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An amphisbaenian skull from the European miocene and the evolution of Mediterranean worm lizards.

Bolet A, Delfino M, Fortuny J, Almécija S, Robles JM, Alba DM - PLoS ONE (2014)

Bottom Line: This specimen, from the Middle Miocene of Abocador de Can Mata (11.6 Ma, MN7+8) in the Vallès-Penedès Basin (Catalonia, NE Iberian Peninsula), unambiguously asserts the presence of Blanus in the Miocene of Europe.This reinforces the referral to this genus of the previously-known, much more incomplete and poorly-diagnostic material from other localities of the European Neogene.This supports previous paleobiogeographic scenarios for blanid evolution and provides a significant minimum divergence time for calibrating molecular analyses of blanid phylogeny.

View Article: PubMed Central - PubMed

Affiliation: Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain.

ABSTRACT
The evolution of blanid amphisbaenians (Mediterranean worm lizards) is mainly inferred based on molecular studies, despite their fossils are common in Cenozoic European localities. This is because the fossil record exclusively consists in isolated elements of limited taxonomic value. We describe the only known fossil amphisbaenian skull from Europe - attributed to Blanus mendezi sp. nov. (Amphisbaenia, Blanidae) - which represents the most informative fossil blanid material ever described. This specimen, from the Middle Miocene of Abocador de Can Mata (11.6 Ma, MN7+8) in the Vallès-Penedès Basin (Catalonia, NE Iberian Peninsula), unambiguously asserts the presence of Blanus in the Miocene of Europe. This reinforces the referral to this genus of the previously-known, much more incomplete and poorly-diagnostic material from other localities of the European Neogene. Our analysis - integrating the available molecular, paleontological and biogeographic data - suggests that the new species postdates the divergence between the two main (Eastern and Western Mediterranean) extant clades of blanids, and probably precedes the split between the Iberian and North-Western African subclades. This supports previous paleobiogeographic scenarios for blanid evolution and provides a significant minimum divergence time for calibrating molecular analyses of blanid phylogeny.

