The “Caverne Marie-Jeanne” (50°13’0”N/4°47’6”E) is an archeological site situated in southeastern Belgium, in the Ardennes region (Fig. 1). The cave, which is formed in the Early Carboniferous (Tournaisian) marine limestones, is located in a small valley, 25 m above the right bank of a small tributary (Féron) of the Meuse River, near the town of Hastière-Lavaux (Ballmann et al., 1980 and Brace et al., 2012). The Meuse River is 1.5 km from the site, and the slope to reach the river is strongly inclined (2%). The overlying plateau is located directly beside the cave (5 m), with a subvertical escarpment of approximately 13 m high. The excavations at this site took place during the summer of 1943 under the direction of M. Gilbert (RBINS). During this field campaign, about 40 m³ of sediment were extracted and screened-washed, recovering a large collection of bones and several plant, mollusk, and archeological remains (Ballmann et al., 1980).

These remains are housed at the RBINS under the General Inventory number 14,138 given on 4 September 1943. During excavation campaigns, ten layers were evidenced in the cave (Fig. 2). At the base of the stratigraphic sequence, layers 10 to 7 are sterile. Then layers 6 to 2 delivered a large collection of faunal remains and lithic tools with some Mousterian artefacts that have been identified mainly in layer 3. These fossiliferous layers are principally composed of silty sands. Among large mammals, Crocuta crocuta spelaea, Coelodonta antiquitatis, Equus cf. remagensis, Cervus elaphus, Bison priscus, and Bos primigenius are the most abundant taxa (Ballmann et al., 1980). The recent revision of the small mammal fauna has revealed a total of 31 species including rodents, insectivores, and bats (López-García et al., 2017), with the predominance of the narrow-headed vole (Microtus gregalis), the common vole (Microtus arvalis), and the Arctic lemming (Dicrostonyx torquatus) in the lower layers (6 to 4) by contrast to layer 2, where the Common vole (M. arvalis), the Common mole (Talpa europaea), the narrow-headed vole (M. gregalis), the common shrew group (S. gr. araneus), the European water vole (Arvicola amphibius), and the Arctic lemming (D. torquatus) are the most abundant species.

The geological interpretation of the cave suggested that, during the formation of layers 10 to 7, the cave was closed and then, from layers 6 to 2, it was connected with the outside. The scarcity of the lithic tools suggests that the cave was probably not inhabited by humans, but that tools were probably accidentally introduced. According to the faunal list and taphonomic studies, the large mammal accumulation from the “Caverne Marie-Jeanne” seems to indicate that the cavity probably functioned as a hyena den or hibernation place. Finally, the uppermost layer 1 is composed of clayey soil mixed with organic remains where fossil and modern faunal remains have been recovered (Ballmann et al., 1980). Numeric dating of the stratigraphic sequence of the “Caverne Marie-Jeanne” (Brace et al., 2012) shows that the lower layers (6 to 4) are dated between ca. 50–40 kyr B.P., and thus pertain to Marine Isotope Stage (MIS) 3, whereas the overlying layer 2 gives somewhat divergent dating comprised between 14,850–13,925 and 25,456–24,497 cal yr. B.P. and thus pertains to MIS 2.

AMPHIBIA Linnaeus, 1758

As a whole, amphibians are represented by 18,980 remains (i.e. 92.6% of the whole material) and have been referred to six taxa belonging to caudates and anurans.

CAUDATA Scopoli, 1777

SALAMANDRIDAE Goldfuss, 1820

Lissotriton gr. L. vulgaris (Linnaeus, 1758)–Palmate or smooth newt (Fig. 4A)

A unique presacral vertebra (Fig. 4A) is attributed to the Lissotriton vulgaris group [i.e. L. vulgaris, L. helveticus (Razoumosky, 1789) and L. italicus (Peracca, 1898)] in the level 4 of the “Caverne Marie-Jeanne”. This vertebra is opisthocoelous, small in size (centrum length, CL = 1.81 mm), weakly elongated (length/width ratio, L/W = 1.7) and possesses well-differenced bifurcated transverse processes visible in lateral view. The neural arch is markedly vaulted (ratio neural arch height/vertebra height = 0.42). In dorsal view, the anterior margin of the neural arch is somewhat slightly concave, its posterior limit reaching the anterior third of the prezygapophyseal articular facets. The well-differentiated neural spine is long, of moderate height, thin anteriorly but slightly enlarged posteriorly, and horizontal in lateral aspect on all its length. It does not reach the anterior margin of the neural arch and posteriorly is bifurcated with a moderately deep and wide median notch. In ventral view, the condyle is robust and shows no postcondylar constriction. On the ventral surface of the centrum, the ventral crests are well developed, but show some variation in their extension. The subcentral foramina are large and, in addition, several other small foramina are also present.

