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Lycorhinus
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Lycorhinus
Lycorhinus is a genus of heterodontosaurid ornithischian dinosaur that lived during the Early Jurassic, in the Sinemurian. It is known from a single species L. angustidens, that was named in 1924 by Sidney H. Haughton as a cynodont for a partial jaw found in the Upper Elliot Formation of South Africa. The genus name is derived from the Ancient Greek words for "wolf" and "nose". The limited material available, which has degraded over time to only be represented now by a single original tooth and the impression of the remaining jaw and teeth, has resulted in multiple different interpretations of the diagnostic nature and synonymy of Lycorhinus, including the treatmens of the type species of Heterodontosaurus, Abrictosaurus, and Lanasaurus as either species of Lycorhinus or synonyms. The latest review of Lycorhinus accepted the synonymy of Lanasaurus scalpridens, named in 1975 by Christopher Gow for a maxilla from Golden Gate Highlands National Park, with Lycorhinus angustidens, and also the referral of a partial skull found at the same locality as the original holotype decades later. Tentative specimens from the Clarens Formation have also been considered allied with Lycorhinus, but they may be better treated as remains of indeterminate heterodontosaurids.
Prior to 1914, Dr. Martin Ricono collected multiple specimens from the "Red Beds" of Paballong, Mount Fletcher district of South Africa, sending them to the South African Museum. Among this material was a lower jaw fragment identified and described in 1924 by Sidney H. Haughton as the holotype of a new cynodont, SAM 3606. This partial jaw showed a canine tooth and 11 molars (four as impressions), and the partial jaw bone supporting them. Only the inner side of the jaw could be seen because of the rock surrounding the specimen, but Haughton gave it the new binomial name Lycorhinus angustidens. From the same deposits within a 0.40 km (0.25 mi) Ricono and Alexander du Toit also collected material of the cynodont Tritheledon and thecodont Sphenosuchus. The genus name comes from the Ancient Greek words λύκος (lykos), meaning "wolf", and ῥῑνός (rhinos), meaning "nose".
Robert Broom revisited Lycorhinus in a 1932 review of South African early mammals, incorrectly identifying the type locality as Witkop near Burgersdorp. He noted that the original specimen is no longer in the same condition, with the jaw and all of the molars being lost and only remaining as an impression of the external surface within the bone; only the canine remained as original fossil. Broom had also mentioned the species "Lycorhinus parvidens" in passing in 1913 as a therocephalian from the Permian of South Africa, but this was a mistaken identity of Alopecorhinus parvidens. The identity of Lycorhinus as a cynodont was maintained until 1962, when Alfred Walter Crompton and Alan Jack Charig described the new Triassic ornithischian Heterodontosaurus, and reidentified Lycorhinus as well after being alerted to it by John Attridge.
The "Red Beds" of South Africa are now known as the Elliot Formation, with the locality of Paballong located at 30°26′S 28°31′E / 30.433°S 28.517°E and within the Upper Elliot Formation. Historically the entire Elliot Formation has been considered Triassic in age, but reevaluations of the fauna has resulted in the Upper Elliot Formation to be interpreted as Early Jurassic, which would make it one of few fossiliferous formations to span the End-Triassic mass extinction event. Uranium-lead dating done in 2020 confirmed that the Upper Elliot Formation spans approximately 10 million years of the Early Jurassic, from approximately the Triassic-Jurassic boundary 201.3 mya until at least the late Sinemurian 191.9 mya. The exact age of Lycorhinus is uncertain as its locality is approximate, but it is likely from the younger sediments of the Upper Elliot Formation.
A second significant specimen was referred to Lycorhinus by Richard Anthony Thulborn in 1962. This specimen was found by Kenneth Kermack at Paballong during a 1960-1961 expedition financed by the Royal Society, and became part of the collections of the University College London as specimen A.100. As it was from the same locality as the holotype of Lycorhinus, Thulborn gave it the designation of topotype, and noted that it was possible but unlikely that it came from the same individual as described by Haughton decades previously. UCL A.100 is fragmentary pieces of a skull, identified by Thulborn as including a partial premaxilla, maxilla, jugal, postorbital, frontal, nasal, and mandible with many teeth. From the similarities to Heterodontosaurus in the teeth and skull, Thulborn considered H. tucki to be referrable to Lycorhinus as the new combination Lycorhinus tucki, rendering Heterodontosaurus a junior synonym, separated by minor aspects of the tooth anatomy and geologic age. For Lycorhinus (including Heterodontosaurus), Thulborn gave the group name "lycorhinids" in 1971, though Heterodontosauridae had been named in 1966 by Oskar Kuhn and Alfred Sherwood Romer independently including Heterodontosaurus but not Lycorhinus.