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Related in: MedlinePlus

Blanus mendezi sp. nov., virtual model of selected skull bones of the holotype (IPS60464).(A–C) Premaxilla in left lateral (A), dorsal (B), and ventral (C) views. (D–G) Right maxilla in labial (D), lingual (E), dorsal (F) and ventral (g) views. (H, I) Right nasal in dorsal (H) and ventral (I) views. (J, K) Right vomer in dorsal (J) and ventral (K) views. (L, M) Right palatine in dorsal (L) and ventral (M) views. (N, O) Right ectopterygoid in labial (N) and anterior (O) views. (P, Q) Right pterygoid in dorsal (P) and ventral (Q) views. (R–U) Right frontal in dorsal (R), ventral (S), lateral (T) and medial (U) views. (V, W) Right prefrontal in lateral (V) and medial (W) views. (X–Z) Parietal/otic-occipital complex/parabasisphenoid in dorsal (X), right lateral (Y) and ventral (Z) views. (AA, AB) Left quadrate in lateral (AA) and medial (AB) views. Colors correspond to those in figure 1. Abbreviations: app, apical process of parietal; appr, alar process of prootic; bps, basipterygoid process; cec, cephalic condyle of quadrate; chp, choanal process of vomer; chv, choanal vault; cp, cultriform process of parabasisphenoid; dcr, dorsal crest of quadrate; dp, descending process of frontal; epm, ectopterygoid process of maxilla; epp, ectopterygoid process of palatine; fnpp, frontal facet for the nasal process of premaxilla; fpm, frontal process of maxilla; fpn, frontal process of nasal; fpp, frontal process of prefrontal; fps, frontoparietal suture; fvo, fenestra vomeronasalis; fvp, facet for palatine vomerine process; Gf, Gasserian foramen; hf, hypoglossal foramen; lptp, lateral pterygoid process of ectopterygoid; mac, mandibular condyle of quadrate; mafa, ectopterygoid facet for the articulation of the ectopterygoid process of maxilla; map, median articular plane; mfo, maxilla labial foramina; mfp, maxillary facial process of nasal; mp, maxillary process of palatine; mpf, maxillary process of frontal; mpp, maxillary process of prefrontal; mrp, maxillary rostral process of nasal; mt, maxillary teeth; mptp, medial pterygoid process of ectopterygoid; mf, frontal facet for maxilla and prefrontal; nc, nasal chamber; np, nassal process of premaxilla; npk, nasal process of premaxilla keel; occ, occipital condyle; oocl, otic-occipital lapet; op, orbital process of maxilla; osp, ventral process of frontal; pa, parietal; paf, frontal facet for parietal; pfa, facet of frontal for the nasal process of premaxilla; pbs, parabasisphenoid; pff, frontal facet for prefrontal; pfp, prefrontal process of maxilla; pmf, premaxilla foramina; pmp, premaxillary process of nasal; pmt, premaxillary teeth; pp, palatal process of premaxilla; ptfa, ectopterygoid facet for pterygoid; ptp, pterygoid process of palatine; pvp, posteroventral process of quadrate; qp, quadrate process of pterygoid; rpm, rostral process of maxilla; rpv, rostral process of vomer; saf, superior alveolar foramen; ss, supradental shelf of maxilla; tp, transverse process of pterygoid; vf, vagus foramen; vlp/X, ventrolateral process/“element X”; vp, vomerine process of palatine. Scale bar equals 2 mm.
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pone-0098082-g003: Blanus mendezi sp. nov., virtual model of selected skull bones of the holotype (IPS60464).(A–C) Premaxilla in left lateral (A), dorsal (B), and ventral (C) views. (D–G) Right maxilla in labial (D), lingual (E), dorsal (F) and ventral (g) views. (H, I) Right nasal in dorsal (H) and ventral (I) views. (J, K) Right vomer in dorsal (J) and ventral (K) views. (L, M) Right palatine in dorsal (L) and ventral (M) views. (N, O) Right ectopterygoid in labial (N) and anterior (O) views. (P, Q) Right pterygoid in dorsal (P) and ventral (Q) views. (R–U) Right frontal in dorsal (R), ventral (S), lateral (T) and medial (U) views. (V, W) Right prefrontal in lateral (V) and medial (W) views. (X–Z) Parietal/otic-occipital complex/parabasisphenoid in dorsal (X), right lateral (Y) and ventral (Z) views. (AA, AB) Left quadrate in lateral (AA) and medial (AB) views. Colors correspond to those in figure 1. Abbreviations: app, apical process of parietal; appr, alar process of prootic; bps, basipterygoid process; cec, cephalic condyle of quadrate; chp, choanal process of vomer; chv, choanal vault; cp, cultriform process of parabasisphenoid; dcr, dorsal crest of quadrate; dp, descending process of frontal; epm, ectopterygoid process of maxilla; epp, ectopterygoid process of palatine; fnpp, frontal facet for the nasal process of premaxilla; fpm, frontal process of maxilla; fpn, frontal process of nasal; fpp, frontal process of prefrontal; fps, frontoparietal suture; fvo, fenestra vomeronasalis; fvp, facet for palatine vomerine process; Gf, Gasserian foramen; hf, hypoglossal foramen; lptp, lateral pterygoid process of ectopterygoid; mac, mandibular condyle of quadrate; mafa, ectopterygoid facet for the articulation of the ectopterygoid process of maxilla; map, median articular plane; mfo, maxilla labial foramina; mfp, maxillary facial process of nasal; mp, maxillary process of palatine; mpf, maxillary process of frontal; mpp, maxillary process of prefrontal; mrp, maxillary rostral process of nasal; mt, maxillary teeth; mptp, medial pterygoid process of ectopterygoid; mf, frontal facet for maxilla and prefrontal; nc, nasal chamber; np, nassal process of premaxilla; npk, nasal process of premaxilla keel; occ, occipital condyle; oocl, otic-occipital lapet; op, orbital process of maxilla; osp, ventral process of frontal; pa, parietal; paf, frontal facet for parietal; pfa, facet of frontal for the nasal process of premaxilla; pbs, parabasisphenoid; pff, frontal facet for prefrontal; pfp, prefrontal process of maxilla; pmf, premaxilla foramina; pmp, premaxillary process of nasal; pmt, premaxillary teeth; pp, palatal process of premaxilla; ptfa, ectopterygoid facet for pterygoid; ptp, pterygoid process of palatine; pvp, posteroventral process of quadrate; qp, quadrate process of pterygoid; rpm, rostral process of maxilla; rpv, rostral process of vomer; saf, superior alveolar foramen; ss, supradental shelf of maxilla; tp, transverse process of pterygoid; vf, vagus foramen; vlp/X, ventrolateral process/“element X”; vp, vomerine process of palatine. Scale bar equals 2 mm.