Among the West-European small-sized salamandrids, the species Triturus marmoratus Latreille, 1800, Triturus pygmaeus Wolterstorff, 1905, Ichthyosaura alpestris (Laurenti, 1768), Lissotriton boscai Lataste and Tourneville in Blanchard, 1879, Lissotriton vulgaris and L. helveticus have presacral vertebrae with a well-developed neural spine that is high along its whole length (i.e. Ratnikov and Litvinchuk, 2007). In Triturus, unlike in Lissotriton, the interzygapophyseal constriction is more pronounced, the posteromedial notch of the neural arch is weak, and the neural spine is not bifurcated posteriorly. The vertebrae of T. cristatus and T. marmoratus are relatively longer than I. alpestris, and both are longer and slenderer than in L. vulgaris and L. helveticus (Gleed-Owen, 1998). Ichthyosaura alpestris has relatively narrow vertebrae, with a more elongate appearance than in L. vulgaris or L. helveticus (Gleed-Owen, 1998). The subcentral foramina are large in the genus Lissotriton, whereas in other genera they are generally smaller or absent (Ratnikov and Litvinchuk, 2007). By its overall shape, this fossil vertebra matches well with the genus Lissotriton.

Holman and Stuart (1991) and Holman (1998) suggested that L. vulgaris can be separated from L. helveticus, when viewed dorsally, by the size of a U-shaped notch in the neural arch, this notch being deeper and more W-shaped in L. vulgaris than in L. helveticus. Gleed-Owen (1998) verified this character, but relates the size of this notch to the slopes of the posterior neural arch ascending at different angles in the two species. The steeper angle in L. vulgaris creates a level platform at the apex (with a deeper notch). In L. helveticus, the sides converge to a peak that gives the neural spine a triangular appearance in anterior view (with a smaller notch). Gleed-Owen (1998) also remarks that not all specimens are as distinctly pointed, relating to position in the vertebral column. This last morphology is the one that seems to appear on our fossil vertebra, in posterior view, with the slopes of the posterior neural arch ascending more weakly than in L. helveticus, however. The notch seems also to be moderately deep in dorsal view, i.e. more similar to what is observed in L. helveticus than to what is observed in L. vulgaris. However, the height of the neural spine in lateral view is relatively lower than what is observed in L. helveticus and more similar to what is observed in L. vulgaris. As stressed by Gleed-Owen (1998) and thereafter by Böhme (2010), there appears to be some ambiguity in the character proposed by Holman and Stuart (1991), and confident diagnosis might not be possible in all cases, thus leading here to a cautious attribution at the level of the group of species only.

Salamandra salamandra (Linnaeus, 1758)–Fire salamander (Fig. 4B–D)

A total of 45 elements have been attributed to the fire salamander: 23 presacral vertebrae, one postsacral vertebra, 7 humeri, 12 femurs, one left ilium, and one tibia. The presacral vertebrae (Fig. 4B) differ from those of the previous salamandrid by their larger size (total length, taken from the anterior margin of the prezygapophyses to the posterior margin of the postzygapophyses, comprised between 5 and 7 mm). They are opisthocoelous, with bifurcated transverse processes. The neural arch is dorsoventrally flattened, with a deeply concave anterior margin, at the level of the middle part of the prezygapophyseal articular facets and a small medial notch in its posterior margin. The neural spine is long, low, and narrow, and is well developed in the middle part of the neural arch only. In ventral view, two small subcentral foramina are visible on the centrum and located anteriorly. All these characters are typical of the genus Salamandra (i.e. Estes, 1981, Ratnikov and Litvinchuk, 2007 and Sanchíz and Młynarski, 1979). The postsacral vertebra is characterized by the presence of only one slightly dorsoventrally flattened rib-bearer. Other elements (Fig. 4C–D), less diagnostical, have been attributed to the genus Salamandra, mainly based on their size and because their morphology does not differ from the one of that species.

Various southern former sub-species within the S. salamandra group have recently been elevated at the species rank: Salamandra atra Laurenti, 1768 (from the French Alps to Albany), Salamandra corsica Savi, 1838 (Isle of Corsica, France), Salamandra lanzai Nascetti, Andreone, Capula, and Bullini, 1988 (in the Alps between France and Italy), and Salamandra longirostris Joger and Steinfartz, 1994 (southernmost Iberian Peninsula) (Speybroeck et al., 2010). No osteological criteria have been provided yet that would permit to diagnose these new species. Consequently, the fossil remains from “Marie-Jeanne” are attributed based on the modern geographical distribution of S. salamandra, the only species of that group currently living in northern Europe.

