Jakapil | |
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Skeletal diagram showing known fossil material | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | † Ornithischia |
Clade: | † Thyreophora |
Genus: | † Jakapil Riguetti, Apesteguía & Pereda-Suberbiola, 2022 |
Species: | †J. kaniukura |
Binomial name | |
†Jakapil kaniukura Riguetti, Apesteguía & Pereda-Suberbiola, 2022 | |
Jakapil (meaning "shield bearer" in Puelchean) is a genus of basal thyreophoran dinosaur from the Candeleros Formation of Argentina. The type species is Jakapil kaniukura. [1]
The holotype, MPCA-PV-630, is a partial skeleton including several 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 generic name, "Jakapil", is derived from "Ja-Kapïl", a Puelchean word meaning "shield bearer". This is also the literal meaning of the clade name Thyreophora. The specific name, "kaniukura", means "crest stone" in Mapudungun, in reference to its uniquely deep jaw. [1]
Jakapil represents a novel morphotype among thyreophorans, including, among other things, the presence of a predentary bone (absent or cartilaginous in other basal thyreophorans), [2] large, low osteoderms, and a bipedal stance, similar to Scutellosaurus . Its describers estimate it to be less than 1.5 metres (4.9 ft) long and 4.5–7 kilograms (9.9–15.4 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. [1]
Due to a combination of features seen in basal ornithischians, basal thyreophorans, and ankylosaurs, a 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. [1] Its discovery in the Late Cretaceous implies the existence of a long basal thyreophoran ghost lineage.
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 marginocephalian or a member of a yet to be known lineage of non-thyreophoran ornithischians. [3]
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 ceratopsian or a marginocephalian, since it required 16 additional steps of enforcement. [4]
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. [1]
The Candeleros Formation is interpreted as an ancient desert known as the Kokorkom desert, with some oases in it, and its fossils represent a faunal assemblage typical of Middle Cretaceous ecosystems in the western remnants of Gondwana. [1] Other animals from this formation include the rhynchocephalians 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 .
Ornithischia is an extinct clade of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name Ornithischia, or "bird-hipped", reflects this similarity and is derived from the Greek stem ornith- (ὀρνιθ-), meaning "bird", and ischion (ἴσχιον), meaning "hip". However, birds are only distantly related to this group, as birds are theropod dinosaurs.
Thyreophora is a group of armored ornithischian dinosaurs that lived from the Early Jurassic until the end of the Cretaceous.
Ankylosauria is a group of herbivorous dinosaurs of the clade Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are known to have first appeared in North Africa during the Middle Jurassic, and persisted until the end of the Late Cretaceous. The two main families of ankylosaurians, Nodosauridae and Ankylosauridae are primarily known from the Northern Hemisphere, but the more basal Parankylosauria are known from southern Gondwana during the Cretaceous.
Muttaburrasaurus was a genus of herbivorous iguanodontian ornithopod dinosaur, which lived in what is now northeastern Australia sometime between 112 and 103 million years ago during the early Cretaceous period. It has been recovered in some analyses as a member of the iguanodontian clade Rhabdodontomorpha. After Kunbarrasaurus, it is Australia's most completely known dinosaur from skeletal remains. It was named after Muttaburra, the site in Queensland, Australia, where it was found.
Scelidosaurus is a genus of herbivorous armoured ornithischian dinosaur from the Jurassic of England.
Minmi is a genus of small herbivorous ankylosaurian dinosaur that lived during the early Cretaceous Period of Australia, about 120 to 112 million years ago.
Micropachycephalosaurus is an extinct genus of basal marginocephalian dinosaur containing only the type species, Micropachycephalosaurus hongtuyanensis. It lived in China during the Late Cretaceous (Campanian) and was found in the Jiangjunding Formation.
