LACERTIDAE, Oppel, 1811AMPHISBAENIA,

Ivanov, Martin, Čerňanský, Andrej, Bonilla-Salomón, Isaac & Luján, Àngel Hernández, 2020, Early Miocene squamate assemblage from the Mokrá-Western Quarry (Czech Republic) and its palaeobiogeographical and palaeoenvironmental implications, Geodiversitas 42 (20), pp. 343-376: 348-349

publication ID

http://doi.org/ 10.5252/geodiversitas2020v42a20

publication LSID

lsid:zoobank.org:pub:urn:lsid:zoobank.org:pub:8FF2A078-CE45-4BF1-A681-00136F57375E

DOI

http://doi.org/10.5281/zenodo.4486565

persistent identifier

http://treatment.plazi.org/id/03C587C7-4303-FFE3-FC31-FD2A4B9BF839

treatment provided by

Felipe

scientific name

LACERTIDAE AMPHISBAENIA
status

 

LACERTIDAE  indet. tooth morphotype 2 ( Fig. 2HView FIG)

MATERIAL. — MWQ, early Miocene, Burdigalian, Orleanian, MN 4: 1/2001 Turtle Joint: One left dentary (Pal. 1401). 

DESCRIPTION

Dentary

The description is based on the fragment of the anterior half of a left dentary. The element bears ten tooth positions (four teeth are still attached). The dental crest is high, and the teeth extend above it only in a quarter of their total height. The subdental shelf (sensu Rage & Augé, 2010) is robust, being only slightly concave in this section. Meckel’s groove is open, narrow in the preserved section, but gradually widening posteriorly. The lateral surface of the bone is smooth, pierced by several labial foramina.

Dentition

The implantation is pleurodont. Teeth are tall and robust. The interdental gaps are small – the size of the gap forms approximately only a 1/4 of the mesiodistal length of the tooth neck. The tooth crowns are bicuspid, with a dominant distal (central) cusp and a smaller mesial cusp. The lingual portion of the crowns bears vertical striations. The striae are almost parallel, and their number is around six. In medial aspect, the tooth necks are more or less as wide as the tooth crowns, in some cases gradually narrowing slightly ventrally. The necks appear slightly more swollen lingually if compared to the tooth crowns. The central part of the tooth base is pierced by a resorption pit.

REMARKS

Although the dentary described here possesses some similarities with the above described lacertid material, e.g. bicuspid teeth, several important differences can be observed: 1) large size; 2) the high dental crest; 3) small interdental gaps; 4) more robust teeth; and 5) low number of lingual striae on the tooth crowns. Because not all of those differences can be explained by ontogenetic changes, we suggest the presence of at least two lacertid taxa in MWQ.

Unranked clade AMPHISBAENIA Gray, 1844

AMPHISBAENIA  indet. ( Fig. 3View FIG)

Blanus  sp. – Ivanov et al. 2006: 229, table 2.

MATERIAL. — MWQ, early Miocene, Burdigalian, Orleanian, MN 4: 2/2003 Reptile Joint: One trunk vertebra (Pal. 1570). 

DESCRIPTION

Trunk vertebra

A single trunk vertebra is preserved. It is small in size. A neural spine is absent, and the dorsal portion of the neural arch forms a median edge. In lateral view, the synapophysis is simple and large. The posterior portion of the neural arch is fused with the postzygapophyses, forming the dorsal roof (or lamina) between the left and right postzygapophyses. The neural canal is subtriangular with distinct lateral sinuses. The interzygapophyseal constriction is distinct and it occurs in the anterior half of the anteroposterior vertebral length. The dorsally tilted prezygapophyseal articular facets have an elliptical shape. A zygosphene is absent. The ventral side of the depressed centrum is flat, pierced by a pair of large subcentral foramina in the anterior 1/3 of the anteroposterior length. The lateral margins (subcentral ridges) are roughly parallel in ventral aspect. No constriction is developed at the base of the damaged condyle. The postzygapophyseal articular facets are oval and slightly enlarged posteriorly. The cotyle is distinctly laterally enlarged.

REMARKS

The vertebra described here can be attributed to Amphisbaenia based on the following combination of features (see Estes 1983): 1) the depressed centrum, having a flat ventral surface; 2) roughly parallel lateral margins in ventral aspect; 3) massive synapophyses; 4) the absence of a zygosphene (enabling distinction of amphisbaenians from scolecophidian snakes ( Estes 1983; Rage 1984); and 5) the sinusoidal neural arch lacking a neural spine.