ANURA Duméril, 1805

Anuran remains are very common in the layers of the “Caverne Marie-Jeanne” (18,934 remains, i.e. 92.4% of the total). Among them, some 9279 fossil remains (mainly incomplete elements) have been referred to only as indeterminate anurans.

BUFONIDAE Gray, 1825

Bufo gr. B. bufo-spinosus (Linnaeus, 1758)–Common toad (Fig. 5A–P)

A total of 4705 bones have been attributed to the common toad: 35 maxillae; 4 frontoparietals, 15 sphenetmoids, 43 pterygoids, 56 squamosals, 2 parasphenoids, 9 prootic-exoccipitals, 4 angulars, 8 atlas, 19 vertebrae, 137 sacra, 176 urostyles, 3 suprascapulars, 6 parascapulars, 293 scapulae, 30 clavicules, 282 coracoids, 730 humeri, 766 radio-ulnae, 842 ilia, 396 femurs, 784 tibiofibulae, 30 tarsals, and 35 phalanxes. The species determination of this taxon rests mostly on the morphology of cranial and post-cranial elements, in accordance with the criteria established by Böhme (1977), Sanchíz (1977), Bailon and Hossini (1990), Bailon, 1991 and Bailon, 1999, and Ratnikov (2001). The maxillae (Fig. 5A) have no teeth, like in all bufonids. The frontoparietals (Fig. 5B) are rectangular, unfused between them and also unfused with the prootic and exoccipital, with a flat dorsal surface and with a well-developed occipital canal. The sphenetmoids (Fig. 5C) are wider than long, with short antero-lateral processes, and without any sella amplificans. In dorsal view, the postero-dorsal margin of the posterior chamber is concave and wide. The pterygoids (Fig. 5D) have three branches of similar width, with no dilatation between the maxillary and posterior branches. The squamosals (Fig. 5E) present a moderately developed lamina alaris and a reduced transverse branch. The atlases (Fig. 5F) have an ogival-shaped neural canal with two anterior condyles and a posterior condyle (procoelous). The neural arch is short and the neural crest is wider posteriorly. The sacral vertebrae (Fig. 5G) have one anterior cotyle and two well-distinct posterior condyles. The transverse processes are moderately elongated, and the neural arch bears a neural crest with no opened fossette at the base of the transverse processes. The urostyles (Fig. 5H) have two anterior well-distinct and slightly dorso-ventrally flattened cotyles. The neural crest is moderately high and the neural canal is subtriangular. The scapulae (Fig. 5I) are higher than wide and present a robust glenoid process, detached and clearly visible in dorsal view. The small supraglenoid fossa is absent. The coracoids (Fig. 5J) are robust, with a short distal extremity. The clavicles (Fig. 5K) are straight and robust. The radio-ulnae (Fig. 5L) are short and robust with a poorly pronounced neck. The humeri (Fig. 5M) have a straight and rather robust diaphysis. The humeral condyle is circular, displaced radially, and generally weakly ossified. The radial epicondyle is poorly developed. In male, the medial crest (crista medialis) is flat and restricted to the distal part of the epiphysis. The ilia (Fig. 5N) do not have a dorsal crest, but a relatively low tuber superior, with a rounded unilobed dorsal limit. As a variation of the general B. gr. bufo-spinosus morphology, some of the ilia from the second layer of the “Caverne Marie-Jeanne” present a bilobate dorsal limit of the tuber superior, but without the typical preacetabular fossa observed in genus Bufotes. The femurs (Fig. 5O) are relatively long, robust and sigmoid, with a femoral crest (or deltoid crest) that is divided and forms a triangular surface. The tibiofibulae (Fig. 5P) are somewhat short and robust, with relatively wide extremities. The other bony elements, which are often incomplete, display the general morphology of the bufonids. The separation of these elements into species has often been performed on the basis of their size, B. gr. bufo-spinosus being generally larger than E. calamita.

Epidalea calamita (Laurenti, 1768) – Natterjack toad (Fig. 5Q–U)

The natterjack toad is rather scarce in the “Caverne Marie-Jeanne”, even if occurring in quite all layers. It is represented by a few elements: three sacral vertebrae, one scapula, four humeri, six ilia, one femur, and three tibiofibulae. The sacral vertebrae (Fig. 5Q) differ from the bufonid described above in having the two posterior condyles more or less joined together and a fossette that opens posteriorly and laterally at the base of the transverse processes. The only scapula (Fig. 5R) is characteristic of E. calamita by the presence of a small supraglenoid fossa above the glenoid apophysis. Humeri (Fig. 5S and T) have a more robust and curved diaphysis than the elements attributed to B. gr. bufo-spinosus, and the condyle and epicondyles are more developed. Ilia (Fig. 5U) differ from B. gr. bufo-spinosus in having a higher and pointed dorsal prominence (tuber superior) and by the presence of a well-developed lateroventral excrescence (calamita blade or calamita ridge) on the ilial shaft. Finally, one femur and three tibiofibulae have been also carefully attributed to E. calamita based on their smaller size and the presence of a narrow and straight femoral crest on the femur.

