Albanerpeton Temporal range: | |
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Albanerpeton inexpectatum | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Amphibia |
Order: | † Allocaudata |
Family: | † Albanerpetontidae |
Genus: | † Albanerpeton Estes and Hoffstetter, 1976 |
Species | |
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Albanerpeton is an extinct genus of salamander-like albanerpetontid amphibian found in North America, Europe and Asia first appearing in Cretaceous-aged strata. There are eight described members of the genus, and one undiagnosed species from the Paskapoo Formation, making it by far the most speciose genus in the family. [1] Members of the genus had a robust head and neck which likely allowed them to actively burrow, characteristic of fossorial species, and they lived in a wide range of environments. This genus of amphibian was the last of its order, surviving until into the Early Pleistocene (Gelasian) of northern Italy, [2] and possibly northern Spain, [3] until around 2 million years ago. It likely became extinct when the region developed its present Mediterranean-type climate, having preferred one that was cold and humid. [2] The monophyly of Albanerpeton has recently been questioned, with some authors regarding the genus as paraphyletic. [4] [5]
Albanerpeton was first described by Estes and Hoffstetter in 1976. However, the genus was re-described by Gardner in 1999 after a large collection of jaws and frontals from Miocene fissure fills near La Grive-Saint-Alban in southeastern France was found. [6] When the type species was originally described, it was considered to be a salamander, despite possessing no known features that were otherwise restricted to Urodela, as its only salamander-like features were held in common with small, limbed, and non-saltatorial amphibians in general. [7] A. inexpectatum had many unique characteristics, distinct from salamanders and other amphibians (such as its feeding apparatus, dermal bones of the skull, and anterior cervical vertebrae) that Fox and Naylor suggested it be classified in its own order, Allocaudata, family, Albanerpetontidae, and genus, Albanerpeton, all of which were new at the time. [7] Seven of the eight species are restricted to the Western Interior of North America, suggesting that the evolutionary history of the genus was centered there, [8] although the presence of a sole species in France, [6] A. inexpectatum, suggests a Tertiary dispersal of an unknown species from North America into Europe. Albanerpeton jaws and frontals are the most commonly recovered Albanerpeton bones found at dig sites, but these bones exhibit many characteristics that are taxonomically and phylogenetically informative for the genus and individual species within it. [6]
The oldest species of Albanerpeton as usually defined are known from the late Early Cretaceous of North America. During the Late Cretaceous, Albanerpeton was widespread in North America, as well as in Europe (and was present in Asia if remains from the Khodzhakul Formation in Uzbekistan are included). The youngest remains of the species in North America are known from the Paskapoo Formation in Canada, dating to the Paleocene. [1] The Cenozoic record of Albanerpeton is largely confined to Europe, spanning from the Oligocene to the final records of the group in the Early Pleistocene of Italy, around 2.13-2 million years ago. [1] [2] Fossils are also known from the Oligocene of Anatolia in Asia. [9]
Albanerpeton is suggested to have had a preference for moist environments. [1] Albanerpetontids are proposed to have been sit-and wait predators that fed on invertebrates via the use of a ballistic tongue similar to that used by chameleons and plethodontid salamanders. [5]
Albanerpeton are distinct from frogs, salamanders, and caecilians, forming their own family of Lissamphibia, Albanerpetontidae. Membership of species in the family is determined by diagnostic character states of the frontals and premaxillary synapomorphies, both of which can be used to further diagnose less inclusive clades in the genus. [10] These less inclusive clades are the gracile-snouted clade and robust-snouted clade, made up of three and four species respectively though only three of the robust-snouted clade have been fully described. The gracile-snouted clade is defined by a triangular to slit-shaped suprapalatal pit. The robust-snouted clade is defined by a robust premaxillae, a short pars dorsalis that is sutured dorsally with the nasal, a short premaxillary lateral process on the maxilla, and an internasal process on frontals that are both narrow and similar to spines. [10] The origins of these sister, snout-based clades can both be traced back to the early Late Cretaceous, and therefore antedate the Campanian. [10] A. arthridion is interpreted as the most primitive species of Albanerpeton, being quite small. Its small size forms the basis for the hypothesis that reduced body size is derived, and was developed at least twice within the genus. [11] Diagnostic characteristics of the genus itself include characteristics of the teeth and skull.