Family level allocation of an isolated vertebra is limited by a lack of clear diagnostic features for identification ( Estes 1983; Augé 2005, 2012; Georgalis et al. 2016b).We can exclude rhineurids, which have a denticulate vertebral posterior margin. The same feature can be observed in trogonophiids as well ( Kearney 2003; Augé 2012; Čerňanský et al. 2016a). Based on the geographical position of the locality and the age of the sediments, this vertebra most likely represents a blanid taxon. According to cranial elements, amphisbaenians reported from the Central European late Oligocene and Miocene localities are almost exclusively identified as belonging to the clade Blanidae  ( Roček 1984; Schleich 1988; Čerňanský & Venczel 2011; Čerňanský et al. 2016a). The morphology and dimensions of the vertebra described here are very similar to those of trunk vertebra of Blanus gracilis Roček, 1984  reported from the Czech early Miocene ( MN 4b) Dolnice site ( Roček 1984: 5, table 16).

AMPHISBAENIA  indet. ( Fig. 3View FIG)

Blanus  sp. – Ivanov et al. 2006: 229, table 2.

MATERIAL. — MWQ, early Miocene, Burdigalian, Orleanian, MN 4: 2/2003 Reptile Joint: One trunk vertebra (Pal. 1570). 

DESCRIPTION

Trunk vertebra

A single trunk vertebra is preserved. It is small in size. A neural spine is absent, and the dorsal portion of the neural arch forms a median edge. In lateral view, the synapophysis is simple and large. The posterior portion of the neural arch is fused with the postzygapophyses, forming the dorsal roof (or lamina) between the left and right postzygapophyses. The neural canal is subtriangular with distinct lateral sinuses. The interzygapophyseal constriction is distinct and it occurs in the anterior half of the anteroposterior vertebral length. The dorsally tilted prezygapophyseal articular facets have an elliptical shape. A zygosphene is absent. The ventral side of the depressed centrum is flat, pierced by a pair of large subcentral foramina in the anterior 1/3 of the anteroposterior length. The lateral margins (subcentral ridges) are roughly parallel in ventral aspect. No constriction is developed at the base of the damaged condyle. The postzygapophyseal articular facets are oval and slightly enlarged posteriorly. The cotyle is distinctly laterally enlarged.

REMARKS

The vertebra described here can be attributed to Amphisbaenia based on the following combination of features (see Estes 1983): 1) the depressed centrum, having a flat ventral surface; 2) roughly parallel lateral margins in ventral aspect; 3) massive synapophyses; 4) the absence of a zygosphene (enabling distinction of amphisbaenians from scolecophidian snakes ( Estes 1983; Rage 1984); and 5) the sinusoidal neural arch lacking a neural spine.

Family level allocation of an isolated vertebra is limited by a lack of clear diagnostic features for identification ( Estes 1983; Augé 2005, 2012; Georgalis et al. 2016b).We can exclude rhineurids, which have a denticulate vertebral posterior margin. The same feature can be observed in trogonophiids as well ( Kearney 2003; Augé 2012; Čerňanský et al. 2016a). Based on the geographical position of the locality and the age of the sediments, this vertebra most likely represents a blanid taxon. According to cranial elements, amphisbaenians reported from the Central European late Oligocene and Miocene localities are almost exclusively identified as belonging to the clade Blanidae  ( Roček 1984; Schleich 1988; Čerňanský & Venczel 2011; Čerňanský et al. 2016a). The morphology and dimensions of the vertebra described here are very similar to those of trunk vertebra of Blanus gracilis Roček, 1984  reported from the Czech early Miocene ( MN 4b) Dolnice site ( Roček 1984: 5, table 16).

MN

Museu Nacional, Universidade Federal do Rio de Janeiro

Kingdom

Animalia

Phylum

Chordata

Class

Reptilia

Order

Squamata

Family

Lacertidae

Kingdom

Animalia

Loc

LACERTIDAE AMPHISBAENIA

Ivanov, Martin, Čerňanský, Andrej, Bonilla-Salomón, Isaac & Luján, Àngel Hernández 2020
2020
Loc

Blanus

Ivanov et al. 2006: 229
2006