Rees & Underwood (2002) found that Paleozoic material referred to the genus Lissodus should be assigned to two separate genera which they left unnamed. They assigned 'Lissodus' wirksworthensis from southern England, 'Lissodus' pectinatus from western Russia and 'Lissodus' sp. from central Russia to 'Palaeozoic Genus 2'.[2] The genus Reesodus was erected in 2013 as a replacement name for 'Palaeozoic Genus 2', with the newly described Reesodus underwoodi from the Khuff Formation of Oman as the type species. Though the known material is identified as belonging to a hybodontiform, Reesodus cannot be confidently assigned to any family (though it is assumed to be close to Lonchidiidae) as the heterodonty pattern and the possible presence of enlarged lateral teeth cannot be assessed, thus it is listed as Hybodontiformesincertae sedis.[1]
Speciesedit
Currently, the following species have been assigned to the genus Reesodus:
The type species, Reesodus underwoodi, is known from 6 complete teeth collected from the Guadalupian-aged Khuff Formation of Oman. The specific name honors Charlie Underwood, who worked on the taxonomy of Lissodus and recognized the Paleozoic specimens to represent separate genera. Teeth of this species always have a triangular labial peg and a lingual peg, and sometimes two accessory nodes. The crown shoulder has a horizontal rim and acute longitudinal crest. The teeth are small and symmetrical, measuring 0.4–0.5 mm high.[1]
Originally described in 1985 as Lissodus wirksworthensis, Reesodus wirksworthensis is known from fossilized teeth found in the Early Carboniferous-aged Eyam Limestone of Derbyshire, England. Its teeth measure 0.75 mm in height and 2 mm mesiodistally, with a longitudinal ridge on the crown shoulder and a moderate labial peg. The basal root has many foramina and is well-developed, reaching a height of 0.35 mm.[3][4]
Reesodus pectinatus was originally described in 1996 as Lissodus pectinatus, but has since been recognized to belong in this separate genus. It is known from teeth collected in Tournaisian-Viséan deposits in western Russia.[5]
Descriptionedit
Reesodus is known from fossil teeth characterized in having a mesio-distally expanded crown with a low profile, as many as 4 lateral cusplets and a very strong crown shoulder. These teeth may be ornamented with varying amounts and density of coarse folds. The labial peg is moderately or well-developed, often accompanied by protuberances near the base of the lateral cusplets and/or a labial root buttress. Compared to those of other hybodonts, the tooth roots of Reesodus are less porous.[1][2]
Referencesedit
^ abcdKoot, Martha B.; Cuny, Gilles; Tintori, Andrea; Twitchett, Richard J. (2013-03-13). "A new diverse shark fauna from the Wordian (Middle Permian) Khuff Formation in the interior Haushi-Huqf area, Sultanate of Oman: CHONDRICHTHYANS FROM THE WORDIAN KHUFF FORMATION OF OMAN". Palaeontology. 56 (2): 303–343. doi:10.1111/j.1475-4983.2012.01199.x. S2CID 86428264.
^ abRees, Jan; Underwood, Charlie J. (2002-09-19). "The status of the shark genus Lissodus Brough, 1935, and the position of nominal Lissodus species within the Hybodontoidea (Selachii)". Journal of Vertebrate Paleontology. 22 (3): 471–479. doi:10.1671/0272-4634(2002)022[0471:TSOTSG]2.0.CO;2. ISSN 0272-4634. S2CID 13836075.
^Smith, Roy; Martill, David M.; Duffin, Christopher (2017-06-01). "The shark-beds of the Eyam Limestone Formation (Lower Carboniferous, Viséan) of Steeplehouse Quarry, Wirksworth, Derbyshire, UK". Proceedings of the Geologists' Association. 128 (3): 374–400. doi:10.1016/j.pgeola.2017.04.004. ISSN 0016-7878.
^Duffin, C. (1985). "Revision of the hybodont selachian genus Lissodus BROUGH (1935)". Palaeontographica Abteilung A-palaozoologie-stratigraphie. S2CID 233061921.
^Lebedev, O. A. (January 1996). "Fish assemblages in the Tournaisian-Viséan environments of the East European Platform". Geological Society, London, Special Publications. 107 (1): 387–415. doi:10.1144/GSL.SP.1996.107.01.28. ISSN 0305-8719. S2CID 129309437.