RANIDAE Rafinesque-Schmaltz, 1814

Rana temporaria Linnaeus, 1758 – Common frog (Fig. 6A–K)

The common frog is represented by 4880 bones: 18 premaxillae, 241 maxillae, 16 sphenetmoids, 9 pterygoids, 4 squamosals, 1 parasphenoid, 7 exoccipitals, 16 angulars, 28 atlases, 796 vertebrae (including 73 eighth vertebrae), 136 sacra, 6 fused 8^th vertebra and sacrum, 272 urostyles, 20 parasterna, 172 scapulae, 195 coracoids, 733 humeri, 478 radio-ulnae, 604 ilia, 219 femurs, 504 tibiofibulae, 34 tarsals, and 371 phalanxes. Premaxillae and maxillae are toothed. The sphenetmoids (Fig. 6A) are as long as wide, with short antero-lateral processes, and without any sella amplificans. The difference with B. bufo is small and relies on the postero-dorsal margin of the posterior chamber, which is somewhat deeper. Pterygoids are slenderer than those of bufonids and present an internal branch much shorter than the posterior one. The squamosals do not have any lamina alaris and the anterior and posterior ends of the transverse branch have a similar development. The atlases and vertebrae possess a small centrum and the lateral walls of the neural arch are generally slenderer than in bufonids. The 8^th vertebra is amphicoelous. The sacral vertebrae (Fig. 6B) have one anterior condyle and two posterior condyles, and the transverse processes are robust and cylindrical. The urostyles (Fig. 6C) have two anterior well distinct and circular cotyles. The neural crest is high and the neural canal generally narrow. The scapulae (Fig. 6D) are higher than wide and, in dorsal view, unlike bufonids, the glenoid process is partially hidden by the acromial process. On the ventral surface of the bone, a long internal crest is visible. The coracoids (Fig. 6E) are robust, with a well-developed and flattened distal extremity. The humeri (Fig. 6F) have a straight diaphysis. The humeral condyle is circular, in line with the main axis of the diaphysis, and generally well ossified. The radial epicondyle is poorly developed. In male, the medial crest, in medial view, is curved at the level of the ulnar epicondyle and then flat and characteristically very long on the diaphysis. The radio-ulnae (Fig. 6G) are somewhat slenderer than those of bufonids, with a well pronounced neck, and the proximal extremity (oleocranium) is generally much more ossified than in bufonids. The ilia (Fig. 6H–J) are characterized by the presence of a long ilial crest, a short ischial process (pars ascendens), a well-developed tuber superior and a posteromedial surface that is smooth and without any interilial sulcus. The ilial crest in most of the ilia attributed to R. temporaria is low, like in brown frogs (genus Rana) and not as vertical as in green frogs (genus Pelophylax). In addition, the junction surface with the ischio-pubis (corpus ossis ilii) is narrow: acetabulum diameter on thickness ratio (d/t, sensu Gleed-Owen, 2000) comprised between 2.83 and 4.16, like in the genus Rana, where the values of d/t lie between 2.75 and 4.00, whereas in genus Pelophylax d/t is comprised between 2.12 and 2.88 (Gleed-Owen, 2000). Within the genus Rana, attribution at the species level is rather difficult, but factors such as size or robustness may suggest an assignation to R. temporaria. Also, the height of the ilial crest is generally lower in R. temporaria, whereas it is higher in other western European species (Bailon, 1999, Blain and Arribas, 2017, Esteban and Sanchíz, 1985, Esteban and Sanchíz, 1991, Gleed-Owen, 1998 and Gleed-Owen, 2000). Femurs have no femoral crest. Finally, other bones (especially tibiofibulae Fig. 6G, tarsals, and phalanxes) present a size and a certain slenderness, when compared with bufonids, that match with an attribution to R. temporaria.

