Lonchidion

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Lonchidion
Temporal range: Middle Triassic to Late Cretaceous
Ladinian–Maastrichtian
Teeth of an indeterminate species from the Tendaguru Formation
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Order: †Hybodontiformes
Family: †Lonchidiidae
Genus: †Lonchidion
Estes, 1964

Lonchidion is a genus of extinct hybodont in the family Lonchidiidae. The genus first appears in the fossil record during the Middle Triassic (Ladinian)[1] and was among the last surviving hybodont genera, with its youngest known fossils dating to the very end of the Cretaceous (Maastrichtian).[2]

Lonchidion was first described by Richard Estes in 1964, and the type species is L. selachas. Fossils of Lonchidion have been found worldwide. The genus has been proposed to be euryhaline, and is often found in freshwater and brackish deposits.[3] Hybodont egg cases (Palaeoxyris) associated with juvenile teeth of L. ferganensis in the Triassic lake deposits of the Madygen Formation of Kyrgyzstan suggests that this species spawned in freshwater environments,[4] with Palaeoxyris egg cases found in freshwater deposits of the Late Triassic Chinle Formation in North America suggested to have been produced by Lonchidion humblei.[5]

While the genus is primarily known from teeth, a preserved body impression of a subadult individual is known from the Early Cretaceous freshwater Las Hoyas site in Spain. This specimen is among the smallest known elasmobranchs, at around 3.5 centimetres (1.4 in) in length.[6] Other possible body remains of Lonchidion have been reported from other Early Cretaceous sites in Spain.[7][8] Lonchidion humblei is suggested to have reached an adult length of 25 centimetres (9.8 in).[9]

The teeth of the genus are low crowned, and probably served to grind hard prey (durophagy).[10]

Species[edit]

  • Lonchidion anitae Thurmond, 1971
  • Lonchidion breve Patterson, 1966
  • Lonchidion crenulatum Patterson, 1966
  • Lonchidion humblei Murry, 1981[11]
  • Lonchidion indicus Yadagiri, 1986
  • Lonchidion inflexum Underwood & Rees, 2002
  • Lonchidion microselachos Estes & Sanchíz, 1982
  • Lonchidion selachas Estes, 1964
  • Lonchidion selachos Estes, 1964
  • Lonchidion striatum Patterson, 1966
  • Lonchidion ferganensis Fischer et al., 2011

References[edit]

  1. ^ Johns, Marjorie J.; Albanesi, Guillermo L.; Voldman, Gustavo G. (2014-04-16). "Freshwater shark teeth (Family Lonchidiidae) from the Middle-Upper Triassic (Ladinian-Carnian) Paramillo Formation in the Mendoza Precordillera, Argentina". Journal of Vertebrate Paleontology. 34 (3): 512–523. doi:10.1080/02724634.2013.803976. hdl:11336/32116. ISSN 0272-4634.
  2. ^ Gates, Terry A.; Gorscak, Eric; Makovicky, Peter J. (May 2019). "New sharks and other chondrichthyans from the latest Maastrichtian (Late Cretaceous) of North America". Journal of Paleontology. 93 (3): 512–530. doi:10.1017/jpa.2018.92. ISSN 0022-3360.
  3. ^ Manzanares, Esther; Pla, Cristina; Martínez-Pérez, Carlos; Ferrón, Humberto; Botella, Héctor (2017-01-02). "Lonchidion derenzii , sp. nov., a new lonchidiid shark (Chondrichthyes, Hybodontiforms) from the Upper Triassic of Spain, with remarks on lonchidiid enameloid". Journal of Vertebrate Paleontology. 37 (1): e1253585. doi:10.1080/02724634.2017.1253585. hdl:10550/85565. ISSN 0272-4634.
  4. ^ Jan Fischer, Sebastian Voigt, Jörg W. Schneider, Michael Buchwitz and Silke Voigt (2011). "A selachian freshwater fauna from the Triassic of Kyrgyzstan and its implication for Mesozoic shark nurseries". Journal of Vertebrate Paleontology 31 (5): 937–953. doi:10.1080/02724634.2011.601729.
  5. ^ Fischer, Jan; Axsmith, Brian J.; Ash, Sidney R. (2010-03-01). "First unequivocal record of the hybodont shark egg capsule Palaeoxyris in the Mesozoic of North America". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 255 (3): 327–344. doi:10.1127/0077-7749/2009/0028. ISSN 0077-7749.
  6. ^ Marugán-Lobón, Jesús; Martín-Abad, Hugo; Buscalioni, Ángela D. (2023-05-05). "The Las Hoyas Lagerstätte: a palaeontological view of an Early Cretaceous wetland". Journal of the Geological Society. 180 (3). doi:10.1144/jgs2022-079. hdl:10486/710760. ISSN 0016-7649.
  7. ^ GOMEZ-PALLEROLA, J. E. 1985. Nuevos Hybodóntidos del Cretácico Inferior de Santa María de Meyá (Lérida) [New Hybodontids from the Early Cretaceous of Santa María de Meyá (Lérida)]. Boletin Geologico y Minero, 96(4):372–380.
  8. ^ GOMEZ-PALLEROLA, J. E. 1992. Nota sobre los tiburones hybodontos de las calizas litográficas del Cretácico Inferior del Montsec (Lérida). [Note on hybodont sharks from the Lower Cretaceous lithographic limestones of Montsec (Lérida)] Boletin Geologico y Minero, 103:3–33.
  9. ^ Vullo, Romain; Néraudeau, Didier; Dépré, Eric (October 2013). "Vertebrate remains from the Cenomanian (Late Cretaceous) plant-bearing Lagerstätte of Puy-Puy (Charente-Maritime, France)". Cretaceous Research. 45: 314–320. doi:10.1016/j.cretres.2013.06.002.
  10. ^ Bermúdez-Rochas, David Didier (November 2009). "New hybodont shark assemblage from the Early Cretaceous of the Basque-Cantabrian Basin". Geobios. 42 (6): 675–686. doi:10.1016/j.geobios.2009.06.004.
  11. ^ A New Species of Freshwater Hybodont from the Dockum Group (Triassic) of Texas Phillip A. Murry. Journal of Paleontology, Vol. 55, No. 3 (May, 1981), pp. 603-607

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