''Hyperodapedon'' is a

genus 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 nom ...

rhynchosaur Rhynchosaurs are a group of extinct herbivorous Triassic archosauromorph reptiles, belonging to the order Rhynchosauria. Members of the group are distinguished by their triangular skulls and elongated, beak like premaxillary bones. Rhynchosaurs ...

s (beaked, archosaur-like reptiles) from the

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

period (

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227 m ...

stage). Fossils of the genus have been found in Africa, Asia, Europe and North and South America. Its first discovery and naming was found by

Thomas Henry Huxley Thomas Henry Huxley (4 May 1825 – 29 June 1895) was an English biologist and anthropologist specialising in comparative anatomy. He has become known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution. The stori ...

in 1859. ''Hyperodapedon'' was a herbivore that used its beaked premaxilla and hindlimbs to dig for plants in dry land.

Description

''Hyperodapedon'' was a heavily built, stocky, animal. ''H. gordoni'' had total length around with skull length of to , but largest species, ''H. huxleyi'' had lower jaw about and skull length is estimated about . Apart from its beak, it had several rows of heavy teeth on each side of the upper jaw, and a single row on each side of the lower jaw, creating a powerful chopping action when it ate. It is believed to have been herbivorous, feeding mainly on

seed fern A seed is an Plant embryogenesis, embryonic plant enclosed in a testa (botany), protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, includ ...

s, and died out when these plants became extinct at the end of the Triassic. The diagnosis of ''Hyperodapedon'' relies on many features of the cranial and postcranial traits which include a longer than wide basipterygoid process, a crest-shaped maxillary cross section next to the main longitudinal groove, deep excavated neural arches on the mid dorsal vertebrae, a long scapular blade, a pronounced deltopectoral crest, and a proximal humeral end which is broader at the distal end. The maxillary tooth plates are easily seen in ''Hyperodapedon'' and there are seven cranial, six postcranial, and three dentition

synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to hav ...

traits. ''Hyperodapedon'' had jaws that allowed them to have a precision-shear bite to break down the tough plants that they ate. The beak-like

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 ...

and hind limbs were used for digging up food. Teeth along 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. T ...

and dentary had open roots which could not be replaced like other reptiles. The forelimbs, on the other hand, were used for movement due to the rotation of; the humerus, however, the femur was not able to rotate. Another unique feature of ''Hyperodapedon'' was the large eyes with sclerotic plates, which allowed for good sense of vision. They had large nasal capsules to sense smell. Since ''Hyperodapedon'' lacked a tympanum, it was believed that they could sense sound by the skin near the quadrate.Benton, M. (1983). The Triassic reptile ''Hyperodapedon'' from Elgin: Functional morphology and relationships. ''Royal Society''. Hyperodapedons also appeared to have transverse rows of cone-shaped teeth along the lateral area of the maxilla.Huxley, T. (1887). Further Observations upon ''Hyperodapedon gordoni''. ''Quarterly Journal of the Geological Society,'' ''43'', 675–694. ''Hyperodapedon's'' closest relative is ''

Rhynchosaurus ''Rhynchosaurus'' (''beaked lizard'') is a genus of rhynchosaur that lived during the Middle Triassic period. It lived in Europe. It was related to the archosaurs, but not within that group. The type species of ''Rhynchosaurus'' is ''R. articep ...

'', and they both share a synapomorphy that the dentary is half the length of the lower jaw. ''Hyperodapedon'' had a longitudinal stapedial canal on the posterior side of the spatulate paroccipital process which the lagenar crest extended laterally to limit the posterior end.Langer, M. C., & Schultz, C. L. (2003). A New Species Of The Late Triassic Rhynchosaur Hyperodapedon From The Santa Maria Formation Of South Brazil. ''Wiley Online Library,'' ''43''(4). Above the ventral margin of the orbit was the upper temporal bar which faced dorsally. A non-directional exploitation of morphospace from smaller ancestors with a smaller size restriction is responsible for a large body size in ''Hyperodapedon''. ''Hyperodapedon'' have a single row of teeth in mandible bites between their two rows of teeth fixed to a plate which is formed by a union of the maxilla with the palatine. Other key traits are the two maxillary grooves and a single dentary blade, along with missing the infraorbital foramen. The supraoccipital and opisthotics are fused together. ''Hyperodapedon'' had a pair of ridges which are absent on the

pterygoid Pterygoid, from the Greek for 'winglike', may refer to: * Pterygoid bone, a bone of the palate of many vertebrates * Pterygoid processes of the sphenoid bone ** Lateral pterygoid plate ** Medial pterygoid plate * Lateral pterygoid muscle * Medi ...