Nodosauridae is a family of ankylosaurian dinosaurs known from the Late Jurassic to the Late Cretaceous periods in what is now Asia, Europe, North America, and possibly South America. While traditionally regarded as a monophyletic clade as the sister taxon to the Ankylosauridae, some analyses recover it as a paraphyletic grade leading to the ankylosaurids.
Neornithischia is a clade of the dinosaur order Ornithischia. It is the sister group of the Thyreophora within the clade Genasauria. Neornithischians are united by having a thicker layer of asymmetrical enamel on the inside of their lower teeth. The teeth wore unevenly with chewing and developed sharp ridges that allowed neornithischians to break down tougher plant food than other dinosaurs.
Lusitanosaurus is a genus of reptile from the Sinemurian stage of Early Jurassic of Portugal, maybe from the Coimbra Formation. It was considered the second example of the Dinosaurian group Thyreophora from the Sinemurian of Europe and it the oldest known dinosaur from the Iberian Peninsula, but this affinity has been contested. It is based on a large left maxilla with teeth that was lost in the fire at Museu Nacional de História Natural e da Ciência, Lisbon, in 1978.
Emausaurus is a genus of thyreophoran or armored dinosaur from the Early Jurassic. Its fossils have been found in Mecklenburg-Vorpommern, northern Germany. Emausaurus is the only known Toarcian thyreophoran, as well as the only dinosaur from the zone of the same age with a formal name.
Siluosaurus is a genus of ornithischian dinosaur from the Barremian-Albian-age Lower Cretaceous Xinminbao Group of Gansu, China. It is based on the specimen IVPP V.11117 (1-2), which consists of two teeth. It is an obscure genus, with no papers doing more than mentioning it since it was described in 1997. The type species is S. zhanggiani.
Albalophosaurus is a genus of marginocephalian ornithischian dinosaur that lived in Japan during the Early Cretaceous. The type species is Albalophosaurus yamaguchiorum.
Koreanosaurus is a genus of orodromine neornithischian dinosaur. One species has been described, Koreanosaurus boseongensis.
Elasmaria is a clade of ornithopods known from Cretaceous deposits in South America, Antarctica, and Australia that contains many bipedal ornithopods that were previously considered "hypsilophodonts".
Laquintasaura is a genus of Venezuelan ornithischian dinosaur containing only the type species Laquintasaura venezuelae. It is known for being one of the most primitive ornithischians in the fossil record, as well as the first dinosaur to have been identified from Venezuela. The name is derived from the La Quinta Formation, where it was discovered and the feminine Greek suffix for lizard, with the specific name referring to the country of Venezuela. It is known from hundreds of fossil elements, all derived from a single extensive bonebed locality. Initially discovered by French palaeontologists, numerous expeditions have been conducted to excavate from the bonebed, largely led by Marcelo R Sánchez-Villagra. Once thought to represent remains of Lesothosaurus, it was formally named in a 2014 study; much of the abundant material was not yet prepared at the time and research remains ongoing.
Isaberrysaura is a genus of stegosaurian ornithischian dinosaur from the Middle Jurassic Los Molles Formation of Patagonia, Argentina. The genus contains a single species, I. mollensis, described by Salgado et al. in 2017 from a single specimen. Although initially classified as a basal neornithischian, subsequent analysis has allied it with the Stegosauria; the morphology of its skull resembles those of other members of the group.
Parankylosauria is a group of basal ankylosaurian dinosaurs known from the Cretaceous of South America, Antarctica, and Australia. It is thought the group split from other ankylosaurs during the mid-Jurassic period, despite this being unpreserved in the fossil record.
Vectipelta is an extinct genus of ankylosaurian dinosaur recovered from the Early Cretaceous Wessex Formation of England. The genus contains a single species, V. barretti, known from a partial skeleton including several osteoderms. It was historically known as the "Spearpoint ankylosaur" prior to its description.
Ampelognathus is a genus of ornithopod dinosaur from the Late Cretaceous (Cenomanian) Lewisville Formation of Texas. The type species is Ampelognathus coheni.