View source for Jakapil

{{Short description|Extinct genus of dinosaurs}}
{{Speciesbox
| fossil_range = [[Late Cretaceous]], [[Cenomanian]]<br>{{fossilrange|97|94}}
| image = Jakapil skeletal.webp
| image_caption = Skeletal diagram showing known fossil material
| parent_authority = Riguetti, Apesteguía & Pereda-Suberbiola, 2022
| genus = Jakapil
| species = kaniukura
| authority = Riguetti, Apesteguía & Pereda-Suberbiola, 2022
}}
'''''Jakapil''''' (meaning "shield bearer" in [[Tehuelche language|Puelchean]]) is a genus of basal [[thyreophoran]] dinosaur from the [[Candeleros Formation]] of Argentina. The type species is '''''Jakapil kaniukura'''''.<ref name=Jakapil>{{cite journal| vauthors = Riguetti FJ, Apesteguía S, Pereda-Suberbiola X |title=A new Cretaceous thyreophoran from Patagonia supports a South American lineage of armoured dinosaurs |year=2022 |journal=Scientific Reports |volume=12 |issue=1 |pages=Article number 11621 |doi=10.1038/s41598-022-15535-6 |pmid=35953515 |pmc=9372066 |bibcode=2022NatSR..1211621R | doi-access = free }}</ref>
== Discovery and naming ==
The [[holotype]], '''MPCA-PV-630''', is a partial skeleton including several [[Osteoderm|osteoderms]] and a complete lower jaw, which were found on land owned by the Mariluan family in 2012 and excavated between 2014 and 2019/2020. The finds were prepared by L. Pazo and J. Kaluza. The [[Genus|generic name]], "''Jakapil''", is derived from "Ja-Kapïl", a [[Puelche language|Puelchean]] word meaning "shield bearer". This is also the literal meaning of the clade name [[Thyreophora]]. The [[Specific name (zoology)|specific name]], "''kaniukura''", means "crest stone" in [[Mapudungun]], in reference to its uniquely deep jaw.<ref name=Jakapil/>
== Description ==
[[File:Jakapil Size Comparison.svg|thumb|Size of ''Jakapil'' compared to a human]]
''Jakapil'' represents a novel morphotype among thyreophorans, including, among other things, the presence of a [[predentary]] bone (absent or cartilaginous in other basal thyreophorans),<ref name="Norman2019Cranium">{{Cite journal|last=Norman|first=David B.|date=2020|title=''Scelidosaurus harrisonii'' from the Early Jurassic of Dorset, England: cranial anatomy|journal=Zoological Journal of the Linnean Society|volume=188|issue=1|pages=1–81|doi=10.1093/zoolinnean/zlz074}}</ref> large, low osteoderms, and a bipedal stance, similar to ''[[Scutellosaurus]]''. Its describers estimate it to be less than {{convert|1.5|m|ft}} long and {{convert|4.5|-|7|kg|lb}} in weight, based on femoral circumference. While the holotype remains do not represent a juvenile individual, it was likely not fully grown and may not have been sexually mature.<ref name=Jakapil />
== Classification ==
Due to a combination of features seen in [[Basal (phylogenetics)|basal]] [[Ornithischia|ornithischians]], basal thyreophorans, and ankylosaurs, a [[Phylogenetics|phylogenetic analysis]] placed it, according to most data matrices, as a basal thyreophoran, outside the clade [[Eurypoda]]. Riguetti ''et al''. (2022) suggest that ''Jakapil'' represents a member of a previously unknown thyreophoran clade. This clade may have diverged from the rest of the thyreophorans during the [[Sinemurian]].<ref name=Jakapil/> Its discovery in the [[Late Cretaceous]] implies the existence of a long basal thyreophoran [[ghost lineage]].
