The Albanerpetontidae are an extinct family of small amphibians, native to the Northern Hemisphere during the

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Creta ...

and

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configu ...

. The only members of the order Allocaudata, they are thought to be allied with living amphibians belonging to

Lissamphibia The Lissamphibia is a group of tetrapods that includes all modern amphibians. Lissamphibians consist of three living groups: the Salientia (frogs, toads, and their extinct relatives), the Caudata (salamanders, newts, and their extinct relative ...

. Despite a superficially salamander-like bodyform, their anatomy is strongly divergent from modern amphibians in numerous aspects. The fossil record of albanerpetontids spans over 160 million years from the

Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations ...

to the beginning of the

Pleistocene The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed ...

, about 2.13-2 million years ago.

History of Research

The earliest specimen of an albanerpetontid to be discovered was that of ''

Celtedens megacephalus ''Celtedens'' is an extinct genus of albanerpetontid amphibian from the Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of t ...

'' from the

Early Cretaceous The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pr ...

(

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± ...

) Pietraroja Plattenkalk of Italy, described by

Oronzio Gabriele Costa Oronzo Gabriele Costa (26 August 1787, Alessano – 7 November 1867 Naples) was an Italian zoologist. At first a physician, he taught zoology at the University of Naples. He wrote 126 papers on various subjects, principally entomology, and in 18 ...

in 1864, and originally placed in the genus ''Triton,'' a junior synonym of the salamander genus ''

Triturus ''Triturus'' is a genus of newts comprising the crested and the marbled newts, which are found from Great Britain through most of continental Europe to westernmost Siberia, Anatolia, and the Caspian Sea region. Their English names refer to thei ...

''. Jaw elements of albanerpetontids from the Cretaceous of North America were assigned to the salamander genus ''

Prosiren ''Prosiren'' is an extinct genus of prehistoric amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wid ...

'' by Richard Estes in 1969, erecting the family Prosirenidae to accommodate the genus. ''Prosiren'' was originally described by Coleman J. Goin and

Walter Auffenberg Walter Auffenberg ( – ) was an American biologist who spent almost 40 years in field research, studying reptile and amphibian paleontology and the systematics and biology of numerous reptile species, including alligators and Komodo dragons. E ...

in 1958, based on vertebrae found in Cretaceous aged deposits in Texas. ''

Albanerpeton ''Albanerpeton'' is an extinct genus of salamander-like lissamphibian found in North America and Europe, first appearing in Cretaceous-aged strata. There are eight described members of the genus, and one undiagnosed species from the Paskapoo ...

'', the

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nomina ...

of the family was first named by Estes and

Robert Hoffstetter Robert Julien Hoffstetter (11 June 1908 in Fargniers – 29 December 1999 in Gennevilliers) was a French taxonomist and herpetologist who was influential in categorizing reptiles Reptiles, as most commonly defined are the animals in the Clas ...

in 1976 for the species of ''A. inexpectatum'' described from a large number of jaws and frontal bones from a

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

aged fissure fill deposit near

Saint-Alban-de-Roche Saint-Alban-de-Roche () is a commune in the Isère department in southeastern France. Population See also *Communes of the Isère department The following is a list of the 512 Communes of France, communes in the French Departments of France ...

in France, and was initially classified as a salamander, and placed in the family Prosirenidae alongside ''Prosiren'' due to the morphological similarity with the jaw fragments attributed to ''Prosiren'' by Estes (1969). Richard Fox and Bruce Naylor in 1982 realised that ''Albanerpeton'' was not a salamander, noting that the holotype vertebra of ''Prosiren'' was different to those of albanerpetontids, concluding that ''Albanerpeton'' was "well isolated from salamanders" and that it "seems no nearer phyletically to any other known amphibians, from

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, w ...

to Recent" erecting the family Albanerpetontidae and the order Allocaudata to accommodate it.

