approaching the prezygapophyseal extremities laterally; hae-mal keel deep and arched ventrally in lateral profile. Furtherdistinctive traits are: vertebrae clearly wider than long;paracotylar and parazygantral foramina absent; zygapophysealplane standing at a high level; prezygapophyseal processessmall; zygosphene thin and slightly wider than cotyle;ventrolateral cotylar processes variably present.

Fig. 3. Szyndlaria aureomontensis nov. gen., nov. sp. 1. Mid-trunk vertebra, holotypevertebra (MHNL, Li 333). Anterior (a), dorsal (d), lateral (l), posterior (p), and ve

Description of holotype: The holotype is a nearly completetrunk vertebra (Fig. 3(1)) that lacks only the tip of the leftprezygapophysis and shows minor damage to the zygospheneand cotylar rim. Its dimensions (in mm) are as follows: widthacross postzygapophyses: 3.6; width of interzygapophysealconstriction: 2.4; approximate length from cotyle rim to tip ofcondyle: 2.2; width of zygosphene: 1.4.

In anterior view, the vertebra appears as tall as wide. Theneural canal is of moderate size. The neural spine is high, with aslightly swollen dorsal border. The zygapophyseal plane islocated high on the neural arch, about half the height of the

(MHNL, Li 331). 2. Anterior trunk vertebra (MHNL, Li 332). 3. Posterior trunkntral (v) views. Scale bar = 5 mm.


neural canal. The prezygapophyses do not strongly projectlaterally and the prezygapophyseal processes are small. Theparadiapophyses markedly extend dorsoventrally and stronglyproject laterally, almost as far as the prezygapophyses; theyclearly project below the level of the cotyle. The zygosphene isslightly wider than the cotyle; it is thin and its roof is concavedorsally. On the left side (right side damaged), the ventralborder of the cotyle forms a weak ventrolateral cotylar process(sensu LaDuke, 1991). Paracotylar foramina are absent.

In dorsal aspect, the vertebra is clearly wider than long, witha relatively shallow interzygapophyseal constriction. Theneural spine is thick; anteriorly, it reaches the posterior limitof the zygosphene. The zygosphene is moderately wide; asmall, hardly protruding lateral lobe is present on the left sidebut the remaining part of the border is damaged. The onlypreserved prezygapophyseal facet is short, and its axis isoblique. The posterior median notch is marked but small. Oneach side, slightly anterolateral to the bulge caused by thezygantrum, the neural arch bears a small ridge.

In lateral view, the anterior border of the neural spine isvertical whereas the posterior one is inclined posteriorly. Theinterzygapophyseal ridge is blunt. The zygosphene has a smallarticular facet. The paradiapophysis is unusually broad; thehemispherical diapophyseal part overhangs the flat, crescenticparapophyseal area. Posterior to the level of the paradiapo-physis, the haemal keel is deep, and its ventral border is archedventrally. The subcentral ridge is poorly marked and weaklyarched dorsally.

In ventral view, the centrum is short and narrow, wideningmoderately anteriorly. The ventral surface is poorly delimitedlaterally by weak subcentral ridges. The haemal keel appears asa clearly delimited prominence restricted to the posterior part ofthe centrum; anteriorly, the centrum is regularly convex intransverse section and without a keel. Subcentral grooves areshallow and short, occupying only the anterior half of thecentrum. In posterior view, the neural arch is depressed; itsposterior border lacks foramina.

Variations: Three additional vertebrae provide informationthat is not available from the holotype. The anterior border ofthe zygosphene forms a wide central lobe and two small,pointed lateral lobes; they are all weakly prominent. Theventrolateral cotylar processes are not present in all specimens;Li 334 and perhaps Li 333 lack them. Similarly, the small ridgeson the neural arch can be absent; they are lacking in Li 332 (notverifiable in Li 335). Li 334 shows marks of exostosis on theneural arch and the left diapophysis. In addition, below thecotyle it bears a short process that does not result fromexostosis. Li 334 is apparently the anteriormost vertebra withinthe sample.