Rana cf. R. arvalis Nilson, 1842 – Moor frog (Fig. 7A–E)

Among the former collection, two fossil ilia were reported by J.-C. Rage (in Ballmann et al., 1980) to pertain to the edible frog (“Rana cf. esculenta”) in layer 5 of the “Caverne Marie-Jeanne”. These ilia (Fig. 7A–B) have a somewhat higher dorsal crest and above all a much more vertical tuber superior than usually reported in R. temporaria. However, their d/t values, respectively 3.25 and 3.8, fall well within the range of genus Rana. The dorsal crest reaches its highest point at the level of the tuber superior, as reported by Böhme (1977), Bailon (1999), Ratnikov (2001), and Ratnikov and Blain (2018) for R. arvalis, whereas in Rana dalmatina Fitzinger, 1839 the dorsal crest is higher than the tuber superior. The dorsal margin of the dorsal crest may be somewhat eroded and does not present the typical continuously high and rounded crest morphology that, according to the consulted comparative material, must correspond to R. arvalis juveniles. In consulted adults of R. arvalis wolterstorffi, the dorsal crest is sometimes a little bit depressed anteriorly to the tuber superior, as it occurs on the fossils of the “Caverne Marie-Jeanne”. Additionally, in comparison with the ilia attributed to R. temporaria, the junction surface with the ischio-pubis seems to be somewhat thinner and, probably due in part to the more vertical orientation of the tuber superior, the supra-acetabular fossa looks deeper. Consequently, these two ilia have been cautiously attributed to R. arvalis.

During the revision of the collections at RBINS, more ilia have been referred to R. arvalis as well as various scapulae and humeri. Consequently, the Moor Frog is now represented in the “Caverne Marie-Jeanne” by a total of 50 bones: 4 scapulae, 33 humeri, and 13 ilia. The morphology of the supplementary ilia is similar to the ones already described. The scapulae (Fig. 7C) attributed to R. arvalis are somewhat slender than those referred to R. temporaria, with a narrower neck and a head representing no more than half of the total bone length. According to Ratnikov (2001), Pelophylax lessonae (Camerano, 1882) and R. arvalis have very similar scapulae, but the anterior margin in P. lessonae is more convex, the neck is comparatively wider, and the internal crest is shorter. The humeri (Fig. 7D–E) are clearly referable to the genus Rana based on the morphology of the lateral and medial crests, which are deflexed dorsally (Bailon, 1999 and Ratnikov, 2001). According to Ratnikov (2001), the morphology of these two crests allows us to distinguish R. arvalis from R. temporaria: R. arvalis has almost equally developed medial and lateral crests with converging proximal ends, whereas the medial crest in R. temporaria is appreciably higher and longer than the lateral one. The distance between the proximal ends is comparatively weaker in R. arvalis than in R. temporaria (Ratnikov and Blain, 2018).

REPTILIA Laurenti, 1768

SQUAMATA Oppel, 1811

LACERTILIA Günther, 1867

“Lizards” are relatively scarce in the assemblage from the “Caverne Marie-Jeanne”, with 1036 remains (5% of all the material). Two lacertids and an anguid lizard have been identified.

LACERTIDAE Batsch, 1788

Lacerta cf. L. agilis Linnaeus, 1758 – Sand Lizard (Fig. 8A–C)

Among the lacertid material from the “Caverne Marie-Jeanne”, there are two size categories. The largest one, comprising one premaxilla, five maxillae, two dentaries and one scapula-coracoid, is referred to the Sand Lizard. The only premaxilla (Fig. 8A) is medium sized, with the maximum width of the premaxilla shelf equal to 2.3 mm. In anterior view, the posterodorsal process is short and leaf-shaped with no ornamentation. Seven or eight tooth positions are visible in posterior view, with three preserved teeth. This premaxilla can be referred to a subadult specimen of Lacerta agilis by the following combination of characters. The short and wide leaf-shaped margins of the posterodorsal process are characteristics of adult specimens of L. agilis; whereas in Zootoca vivipara (Lichtenstein, 1823) and Lacerta bilineata Daudin, 1802 this process is generally long and narrow leaf-shaped, and unlike Podarcis muralis (Laurenti, 1768), where it is more variable (Barahona Quintana, 1996 and Barahona and Barbadillo, 1997). However, ornamentation is lacking on the posterior portion of the posterodorsal process, which may suggest that the specimens was not fully adult. The number of tooth positions is rather ambiguous, as it is equal to seven in P. muralis and Z. vivipara; and usually in higher number in L. bilineata and L. agilis (Barahona Quintana, 1996 and Barahona and Barbadillo, 1997; personal observations). However, here again, it must be due to the not fully-adult characters of the fossil. Finally, the size of the fossil estimated by the maximum width of the premaxilla shelf enters the range of L. agilis (1.9–2.5 mm), whereas it is slightly smaller than L. bilineata (more than 2.4 mm) and much larger than Z. vivipara (1.2–1.5 mm) and P. muralis (1.6–2.0 mm). The maxillae (Fig. 8B) are somewhat incomplete, ever lacking the dorsal process. They bear pleurodont, isodont, cylindrical, and mono- or bicuspid teeth. A small step is visible on the posterior process like in P. muralis, L. bilineata, and L. agilis, whereas in Z. vivipara there is no step (Barahona Quintana, 1996 and Barahona and Barbadillo, 1997). Finally, the length of the maxillary shelf in our fossils (between 7.1 and 8.0 mm) enters the range of adults of L. agilis and L. bilineata (more than 7 mm); whereas P. muralis (4.8–6.0 mm) is usually smaller and well outside the range of Z. vivipara (4.3–4.6 mm). The fragments of dentary (Fig. 8C) possess the morphological characteristics of the Lacertidae, bearing pleurodont, isodont, cylindrical, and mono- or bicuspid and with a Meckelian sulcus open along its entire length. The posterior part of the element is not represented. These elements are cautiously attributed to L. agilis on the basis of their size (probably equal or superior to 10 mm for the complete dentary). The dentaries of P. muralis and Z. vivipara are generally smaller, and those of L. bilineata are somewhat more robust (Rauscher, 1992; and personal observations). A scapulo-coracoid is also referred to the size category of L. agilis.