Mentions: IPS60464 is an almost complete skull (11.3 mm in length) that includes the right lower jaw in articulation (Figs. 1 and 2). The specimen is exceptionally well preserved, including all unpaired elements, whereas all paired bones are represented at least in one side (Figs. 2 and 3). The skull is however covered by a carbonate concretion that obscures most of its external morphology. It also displays a matrix infilling that precludes the observation of the palate, the inner surfaces of the skull roof and the lingual surfaces of the lower jaw. The small size and fragility of the specimen precluded mechanical preparation, so its description is based on computed tomography (CT) scans. The latter not only revealed the external morphology, but further granted access to the internal cranial morphology (otherwise unobservable), thereby enabling the description of isolated bones and their joint surfaces. A description of the skull and vertebrae (Fig. 2 and Fig. S1) is provided below, followed by comparisons with fossil and extinct blanids.


An amphisbaenian skull from the European miocene and the evolution of Mediterranean worm lizards.

Bolet A, Delfino M, Fortuny J, Almécija S, Robles JM, Alba DM - PLoS ONE (2014)

Blanus mendezi sp. nov., virtual model of selected skull bones of the holotype (IPS60464).(A–C) Premaxilla in left lateral (A), dorsal (B), and ventral (C) views. (D–G) Right maxilla in labial (D), lingual (E), dorsal (F) and ventral (g) views. (H, I) Right nasal in dorsal (H) and ventral (I) views. (J, K) Right vomer in dorsal (J) and ventral (K) views. (L, M) Right palatine in dorsal (L) and ventral (M) views. (N, O) Right ectopterygoid in labial (N) and anterior (O) views. (P, Q) Right pterygoid in dorsal (P) and ventral (Q) views. (R–U) Right frontal in dorsal (R), ventral (S), lateral (T) and medial (U) views. (V, W) Right prefrontal in lateral (V) and medial (W) views. (X–Z) Parietal/otic-occipital complex/parabasisphenoid in dorsal (X), right lateral (Y) and ventral (Z) views. (AA, AB) Left quadrate in lateral (AA) and medial (AB) views. Colors correspond to those in figure 1. Abbreviations: app, apical process of parietal; appr, alar process of prootic; bps, basipterygoid process; cec, cephalic condyle of quadrate; chp, choanal process of vomer; chv, choanal vault; cp, cultriform process of parabasisphenoid; dcr, dorsal crest of quadrate; dp, descending process of frontal; epm, ectopterygoid process of maxilla; epp, ectopterygoid process of palatine; fnpp, frontal facet for the nasal process of premaxilla; fpm, frontal process of maxilla; fpn, frontal process of nasal; fpp, frontal process of prefrontal; fps, frontoparietal suture; fvo, fenestra vomeronasalis; fvp, facet for palatine vomerine process; Gf, Gasserian foramen; hf, hypoglossal foramen; lptp, lateral pterygoid process of ectopterygoid; mac, mandibular condyle of quadrate; mafa, ectopterygoid facet for the articulation of the ectopterygoid process of maxilla; map, median articular plane; mfo, maxilla labial foramina; mfp, maxillary facial process of nasal; mp, maxillary process of palatine; mpf, maxillary process of frontal; mpp, maxillary process of prefrontal; mrp, maxillary rostral process of nasal; mt, maxillary teeth; mptp, medial pterygoid process of ectopterygoid; mf, frontal facet for maxilla and prefrontal; nc, nasal chamber; np, nassal process of premaxilla; npk, nasal process of premaxilla keel; occ, occipital condyle; oocl, otic-occipital lapet; op, orbital process of maxilla; osp, ventral process of frontal; pa, parietal; paf, frontal facet for parietal; pfa, facet of frontal for the nasal process of premaxilla; pbs, parabasisphenoid; pff, frontal facet for prefrontal; pfp, prefrontal process of maxilla; pmf, premaxilla foramina; pmp, premaxillary process of nasal; pmt, premaxillary teeth; pp, palatal process of premaxilla; ptfa, ectopterygoid facet for pterygoid; ptp, pterygoid process of palatine; pvp, posteroventral process of quadrate; qp, quadrate process of pterygoid; rpm, rostral process of maxilla; rpv, rostral process of vomer; saf, superior alveolar foramen; ss, supradental shelf of maxilla; tp, transverse process of pterygoid; vf, vagus foramen; vlp/X, ventrolateral process/“element X”; vp, vomerine process of palatine. Scale bar equals 2 mm.