Albanerpeton teeth are about one-third of the distance from the anterior end of the tooth row, and these are markedly larger than other nearby teeth. Additionally, the dorsal edge of the dental boundary is curved on its lingual side. [10]
In 2013, Maddin et al. created a computer-generated tomography of a partially preserved, three-dimensional A. pannonicum neurocranium which deposited during the Pliocene in Hungary. The structure of this specimen is in line with what is known of older Albanerpeton neurocrania, and therefore a good reference for what the neurocranium of the whole genus is like. [12] Features of the reconstructed skull consist of a robust, box-like unit composed of coossification of the parasphenoid, otic capsules, and occipital elements with no trace of fusion or sutural points of contact among these components. Additionally, the anterior three-quarters of the dorsal surface is open, but the furthest posterior portion, tectum synoticum, is fused. The ventral surface of Albanerpeton neurocrania are fully ossified, solid bone. [12] The neurocranium of Albanerpeton is in contact dorsally with paired parietals, forming the roof of the brain cavity while contacting laterally with the squamosal. [12] Overall, the robust construct of Albanerpeton's neurocranium is consistent with the theory that the genus was fossorial in nature, as the thickened and strengthened skull would have lent itself to burrowing. [8]
Albanerpeton have ossified antotic pillars which sit in front of the otic capsules. Additionally, there are a pair of small, robust bony pedestals that are located ventrolaterally in front of the otic capsules, which likely served to brace the neurocranium against the palatal region and suspensorium. [12] In Albanerpeton, the otic capsules themselves are moderately inflated with a large, rhomboid-shaped fenestra vestibuli present on both capsules. These fenestrae can be used to imply the presence of middle ear ossicles in Albanerpeton. Albanerpeton had well-developed semicircular canals with a modestly developed ventral auditory region as well. [12]
Current accepted species:
Genus AlbanerpetonEstes & Hoffstetter 1976
The genus Albanerpeton is part of the family Albanerpetontidae which is part of the order Allocaudata within superorder Batrachia and class Amphibia. Members of genus Albanerpeton are considered to be Lissamphibia who are distinct in character from frogs, salamanders, and caecilians. In 2018, a closely related species, named Shirepeton isajii, was discovered and described in the Kuwajima Formation of Japan. While it is closely related to members of Albanerpeton, it does not fall within the clade. [4] Many remains attributed to Albanerpeton from the Late Cretaceous of Europe, such as those from the Maastrichtian aged Densuş-Ciula Formation, Sânpetru Formation and Sard Formation of Romania and the Maastrichtian aged Tremp Formation of Spain, are probably only diagnostic to family level. [13]
Cladogram from Venczel and Gardner (2005): [14]
Albanerpetontidae |
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In 2020 it was found that Albanerpeton is paraphyletic with respect to Shirerpeton and Yaksha, and it has been suggested that Albanerpeton be restricted to the Cenozoic species, with the Cretaceous species being given separate genera. [5]
Cladogram from Daza et al. (2020)
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Finally, with the description of Albanerpeton ektopistikon by Carrano et al. (2022), based on the data matrix from the 2018 description of Shirepeton isajii, also recovered Albanerpeton as a paraphyletic genus, further separated than in Daza et al., (2020). Instead of restricting Albanerpeton, they provisionally suggested to include Shirerpeton and Wesserpeton into the genus, turning their type species into A. isajii and A. evansae, respectively, though they also suggested that the genus could be split into separate genera. Cladogram from Carrano et al. (2022): [1]
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The Lissamphibia is a group of tetrapods that includes all modern amphibians. Lissamphibians consist of three living groups: the Salientia, the Caudata, and the Gymnophiona.
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 more recently been defined in a phylogenetic sense as a node-based taxon that includes the last common ancestor of frogs and salamanders and all of its descendants. The idea that frogs and salamanders are more closely related to each other than either is to caecilians is strongly supported by morphological and molecular evidence; they are, for instance, the only vertebrates able to raise and lower their eyes. However, an alternative hypothesis exists in which salamanders and caecilians are each other's closest relatives as part of a clade called the Procera, with frogs positioned as the sister taxon of this group.