Zootoca vivipara (Lichtenstein, 1823) – Viviparous Lizard (Fig. 8D–F)

A total of 701 bones have been attributed to the viviparous lizard: 34 maxillae, 203 dentaries, 317 vertebrae, 74 sacra, 7 caudal vertebrae, 1 scapulo-coracoid, 22 humeri, 11 femora, 3 tibiae, and 29 hemipelves. These bones are much smaller than the fossils attributed to the previous lacertid. The maxillae (Fig. 8D) bear pleurodont, isodont, cylindrical and mono- or bicuspid teeth. The anterior projection of the dorsal process is poorly developed, a characteristic of adults of Z. vivipara and juveniles from other species (Barahona Quintana, 1996 and Barahona and Barbadillo, 1997). There is no step on the posterior process like in Z. vivipara and differing from P. muralis, L. bilineata, and L. agilis, where a step is always present (Barahona Quintana, 1996 and Barahona and Barbadillo, 1997; personal observations). Finally, the length of the maxillary shelf in our fossils (around 5.2 mm in the best-preserved elements) is somewhat higher than the range of Z. vivipara (4.3–4.6 mm) given by Barahona and Barbadillo (1997). The dentaries (Fig. 8E) possess pleurodont, isodont, cylindrical, and mono- or bicuspid, a Meckelian sulcus open along its entire length and, in lateral view, the impression of the coronoid is well visible. In some elements, the ventral posterior projection seems to be longer than the dorsal posterior projection, like in Z. vivipara, and in opposition to what is observed in L. bilineata and L. agilis, where these two projections are almost the same size (Barahona Quintana, 1996 and Barahona and Barbadillo, 1997; personal observations) and the notch on the posterior margin of the bone is no so deep as seen in Z. vivipara and P. muralis. When compared with P. muralis, the ventral posterior projection is more robust on our fossils than in this species, and in a similar way than on the consulted specimens of Z. vivipara. This character is also visible in Rauscher (1992). Finally, the length of the dental shelf has been estimated on the best-preserved elements from the “Caverne Marie-Jeanne” to be roughly comprised between 4.8 and 5.6 mm and thus entering the range of adult Z. vivipara (5.2–5.5 mm) and slightly smaller than the range of P. muralis (5.7–6.9 mm) and L. agilis (6 mm), but well outside of the range of L. bilineata (more than 8.4 mm). A large amount of procoelous small (centrum length comprised between 1.4 and 3.2 mm) vertebrae are represented in the “Caverne Marie-Jeanne”. These vertebrae (Fig. 8F) are more or less elongated and with a small interzygapophyseal constriction. The neural spine is long, thin and low. Posteriorly, it ends as a short interzygapophyseal point. In ventral view, the centrum is cylindrical, with a rather wide hemal keel with indistinct lateral edges. The cotyle and condyle are slightly flattened dorso-ventrally. Like the other less diagnostical elements (scapulo-coracoid, humeri, femora, tibiae and hemipelves), these vertebrae have been referred to Z. vivipara due to their small size.