February 09, 2024
reesodus, extinct, genus, hybodontiform, lived, from, tournaisian, early, carboniferous, wordian, permian, remains, have, been, found, england, russia, oman, generic, name, honors, rees, first, realized, that, fossils, belong, distinct, genus, temporal, range,. Reesodus is an extinct genus of hybodontiform It lived from the Tournaisian age of the Early Carboniferous to the Wordian age of the Permian and remains have been found in England Russia and Oman The generic name honors Jan Rees who first realized that the fossils belong to a distinct genus 1 ReesodusTemporal range Tournaisian Wordian PreꞒ Ꞓ O S D C P T J K Pg NScientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataClass ChondrichthyesSubclass ElasmobranchiiOrder HybodontiformesGenus ReesodusKoot Cuny Tintori amp Twitchett 2013Type speciesReesodus underwoodiKoot Cuny Tintori amp Twitchett 2013SpeciesR pectinatus Lebedev 1996 R underwoodi Koot Cuny Tintori amp Twitchett 2013 R wirksworthensis Duffin 1985 Contents 1 Taxonomy 1 1 Species 2 Description 3 ReferencesTaxonomy editRees amp Underwood 2002 found that Paleozoic material referred to the genus Lissodus should be assigned to two separate genera which they left unnamed They assigned Lissodus wirksworthensis from southern England Lissodus pectinatus from western Russia and Lissodus sp from central Russia to Palaeozoic Genus 2 2 The genus Reesodus was erected in 2013 as a replacement name for Palaeozoic Genus 2 with the newly described Reesodus underwoodi from the Khuff Formation of Oman as the type species Though the known material is identified as belonging to a hybodontiform Reesodus cannot be confidently assigned to any family though it is assumed to be close to Lonchidiidae as the heterodonty pattern and the possible presence of enlarged lateral teeth cannot be assessed thus it is listed as Hybodontiformes incertae sedis 1 Species edit Currently the following species have been assigned to the genus Reesodus The type species Reesodus underwoodi is known from 6 complete teeth collected from the Guadalupian aged Khuff Formation of Oman The specific name honors Charlie Underwood who worked on the taxonomy of Lissodus and recognized the Paleozoic specimens to represent separate genera Teeth of this species always have a triangular labial peg and a lingual peg and sometimes two accessory nodes The crown shoulder has a horizontal rim and acute longitudinal crest The teeth are small and symmetrical measuring 0 4 0 5 mm high 1 Originally described in 1985 as Lissodus wirksworthensis Reesodus wirksworthensis is known from fossilized teeth found in the Early Carboniferous aged Eyam Limestone of Derbyshire England Its teeth measure 0 75 mm in height and 2 mm mesiodistally with a longitudinal ridge on the crown shoulder and a moderate labial peg The basal root has many foramina and is well developed reaching a height of 0 35 mm 3 4 Reesodus pectinatus was originally described in 1996 as Lissodus pectinatus but has since been recognized to belong in this separate genus It is known from teeth collected in Tournaisian Visean deposits in western Russia 5 Description editReesodus is known from fossil teeth characterized in having a mesio distally expanded crown with a low profile as many as 4 lateral cusplets and a very strong crown shoulder These teeth may be ornamented with varying amounts and density of coarse folds The labial peg is moderately or well developed often accompanied by protuberances near the base of the lateral cusplets and or a labial root buttress Compared to those of other hybodonts the tooth roots of Reesodus are less porous 1 2 References edit a b c d Koot Martha B Cuny Gilles Tintori Andrea Twitchett Richard J 2013 03 13 A new diverse shark fauna from the Wordian Middle Permian Khuff Formation in the interior Haushi Huqf area Sultanate of Oman CHONDRICHTHYANS FROM THE WORDIAN KHUFF FORMATION OF OMAN Palaeontology 56 2 303 343 doi 10 1111 j 1475 4983 2012 01199 x S2CID 86428264 a b Rees Jan Underwood Charlie J 2002 09 19 The status of the shark genus Lissodus Brough 1935 and the position of nominal Lissodus species within the Hybodontoidea Selachii Journal of Vertebrate Paleontology 22 3 471 479 doi 10 1671 0272 4634 2002 022 0471 TSOTSG 2 0 CO 2 ISSN 0272 4634 S2CID 13836075 Smith Roy Martill David M Duffin Christopher 2017 06 01 The shark beds of the Eyam Limestone Formation Lower Carboniferous Visean of Steeplehouse Quarry Wirksworth Derbyshire UK Proceedings of the Geologists Association 128 3 374 400 doi 10 1016 j pgeola 2017 04 004 ISSN 0016 7878 Duffin C 1985 Revision of the hybodont selachian genus Lissodus BROUGH 1935 Palaeontographica Abteilung A palaozoologie stratigraphie S2CID 233061921 Lebedev O A January 1996 Fish assemblages in the Tournaisian Visean environments of the East European Platform Geological Society London Special Publications 107 1 387 415 doi 10 1144 GSL SP 1996 107 01 28 ISSN 0305 8719 S2CID 129309437 Retrieved from https en wikipedia org w index php title Reesodus amp oldid 1195936633, wikipedia, wiki, book, books, library,
