Lycorhinus

Lycorhinus is a genus of heterodontosaurid ornithischian dinosaur hailing from the Early Jurassic (Hettangian to Sinemurian ages) strata of the Elliot Formation located in the Cape Province, South Africa.

Lycorhinus
Temporal range: Early Jurassic, 197 Ma
Lycorhinus
Cast of holotype UCRC PVC10
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Family: Heterodontosauridae
Subfamily: Heterodontosaurinae
Genus: Lycorhinus
Haughton, 1924
Type species
Lycorhinus angustidens
Haughton, 1924
Synonyms
  • Lanasaurus Gow, 1975

Description

Lycorhinus angustidens
Mandible end

Lycorhinus, including the remains described by Gow in 1975 as Lanasaurus, is a small (1.2 metres (47 in) in length) herbivorous dinosaur despite the long canines it sported in its jaws.

History of discovery

The fossil material consists of dentaries and maxillae, hence the characters mentioned by the name Lycorhinus angustidens that Sidney H. Haughton attributed to the remains in 1924, where the generic name means "wolf snout", as it was at first misidentified as a cynodont, and the specific descriptor means "constricted tooth".[1]

The holotype, SAM 3606, consists of a mandible found by Dr M. Ricono. Three other species of Lycorhinus have been named. Lycorhinus parvidens was created by Robert Broom and Lycorhinus tucki by Richard Anthony Thulborn in 1970 renaming Heterodontosaurus tucki,[2] but these have failed to find recognition.[3] Lycorhinus consors, named by Thulborn in 1974, was renamed Abrictosaurus by James Hopson in 1975.[4]

Lanasaurus

The type and only species of Lanasaurus is L. scalpridens, described by Christopher Gow in 1975 from the same horizon as Lycorhinus. The generic name is derived from Latin lana, "wool" and Greek saurus, "lizard", and honours Professor Alfred Walter Crompton, nicknamed "Fuzz" because of his woolly hair. The specific name is derived from Latin scalprum, "chisel", and dens, "tooth". It is based on a partial upper jaw bone, the maxilla, holotype BP/1/4244, found in the Upper Elliot Formation of Free State. The teeth show a typical replacement pattern in which during each replacement cycle every third tooth is renewed.[5]

Gow himself in 1990 concluded that the holotype of Lanasaurus was actually a specimen of Lycorhinus angustidens.[6] This has been commonly accepted since.[7][8][9][10]

Classification

L. angustidens is thought to be allied to Heterodontosaurus. Only in 1962 Alfred Walter Crompton recognised it was an ornithischian dinosaur. Thulborn in 1971 created a separate Lycorhinidae[11] but this group was in 1972 equated with Heterodontosauridae by Peter Galton.

References

  1. ^ S.H. Haughton, 1924, "The fauna and stratigraphy of the Stormberg Series", Annals of the South African Museum 12: 323-497
  2. ^ R.A. Thulborn, 1970, "The systematic position of the Triassic ornithischian dinosaur Lycorhinus angustidens", Zoological Journal of the Linnean Society 49: 235-245
  3. ^ Charig, A.J. and Crompton, A.W., 1974, "The alleged synonymy of Lycorhinus and Heterodontosaurus", Annals of the South African Museum 64: 167-89
  4. ^ J.A. Hopson, 1975, "On the generic separation of the ornithischian dinosaurs Lycorhinus and Heterodontosaurus from the Stormberg Series (Upper Triassic) of South Africa", South African Journal of Science 71: 302-305
  5. ^ C.E. Gow, 1975, "A new heterodontosaurid from the Redbeds of South Africa showing clear evidence of tooth replacement", Zoological Journal of the Linnean Society 57: 335-339
  6. ^ Gow, C.E., 1990, "A tooth-bearing maxilla referable to Lycorhinus angustidens Haughton, 1924 (Dinosauria, Ornithischia)", Annals of the South African Museum 99: 367–380
  7. ^ Norman, D.B., Sues, H.D., Witmer, L.M. and Coria, R.A.. (2004). "Basal Ornithopoda". In D. B. Weishampel, H. Osmólska, and P. Dodson (eds.), The Dinosauria (2nd edition). University of California Press, Berkeley 393-412
  8. ^ Butler, Richard J.; Galton, Peter M.; Porro, Laura B.; Chiappe, Luis M.; Henderson, D. M.; Erickson, Gregory M. (2010). "Lower limits of ornithischian dinosaur body size inferred from a new Upper Jurassic heterodontosaurid from North America" (PDF). Proceedings of the Royal Society B. 277 (1680): 375–381. doi:10.1098/rspb.2009.1494. PMC 2842649. PMID 19846460.
  9. ^ Pol, D.; Rauhut, O.W.M.; Becerra, M. (2011). "A Middle Jurassic heterodontosaurid dinosaur from Patagonia and the evolution of heterodontosaurids". Naturwissenschaften. 98 (5): 369–379. Bibcode:2011NW.....98..369P. doi:10.1007/s00114-011-0780-5. PMID 21452054.
  10. ^ Richard J. Butler, Jin Liyong, Chen Jun, Pascal Godefroit (2011). "The postcranial osteology and phylogenetic position of the small ornithischian dinosaur Changchunsaurus parvus from the Quantou Formation (Cretaceous: Aptian–Cenomanian) of Jilin Province, north-eastern China". Palaeontology. 54 (3): 667–683. doi:10.1111/j.1475-4983.2011.01046.x.CS1 maint: Multiple names: authors list (link)
  11. ^ R.A. Thulborn, 1971, "Origins and evolution of ornithischian dinosaurs", Nature 234(5324): 75-78
Abrictosaurus