Dissorophoidea is a clade of medium-sized, temnospondyl amphibians that appeared during the Moscovian in Euramerica, and continued through to the Late Permian and the Early Triassic of Gondwana. They are distinguished by various details of the skull, and many species seem to have been well adapted for life on land.
Temnospondyli or temnospondyls is a diverse ancient order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carboniferous, Permian and Triassic periods, with fossils being found on every continent. A few species continued into the Jurassic and Early Cretaceous periods, but all had gone extinct by the Late Cretaceous. During about 210 million years of evolutionary history, they adapted to a wide range of habitats, including freshwater, terrestrial, and even coastal marine environments. Their life history is well understood, with fossils known from the larval stage, metamorphosis and maturity. Most temnospondyls were semiaquatic, although some were almost fully terrestrial, returning to the water only to breed. These temnospondyls were some of the first vertebrates fully adapted to life on land. Although temnospondyls are amphibians, many had characteristics such as scales and armour-like bony plates that distinguish them from the modern soft-bodied lissamphibians.
Apodops is an extinct genus of early caecilians from the Early Eocene Itaboraí Formation of Brazil. The type species of the genus is A. pricei, described based on an isolated and broken trunk vertebra.
The Albanerpetontidae are an extinct family of small amphibians, native to the Northern Hemisphere during the Mesozoic and Cenozoic. The only members of the order Allocaudata, they are thought to be allied with living amphibians belonging to Lissamphibia. 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 to the beginning of the Pleistocene, about 2.13–2 million years ago.
Rhinesuchidae is a family of tetrapods that lived primarily in the Permian period. They belonged to the broad group Temnospondyli, a successful and diverse collection of semiaquatic tetrapods which modern amphibians are probably descended from. Rhinesuchids can be differentiated from other temnospondyls by details of their skulls, most notably the interior structure of their otic notches at the back of the skull. They were among the earliest-diverging members of the Stereospondyli, a subgroup of temnospondyls with flat heads and aquatic habits. Although more advanced stereospondyls evolved to reach worldwide distribution in the Triassic period, rhinesuchids primarily lived in the high-latitude environments of Gondwana during the Guadalupian and Lopingian epochs of the Permian. The taxonomy of this family has been convoluted, with more than twenty species having been named in the past; a 2017 review recognized only eight of them to be valid. While several purported members of this group have been reported to have lived in the Triassic period, most are either dubious or do not belong to the group. However, at least one valid genus of rhinesuchid is known from the early Triassic, a small member known as Broomistega. The most recent formal definition of Rhinesuchidae, advocated by Mariscano et al. (2017) is that of a stem-based clade containing all taxa more closely related to Rhinesuchus whaitsi than to Lydekkerina huxleyi or Peltobatrachus pustulatus. A similar alternate definition is that Rhinesuchidae is a stem-based clade containing all taxa more closely related to Uranocentrodon senekalensis than to Lydekkerina huxleyi, Trematosaurus brauni, or Mastodonsaurus giganteus.
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 Jurassic (Bathonian) aged Forest Marble and Kilmaluag formations of England and Scotland, and Anoualerpeton unicus from Late Jurassic-Early Cretaceous (Tithonian-Berriasian) Ksar Metlili Formation of Morocco. A. unicus is the only named albanerpetontid from Gondwana.
Celtedens is an extinct genus of albanerpetontid amphibian from the Early Cretaceous of England, Spain, Sweden and Italy, and the Late Jurassic of Portugal.
Doleserpeton is an extinct, monospecific genus of dissorophoidean temnospondyl within the family Amphibamidae that lived during the Upper Permian, 285 million years ago. Doleserpeton is represented by a single species, Doleserpeton annectens, which was first described by John R. Bolt in 1969. Fossil evidence of Doleserpeton was recovered from the Dolese Brothers Limestone Quarry in Fort Sill, Oklahoma. The genus name Doleserpeton is derived from the initial discovery site in Dolese quarry of Oklahoma and the Greek root "herp-", meaning "low or close to the ground". This transitional fossil displays primitive traits of amphibians that allowed for successful adaptation from aquatic to terrestrial environments. In many phylogenies, lissamphibians appear as the sister group of Doleserpeton.