Intracolumnar variations are not marked. The identificationof the vertebral regions from which the specimens come mainlyrests on the height of the neural spine and cannot be regarded ascertain. It is assumed that, as in almost all snakes, the neuralspine is taller in anterior than in posterior trunk vertebrae andthat the height decreases more or less steadily. No very anteriorvertebra, with a hypapophysis, is known. The depth of thehaemal keel does not vary significantly, which is unusual.

However, it is anteroposteriorly longer in anterior than in mid-trunk vertebrae; as is usual, it re-develops in the posterior trunkregion where it is longer than in mid-trunk vertebrae.Surprisingly, the degree of vaulting of the neural arch andthe size and position of the paradiapophyses do not undergonoticeable variations, if any. As is usual, in the posterior trunkregion the centrum is wider anteriorly and the subcentralgrooves are more marked, but in Szyndlaria nov. gen. they areneither deep nor well-delimited anywhere.

Comments: Szyndlaria aureomontensis nov. gen., nov. sp.unquestionably displays the vertebral morphology that ischaracteristic of the booids. Within this assemblage, thecombination of a depressed neural arch with a tall neural spineis very uncommon. Among living booids, it occurs only in theloxocemid Loxocemus, the boid Candoia, the Tropidophiinae,and, to a lesser degree, in the enigmatic booid Calabaria. Inextinct booids, it is known in Cadurcoboa (see below), theenigmatic Geringophis (Oligocene and Miocene of NorthAmerica; Holman, 2000) and in a snake from the Paleocene ofBrazil (Rage, in press). Szyndlaria nov. gen. markedly differsfrom these genera in having strongly projecting paradiapo-physes that closely approach the level of the prezygapophysealtip laterally. Apart from Szyndlaria nov. gen., this peculiarfeature occurs only in the Madtsoiidae (Cretaceous-Pleisto-cene), a group that shows an overall booid vertebralmorphology. However, referral of Szyndlaria nov. gen. to themadtsoiids may be indisputably ruled out because its vertebraehave prezygapophyseal processes and lack parazygantral andparacotylar foramina. Within the booid grade, Szyndlaria nov.gen. appears to be consistent only with the Tropidophiinae. Thisis suggested by the following combination of characters:depressed neural arch; strongly developed, high neural spine;centrum narrow by booid standards; haemal keel well-developed (Szyndlar et al., 2008). In addition, the presenceof ventrolateral cotylar processes, thickening of the dorsalborder of the neural spine, and the presence of ridges on theneural arch of Szyndlaria nov. gen. support this assignment.

Unfortunately, caudal vertebrae of Szyndlaria nov. gen. areunknown; such vertebrae are key elements for identification of,and within ‘‘tropidophiids’’ (Szyndlar and Böhme, 1996;Szyndlar et al., 2008). As a result, the referral of Szyndlaria nov.gen. to the Tropidophiinae cannot be regarded as definitelyconfirmed.

Today, the Tropidophiinae occur in northern South Americaand in Caribbean islands. Aside from Szyndlaria nov. gen., onlyrare fossils may be tentatively assigned to this taxon: Falseryx(Oligocene and Miocene; Szyndlar et al., 2008), Rottophis(Oligocene; Szyndlar and Böhme, 1996), both from Europe, andperhaps a snake from the Paleocene of Brazil (Rage, in press).

‘‘TROPIDOPHIIDS’’ incertae sedisGenus Dunnophis Hecht, 1959Dunnophis is a snake known only from disarticulated

vertebrae. Three species were described: D. microechinis, thetype species, from the late early Eocene of North America(Hecht, 1959; Holman, 2000), D. matronensis and D.cadurcensis from the Eocene of Europe (Rage, 2006).


In addition, another species might be present in the Eoceneof Europe. Messelophis variatus from the middle Eocene (MP11) of Messel (Germany) has vertebrae that closely resemblethose of Dunnophis (Baszio, 2004). M. variatus is representedby articulated specimens (skull included) and some isolatedvertebrae that are not well-preserved. Comparisons with thedisarticulated vertebrae of Dunnophis are difficult, but on thebasis of the available evidence a case could be made forreferring M. variatus to Dunnophis; Baszio (2004: 61) hinted atthis possibility. It is worth noting that if further studies confirmsuch referral, then Dunnophis should be excluded from the‘‘tropidophiid’’ assemblage because the skull and number ofvertebrae in M. variatus argue against this assignment(Szyndlar et al., 2008).