, they are missing the palatal dentition, and the prefrontal is concave deeply on the dorsal side.

Discovery

The first discovery was from

in 1859, who named ''Hyperodapedon gordoni'' in honor of Rev. Dr. Gordon's contributions in Elgin County.Burckhardt, R. (1900). I.—On ''Hyperodapedon gordoni''. ''Geological Magazine,7''(12), 529. doi:10.1017/s0016756800183529 T.H. Huxley found many series of subcylindrical palatal teeth which was the main trait of ''Hyperodapedon''. Huxley was able to distinguish ''Hyperodapedon'' from ''Rhynchosaurus'' articeps by the maxillary tooth rows. Later on, Lydekker realized that ''Hyperodapedon'' have more than two rows of teeth in both the maxilla and palatine. The type species of ''Scaphonyx'' (meaning ''canoe claw''), ''Scaphonyx fischeri'' that was once thought to be a

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

, is now known to be based on dubious material and therefore should be a '' nomen dubium''. The name ''Paradapedon'' was elected for the Indian species ''H. huxleyi'' (Lydekker, 1881). Benton, 1983, concluded that this rhynchosaur should be considered a species of ''Hyperodapedon''. ''Hyperodapedon'' is known from several species and has been found in many areas of the world, due to the continents being joined in the supercontinent

Pangaea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...

during the

Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...

. Fossils from the various species have been identified from Argentina, Brazil, India, Scotland, Tanzania, Zimbabwe and possibly from

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the s ...

(United States).

Classification

Langer ''et al.'' (2000) defined ''Hyperodapedon'' as a

stem-based taxon Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a '' type'', which ...

that includes all

s closer to ''Hyperodapedon gordoni'' than to ''"Scaphonyx" sulcognathus'' (now '' Teyumbaita''). The

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

below follows their

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis of Mukherjee & Ray (2014).Mukherjee, D., Ray, S. (2014)
A new ''Hyperodapedon'' (Archosauromorpha, Rhynchosauria) from the Upper Triassic of India: implications for rhynchosaur phylogeny
''Palaeontology''. doi: 10.1111/pala.12113 Valid species that were first assigned to ''

Scaphonyx ''Hyperodapedon'' is a genus of rhynchosaurs (beaked, archosaur-like reptiles) from the Late Triassic period (Carnian stage). Fossils of the genus have been found in Africa, Asia, Europe and North and South America. Its first discovery and naming ...

''. A quantitative

phylogenetic analysis In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

found a paraphyletic genus ''Rhynchosaurus'', with ''Rhynchosaurus brodiei'' more closely related to hyperodapedontines than to ''Rhynchosaurus articeps''. ''Hyperodapedon'' is the most commonly found tetrapod along the oldest dinosaur lineage which results in a broad

biostratigraphic Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Bio ...

correlation.Ezcurra, M. D., Montefeltro, F., & Butler, R. J. (2016). The Early Evolution of Rhynchosaurs. ''Front. Ecol'' Rhynchosaurs are archosauromorph

diapsid Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The group first appeared about three hundred million years a ...

s which is believed to ''

Trilophosaurus ''Trilophosaurus'' (Greek for "lizard with three ridges") is a lizard-like trilophosaurid allokotosaur known from the Late Triassic of North America. It was a herbivore up to 2.5 m long. It had a short, unusually heavily built skull, equipped wi ...

'', and sister group to

Prolacertiformes Protorosauria is an extinct polyphyletic group of archosauromorph reptiles from the latest Middle Permian ( Capitanian stage) to the end of the Late Triassic (Rhaetian stage) of Asia, Europe and North America. It was named by the English anatom ...

and Archosauria. A cladistic analysis of Rhynchosauria reveals that Hyperodapedontinae is a major subgroup of the late Triassic. ''

Stenaulorhynchus ''Stenaulorhynchus'' (possibly meaning "narrow tube beak") is an extinct genus of hyperodapedontid rhynchosaur known from the Middle Triassic (late Anisian stage) deposits of Tanganyika Territory, Tanzania. It was found in the Lifua Member of th ...

'' and ''Rhynchosaurus'' are close outgroups to Hyperdapedontinae during the middle Triassic. They share the synapomorphy of the dentary is well over half the length of the lower jaw. Rhynchosaurs were basal archosauromorphs that were herbivorous on dry land in Triassic Pangea. Some rare forms are ''

Mesosuchus ''Mesosuchus'' ("middle crocodile") is an extinct genus of basal Rhynchosaur from early Middle Triassic (early Anisian stage) deposits of Eastern Cape, South Africa. It is known from the holotype SAM 5882, a partial skeleton, and from the ...