{{clade
|label1=[[Thyreophora]]
|1={{clade
|1=''[[Scutellosaurus]]'' <span style="{{MirrorH}}">[[File:Scutellosaurus illustration by Ritterbush.svg|70 px]]</span>
|2={{clade
|1=''[[Emausaurus]]''
|2=''[[Scelidosaurus]]'' [[File:Scelidosaurus harrisonii.png|70 px]]
|3={{clade
|1='''''Jakapil''''' [[File:Jakapil UDL.png|70 px]]
|label2=[[Eurypoda]]
|2={{clade
|1=[[Stegosauria]] [[File:Stegosaurus stenops sophie wiki martyniuk flipped.png|70 px]]
|2=[[Ankylosauria]] <span style="{{MirrorH}}">[[File:Ankylosaurus magniventris by sphenaphinae.png|70 px]]</span>}} }} }} }}
}}
The status of ''Jakapil'' as a thyreophoran has been disputed by some researchers; a study focused on the phylogenetic relationships of the Thyreophora noted that the only thyreophoran characteristic it possessed was dermal armor, while presenting features not present in any other thyreophoran. The premaxilla of ''Jakapil'' had no teeth, a feature not known in any thyreophoran, while the shape and depth of the dentary are more similar to those of basal [[neoceratopsians]]. Additionally, the teeth of ''Jakapil'' have a morphology distinct from any other ornithischian. Therefore, the study concluded that ''Jakapil'' most likely represents an armored [[Marginocephalia|marginocephalian]] or a member of a yet to be known lineage of non-thyreophoran ornithischians.<ref>{{Cite journal |last1=Raven |first1=Thomas J. |last2=Barrett |first2=Paul M. |last3=Joyce |first3=Chris B. |last4=Maidment |first4=Susannah C. R. |date=2023-05-18 |title=The phylogenetic relationships and evolutionary history of the armoured dinosaurs (Ornithischia: Thyreophora) |url=https://www.tandfonline.com/doi/full/10.1080/14772019.2023.2205433 |journal=Journal of Systematic Palaeontology |language=en |volume=21 |issue=1 |doi=10.1080/14772019.2023.2205433 |bibcode=2023JSPal..2105433R |s2cid=258802937 |issn=1477-2019}}</ref>
In 2024, Fonseca and colleagues placed the thyreophoroid ''Jakapil'' within [[Ankylosauria]], specifically as a sister taxon to both [[Euankylosauria]] and [[Parankylosauria]], based on weighted phylogenetic analyses and anatomical comparison with ''[[Stegouros]]''. They argued that ''Jakapil'' is not likely a [[ceratopsia]]n or a [[marginocephalia]]n, since it required 16 additional steps of enforcement.<ref>{{Cite journal|last1=Fonseca |first1=A. O. |last2=Reid |first2=I. J. |last3=Venner |first3=A. |last4=Duncan |first4=R. J. |last5=Garcia |first5=M. S. |last6=Müller |first6=R. T. |year=2024 |title=A comprehensive phylogenetic analysis on early ornithischian evolution |journal=Journal of Systematic Palaeontology |volume=22 |issue=1 |at=2346577 |doi=10.1080/14772019.2024.2346577 |bibcode=2024JSPal..2246577F }}</ref>
== Paleobiology ==
[[File:Jakapil_Lower_Jaw.webp|left|thumb|''Jakapil'' holotype lower jaw]]
In light of its straight, narrow snout, Riguetti ''et al.'' (2022) suggest that ''Jakapil'' did not use its teeth and jaws to shear leaves, but instead likely processed tough plant material via [[mastication]], as evidenced by the high amount of wear on the teeth.<ref name=Jakapil />
== Paleoenvironment ==
The [[Candeleros Formation]] is interpreted as an ancient [[desert]] known as the Kokorkom desert, with some [[oasis|oases]] in it, and its [[fossils]] represent a faunal assemblage typical of Middle Cretaceous ecosystems in the western remnants of [[Gondwana]].<ref name=Jakapil /> Other animals from this formation include the [[Rhynchocephalia|rhynchocephalians]] ''[[Tika giacchinoi|Tika]]'' and ''[[Priosphenodon]]'', the snake ''[[Najash]]'', the [[mammal]] ''[[Cronopio dentiacutus]]'', the theropods ''[[Alnashetri]]'', ''[[Buitreraptor]]'', ''[[Ekrixinatosaurus]],'' and ''[[Giganotosaurus]]'', as well as the sauropods ''[[Andesaurus]]'' and ''[[Limaysaurus]]''.
== References ==
{{Reflist}}
{{Ornithischia|H.}}
{{Taxonbar|from1=Q113494797}}
[[Category:Thyreophorans]]
[[Category:Ornithischian genera]]
[[Category:Late Cretaceous dinosaurs of South America]]
[[Category:Cretaceous Argentina]]
[[Category:Fossils of Argentina]]
[[Category:Fossil taxa described in 2022]]