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pone-0098082-g003: Blanus mendezi sp. nov., virtual model of selected skull bones of the holotype (IPS60464).(A–C) Premaxilla in left lateral (A), dorsal (B), and ventral (C) views. (D–G) Right maxilla in labial (D), lingual (E), dorsal (F) and ventral (g) views. (H, I) Right nasal in dorsal (H) and ventral (I) views. (J, K) Right vomer in dorsal (J) and ventral (K) views. (L, M) Right palatine in dorsal (L) and ventral (M) views. (N, O) Right ectopterygoid in labial (N) and anterior (O) views. (P, Q) Right pterygoid in dorsal (P) and ventral (Q) views. (R–U) Right frontal in dorsal (R), ventral (S), lateral (T) and medial (U) views. (V, W) Right prefrontal in lateral (V) and medial (W) views. (X–Z) Parietal/otic-occipital complex/parabasisphenoid in dorsal (X), right lateral (Y) and ventral (Z) views. (AA, AB) Left quadrate in lateral (AA) and medial (AB) views. Colors correspond to those in figure 1. Abbreviations: app, apical process of parietal; appr, alar process of prootic; bps, basipterygoid process; cec, cephalic condyle of quadrate; chp, choanal process of vomer; chv, choanal vault; cp, cultriform process of parabasisphenoid; dcr, dorsal crest of quadrate; dp, descending process of frontal; epm, ectopterygoid process of maxilla; epp, ectopterygoid process of palatine; fnpp, frontal facet for the nasal process of premaxilla; fpm, frontal process of maxilla; fpn, frontal process of nasal; fpp, frontal process of prefrontal; fps, frontoparietal suture; fvo, fenestra vomeronasalis; fvp, facet for palatine vomerine process; Gf, Gasserian foramen; hf, hypoglossal foramen; lptp, lateral pterygoid process of ectopterygoid; mac, mandibular condyle of quadrate; mafa, ectopterygoid facet for the articulation of the ectopterygoid process of maxilla; map, median articular plane; mfo, maxilla labial foramina; mfp, maxillary facial process of nasal; mp, maxillary process of palatine; mpf, maxillary process of frontal; mpp, maxillary process of prefrontal; mrp, maxillary rostral process of nasal; mt, maxillary teeth; mptp, medial pterygoid process of ectopterygoid; mf, frontal facet for maxilla and prefrontal; nc, nasal chamber; np, nassal process of premaxilla; npk, nasal process of premaxilla keel; occ, occipital condyle; oocl, otic-occipital lapet; op, orbital process of maxilla; osp, ventral process of frontal; pa, parietal; paf, frontal facet for parietal; pfa, facet of frontal for the nasal process of premaxilla; pbs, parabasisphenoid; pff, frontal facet for prefrontal; pfp, prefrontal process of maxilla; pmf, premaxilla foramina; pmp, premaxillary process of nasal; pmt, premaxillary teeth; pp, palatal process of premaxilla; ptfa, ectopterygoid facet for pterygoid; ptp, pterygoid process of palatine; pvp, posteroventral process of quadrate; qp, quadrate process of pterygoid; rpm, rostral process of maxilla; rpv, rostral process of vomer; saf, superior alveolar foramen; ss, supradental shelf of maxilla; tp, transverse process of pterygoid; vf, vagus foramen; vlp/X, ventrolateral process/“element X”; vp, vomerine process of palatine. Scale bar equals 2 mm.
Mentions: IPS60464 is an almost complete skull (11.3 mm in length) that includes the right lower jaw in articulation (Figs. 1 and 2). The specimen is exceptionally well preserved, including all unpaired elements, whereas all paired bones are represented at least in one side (Figs. 2 and 3). The skull is however covered by a carbonate concretion that obscures most of its external morphology. It also displays a matrix infilling that precludes the observation of the palate, the inner surfaces of the skull roof and the lingual surfaces of the lower jaw. The small size and fragility of the specimen precluded mechanical preparation, so its description is based on computed tomography (CT) scans. The latter not only revealed the external morphology, but further granted access to the internal cranial morphology (otherwise unobservable), thereby enabling the description of isolated bones and their joint surfaces. A description of the skull and vertebrae (Fig. 2 and Fig. S1) is provided below, followed by comparisons with fossil and extinct blanids.