Description

Albanerpetontids were small (several cm to several tens of centimetres in length) and superficially lizard-like. The skin of albanerpetontids was embedded with bony, fish like scales. The morphology of the complete 3 dimensionally preserved skull of '' Yaksha peretti'' suggests that albanerpetontids had ballistic tongues akin to those of chameleons and

plethodontid Plethodontidae, or lungless salamanders, are a family of salamanders. Most species are native to the Western Hemisphere, from British Columbia to Brazil, although a few species are found in Sardinia, Europe south of the Alps, and South Korea. ...

salamanders, as evidenced by the presence of an elongated rod shaped bone in the jaw cavity, dubbed the

hyoid The hyoid bone (lingual bone or tongue-bone) () is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies between the base of the mandible and the third cervical vertebra. ...

entoglossal process, which in life was embedded within the tongue. Analogous bones exists in chameleons and plethodontids, which allow rapid propulsion of the tongue. A hyoid entoglossal process is also known from ''Celtedens megacephalus'', suggesting that the presence of a ballistic tongue is characteristic for the group. Distinguishing apomorphic traits characteristic of albanerpetontids include a complex

mortise and tenon A mortise and tenon (occasionally mortice and tenon) joint connects two pieces of wood or other material. Woodworkers around the world have used it for thousands of years to join pieces of wood, mainly when the adjoining pieces connect at righ ...

like joint connecting the dentary bones at the front of the jaw, teeth which are non-

pedicellate In botany, a pedicel is a stem that attaches a single flower to the inflorescence. Such inflorescences are described as ''pedicellate''. Description Pedicel refers to a structure connecting a single flower to its inflorescence. In the absenc ...

and slightly tricuspid (bearing three cusps), the

frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, pa ...

s of the skull display raised polygonal sculpturing, and three anterior

cervical In anatomy, cervical is an adjective that has two meanings: # of or pertaining to any neck. # of or pertaining to the female cervix: i.e., the ''neck'' of the uterus. *Commonly used medical phrases involving the neck are **cervical collar **cervic ...

components form an '

atlas An atlas is a collection of maps; it is typically a bundle of maps of Earth or of a region of Earth. Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geograp ...

axis An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to: Mathematics * Axis of rotation: see rotation around a fixed axis * Axis (mathematics), a designator for a Cartesian-coordinat ...

' complex, similar to that of amniotes.

Paleobiology

The morphology of albanerpetontids suggests that they were sit-and-wait terrestrial predators and fed on invertebrates, similar to living plethodontids. The fact that the skull of the juvenile paratype of ''Yaksha'' was around 1/4 of the size of the adult suggests that albanerpetontids grew by direct development and did not have a

metamorphic Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock ( protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, cau ...

larval stage. It has been suggested that albanerpetontids absorbed oxygen entirely through the skin via

cutaneous respiration Cutaneous respiration, or cutaneous gas exchange (sometimes called, skin breathing), is a form of respiration in which gas exchange occurs across the skin or outer integument of an organism rather than gills or lungs. Cutaneous respiration may ...

and lacked lungs like plethodontid salamanders, due to the length of the hyoid entoglossal process. This proposal is supported by the internal

vascularisation Angiogenesis is the physiological process through which new blood vessels form from pre-existing vessels, formed in the earlier stage of vasculogenesis. Angiogenesis continues the growth of the vasculature by processes of sprouting and splitting ...

and lack of

Sharpey's fibres Sharpey's fibres (bone fibres, or perforating fibres) are a matrix of connective tissue consisting of bundles of strong predominantly type I collagen fibres connecting periosteum to bone. They are part of the outer fibrous layer of periosteum, e ...

in the frontal bones.

Distribution

The distribution of albanerpetontids is largely confined to

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...

and North America, with remains also known from Morocco in North Africa. The first albanerpetontids are known from the western

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Si ...

(Europe and North Africa) in the

(

Bathonian In the geologic timescale the Bathonian is an age and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age. St ...

~168-166 million years ago), with the first known remains from North America occurring in the latter half of the

. The last known remains of albanerpetontids in North America are from the

Paskapoo Formation The Paskapoo Formation is a stratigraphic unit of Middle to Late Paleocene age in the Western Canada Sedimentary Basin. The Paskapoo underlies much of southwestern Alberta, and takes the name from the Blindman River (''paskapoo'' means "blind ...

in Canada, dating to the

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...

. All other

members of the family, belonging to the genus ''Albanerpeton'', are known from Europe and

Western Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion of the larger geographical region of Asia, as defined by some academics, UN bodies and other institutions. It is almost entirely a part of the Middle East, and includes A ...

, from the

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but ...

onwards, after an unexplained hiatus in the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

, until their final appearance in Italy during the Early Pleistocene, around 2 million years ago.

