Tribodus
{{short description|Genus of hybodont shark from the Early Cretaceous period}}
{{Automatic taxobox
| fossil_range = {{fossilrange|Albian|Cenomanian}}
| taxon = Tribodus
| authority = Brito & Ferreira, 1989
| type_species = {{extinct}}Tribodus limae
| type_species_authority = Brito & Ferreira, 1989
| subdivision_ranks = Other species
| subdivision = *Tribodus morlati Landemaine, 1991
}}
Tribodus is an extinct genus of hybodont. It lived during the mid Cretaceous (Albian-Cenomanian) with fossils being known from northern South America, North Africa, and southern Europe.R. Vullo, D. Néraudeau [https://geojournals.pgi.gov.pl/agp/article/view/10011 When the “primitive” shark Tribodus (Hybodontiformes) meets the “modern” ray Pseudohypolophus (Rajiformes), the unique co-occurrence of these two durophagous Cretaceous selachians in Charentes (SW France)] Acta Geologica Polonica, 58 (2) (2008), pp. 249-255
Description
This genus is known from articulated and somewhat complete specimens of Tribodus limae from the Romualdo Formation, Açu Formation and Alcântara Formation of northeastern Brazil, making it one of the few hybodonts to be known from full body remains.{{cite journal|last1=Maisey|first1=J.G.|last2=Denton|first2=J.S.S.|year=2016|title=Dermal denticle patterning in the Cretaceous hybodont shark Tribodus limae (Euselachii, Hybodontiformes), and its implications for the evolution of patterning in the chondrichthyan dermal skeleton|journal=Journal of Vertebrate Paleontology|pages=e1179200-2|volume=36|issue=5|doi=10.1080/02724634.2016.1179200|bibcode=2016JVPal..36E9200M |doi-access=free}}{{Cite journal|last1=Lane|first1=Jennifer A.|last2=Maisey|first2=John G.|date=2012|title=The Visceral Skeleton and Jaw Suspension In the Durophagous Hybodontid Shark Tribodus limae from the Lower Cretaceous of Brazil|url=https://bioone.org/journals/Journal-of-Paleontology/volume-86/issue-5/11-139.1/The-Visceral-Skeleton-and-Jaw-Suspension-In-the-Durophagous-Hybodontid/10.1666/11-139.1.full|journal=Journal of Paleontology|volume=86|issue=5|pages=886–905|doi=10.1666/11-139.1|bibcode=2012JPal...86..886L |s2cid=86285896|issn=0022-3360}} Like other hybodonts, Tribodus had dorsal fin-spines and cephalic spines in male individuals. The skin of Tribodus had two distinct types of dermal denticles.{{Cite journal |last1=Maisey |first1=John G. |last2=Denton |first2=John S. S. |date=2016-09-02 |title=Dermal denticle patterning in the Cretaceous hybodont shark Tribodus limae (Euselachii, Hybodontiformes), and its implications for the evolution of patterning in the chondrichthyan dermal skeleton |journal=Journal of Vertebrate Paleontology |language=en |volume=36 |issue=5 |pages=e1179200 |doi=10.1080/02724634.2016.1179200 |bibcode=2016JVPal..36E9200M |s2cid=88591830 |issn=0272-4634|doi-access=free }} Tribodus limae reached a total length of about {{Convert|1|m|ft}}.{{Cite journal |last1=Vullo |first1=Romain |last2=Néraudeau |first2=Didier |last3=Dépré |first3=Eric |date=October 2013 |title=Vertebrate remains from the Cenomanian (Late Cretaceous) plant-bearing Lagerstätte of Puy-Puy (Charente-Maritime, France) |url=https://linkinghub.elsevier.com/retrieve/pii/S0195667113001043 |journal=Cretaceous Research |language=en |volume=45 |pages=314–320 |bibcode=2013CrRes..45..314V |doi=10.1016/j.cretres.2013.06.002}} The lower jaw was relatively short and did not extend to the snout region and articulated with the upper jaw at exclusively at the hyoid arch unlike other hybodonts, with a number of cartilage struts connecting the upper and lower jaws which enhanced jaw strength. The teeth of Tribodus were specialised for durophagy (consuming hard shelled organisms). They were small, less than {{Convert|5|mm|in|frac=32}} across and polygonal with a low cusp, and collectively formed a flat pavement that was effective at grinding, similar to those of living myliobatoid rays.{{Cite journal |last1=Benyoucef |first1=Madani |last2=Pérez-García |first2=Adán |last3=Bendella |first3=Mohamed |last4=Ortega |first4=Francisco |last5=Vullo |first5=Romain |last6=Bouchemla |first6=Imad |last7=Ferré |first7=Bruno |date=2022-07-06 |title=The "mid"-Cretaceous (Lower Cenomanian) Continental Vertebrates of Gara Samani, Algeria. Sedimentological Framework and Palaeodiversity |journal=Frontiers in Earth Science |volume=10 |doi=10.3389/feart.2022.927059 |bibcode=2022FrEaS..10.7059B |issn=2296-6463 |doi-access=free }} It is suggested to have been a benthic feeder, with shrimp being discovered as stomach contents in some specimens.
Species of Tribodus have been found in shallow marine as well as fluvial and deltaic environments. It may have spawned in shallow-water vegetated areas.
Classification
Its placement within the Hybodontiformes is uncertain. Historically it has been asserted to be a member of the family Acrodontidae with other durophagous hybodonts, based on the presence of columnar osteodentine in its teeth. However, other authors have suggested that it should instead be placed in the family Distobatidae due the morphology of its teeth closely resembling members of that family.{{Cite journal |last1=Stumpf |first1=Sebastian |last2=López-Romero |first2=Faviel A. |last3=Kindlimann |first3=René |last4=Lacombat |first4=Frederic |last5=Pohl |first5=Burkhard |last6=Kriwet |first6=Jürgen |date=August 2021 |editor-last=Cavin |editor-first=Lionel |title=A unique hybodontiform skeleton provides novel insights into Mesozoic chondrichthyan life |journal=Papers in Palaeontology |language=en |volume=7 |issue=3 |pages=1479–1505 |doi=10.1002/spp2.1350 |issn=2056-2799 |doi-access=free|bibcode=2021PPal....7.1479S }}
References
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Category:Cretaceous cartilaginous fish
Category:Prehistoric fish of South America
Category:Early Cretaceous animals of South America
Category:Fish described in 1989
Category:Taxa named by Alberto Brito
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