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Albanerpetontids are an extinct clade of salamander-like lissamphibians characterised by features such as fused frontals and sculptured skull roof bones. Here we provide a histological analysis of ...

The Lowerverse local fauna of West Texas, USA, preserves a rare, early Campanian assemblage of microvertebrates from Laramidia. The recovery of 137 fragmentary specimens reveals that albanerpetontids were locally abundant here and also widespread throughout much of the Western Interior of North America by early Campanian time. Both gracile- and robust-snouted species are represented within the assemblage. Among these, the occurrence of Albanerpeton nexuosum is consistent with its occurrence in paracontemporaneous deposits elsewhere in the Western Interior. The referral of two specimens to Albanerpeton sp., cf. Albanerpeton galaktion, strongly suggests that this long-lived taxon was far more widespread during the early Campanian than previously known and its likely occurrence in West Texas represents a significant geotemporal range extension for the species. However, Albanerpeton gracile is seemingly restricted to Judithian “age” deposits in North America and was not identified at Lowerverse. The Lowerverse assemblage supports the current paradigm involving the occurrence of these three named albanerpetontids during middle Campanian – Maastrichtian time in the Western Interior of North America.

Albanerpetontids are an extinct clade of superficially salamander-like lissamphibians that range from the Middle Jurassic (Bathonian)-Early Pleistocene and have a primarily Laurasian distribution. The best Cenozoic record for the clade is in Europe, where two species in the type genus Albanerpeton Estes & Hoffstetter, 1976 occur in over 40 localities of early Oligocene-Early Pleistocene age in Austria, Czech Republic, France, Germany, Hungary, Italy, and Serbia. From the post-evaporitic Messinian (5.41-5.33 Ma or latest Miocene) succession at Moncucco Torinese, in the Piedmont Basin, northwestern Italy, here we describe isolated albanerpetontid jaws and vertebrae referable to A. pannonicum Venczel & Gardner, 2005. This Italian occurrence extends the temporal record for A. pannonicum from the Early Pleistocene and Pliocene back into the latest Miocene and it narrows the temporal gap between that species and its European congener, A. inexpectatum Estes & Hoffstetter, 1976 (early Oligocene-late Miocene). Les albanerpetontidés représentent un clade éteint de lissamphibiens ressemblant superficiellement à des salamandres, dont l'aire de répartition s'étend du Jurassique moyen (Bathonien) au Pléistocène inférieur, et dont la distribution est principalement laurasiatique. Le meilleur registre cénozoïque pour ce clade se trouve en Europe, où deux espèces du genre-type Albanerpeton Estes & Hoffstetter, 1976 sont présentes dans plus de 40 localités de l'Oligocène inférieur-Pléistocène inférieur d'Autriche, Tchéquie, France, Allemagne, Hongrie, Italie et Serbie. Nous décrivons ici des mâchoires et des vertèbres isolées d'albanerpetontidés pouvant être attribuées à A. pannonicum Venczel & Gardner, 2005, provenant de la succession post-évaporitique du Messinien (5,41-5,33 Ma ou Miocène terminal) à Moncucco Torinese, dans le bassin du Piémont, au nord-ouest de l'Italie. Cette occurrence italienne étend l'enregistrement stratigraphique d'A. pannonicum du Pléistocène inférieur et du Pliocène jusqu'au Miocène supérieur, et réduit l'écart temporel entre cette espèce et son congénère européen, A. inexpectatum Estes & Hoffstetter, 1976 (Oligocène inférieur-Miocène supérieur).

The Albanerpetontidae, small salamander-like tetrapods from the Middle Jurassic-Neogene of Laurasia and northern Africa, are widely considered to be lissamphibians; however, relationships among major lissamphibian clades are unresolved. A recently identified, isolated, and three-dimensionally preserved neurocranium (early Pliocene, Hungary) referred to Albanerpeton pannonicum is described, incorporating information gained from the application of micro-computed tomography. It is revealed that the neurocranium is a robust, box-like structure composed of the coossification of the parasphenoid, otic capsules, and occipital elements. The otic capsule endocast reveals the morphology of the endosseous labyrinth, complete with well-defined endosseous semicircular canals and a modestly developed ventral endosseous auditory region; however, details of the individual auditory organs are not discernable from the endocast. Features of the neurocranium and endosseous labyrinth are consistent with the hypothesis that A. pannonicum, and albanerpetontids in general, were somewhat fossorial. The neurocranium and endosseous labyrinth exhibit a mosaic of anuran, urodele, and apodan traits, thus precluding refinement of the phylogenetic position of albanerpetontids. In general, the neurocranium and endosseous labyrinth appear most similar to urodeles, and similarities with apodans and anurans may be due to convergent evolution resulting from similar habits and responses to inner ear stimulation. This new neurocranium represents the best-known specimen of its kind for albanerpetontids, and the data presented here combined with future comparative studies will contribute to a better understanding of the biology and evolution of this group.

The first phylogenetic analysis of the Euramerican Early Cretaceous–Miocene genus Albanerpeton is presented based on 16 characters of the jaws, frontals, and inferred body size scored for the seven recognized species in the genus and three other albanerpetontid taxa. Monophyly of Albanerpeton is corroborated and nested sets of synapomorphies yield the following hypothesized relationships: A. arthridion ((A. cifellii + A. galaktion + A. gracilis) (A. nexuosus (unnamed late Paleocene species + A. inexpectatum))). Osteological modifications identified in Albanerpeton initially involve the frontals, then shift largely to the jaws. Many of these changes are interpreted to be associated with broadening the head and strengthening the snout and jaws, presumably for feeding and burrowing. The first half or more (latest Aptian/earliest Albian to late Paleocene) of the known record for Albanerpeton and six of the seven species are restricted to the North American Western Interior. These occurrences and the ...