Classification

Albanerpetontids were long thought to be salamanders because of their small size and generalized body plans.Duellman, W.E. & Trueb, L. (1994): Biology of amphibians. The Johns Hopkins University Press However, these features are now thought to be ancestral for lissamphibians and not indicative of close relationships between the two groups. Albanerpetontids share with living lissamphibians an

atlanto-occipital joint The atlanto-occipital joint (''Capsula articularis atlantooccipitalis'') is an articulation between the atlas bone and the occipital bone. It consists of a pair of condyloid joints. It is a synovial joint. Structure The atlanto-occipital joint ...

with two cotyles, a four fingered forelimb (manus), ectochordal (spoon shaped with open centra) vertebrae with cylindrical centra, ribs that do not encircle the body, and a salamander-like quadrate-

squamosal The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral co ...

articulation, but are distinguished from the three living groups of lissamphibians by their possession of

keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, ...

ized claw sheaths and their retention of skull bones lost in other lissamphibians, including

epipterygoid The epipterygoid is a paired cranial bone present in many tetrapods. It acts as a vertical strut connecting the pterygoid bone of the palate to the outer surface of the braincase or the underside of the skull roof. The epipterygoid is an endochond ...

s, supraoccipitals and large

palatines Palatines (german: Pfälzer), also known as the Palatine Dutch, are the people and princes of Palatinates (Holy Roman principalities) of the Holy Roman Empire. The Palatine diaspora includes the Pennsylvania Dutch and New York Dutch. In 1709 ...

, as well as the absence of pedicellate teeth or a wide

parasphenoid The parasphenoid is a bone which can be found in the cranium of many vertebrates. It is an unpaired dermal bone which lies at the midline of the roof of the mouth. In many reptiles (including birds), it fuses to the endochondral (cartilage-derived) ...

cultriform process. Albanerpetontids are now recognized as a distinct clade of lissamphibians separate from the three living orders of amphibians – Anura (frogs),

Caudata The Caudata are a group of amphibians containing the extant salamanders ( Urodela) and all extinct species of amphibians more closely related to salamanders than to frogs. They are typically characterized by a superficially lizard-like appearan ...

(salamanders), and

Gymnophiona Caecilians (; ) are a group of limbless, vermiform or serpentine amphibians. They mostly live hidden in the ground and in stream substrates, making them the least familiar order of amphibians. Caecilians are mostly distributed in the tropics ...

(caecilians). Most studies show them as more closely related to frogs and salamanders than to caecilians, but bootstrap and

Bayesian Thomas Bayes (/beɪz/; c. 1701 – 1761) was an English statistician, philosopher, and Presbyterian minister. Bayesian () refers either to a range of concepts and approaches that relate to statistical methods based on Bayes' theorem, or a follower ...

analyses show that this result is not robust and that they could also be sister-group of the

. The presence of epipterygoids and a separate supraoccipital at least argues against a position within

Batrachia The Batrachia are a clade of amphibians that includes frogs and salamanders, but not caecilians nor the extinct allocaudates. The name Batrachia was first used by French zoologist Pierre André Latreille in 1800 to refer to frogs, but has mor ...

. A phylogenetic analysis in 2020 among lissamphibian relationships using multiple methods found no consensus for the position of Albanerpetontidae in relation to other lissamphibians, but they were always placed closer to lissamphibians than to other extinct groups of amphibians, such as

lepospondyls Lepospondyli is a diverse taxon of early tetrapods. With the exception of one late-surviving lepospondyl from the Late Permian of Morocco ('' Diplocaulus minumus''), lepospondyls lived from the Early Carboniferous (Mississippian) to the Early ...

and

temnospondyls Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carb ...

Taxonomy

* Genus ''

Shirerpeton ''Shirerpeton'' is an extinct genus of albanerpetontid amphibian from the Early Cretaceous Kuwajima Formation, which is located in Japan.Fujita, M. (2003). "Geological age and correlation of the vertebrate-bearing horizons in the Tetori Group" ...

'' Matsumoto & Evans, 2018 **'' Shirerpeton isajii'' Matsumoto & Evans, 2018 Early Cretaceous, Japan * Genus ''

Wesserpeton ''Wesserpeton'' is an extinct genus of albanerpetontid amphibian known from the Isle of Wight, southern England. Description ''Wesserpeton'' is known from the holotype NHMUK PV R36521, nearly complete fused frontals and from the ...

'' Sweetman & Gardner 2013 ** ''Wesserpeton evansae'' Sweetman & Gardner 2013 Early Cretaceous, United Kingdom * Genus ''

Anoualerpeton ''Anoualerpeton'' is an extinct genus of lissamphibian in the family Albanerpetontidae. It is the oldest and most primitive albanerpetontid known. Fossils have been found of two different species, ''Anoualerpeton priscus'' from the Middle Jurassi ...