ANGUIDAE Gray, 1825

Anguis gr. A. fragilis Linnaeus, 1758 – Slow Worm (Fig. 8G–H)

The Slow Worm is discretely represented in the “Caverne Marie-Jeanne” by some 326 elements: 2 maxillae, 19 dentaries, 173 trunk vertebrae, 131 caudal vertebrae, and one rib. No osteoderm, usually abundant in other contemporary localities, has been found during the whole revision of the fossil materials stored at RBINS. Maxillae are small and bear large, conical, monocuspid teeth, strongly curving posteriorly at the tip. Teeth are well spaced from each other and do not show striae. The tooth positions are equal to 6 on the best-preserved element. Dentaries (Fig. 8G) are small and distinctly curved dorsally in the posterior portion. They bear teeth similar to those of the maxillae. Tooth positions are comprised between 7 and 9 on the best-preserved elements. In lateral view, the dental crest covers less than a half of the length of the teeth. The intramandibular septum ends by the last tooth position or slightly anteriorly. No surangular spine can be seen on the posterior margin of the bone. The trunk vertebrae (Fig. 8H) are small (CL < 3 mm) and procoelous, with a posterior condyle and anterior cotyle that are dorsoventrally flattened. In lateral view, the neural spine is long and moderately high, and posteriorly it forms an interzygapophyseal tip that does not go beyond the posterior limit of the postzygapophyses. The articular surfaces of the pre- and postzygapophyses are more or less oval, moderately forward-directed and upward-inclined. In ventral view, the centrum, which is longer than wide, has a flat ventral surface and has lateral margins that are parallel for more than half of their length. When present, the subcentral foramina are small and are located on the anterior half of the vertebra. The caudal vertebrae show greater elongation than the trunk vertebrae, hemapophyses fused to the centrum on its posterior half, and the transverse processes that are well developed and dorsoventrally flattened. Some centra show the line of autotomy. The trunk vertebrae are distinguished from those of other anguines (Ophisaurus and Pseudopus) mainly by their smaller size, but also by their relatively elongated shape and the lateral margins of the centrum, which are more or less parallel. The fossils from the “Caverne Marie-Jeanne” do not display any morphological difference with those of the present-day A. fragilis group, comprising the newly erected species, but still not diagnosed osteologically: A. cephallonica Werner, 1894, A. colchica (Nordmann, 1840), A. fragilis Linnaeus, 1758, A. graeca Bedriaga, 1881, and A. veronensis Pollini, 1818 (Gvoždik et al., 2013).

SERPENTES Linnaeus, 1758

Only 483 snake remains (2.4% of all the material) have been found in the “Caverne Marie-Jeanne”. These are mainly represented by small-sized vertebrae. Members of the families Natricidae, Colubridae and Viperidae have been identified.

NATRICIDAE Bonaparte, 1840

Natrix gr. N. natrix (Linnaeus, 1758) – Grass Snake (Fig. 9A)

Seven trunk vertebrae have been referred to the Grass Snake group, including Natrix helvetica (Lacépède, 1789) (Britain, France, Netherlands, Belgium, Germany and Switzerland), Natrix (Linnaeus, 1758) (central and eastern Europe, southernmost Scandinavian Peninsula and Balkan Peninsula) and its Iberian representative N. astreptophora (Seoane, 1885) (Kindler and Fritz, 2018, Kindler et al., 2017, Kindler et al., 2018a, Kindler et al., 2018b and Pokrant et al., 2016). The trunk vertebrae have a somewhat sigmoid hypapophysis, and the neural arch is convex in posterior view. The condyle and the cotyle are small and circular. Their centrum length is comprised between 3.4 and 5.2 mm. The trunk vertebrae attributed to Natrix gr. N. natrix are distinguished above all by the morphology of the centrum, this being generally flat or concave and the lateral margins are clearly marked, whereas in Natrix maura (Linnaeus, 1758) the centrum is slightly convex and with lateral margins that are more or less diffuse (Szyndlar, 1984). In addition, the morphology of the extremity of the hypapophysis and the paradiapophysis (i.e. diapophysis plus parapophysis) is robust and blunt like in N. gr. N. natrix whereas in N. maura these extremities are more gracile and pointed (Szyndlar, 1984).

COLUBRIDAE Oppel, 1811

Coronella austriaca Laurenti, 1768 – Smooth Snake (Fig. 9B–C)