Abrictosaurus (; "wakeful lizard") is a genus of heterodontosaurid dinosaur from the Early Jurassic Period of what is now southern Africa. It was a small bipedal herbivore or omnivore, approximately 1.2 meters (4 feet) long, and weighing less than 45 kilograms (100 pounds).

This dinosaur is known from the fossil remains of only two individuals, found in the Upper Elliot Formation of Qacha's Nek District in Lesotho and Cape Province in South Africa. The Upper Elliot is thought to date from the Hettangian and Sinemurian stages of the Early Jurassic Period, approximately 200 to 190 million years ago. This formation is thought to preserve sand dunes as well as seasonal floodplains, in a semiarid environment with sporadic rainfall. Other dinosaurs found in this formation include the theropod Megapnosaurus, the sauropodomorph Massospondylus, as well as other heterodontosaurids like Heterodontosaurus and Lycorhinus. Remains of terrestrial crocodylomorphs, cynodonts and early mammals are also abundant.

Averostra

Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs that have a promaxillary fenestra (fenestra promaxillaris), an extra opening in the front outer side of the maxilla, the bone that makes up the upper jaw. Two groups of averostrans, the Ceratosauria and the Orionides, survived into the Cretaceous period. When the Cretaceous–Paleogene extinction event occurred, ceratosaurians and two groups of orionideans within the clade Coelurosauria, the Tyrannosauroidea and Maniraptoriformes, were still extant. Only one subgroup of maniraptoriformes, Aves, survived the extinction event and persisted to the present day.

Avetheropoda

Avetheropoda, or "bird theropods", is a clade that includes carnosaurians and coelurosaurs to the exclusion of other dinosaurs.

Cerapoda

Cerapoda ("ceratopsians and ornithopods") is a clade of the dinosaur order Ornithischia.

Dinosauriformes

Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs and a partially to fully perforated acetabulum, the hole in the hip socket traditionally used to define dinosaurs. The oldest known member is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic period.

Echinodon

Echinodon (pronounced eh-KY-no-don) meaning "hedgehog tooth" in reference to the spines on its teeth (Ancient Greek: εχινος, romanized: echinos, lit. 'hedgehog', + ὀδών, odṓn, 'tooth'), occasionally known as Saurechinodon, is a genus of small European dinosaur of the early Cretaceous Period (Berriasian age), 140 million years ago.

Fruitadens

Fruitadens is a genus of heterodontosaurid dinosaur. The name means "Fruita tooth", in reference to Fruita, Colorado (USA), where its fossils were first found. It is known from partial skulls and skeletons from at least four individuals of differing biological ages, found in Tithonian (Late Jurassic) rocks of the Morrison Formation in Colorado. Fruitadens is the smallest known ornithischian dinosaur, with young adults estimated at 65 to 75 cm (26 to 30 in) in length and 0.5 to 0.75 kg (1.1 to 1.7 lb) in weight. It is interpreted as an omnivore and represents one of the latest-surviving heterodontosaurids.

Heterodontosauridae

Heterodontosauridae is a family of early ornithischian dinosaurs that were likely among the most basal (primitive) members of the group. Although their fossils are relatively rare and their group small in numbers, they lived across all continents except Australia for approximately 100 million years, from the Late Triassic to the Early Cretaceous.

Heterodontosaurids were fox-sized dinosaurs less than 2 metres (6.6 feet) in length, including a long tail. They are known mainly for their characteristic teeth, including enlarged canine-like tusks and cheek teeth adapted for chewing, analogous to those of Cretaceous hadrosaurids. Their diet was herbivorous or possibly omnivorous.