The specimens from Lissieu are consistent with the Europeanspecies in having subcentral grooves that do not reach thecondyle, although in a posterior-most trunk vertebra (Li 329)they approach it. The two confirmed European species aredistinguished on the basis of the morphology of the zygospheneand neural spine; they are perhaps both present at Lissieu.

Dunnophis matronensis Rage, 19731973. Dunnophis matronensis nov. sp. - Rage, pp. 76–78,

Fig. 1.1984. Dunnophis matronensis - Rage, p. 29, fig. 17B.1997. Dunnophis matronensis - Augé et al., p. 30, Table 1.2006. Dunnophis matronensis - Rage, p. 167, table 3.Material: Two vertebrae (MHNL, Li 327, Li 328).Comments: In these two vertebrae, the low neural spine is

restricted to the posterior part of the neural arch from which itrises sharply; it is prolonged anteriorly by a very low keel. Thecentral lobe of the zygosphene is broad and rounded. Thesefeatures are characteristic of D. matronensis. This species waspreviously reported from the early and early middle Eocene (MP7-MP 13) of western Europe (Rage, 2006: table 3); the specimensfrom Lissieu are the youngest representatives of the species.

Dunnophis cf. D. cadurcensis Rage, 1974Material: Two vertebrae (MHNL, Li 329, Li 330).Comments: The neural spine is low and anteroposteriorly

long, it reaches the zygosphenal roof. From the zygosphene, itgently slopes posteriorly and reaches its maximum height in theposterior part of the neural arch. The central lobe of zygospheneis narrower than in D. matronensis and more or less pointed;however, it appears to be less protruding than in the specimens ofD. cadurcensis from the late Eocene, which prevents asecure assignment to this species. Confirmed representativesof D. cadurcensis were recovered from the latest middleand late Eocene (MP 16-MP 19) of western Europe (Rage, 2006:table 3).

Remark about the stratigraphical ranges: Lissieu is thefirst locality that has perhaps produced both D. matronensis andD. cadurcensis. Unfortunately, the presence of the latter cannotbe regarded as confirmed. Lissieu standing between the rangesformerly known for the two species, their stratigraphicalextensions may logically overlap in MP 14; however, this canbe definitely confirmed only if the presence of D. cadurcensis inMP 14 is corroborated by another locality.

BOOID GRADE SNAKES incertae sedisGenus Cadurcoboa Rage, 1978Cadurcoboa is a small booid that was first considered

Boidae incertae sedis (Rage, 1978, 1984), but it may no longerbe assigned to Boidae as they are understood at present. Weregard it as a booid incertae sedis. The genus includes a singlespecies, C. insolita (Rage, 1978). Only one vertebra fromLissieu is referred to Cadurcoboa.

Cadurcoboa sp.Material: One trunk vertebra (MHNL, Li 337).Description: This specimen displays the suite of characters

that is typical of Cadurcoboa: vertebrae short and wide, neuralarch depressed, neural spine tall, zygosphene wider than cotyle,zygosphenal roof flat, facets of the zygosphene elongatedanteroposteriorly and with a subhorizontal axis, prezygapo-physeal processes deep and weakly to scarcely projectinglaterally. However, the specimen from Lissieu differs from C.insolita; its neural spine is not so tall, the anterodorsal corner ofthe spine is angular whereas it is rounded in C. insolita, andconversely the posterodorsal corner is rounded in the Lissieuspecimen but pointed in C. insolita.