In 1974 Thulborn named another species of Lycorhinus, L. consors. This species was founded upon UCL B54, found by Kermack and Frances Mussett during the 1963-1964 expedition of the UCL to Lesotho (then known as Basutoland) between the settlements of Whitehill and Qacha's Nek at the village of Noosi. The specimen was collected from a stream flowing north into the Orange River that is crossed at the village by the road from Whitehill to Qacha's Nek around 6.1 m (20 ft) below a small waterfall. These sediments form part of the top of the "Red Beds", but no finer stratigraphy could be determined. UCL B54 was the only known specimen and holotype of L. consors, preserving a partial skull and skeleton, though the quality of preservation of the skeleton meant further fossil preparation was required before it could be adequately described.
The synonymy of Lycorhinus and Heterodontosaurus, as well as their taxonomy, were contested by Crompton and Charig in 1974. They noted that regardless of synonymy, Heterodontosauridae would have priority over Lycorhinidae, and if they were members of Hypsilophodontidae the name Heterodontosaurinae would be appropriate. As the material of Heterodontosaurus is much better, it did not make sense to consider the two genera synonyms but the species separate, instead of retaining the genera as separate, so that the better material could remain diagnostic of a genus. Charig and Crompton found that UCL A.100 could not be considered the same species as Lycorhinus angustidens, weakening the synonymy of the genera, and instead supported that at least three separate heterodontosaurids were present in South Africa, all distinguished by anatomy of the lower jaws and teeth. Despite the differences between Heterodontosaurus tucki, UCL A.100, and Lycorhinus angustidens in the teeth, Charig and Crompton found the limited and poor material of the latter was insufficient to determine if it could be the same genera and thus considered Lycorhinus a nomen dubium.
James Hopson assessed the synonymy of Lycorhinus and Heterodontosaurus in 1975 using access to the original material of all the relevant species. The holotype of Lycorhinus preserved only the original canine in medial view within a chunk of mudstone, with the remaining teeth and jaw as an impression of the lateral surface. Though differences in the presence of denticles along the canine tooth were used to separate Lycorhinus and Heterodontosaurus, their absence in the former was determined to be the result of damage; originally they were present on both margins. The nature of wear on the tooth crowns and their replacement were also revised, supporting the separation of Lycorhinus angustidens from UCL A.100 as well as L. consors, for which Hopson gave the new genus name Abrictosaurus. The differences from Heterodontosaurus were also sufficient enough that Hopson considered Lycorhinus diagnostic rather than dubious, and that at least three genera of heterodontosaurids were present. UCL A.100 was provisionally referred to Abrictosaurus as their tooth anatomy were not distinct enough to justify separation, though canines are present in UCL A.100 and absent in UCL B54.
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Lycorhinus
Lycorhinus is a genus of heterodontosaurid ornithischian dinosaur that lived during the Early Jurassic, in the Sinemurian. It is known from a single species L. angustidens, that was named in 1924 by Sidney H. Haughton as a cynodont for a partial jaw found in the Upper Elliot Formation of South Africa. The genus name is derived from the Ancient Greek words for "wolf" and "nose". The limited material available, which has degraded over time to only be represented now by a single original tooth and the impression of the remaining jaw and teeth, has resulted in multiple different interpretations of the diagnostic nature and synonymy of Lycorhinus, including the treatmens of the type species of Heterodontosaurus, Abrictosaurus, and Lanasaurus as either species of Lycorhinus or synonyms. The latest review of Lycorhinus accepted the synonymy of Lanasaurus scalpridens, named in 1975 by Christopher Gow for a maxilla from Golden Gate Highlands National Park, with Lycorhinus angustidens, and also the referral of a partial skull found at the same locality as the original holotype decades later. Tentative specimens from the Clarens Formation have also been considered allied with Lycorhinus, but they may be better treated as remains of indeterminate heterodontosaurids.
Prior to 1914, Dr. Martin Ricono collected multiple specimens from the "Red Beds" of Paballong, Mount Fletcher district of South Africa, sending them to the South African Museum. Among this material was a lower jaw fragment identified and described in 1924 by Sidney H. Haughton as the holotype of a new cynodont, SAM 3606. This partial jaw showed a canine tooth and 11 molars (four as impressions), and the partial jaw bone supporting them. Only the inner side of the jaw could be seen because of the rock surrounding the specimen, but Haughton gave it the new binomial name Lycorhinus angustidens. From the same deposits within a 0.40 km (0.25 mi) Ricono and Alexander du Toit also collected material of the cynodont Tritheledon and thecodont Sphenosuchus. The genus name comes from the Ancient Greek words λύκος (lykos), meaning "wolf", and ῥῑνός (rhinos), meaning "nose".
Robert Broom revisited Lycorhinus in a 1932 review of South African early mammals, incorrectly identifying the type locality as Witkop near Burgersdorp. He noted that the original specimen is no longer in the same condition, with the jaw and all of the molars being lost and only remaining as an impression of the external surface within the bone; only the canine remained as original fossil. Broom had also mentioned the species "Lycorhinus parvidens" in passing in 1913 as a therocephalian from the Permian of South Africa, but this was a mistaken identity of Alopecorhinus parvidens. The identity of Lycorhinus as a cynodont was maintained until 1962, when Alfred Walter Crompton and Alan Jack Charig described the new Triassic ornithischian Heterodontosaurus, and reidentified Lycorhinus as well after being alerted to it by John Attridge.