Heterodontosaurinae

Heterodontosaurinae is an extinct subfamily of heterodontosaurid ornithischian dinosaurs from the earliest to the mid Middle Jurassic (Hettangian - Bajocian) of Africa and South America. Currently, the basalmost known heterodontosaurine is Lycorhinus angustidens from the Early Jurassic of Cape Province, South Africa. Heterodontosaurines are small-bodied ornithischians characterized by their cheek tooth crowns that are taller than wide, and jaw joint set below the axis of occlusion between maxillary and dentary teeth. Heterodontosaurinae was implicitly named in 1966 by Oskar Kuhn as he is the author of the family Heterodontosauridae. It is a stem-based taxon defined phylogenetically for the first time by Paul Sereno in 2012 as "the most inclusive clade containing Heterodontosaurus tucki Crompton and Charig 1962 but not Tianyulong confuciusi Zheng et al. 2009, Fruitadens haagarorum Butler et al. 2010, Echinodon becklesii Owen 1861."

Heterodontosaurus

Heterodontosaurus is a genus of heterodontosaurid dinosaur that lived during the Early Jurassic, 200–190 million years ago. Its only known member species, Heterodontosaurus tucki, was named in 1962 based on a skull discovered in South Africa. The genus name means "different toothed lizard", in reference to its unusual, heterodont dentition; the specific name honors G. C. Tuck, who supported the discoverers. Further specimens have since been found, including an almost complete skeleton in 1966.

Though it was a small dinosaur, Heterodontosaurus was one of the largest members of its family, reaching between 1.18 m (3 ft 10 in) and possibly 1.75 m (5 ft 9 in) in length, and weighing between 2 and 10 kg (4.4 and 22.0 lb). The body was short with a long tail. The five-fingered forelimbs were long and relatively robust, whereas the hind-limbs were long, slender, and had four toes. The skull was elongated, narrow, and triangular when viewed from the side. The front of the jaws were covered in a horny beak. It had three types of teeth; in the upper jaw, small, incisor-like teeth were followed by long, canine-like tusks. A gap divided the tusks from the chisel-like cheek-teeth.

Heterodontosaurus is the eponymous and best-known member of the family Heterodontosauridae. This family is considered one of the most primitive or basal groups within the order of ornithischian dinosaurs. In spite of the large tusks, Heterodontosaurus is thought to have been herbivorous, or at least omnivorous. Though it was formerly thought to have been capable of quadrupedal locomotion, it is now thought to have been bipedal. Tooth replacement was sporadic and not continuous, unlike its relatives. At least four other heterodontosaurid genera are known from the same geological formations as Heterodontosaurus.

Jeholosauridae

Jeholosaurids were herbivorous neornithischian dinosaurs from the Cretaceous Period (Aptian - Santonian, with a possible Campanian record) of Asia. The family was first proposed by Han et al. in 2012. The jeholosaurids were defined as those ornithischians more closely related to Jeholosaurus shangyuanensis than to Hypsilophodon foxii, Iguanodon bernissartensis, Protoceratops andrewsi, Pachycephalosaurus wyomingensis, or Thescelosaurus neglectus. The Jeholosauridae includes the type genus Jeholosaurus and Yueosaurus.

Jingshanosaurus

Jingshanosaurus (meaning "Jingshan lizard") is a genus of sauropodomorph dinosaurs from the early Jurassic period.

Manidens

Manidens is a genus of heterodontosaurid dinosaur from the Middle Jurassic of Patagonia. Fossils have been found in the Cañadón Asfalto Formation in Chubut Province, Argentina, dating to the Bajocian.

Neotheropoda

Neotheropoda (meaning "new theropods") is a clade that includes coelophysoids and more advanced theropod dinosaurs, and the only group of theropods who survived the Triassic–Jurassic extinction event. Yet all of the neotheropods became extinct during the early Jurassic period except for Averostra.

Orionides

Orionides is a clade of tetanuran theropod dinosaurs from the Middle Jurassic to the Present. The clade includes most theropod dinosaurs, including birds.

Orodrominae

Orodrominae is a subfamily of parksosaurid dinosaurs from the Cretaceous of North America and Asia.

Riojasauridae

Riojasauridae is a family of sauropod-like dinosaurs from the Upper Triassic. It is known primarily from the genera Riojasaurus and Eucnemesaurus. Sites containing Riojasauridae include the Lower Elliot Formation of Orange Free State, South Africa (where fossils of Eucnemesaurus have been found), and Ischigualasto, in La Rioja Province, Argentina ( where fossils of Riojasaurus have been recovered).

Tianyulong

Tianyulong (Chinese: 天宇龍; Pinyin: tiānyǔlóng; named for the Shandong Tianyu Museum of Nature where the holotype fossil is housed) was a genus of heterodontosaurid ornithischian dinosaur. The only species was T. confuciusi, whose remains were discovered in Jianchang County, Western Liaoning Province, China.

Xixiposaurus

Xixiposaurus is a genus of prosauropod dinosaur which existed in what is now Lower Lufeng Formation, China during the lower Jurassic period. It was first named by Sekiya Toru in 2010 and the type species is Xixiposaurus suni.

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