Comments: The differences in the morphology of the neuralspine appear to be significant at the species level. Rage (2006:table 3) reported C. insolita from MP 14 to MP 20, its presencein MP 14 being based on a single vertebra from Laprade, France(the name of this locality was not cited in the article). However,the latter specimen closely resembles that from Lissieu, whichsuggests that it does not belong to C. insolita. In fact, C. insolitaappears to be present only from MP 18 to MP 20. From MP 14to MP 17, vertebrae belonging to Cadurcoboa are rare and aresimilar to that from Lissieu. They likely represent a speciesdistinct from C. insolita; unfortunately, the available material isnot sufficient for the erection of a new species.

All the above reports are from France, but it is worth notingthat Holman (1996) described a snakeverysimilar toCadurcoboafrom the late Eocene (MP 17) of England. This taxon, namelyHordleophis balconae, compares favorably with the Cadurcoboaspecimens from MP 14–MP17 (including that from Lissieu). H.balconae differs from the latter specimens only by the roundedanterodorsal corner of the neural spine and perhaps the less deepprezygapophyseal processes. It more distinctly differs fromC. insolita by its somewhat lower neural spine and roundedantero- and posterodorsal corners. Unfortunately, H. balconae isknown by only four vertebrae that cannot be conclusivelycompared to the rare specimens from MP 14–MP 17 in France.

Boid K1981. Boïdé K - Crochet et al., p. 251, table 2-1.1988. cf. ‘Boïdé K’ - Rage, pp. 21–22.2006. ‘Boidae K’ - Rage, p. 167, table 3.A snake from the late Eocene of France was referred to as

‘Boïdé K’ by Crochet et al. (1981: table 2-1). It is present inseveral localities but specimens are not numerous in any of them.

Material: 12 isolated vertebrae (MHNL, Li 338-340) andperhaps three articulated vertebrae (MHNL, Li 341).

Description: The vertebrae display the typical booidmorphology. In addition, they are characterized by the


following combination of characters: vertebrae relativelynarrow by booid standards, not depressed as a whole butneural arch depressed to moderately vaulted; centrumcomparatively narrow; zygosphene crenate with a flat, thinroof, wider than cotyle; zygapophyses clearly above floor ofneural canal; prezygapophyseal facets short, not markedlyprojecting laterally, and slightly inclined; neural spine longanteroposteriorly and moderately tall.

Comments: This snake represents a new taxon (Rage,1988). However, the adequate description of such a booid,differing only in subtle features, would require several,sufficiently well-preserved vertebrae from different portionsof the vertebral column. The sample from Lissieu does notallow erection of a new taxon. ‘‘Boid K’’ was regarded as a boidby Rage (1988). However, at that time, the conception of theBoidae was broader than today. It is not possible to demonstratethat this fossil belongs to the boids as they are accepted atpresent, but we retain the name ‘‘Boid K’’ for the sake ofstability, pending the description of this booid taxon.

Crochet et al. (1981: Table 2-1) reported ‘‘Boid K’’ from thelevel of Le Bretou (MP 16) to the locality of Tabarly (MP 20).Rage (1988) noted that the specimens from Le Bretou, i.e. theearliest representatives of the taxon known at that time, aresmaller than those from younger levels and he referred them toas ‘‘cf. Boïdé K’’. However, a locality (Lavergne), which iscoeval with Le Bretou (MP 16), and the older Lissieu (MP 14)have produced specimens as large as those from MP 17–MP 20.The smaller size at Le Bretou is likely not significant and ‘‘BoidK’’ may be regarded as extending from MP 14 (Lissieu) to MP20 (Tabarly). This snake has been reported only from France.

Booid A1997. cf. Dunnophis - Augé et al., p. 30.Fig. 4(1, 2)Material: Two trunk vertebrae (MHNL, Li 342, Li 343).Description: This snake is reminiscent of Dunnophis in the

morphology of the neural spine and centrum. Li 343 is aDunnophis-like posterior trunk vertebra. The centrum ismarkedly narrow and elongate and the haemal keel is not welldelimited laterally. Li 342 comes from the mid-trunk region; it ismore booid-like than Li 343 in being wider and shorter, but itscentrum is narrow. The haemal keel is wide, shallow and welldelimited laterally by marked subcentral grooves (Fig. 4(1)). Apeculiarcharacter is thecontinuitybetween theventral edge of theparapophysis and the subcentral ridge. Moreover, the junctionbetween the parapophysis and the subcentral ridge is more or lesssheet-like. Unfortunately, this character cannot be clearly seen inLi 343, the ventral borders of the parapophyses being worn.