A total of 45 elements have been attributed to the smooth snake in the “Caverne Marie-Jeanne”: 3 dentaries, 13 anterior trunk vertebrae, 43 trunk vertebrae, and 4 caudal vertebrae. The fossil trunk vertebrae (Fig. 9B) are small in size (CL < 4 mm), do not have a hypapophysis, and have a neural arch that is markedly flattened dorsoventrally, as in the genus Coronella. The precondylar constriction is particularly well marked, a characteristic of the genus Coronella that usually differs from the case of juveniles/adults of all the other colubrines (Blain, 2005 and Blain, 2009). The prezygapophyseal processes are relatively wide at the base and with blunted ends like in C. austriaca, and differing from Coronella girondica (Daudin, 1803), where these processes are generally narrower and pointed (Bailon, 1991 and Szyndlar, 1984). Finally, in ventral view, the parapophyses are somewhat longer than the diapophyses, like in C. austriaca, whereas in C. girondica they have a similar length (Bailon, 1991 and Szyndlar, 1984). Dentaries (Fig. 9C) are somewhat well preserved. Dentaries are straight and slender. In dorsal view, the anterior end of the bone is strongly curved inside. The bone is generally isodontic, except 2–3 minute anteriormost teeth. A complete dentary has 26 tooth positions. The somewhat elongate small mental foramen lies at the level of the 9th tooth. The compound notch on the lateral surface is situated at the level of the 14th tooth. Meckel's groove opens widely into compound notch, and anteriorly completely closed by the 11th or 12th tooth.

VIPERIDAE Oppel, 1811

Vipera berus (Linnaeus, 1758) – Adder (Fig. 9D–F)

The adder is by far the most represented snake in the “Caverne Marie-Jeanne”, with a total of 191 fossil remains: 1 venom fang, 2 left dentaries, 17 anterior trunk vertebrae, and 171 trunk vertebrae. The trunk vertebrae (Fig. 9E) show the typical characteristics of the family: presence of a straight and distally pointed hypapophysis; neural arch dorsoventrally flattened; centrum convex in transverse section and not well-marked lateral margins; developed and round condyle and cotyle; and upwardly inclined articular surface of the zygapophyses. The trunk vertebrae from the “Caverne Marie-Jeanne” are somewhat small with a centrum length shorter than 4 mm. The vertebral morphology permits two groups to be differentiated within the European vipers: the “Vipera aspis complex” and the “Vipera berus complex”. The neural spine of the trunk vertebrae is very low and the hypapophysis is sigmoid-shaped, with an obtuse apex like in the “V. berus complex” (Szyndlar, 1984). European members of the “V. berus complex” [V. berus (Linnaeus, 1758), Vipera ursinii (Bonaparte, 1835) and Vipera seoanei Latastei, 1879] display homogenous vertebra morphology and are hardly distinguishable from one another (Szyndlar, 1984 and Szyndlar and Rage, 1999). Nevertheless, the morphology of the fossil vertebrae fits well with V. berus, the only adder currently present in northern Europe. The anterior trunk vertebrae are characterized by a hypapophysis that is usually shorter than the centrum and a relatively low neural spine(Fig. 9D). The only venom fang is long, tubular and slightly curved, and on its anterior surface the suture of the venom canal is not visible, like in viperids (Jackson, 2002). The two dentaries are much shorter and straighter than the dentary of Coronella austriaca previously described. Teeth are badly preserved, but one of them shows some 14 tooth positions (Fig. 9F). In dorsal view, the anterior end of the bone is more or less curved inside. The mental foramen, filled with sediment in the two specimens, is well elongated and lies at the level of the 7th and 8th teeth. The compound notch on the lateral surface approaches by the 11th tooth. Meckel's groove opens into compound notch at the level of the 9th tooth, and is anteriorly reduced to a narrow slit or completely closed (Fig. 9F).

The revision of the late Pleistocene (Marine Isotope Stages 3 and 2) collection of the “Caverne Marie-Jeanne” (Hastière-Lavaux, Namur) stored in the Royal Belgian Institute of Natural Sciences (RBINS) Quaternary collections has been done in order to complete the preliminary study (Rage in Ballmann et al., 1980) on the fossil amphibians and reptiles from this site and to propose a paleoenvironmental and paleoclimatic reconstruction for the latest Pleistocene of Belgium. Our conclusions are given below. 1)

More than 20,500 recognized bones of amphibians and reptiles have been identified and catalogued. The faunal list comprises now two urodeles (Lissotriton gr. L. vulgaris and Salamandra salamandra), four anurans (Bufo gr. B. bufo-spinosus, Epidalea calamita, Rana temporaria, and Rana cf. R. arvalis), three lizards (Lacerta cf. L. agilis, Zootoca vivipara and Anguis gr. A. fragilis) and three snakes (Natrix gr. N. natrix, Coronella austriaca and Vipera berus). Thus, the previous faunal list has been actualized, with five new taxa (L. gr. L. vulgaris, R. cf. R. arvalis, Z. vivipara, N. gr. N. natrix, and C. austriaca), one removal (Pelophylax cf. esculentus), and updated thanks to the recovery of new diagnostical elements, like vertebrae for snakes and urodeles.