The Albanerpetontidae are Middle Jurassic–Miocene amphibians that have variously been regarded as caudates (salamanders), a clade distinct from caudates, or incertae sedis lissamphibians. Here I test for monophyly of the Albanerpetontidae and examine the affinities of the group, within the framework of a more inclusive Temnospondyli, by performing a cladistic analysis using 59 informative characters scored for four non-lissamphibian temnospondyl genera, stem- and crown-clade caudates, salientians (frogs), gymnophionans (caecilians), and the two recognized albanerpetontid genera Albanerpeton andCeltedens . Monophyly of the Albanerpetontidae is corroborated. I interpret synapomorphies of the marginal teeth (non-pedicellate; crowns chisel like, labiolingually compressed, with three mesiodistally aligned cuspules) in albanerpetontids as being associated with a shearing bite. Other synapomorphies evidently strengthened and increased the mobility of the skull, mandible, and cervical region for burrowing, feeding, or both. Nested sets of synapomorphies place the Albanerpetontidae within the Lissamphibia, as the sister-taxon of Caudata plus Salientia. None of the 17 characters previously advanced as albanerpetontid–caudate synapomorphies convincingly places the Albanerpetontidae within the Caudata or allies the two groups as sister-taxa. Albanerpetontids are better interpreted not as aberrant caudates, but as a distinct clade of lissamphibians in which numerous apomorphies are superimposed upon an otherwise primitive lissamphibian body plan.

Albanerpeton inexpectatum Estes and Hoffstetter, 1976 , the type species of Albanerpeton and the geologically youngest albanerpetontid, is rediagnosed and redescribed based on a large collection of jaws and frontals from Miocene fissure fills near La Grive-Saint-Alban, southeastern France. Intraspecific variation is documented in these elements, and is attributed to growth and individual differences. Synapomorphies of the upper jaws indicate that A. inexpectatum a) belongs in a clade whose members are otherwise known from the Upper Cretaceous-Paleocene of North America and b) is the sister species of an undescribed North American Paleocene species. The presence of A. inexpectatum in the Miocene of France is postulated to be the result of an Early or Middle Tertiary dispersal of an unknown ancestral species from North America into Europe. Cranial apomorphies of A. inexpectatum are interpreted as having strengthened the skull for burrowing in rocky soil and feeding.

A new albanerpetontid, Wesserpeton evansae gen. et sp. nov., from the Early Cretaceous (Barremian) Wessex Formation of the Isle of Wight, southern England, is described. Wesserpeton is established on the basis of a unique combination of primitive and derived characters relating to the frontals and jaws which render it distinct from currently recognized albanerpetontid genera: Albanerpeton (Late Cretaceous to Pliocene of Europe, Early Cretaceous to Paleocene of North America and Late Cretaceous of Asia); Celtedens (Late Jurassic to Early Cretaceous of Europe); and Anoualerpeton (Middle Jurassic of Europe and Early Cretaceous of North Africa). Although Wesserpeton exhibits considerable intraspecific variation in characters pertaining to the jaws and, to a lesser extent, frontals, the new taxon differs from Celtedens in the shape of the internasal process and gross morphology of the frontals in dorsal or ventral view. It differs from Anoualerpeton in the lack of pronounced heterodonty of dentary and maxillary teeth; and in the more medial location and direction of opening of the suprapalatal pit. The new taxon cannot be referred to Albanerpeton on the basis of the morphology of the frontals. Wesserpeton currently represents the youngest record of Albanerpetontidae in Britain.

ALBANERPETONTIDS are a group of enigmatic salamander-like fossil amphibians known from deposits of middle Jurassic to Miocene age across Euramerica and Central Asia. Throughout a long history they remained remarkably conservative but can be diagnosed by a suite of unique derived character states, including an anterior peg-and-socket joint between the mandibles, non-pedicellate tricuspate teeth, a distinctive polygonal dermal sculpture pattern, and a two-part craniovertebral joint analogous to that of amniotes. Previous interpretations have placed albanerpetontids within salamanders1, 2 or as a separate amphibian group3, 4. We report here on the recovery of the first complete albanerpetontid specimens (including traces of skin and possible male courtship glands) from the early Cretaceous of Spain. The new material supports the interpretation of albanerpetontids as predominantly terrestrial animals. Albanerpetontids resemble salamanders only in retaining an unspecialized tailed body form; cladistic analysis suggests they represent a distinct lissamphibian lineage.

Previously thought to be a salamander (Prosirenidae), Albanerpeton Estes and Hoffstetter (Jurassic to Miocene) possesses no known features otherwise restricted to salamanders. Its salamander-like features are only those held in common with small, limbed, non-saltatorial amphibians in general. In still other aspects (including feeding apparatus, dermal bones of the skull, and anterior cervical vertebrae), Albanerpeton appears unique. Already well isolated from salamanders, Albanerpeton seems no nearer phyletically to any other known amphibians, from Devonian to Recent. The relationships of Albanerpeton are most consistently indicated by classification in its own family (Albanerpetontidae, new) and order (Allocaudata, new), perhaps referrable to the Lissamphibia.