The two vertebrae share a suite of peculiar characters: broadzygosphenal facets; low neural spine comprising a thickposterior portion and a thin anterior keel that reaches thezygosphene; presence of a tubercule on each side of the anteriorface, between the cotyle and the diapophysis; presence of aparacotylar foramen on either side; absence of clear evidence ofprojecting prezygapophyseal processes.

Comments: Li 343 is markedly reminiscent of Dunnophisand, although somewhat different, Li 342 has a clearly

Dunnophis-like neural spine and a centrum consistent with thisgenus. A similar snake is present in the early Eocene (MP 10) ofPrémontré (France). It was reported as ‘‘cf. Dunnophis’’ by Augéet al. (1997). More specifically, ‘‘Booid A’’ from Lissieu and cf.Dunnophis from Prémontré display the same peculiar connexionbetween the parapophysis and subcentral ridge. This feature islacking in Dunnophis but it is present in the russellophiidRussellophis from the Eocene, in which there is however nosheet-like part (Rage et al., 2008), and in the living loxocemidLoxocemus, in which the junction is sheet-like (Szyndlar andBöhme, 1996). This trait and the presence of paracotylarforamina argue against close relationships with Dunnophis. Onthe other hand, the Dunnophis-like overall morphology of theposterior trunk vertebra (Li 343) is striking.

Unfortunately, this snake is known from only two vertebraefrom Lissieu and rare vertebrae from Prémontré (only one ofthem being well preserved). It may also be present in the earlyEocene (MP 8 + 9) of Condé-en-Brie (France), but this cannotbe confirmed because of the scarcity and poor preservation ofmaterial. This snake likely belongs to the alethinophidian booidgrade, but its precise relationships cannot be determined.

COLUBROIDEA Oppel, 1811Colubroidea are advanced snakes that apparently began to

diversify during the Eocene. However, the earliest representa-tives of an extant colubroid group, i.e., the colubrid assemblage,are known from the latest Eocene only, in North America(Parmley and Holman, 2003) and Asia (Rage et al., 1992). AtLissieu, an archaic group of colubroids is perhaps present.

?RUSSELLOPHIIDAE Rage, 1978Genus and species indeterminateFig. 4(3)Material: Two trunk vertebrae (MHNL, Li 344, Li 345).Description and comments: The two vertebrae show

several characters that point to the Russellophiidae: vertebraenot short; neural arch vaulted and clearly swelling out above thezygantrum; centrum narrow, elongate, and delimited by markedsubcentral ridges; haemal keel relatively thin, clearly markedoff from the centrum; zygapophyses horizontal or weaklyinclined. However, in russellophiids, the prezygapophysealbuttresses are compressed and form a more or less verticalridge. In the snake from Lissieu, the prezygapophyses aredamaged, but from the remaining parts the buttresses appear tobe hardly compressed, perhaps not at all compressed in Li 345.Therefore, the morphology of the prezygapophyses, coupledwith the absence of clear elongation of vertebrae cast doubt onthe referral to the Russellophiidae. On the other hand, in thesnake from Lissieu the parapophyseal area largely extendsposteriorly as a thick blade that connects with the subcentralridge (Fig. 4(3)). Posterior extension of the parapophysis veryrarely occurs; irrespective of the continuity between the ventralborder of parapophysis and subcentral ridge, a blade-likeposterior extension of the parapophysis is known only in theliving Loxocemus (Szyndlar and Böhme, 1996), the abovedescribed ‘‘Booid A’’ and in the present possible russellophiid.It is worth noting that two of these rare snakes are present at

Fig. 4. 1, 2. Booid A; 1, mid-trunk vertebra (MHNL, Li 342); 2, posterior trunk vertebra (MHNL, Li 343). 3. ?Russellophiidae, genus and species indeterminate,trunk vertebra (MHNL, Li 344). Anterior (a), lateral (l), and ventral (v) views. Scale bars = 5 mm.