'' Gardner, Evans & Sigogneau-Russell 2003 ** ''Anoualerpeton priscus'' Gardner, Evans & Sigogneau-Russell 2003 Middle Jurassic, United Kingdom ** ''Anoualerpeton unicus'' Gardner, Evans & Sigogneau-Russell 2003 Late Jurassic, Morocco * Genus ''

Celtedens ''Celtedens'' is an extinct genus of albanerpetontid amphibian from the Early Cretaceous of England, Spain, Sweden and Italy, and the Late Jurassic of Portugal. Taxonomy * †''Celtedens ibericus'' McGowan and Evans 1995 La Huérguina Form ...

'' McGowan & Evans 1995 Late Jurassic-Early Cretaceous, Europe ** ''Celtedens megacephalus'' (Costa 1864) Early Cretaceous, Italy, United Kingdom ** ''Celtedens'' ''ibericus'' McGowan & Evans 1995 Early Cretaceous, Spain * Genus ''

'' Estes & Hoffstetter 1976 ** ''Albanerpeton arthridion'' Fox & Naylor 1982 Early Cretaceous, United States ** Clade "Gracile-snouted" *** ''Albanerpeton gracilis'' Gardner 2000 Late Cretaceous, North America *** ''Albanerpeton cifellii'' Gardner 1999 Late Cretaceous, United States *** ''Albanerpeton galaktion'' Fox & Naylor 1982 Late Cretaceous, North America ** Clade "Robust-snouted" *** ''Albanerpeton nexuosus'' Estes 1981 Late Cretaceous, North America *** ''Albanerpeton pannonicus'' Venczel & Gardner 2005 latest Miocene-Early Pleistocene Hungary, Italy *** ''Albanerpeton inexpectatum'' Estes & Hoffstetter 1976 Early Oligocene- Late Miocene, Europe *Genus ''

Yaksha The yakshas ( sa, यक्ष ; pi, yakkha, i=yes) are a broad class of nature-spirits, usually benevolent, but sometimes mischievous or capricious, connected with water, fertility, trees, the forest, treasure and wilderness. They appear in ...

'' Daza et al, 2020 **''Yaksha perettii'' Daza et al, 2020 Late Cretaceous, Myanmar *Fragmentary remains of albanerpetontids are also known from the Bathonian aged Anoual Formation of Morocco, The Bathonian aged

Aveyron Aveyron (; oc, Avairon; ) is a department in the region of Occitania, Southern France. It was named after the river Aveyron. Its inhabitants are known as ''Aveyronnais'' (masculine) or ''Aveyronnaises'' (feminine) in French. The inhabitants of ...

locality of France, the

Tithonian In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by t ...

aged Chassiron locality of France, the

Berriasian In the geological timescale, the Berriasian is an age/ stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 145.0 ± 4.0 Ma and 139.8 ± 3.0 Ma (million years a ...

aged Cherves-de-Cognac locality and

Angeac-Charente bonebed The Angeac-Charente bonebed is a fossil deposit located near Angeac-Charente in western France. It dates to the Berriasian stage of the Early Cretaceous, and is coeval with the Purbeck Group of Southern England. It has amongst the most diverse ass ...

of France,Ronan Allain, Romain Vullo, Lee Rozada, Jérémy Anquetin, Renaud Bourgeais, et al.
Vertebrate paleobiodiversity of the Early Cretaceous (Berriasian) Angeac-Charente Lagerstätte (southwestern France): implications for continental faunal turnover at the J/K boundary
Geodiversitas, Museum National d'Histoire Naturelle Paris, In press. ffhal-03264773f Cenomanian-

Turonian The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded ...

Khodzhakul and

Bissekty Formation The Bissekty Formation (sometimes referred to as Bissekt) is a geologic formation and Lagerstätte which crops out in the Kyzyl Kum desert of Uzbekistan, and dates to the Late Cretaceous Period. Laid down in the mid to late Turonian, it is dated ...

s of Uzbekistan, originally assigned to the dubious genus ''Nukusaurus'' and the

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. ...

aged Csehbánya Formation of Hungary.

Phylogeny

From Daza et al 2020.

References

External links

Albanerpetontidae phylogeny.
{{Taxonbar, from=Q144257 Amphibian families Bathonian first appearances Piacenzian extinctions Tertiary extinctions of vertebrate taxa