Lysorophia is an

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

fossorial A fossorial () animal is one adapted to digging which lives primarily, but not solely, underground. Some examples are badgers, naked mole-rats, clams, meerkats, and mole salamanders, as well as many beetles, wasps, and bees. Prehistoric eviden ...

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

and

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

tetrapods within the

Recumbirostra Recumbirostra is a clade of tetrapods which lived during the Carboniferous and Permian periods. They are thought to have had a fossorial (burrowing) lifestyle and the group includes both short-bodied and long-bodied snake-like forms. At least one ...

. Lysorophians resembled small

snake Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...

s, as their bodies are extremely elongate. There is a single

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

, the Molgophidae (previously known as Lysorophidae). Currently there are around five

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

included within Lysorophia, although many may not be valid.

Description

The

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

is heavily built but with large lateral openings to accommodate jaw musculature, with small orbits restricted to the anterior edge of the large fenestrae. The intertemporal, supratemporal, postfrontal, and jugal bones of the

have disappeared. The

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

s are short and robust with a small number of large triangular teeth. Although it was initially thought that the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

and

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has b ...

were freely movable, detailed anatomical studies show that this is not the case. The braincase is extremely robust, suggesting that lysorophians engaged in headfirst burrowing. The torso is very elongate, the limbs diminutive or absent, and the tail short. There are up to 99 pre-sacral (i.e. not including the hips and tail)

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

e. Based on morphology of the cranio-vertebral articulation and internal structure of the head, lysorophians are usually considered to be related to the Microsauria, although the pattern of bones of the skull is somewhat different.

Distribution

Lysorophians are known mainly from the Pennsylvanian and

Early Permian 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), 01'' (Richard Müller album), 2001 * 01 (Son of Dave album), ''01'' (Son of Dave album), 2000 * 01 (Urban ...

of North America. In North America, fossils of lysorophians have been found from places such as the Cutler Formation in San Juan County,

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

and the Mazon Creek fossil beds in Grundy County,

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

. Carboniferous lysorophians are also known from Europe, having been found from Britain and

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

. Possible remains of a lysorophian have also been found from La Machine,

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

, although they may belong to an

aïstopod Aistopoda (Greek for " avingnot-visible feet") is an order of highly specialised snake-like stegocephalians known from the Carboniferous and Early Permian of Europe and North America, ranging from tiny forms only , to nearly in length. They fir ...

Paleoecology

Swim traces referrable to lysorophians have been found at the

Robledo mountains The Robledo Mountains are a mountain range in Doña Ana County, New Mexico just northwest of Las Cruces. They are an uplifted block of Paleozoic rocks on the west side of the Rio Grande Rift. The range was named for Pedro Robledo, who died on Ma ...

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

, an area famous for its Permian tetrapod trackways. Designated as the ichnogenus ''Serpentichnus'', these marks occur as a series of L-shaped grooves, which are divided into two shafts: a long, diagonal shaft preceded by a shorter, forward-pointing shaft offset at a 150∘ angle. What seem to be tiny foot impressions occur on either side of the series of groves. When originally described in 2003, ''Serpentichnus'' tracks were argued to have been formed by a long-bodied animal with small limbs, moving in a " sidewinding" motion along a riverbed. Lysorophians such as ''Brachydectes'' were considered to be the most likely candidates for these swim traces. However, some paleontologists have argued that ''Serpentichnus'' traces were not actually formed by animals. These sources argue that the grooves were "tool marks", meaning that they were formed by rocks or vegetation brushing against the riverbed while being carried by a current.

References

General references

* Carroll, RL (1988), ''Vertebrate Paleontology and Evolution'', WH Freeman & Co. p. 180 * von Zittel, K.A (1932), ''Textbook of Paleontology'', C.R. Eastman (transl. and ed), 2nd edition, vol.2, p. 225-6, Macmillan & Co.

External links

Lysorophia - Palaeos

{{Taxonbar, from=Q134940 Carboniferous amphibians of North America Permian amphibians of North America Pennsylvanian animals of North America Cisuralian animals of North America Pennsylvanian first appearances Cisuralian extinctions