Lissieu. However, in Loxocemus and ‘‘Booid A’’ the laminar,sheet-like part is continuous with the subcentral ridge, whereasin the present possible russellophiid there is a marked anglebetween the two parts. In addition, this laminar part is clearlylarger and thicker in the latter snake than in the other two.Ultimately, although several characters argue for assignment tothe Russellophiidae, some traits do not permit a secure referralto this family.

Russellophiids have been reported from the mid-Cretaceousof Africa, the early and middle Eocene of Eurasia, and perhapsthe Paleocene of South America (Rage et al., 2008; Rage, inpress).

4. Discussion

The squamate fauna from Lissieu (MP 14) is one of the raresquamate assemblages from the middle Eocene of Europe.Some faunas are known from the latest middle Eocene (MP 16),but squamates previously described from the MP 11–MP 15interval came only from Messel (MP 11) and the Mittelkohlelevel of Geiseltal (MP 12 and MP 13) in Germany. The faunafrom Lissieu is approximately as diverse as that from Messel,for which Morlo et al. (2004) listed 18 species; however,according to K. Smith (pers. comm.) three or four speciesshould be added to this list. It is more diverse than those fromthe Geiseltal sites as they are presently known; the latter sites

taken as a whole have yielded 10 taxa (Haubold andKrumbiegel, 1984; Sullivan, 1999); the sites that producedthe most diverse squamate faunas (i.e., Cecilie III and IV, bothreferred to MP 13) yielded eight taxa each (Estes, 1983;Haubold and Krumbiegel, 1984). Lissieu is the only fauna ofsquamates reported from the level MP 14.

Squamates from Lissieu are not abundant but they arediverse. They include 17 distinct taxa; however, these taxacannot be all identified to the species or genus levels (Table 2).

From a stratigraphical point of view, the fauna from Lissieu isa mixture of taxa known from the middle Eocene only, taxa fromolder or younger levels, and taxa with broad stratigraphic ranges(Fig. 5). Only two taxa are known from both the early and middleEocene: D. matronensis and the snake referred to as ‘‘Booid A’’.Previously, D. matronensis was reported from MP 7 to MP 13 and‘‘Booid A’’ was known only from MP 10 and perhaps MP 8 + 9.Their ranges are now extended up to MP 14. Taxa occurring atLissieu and in the late Eocene are more numerous; they include P.lydekkeri, Palaeopython (but see below: a possible speciesrestricted to the middle Eocene), Cadurcoboa, ‘‘Boid K’’, andperhaps D. cadurcensis (if identification of the latter at Lissieu isconfirmed). The previously known earliest occurrences of thesetaxa were MP 11 (Palaeopython), MP 14 (P. lydekkeri,Cadurcoboa), and MP 16 (‘‘Boid K’’, D. cadurcensis). There-fore, Lissieu is the oldest, or one of the oldest localities thatyielded P. lydekkeri, Cadurcoboa, ‘‘Boid K’’, and perhaps D.

Fig. 5. Stratigraphic ranges of significant taxa from Lissieu. Grey portionsrepresent extensions of ranges resulting from recoveries from Lissieu (*: knownby only one specimen; **: known only from Lissieu).


cadurcensis. Three taxa, perhaps four are restricted to the middleEocene, in fact to MP 14: Rhodanogekko vireti (known by asingle specimen), the indeterminate thecoglossan, and Szyn-dlaria aureomontensis nov. gen., nov. sp., which are known onlyfrom Lissieu, and the possibly distinct, unnamed species ofPalaeopython that is reported from Lissieu and Laprade.Coniophis and the presumed russellophiid represent ‘‘archaic’’taxa in the fauna since they are both known from the mid-Cretaceous to the late and middle Eocene, respectively.Conversely, Anguis appears as a modern component; this extanttaxon is first reported in the fossil record in the early Eocene.Finally, the Glyptosaurinae are typical, frequent components ofEocene faunas in Europe; but the taxon from Lissieu isindeterminate and it cannot provide stratigraphical informationwithin the Eocene. It is worth noting that Lissieu lacksamphisbaenians (Augé, 2005); these squamates occur in mostlocalities of the European Eocene.

