''Diphydontosaurus'' is an extinct genus of small

rhynchocephalian Rhynchocephalia (; ) is an order of lizard-like reptiles that includes only one living species, the tuatara (''Sphenodon punctatus'') of New Zealand. Despite its current lack of diversity, during the Mesozoic rhynchocephalians were a speciose g ...

reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...

from the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...

of Europe. It is the most primitive known member of Sphenodontia.

Description

''Diphydontosaurus'' was one of the smallest sphenodontians, measuring up to long. It had long, sharp claws to help it catch its prey. The skull, which was around long, had large

orbits In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an satellite, artificia ...

(eye sockets), as well as a combination of 17 regularly replaced conical

pleurodont Pleurodont is a form of tooth implantation common in reptiles of the order Squamata, as well as in at least one temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 've ...

teeth on the front of the jaws and 11 larger permanent

acrodont Acrodonty (from Greek ''akros'' 'highest' + ''odont-'' 'tooth') is an anatomical placement of the teeth at the summit of the alveolar ridge of the jaw, without sockets, characteristic of bony fish. Functionally, acrodont tooth implantation may be r ...

teeth in the posterior jaws. It was likely an

insectivore file:Common brown robberfly with prey.jpg, A Asilidae, robber fly eating a hoverfly An insectivore is a carnivore, carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the Entomophagy ...

which used its acrodont posterior teeth to dismember prey.

Classification

''Diphydontosaurus avonis'' is known from abundant remains covering most of the skeleton found in fissure fill deposits in Southwest Britain. A skeleton of a juvenile sphenodontian tentatively referred to ''Diphydontosaurus'' was reported in 1996 from the Norian of Lombardy in Italy.Renesto, S., 1995, A sphenodontid from the Norian (Late Triassic) of Lombardy (Northern Italy): a preliminary note: Modern Geology, v. 20, p. 149–158. In most recent analyses it has been recovered as the most basal

sphenodontian Rhynchocephalia (; ) is an order (biology), order of lizard-like reptiles that includes only one living species, the tuatara (''Sphenodon punctatus'') of New Zealand. Despite its current lack of diversity, during the Mesozoic rhynchocephalians ...

Paleoecology

''Diphydontosaurus avonis'' was a small animal that lived in the

Bristol Channel The Bristol Channel (, literal translation: "Severn Sea") is a major inlet in the island of Great Britain, separating South Wales (from Pembrokeshire to the Vale of Glamorgan) and South West England (from Devon to North Somerset). It extends ...

region of

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

. It lived during the Late

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

about 205 mya. The deposits in which it is from are complete enough for its ecosystem to be reconstructed in 2012. In the Late Triassic, the regions that ''Diphydontosaurus'' lived in were numerous rocky, small caves, that sat on a

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

bed. It is likely that the caves were eroded by possibly acidic rainwater. ''Diphydontosaurus'' is very well known from these deposits, potentially because they drowned after a rainstorm or monsoon.

References

Footnotes

Citations

* * * * * {{Taxonbar, from=Q5279784 Rhynchocephalia Late Triassic reptiles of Europe Prehistoric reptile genera