The "Red Beds" of South Africa are now known as the Elliot Formation, with the locality of Paballong located at 30°26′S 28°31′E / 30.433°S 28.517°E and within the Upper Elliot Formation. Historically the entire Elliot Formation has been considered Triassic in age, but reevaluations of the fauna has resulted in the Upper Elliot Formation to be interpreted as Early Jurassic, which would make it one of few fossiliferous formations to span the End-Triassic mass extinction event. Uranium-lead dating done in 2020 confirmed that the Upper Elliot Formation spans approximately 10 million years of the Early Jurassic, from approximately the Triassic-Jurassic boundary 201.3 mya until at least the late Sinemurian 191.9 mya. The exact age of Lycorhinus is uncertain as its locality is approximate, but it is likely from the younger sediments of the Upper Elliot Formation.
A second significant specimen was referred to Lycorhinus by Richard Anthony Thulborn in 1962. This specimen was found by Kenneth Kermack at Paballong during a 1960-1961 expedition financed by the Royal Society, and became part of the collections of the University College London as specimen A.100. As it was from the same locality as the holotype of Lycorhinus, Thulborn gave it the designation of topotype, and noted that it was possible but unlikely that it came from the same individual as described by Haughton decades previously. UCL A.100 is fragmentary pieces of a skull, identified by Thulborn as including a partial premaxilla, maxilla, jugal, postorbital, frontal, nasal, and mandible with many teeth. From the similarities to Heterodontosaurus in the teeth and skull, Thulborn considered H. tucki to be referrable to Lycorhinus as the new combination Lycorhinus tucki, rendering Heterodontosaurus a junior synonym, separated by minor aspects of the tooth anatomy and geologic age. For Lycorhinus (including Heterodontosaurus), Thulborn gave the group name "lycorhinids" in 1971, though Heterodontosauridae had been named in 1966 by Oskar Kuhn and Alfred Sherwood Romer independently including Heterodontosaurus but not Lycorhinus.
In 1974 Thulborn named another species of Lycorhinus, L. consors. This species was founded upon UCL B54, found by Kermack and Frances Mussett during the 1963-1964 expedition of the UCL to Lesotho (then known as Basutoland) between the settlements of Whitehill and Qacha's Nek at the village of Noosi. The specimen was collected from a stream flowing north into the Orange River that is crossed at the village by the road from Whitehill to Qacha's Nek around 6.1 m (20 ft) below a small waterfall. These sediments form part of the top of the "Red Beds", but no finer stratigraphy could be determined. UCL B54 was the only known specimen and holotype of L. consors, preserving a partial skull and skeleton, though the quality of preservation of the skeleton meant further fossil preparation was required before it could be adequately described.
The synonymy of Lycorhinus and Heterodontosaurus, as well as their taxonomy, were contested by Crompton and Charig in 1974. They noted that regardless of synonymy, Heterodontosauridae would have priority over Lycorhinidae, and if they were members of Hypsilophodontidae the name Heterodontosaurinae would be appropriate. As the material of Heterodontosaurus is much better, it did not make sense to consider the two genera synonyms but the species separate, instead of retaining the genera as separate, so that the better material could remain diagnostic of a genus. Charig and Crompton found that UCL A.100 could not be considered the same species as Lycorhinus angustidens, weakening the synonymy of the genera, and instead supported that at least three separate heterodontosaurids were present in South Africa, all distinguished by anatomy of the lower jaws and teeth. Despite the differences between Heterodontosaurus tucki, UCL A.100, and Lycorhinus angustidens in the teeth, Charig and Crompton found the limited and poor material of the latter was insufficient to determine if it could be the same genera and thus considered Lycorhinus a nomen dubium.
James Hopson assessed the synonymy of Lycorhinus and Heterodontosaurus in 1975 using access to the original material of all the relevant species. The holotype of Lycorhinus preserved only the original canine in medial view within a chunk of mudstone, with the remaining teeth and jaw as an impression of the lateral surface. Though differences in the presence of denticles along the canine tooth were used to separate Lycorhinus and Heterodontosaurus, their absence in the former was determined to be the result of damage; originally they were present on both margins. The nature of wear on the tooth crowns and their replacement were also revised, supporting the separation of Lycorhinus angustidens from UCL A.100 as well as L. consors, for which Hopson gave the new genus name Abrictosaurus. The differences from Heterodontosaurus were also sufficient enough that Hopson considered Lycorhinus diagnostic rather than dubious, and that at least three genera of heterodontosaurids were present. UCL A.100 was provisionally referred to Abrictosaurus as their tooth anatomy were not distinct enough to justify separation, though canines are present in UCL A.100 and absent in UCL B54.
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