Comparison of the fauna from Lissieu with otherassemblages from the middle Eocene of Europe is difficult.Only the genus Palaeopython was recovered from all threeother localities in the MP 11–MP 15 interval: Messel (MP 11),Geiseltal obere Mittelkohle (MP 13), and Laprade (MP 14). Theform from Lissieu likely represents a distinct, undescribedspecies that is also present at Laprade (pers. obs.), but thatdiffers from both P. fischeri from Messel and P. ceciliensis fromthe Geiseltal obere Mittelkohle. Cadurcoboa appears to berepresented by the same, unnamed species at Lissieu and

Table 2Checklist of squamates from the middle Eocene of Lissieu.

‘‘Iguanids’’ Genus and species indeterminate

Gekkonidae Rhodanogekko vireti Hoffstetter, 1946

Lacertidae Plesiolacerta lydekkeriHoffstetter, 1942

AnguidaeAnguinae Anguis sp.

Genus and species indeterminateGlyptosaurinae Genus and species indeterminate

ThecoglossaFamily indeterminate Genus and species indeterminate

OphidiaOphidia incertae sedis Coniophis sp.

SerpentesBoidae Palaeopython sp.

Genus and species indeterminate‘‘Tropidophiids’’

?Tropidophiinae Szyndlaria aureomontensisnov. gen. nov. sp.

‘‘Tropidophiids’’ incertae sedis Dunnophis matronensis Rage, 1973Dunnophis cf. D. cadurcensisRage, 1974

Booid grade snakes incertae sedisCadurcoboa sp.Boid KBooid A

?RussellophiidaeGenus and species indeterminate

Laprade. The iguanid Geiseltaliellus longicaudus known fromMessel (MP 11) and Geiseltal untere and obere Mittelkohle(MP 12 and MP 13; Haubold and Krumbiegel, 1984;Rossmann, 2000), but reported also from the early Eocene(Augé, 2005), may be present at Lissieu, but this cannot beconfirmed on the basis of the available material. It is not yetpossible to determine whether the low taxonomic similarity ofthe rare middle Eocene localities of Europe results from the factthat these localities are not precisely coeval or, more likely,follows from different environments and/or still incompleteknowledge of these faunas.

Several taxa from Lissieu appear to be new. However, exceptfor Szyndlaria aureomontensis nov. gen., nov. sp., they cannotbe adequately diagnosed or described on the basis of thematerial that is available from Lissieu only (Anguis sp., theindeterminate thecoglossan) or from Lissieu plus some otherlocalities (Palaeopython sp., ‘‘Boid K’’, Cadurcoboa sp.,‘‘Booid A’’).

Most taxa from Lissieu are characteristic of Laurasiancontinents. Some of them are known only from Europe(Plesiolacerta lydekkeri, Palaeopython). Dunnophis is a relictof the Euroamerican fauna that thrived in the former European-North American faunal province. Anguids are typical of allLaurasian continents. Other taxa are biogeographicallyinsignificant, in most cases because they are still known fromtoo restricted areas, even only from Lissieu. It should be notedthat, as is the case for anurans in Europe (Rage and Rocek,2003), there are no squamates with African affinities, althoughinterchanges between Africa and Eurasia at that time areevidenced by mammals (Gheerbrant and Rage, 2006).


None of the taxa from Lissieu displays peculiar features thatwould point to a specialized lifestyle. Information on thepaleoenvironment cannot be drawn from this fauna.

Acknowledgements

We are grateful to Didier Berthet (Musée des Confluences,Lyon) and Michel Philippe (formerly at the same Museum) forthe loan of the material. Krister Smith (Museum undForschungsinstitut Senckenberg, Frankfurt am Main) kindlyprovided information about Eocene squamates from Germany.Z. Szyndlar (Cracow) and an anonymous reviewer made helpfulsuggestions.

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squamate reptiles from the middle eocene of lissieu (france). a landmark in the middle eocene of...

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