Bottom Line: This specimen, from the Middle Miocene of Abocador de Can Mata (11.6 Ma, MN7+8) in the Vallès-Penedès Basin (Catalonia, NE Iberian Peninsula), unambiguously asserts the presence of Blanus in the Miocene of Europe.This reinforces the referral to this genus of the previously-known, much more incomplete and poorly-diagnostic material from other localities of the European Neogene.This supports previous paleobiogeographic scenarios for blanid evolution and provides a significant minimum divergence time for calibrating molecular analyses of blanid phylogeny.

View Article: PubMed Central - PubMed

Affiliation: Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, Spain.

ABSTRACT
The evolution of blanid amphisbaenians (Mediterranean worm lizards) is mainly inferred based on molecular studies, despite their fossils are common in Cenozoic European localities. This is because the fossil record exclusively consists in isolated elements of limited taxonomic value. We describe the only known fossil amphisbaenian skull from Europe - attributed to Blanus mendezi sp. nov. (Amphisbaenia, Blanidae) - which represents the most informative fossil blanid material ever described. This specimen, from the Middle Miocene of Abocador de Can Mata (11.6 Ma, MN7+8) in the Vallès-Penedès Basin (Catalonia, NE Iberian Peninsula), unambiguously asserts the presence of Blanus in the Miocene of Europe. This reinforces the referral to this genus of the previously-known, much more incomplete and poorly-diagnostic material from other localities of the European Neogene. Our analysis - integrating the available molecular, paleontological and biogeographic data - suggests that the new species postdates the divergence between the two main (Eastern and Western Mediterranean) extant clades of blanids, and probably precedes the split between the Iberian and North-Western African subclades. This supports previous paleobiogeographic scenarios for blanid evolution and provides a significant minimum divergence time for calibrating molecular analyses of blanid phylogeny.

Show MeSH
Related in: MedlinePlus