'' and '' Howesia''. ''Hyperodapedon'' and ''Scaphonyx'' are included in the subfamily of Hyperodapedontinae.Huxley, T. (1869). On ''Hyperodapedon''. ''Quarterly Journal of the Geological Society,'' ''25'', 138–152. Hyperodapedontinae consist of ''Hyperodapedon huxleyi'' and ''Scaphonyx sulcognathus''.

Palaeoecology

''Hyperodapedon'' are commonly found in aeolian sand in Elgin, India, Brazil, and Argentina. They are a widely distributed tetrapod during the Upper Triassic and are present in locations where

phytosaur Phytosaurs (Φυτόσαυροι in greek) are an extinct group of large, mostly semiaquatic Late Triassic archosauriform reptiles. Phytosaurs belong to the order Phytosauria. Phytosauria and Phytosauridae are often considered to be equivalent g ...

s are absent. ''Hyperodapedon'' localities are found in the

Popo Agie Formation The Popo Agie Formation is a Triassic geologic formation that crops out in western Wyoming, western Colorado, and Utah. It was deposited during the Late Triassic in fluvial (river) and lacustrine (lake) environments that existed across much of ...

in Wyoming that dates to the Otischalkian. They are also found in Scotland in the

Lossiemouth Lossiemouth ( gd, Inbhir Losaidh) is a town in Moray, Scotland. Originally the port belonging to Elgin, it became an important fishing town. Although there has been over 1,000 years of settlement in the area, the present day town was formed over ...

Sandstone dating to the Adamanian, Maleri Formations in India,

Pebbly Arkose Formation The Pebbly Arkose Formation is a Late Triassic geologic formation found in southern Africa. Geology Description The formation comprises mainly coarse, arkosic sandstones. Extent The Pebbly Arkose Formation is found in Botswana, Zambia and ...

in Zimbabwe,

Ischigualasto Formation The Ischigualasto Formation is a Late Triassic fossiliferous formation and Lagerstätte in the Ischigualasto-Villa Unión Basin of the southwestern La Rioja Province and northeastern San Juan Province in northwestern Argentina. The formation ...

in Argentina, and

Santa Maria Formation The Santa Maria Formation is a sedimentary rock formation found in Rio Grande do Sul, Brazil. It is primarily Carnian in age (Late Triassic), and is notable for its fossils of cynodonts, "rauisuchian" pseudosuchians, and early dinosaurs and other ...

in Brazil that vary between Otischalkian and Adamanian.Lucas, S. G. (2002). The ''Hyperodapedon'' Biochron, Late Triassic of Pangea. ''Albertiana''. Similarly, ''

'' is found in fluvial-intertidal deposits with desiccation along with aeolian deposits with common flash floods.Benton, M. J. (1990). The Species of ''Rhynchosaurus'', A Rhynchosaur (Reptilia, Diapsida) from the Middle Triassic of England. ''Philosophical Transactions of the Royal Society B: Biological Sciences,'' ''328''(1247), 213–306. doi:10.1098/rstb.1990.0114

Distribution

Fossils of ''Hyperodapedon'' have been found in:''Hyperodapedon''
at Fossilworks.org *

, Argentina * Caturrita and

s, Brazil * Lower Maleri and Tiki Formations, India * Ruvuma, Tanzania *

Lossiemouth Sandstone The Lossiemouth Sandstone is a Middle to Late Triassic (Ladinian to Norian) age geological formation. It is exposed on the south side of the Moray Firth near Lossiemouth and near Golspie in Sutherland. Dinosaur remains are among the fossils th ...

, Scotland *

, United States *

, Zimbabwe

References

External links

* {{Taxonbar, from=Q134317 Rhynchosaurs Prehistoric reptile genera Carnian genera Late Triassic reptiles of Africa Fossils of Tanzania Fossils of Zimbabwe Late Triassic reptiles of Asia Fossils of India Late Triassic reptiles of Europe Triassic Scotland Fossils of Scotland Late Triassic reptiles of North America Triassic United States Fossils of the United States Paleontology in Wyoming Late Triassic reptiles of South America Triassic Argentina Fossils of Argentina Ischigualasto Formation Triassic Brazil Fossils of Brazil Santa Maria Formation Paraná Basin Fossil taxa described in 1859 Taxa named by Thomas Henry Huxley