Jakapil

Extinct genus of dinosaurs

Jakapil
Temporal range: Late Cretaceous 22, Cenomanian
97–94 Ma
Jakapil skeletal.webp
Skeletal diagram showing known fossil material
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: 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]

Discovery and naming

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]

Description

Jakapil holotype lower jaw

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.[1]

Classification

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]

Thyreophora

Scutellosaurus Scutellosaurus illustration by Ritterbush.svg

Emausaurus

Scelidosaurus Scelidosaurus harrisonii.png

Jakapil

Eurypoda

Stegosauria Stegosaurus stenops sophie wiki martyniuk flipped.png

Ankylosauria Ankylosaurus magniventris by sphenaphinae.png

The status of Jakapil as a thyreophoran has been disputed by some researchers; paleontologist Susannah Maidment of the Natural History Museum in London has instead suggested that it may be an armored, basal ceratopsian (based on jaw anatomy), or that it may even belong to an entirely distinct, previously unknown clade of ornithischians.[3]

Paleobiology

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]

Paleoenvironment

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.

References

  1. ^ a b c d e f Riguetti FJ, Apesteguía S, Pereda-Suberbiola X (2022). "A new Cretaceous thyreophoran from Patagonia supports a South American lineage of armoured dinosaurs". Scientific Reports. 12 (1): Article number 11621. doi:10.1038/s41598-022-15535-6.
  2. ^ Norman, David B. (2020). "Scelidosaurus harrisonii from the Early Jurassic of Dorset, England: cranial anatomy". Zoological Journal of the Linnean Society. 188 (1): 1–81. doi:10.1093/zoolinnean/zlz074.
  3. ^ Susannah Maidment [@Tweetisaurus] (August 11, 2022). "I'm excited to see this paper out. Jakapil is described here as a *Late Cretaceous* basal thyreophoran. I reviewed this and I don't think it is. I think it's an armoured ceratopsian, or perhaps a new, entirely unknown clade. Fascinating" (Tweet) – via Twitter.
Avemetatarsalia
    • see Avemetatarsalia
Ornithischia
    • see Ornithischia
Thyreophora
    • see below↓
Huayangosauridae
Stegosauridae
Dacentrurinae
Stegosaurinae
Ankylosauria
    • see below↓
Scutellosaurus lawleri Stegosaurus stenops
Parankylosauria
Nodosauridae
Polacanthinae
Nodosaurinae
Panoplosaurini
Struthiosaurini
Ankylosauridae
Shamosaurinae
Ankylosaurinae
Ankylosaurini
Sauropelta edwardsorum Ankylosaurus magniventris
  • Thyreophorans
  • Stegosaurs
  • Ankylosaurs