Horezmia is an extinct Mesozoic genus of prehistoric salamanders. The fossils have been found in Russia. It is comparable to modern advanced salamanders, though its phylogenetic placement within Salamandroidea is uncertain.
The Kuwajima Formation is an Early Cretaceous geologic formation in Japan. Its precise age is uncertain due to a lack of identifying fossils, and it was previously considered likely Valanginian to Hauterivian in age. However, it is now considered to probably be Barremian in age. Dinosaurs and other vertebrates has been recovered from the Kaseki-kabe "Fossil-bluff" locality in the uppermost part of the formation.
The Csehbánya Formation is a geological formation in the Transdanubian Mountains of Veszprém County, Hungary. The formation dates to the Late Santonian of the Late Cretaceous. It represents a floodplain environment as opposed to the swampy lacustrine environment of the simultaneous Ajka Coal Formation, though there is complete overlap in terms of fauna. It underlies the Jákó Marl Formation, and laterally transitions to the Ajka Coal Formation.
Wesserpeton is an extinct genus of albanerpetontid amphibian known from the Isle of Wight, southern England.
The Karauridae are a family of stem-group salamanders (Caudata) that are known from the Middle Jurassic to Early Cretaceous in Central Asia, Northern Asia and Western Europe. The family includes four members: Karaurus from the Middle-Late Jurassic Karabastau Formation of Kazakhstan, Kokartus from the Middle Jurassic Balabansai Formation of Kyrgyzstan, Marmorerpeton from the Middle Jurassic Forest Marble Formation of England and Kilmaluag Formation of Scotland, and Kuzbassia from the Early Cretaceous (Aptian) Ilek Formation. The members are some of the oldest known salamanders. The family is united by several morphological characters, including sculptured skull roof bones. Like some modern salamanders, karaurids were neotenic. Members of the family likely fed via suction feeding on small fish and invertebrates. The Early Cretaceous Siberian Kulgeriherpeton has been suggested to be a karaurid by some authors.
Shirerpeton is an extinct genus of albanerpetontid amphibian from the Early Cretaceous Kuwajima Formation, which is located in Japan. The type species is Shirerpeton isajii, which was described by Masumoto & Evans in 2018. Shirerpeton represents the first record of Albanerpetontidae in East Asia and the holotype is SBEI 2459, a small block bearing most of a disarticulated but associated skull with some postcranial elements present as well.
Chinlestegophis is a diminutive Late Triassic stereospondyl that has been interpreted as a putative stem caecilian, a living group of legless burrowing amphibians. If Chinlestegophis is indeed both an advanced stereospondyl and a relative of caecilians, this means that stereospondyls survived to the present day; historically the group was thought to have gone extinct by the early Cretaceous. Chinlestegophis jenkinsi, the type and only species, is known from two partial skulls discovered in the Chinle Formation in Colorado.
The Ksar Metlili Formation is a geological formation in eastern High Atlas of Morocco, it is late Tithonian to Berriasian in age. It is approximately 80 metres (260 ft) thick and primarily consists of mudstone and sandstone, with thin calcareous beds. One of these calcareous beds near the middle of the sequence is an important microvertebrate locality. Subsequent to the original site, several other localities have been sampled. The depositional environment is thought to be near shore deltaic.
Yaksha perettii is an extinct species of albanerpetontid amphibian, and the only species in the genus Yaksha. It is known from three specimens found in Cenomanian aged Burmese amber from Myanmar. The remains of Yaksha perettii are the best preserved of all albanerpetontids, which usually consist of isolated fragments or crushed flat, and have provided significant insights in the morphology and lifestyle of the group.
This list of fossil amphibians described in 2020 is a list of new taxa of fossil amphibians that were described during the year 2020, as well as other significant discoveries and events related to amphibian paleontology that occurred in 2020.