Ankylosauria

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Ankylosaurs
Temporal range:
Middle Jurassic—Late Cretaceous, Bajocian–Maastrichtian
Ankylosauria Diversity.jpg
Collection of ankylosaurs. From top left to right: Liaoningosaurus , Edmontonia , Tianzhenosaurus , Gargoyleosaurus , Scolosaurus , Denversaurus , Gastonia , Borealopelta and Akainacephalus .
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade:† Ornithischia
Clade:† Thyreophora
Clade:† Eurypoda
Clade:† Ankylosauria
Osborn, 1923
Subgroups
Synonyms [2]
  • AnkylosauromorphaCarpenter, 2001

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 the Middle Jurassic, and persisted until the end of the Cretaceous Period. The two main families of Ankylosaurs, Nodosauridae and Ankylosauridae are primarily known from the Northern Hemisphere, but the more basal Parankylosauria are known from southern Gondwana during the Cretaceous.

Contents

Ankylosauria was first named by Henry Fairfield Osborn in 1923. [3] In the Linnaean classification system, the group is usually considered either a suborder or an infraorder. It is contained within the group Thyreophora, which also includes the stegosaurs, armored dinosaurs known for their combination of plates and spikes.

Etymology

The name of this group of dinosaurs is associated with a number of anatomical features in which small and large bony shields fused together, completely covering their back and sides. On the skull these shields fused with the underlying bones, and the dorsal ribs fit snugly to the vertebrae. The Latin name Ankylosauria is derived from the Greek ἀγκύλος [ankylos] — "curved", "bent" with the anatomical meaning "hard" or "fused" and σαῦρος [sauros] — "lizard". [4]

In the 1908 description of the genus Ankylosaurus, Barnum Brown described the family Ankylosauridae as a group of representatives with a "rigid spine", but noted the wide, curved shape of the ribs, suggesting a "strongly curved" back [5] (an error based on the alleged similarity to stegosaurs and glyptodonts, as ankylosaurs have flat backs). Therefore, "rigid lizard" and "curved lizard" could be additional meanings applied to the name of ankylosaurs. [4]

Classification

Ankylosauria and Stegosauria together form the two major subgroups of Thyreophora, a group of armoured dinosaurs distinct from ornithopods and marginocephalians. [2] Historically used for forms lacking large vertical plates, Kenneth Carpenter proposed in 1997 the first informal definition of the group, as all ornithischians closer to Ankylosaurus than Stegosaurus . [6] This definition was further refined by Paul Sereno in 2005 to specify Ankylosaurus magniventris and Stegosaurus stenops , the type species of both genera, a definition that was followed by Madzia and colleagues in 2021 when the group name and definition was formalized following the PhyloCode. [2] Phylogenetic and morphological studies have differed on the inclusion of certain early taxa into Ankylosauria, especially the armoured Early Jurassic form Scelidosaurus . As some analyses, like that of Carpenter from 2001 or David B. Norman in 2021 find Scelidosaurus and possibly other early forms like Emausaurus and Scutellosaurus to fall closer to Ankylosaurus than Stegosaurus, Carpenter and later Norman suggested redefining Ankylosauria to limit it to the two subclades Nodosauridae and Ankylosauridae, creating the new clade Ankylosauromorpha for all taxa closer to Ankylosaurus than Stegosaurus. [2] [7] [8] However, as historically even these primitive forms were considered ankylosaurs if they were more derived than Stegosaurus, Madzia and colleagues considered a redefinition of Ankylosauria to be undesirable, instead preferring to abandon Ankylosauromorpha as a same-definition junior synonym of Ankylosauria. The informal clade Euankylosauria, suggested by Norman as an alternative to redefining Ankylosauria, was discussed as potentially being useful in future for the typical group of nodosaurids and ankylosaurids, [2] and was defined in 2021 by Soto-Acuña and colleagues as such as the result of their novel phylogenetic results, which grouped Antarctopelta , Kunbarrasaurus ( Minmi sp. of earlier analyses) and their new taxon Stegouros as a unique group of non-euankylosaurian ankylosaurs, which they gave the name Parankylosauria. The result of their phylogenetic analysis is below. [1]

Thyreophora

A 2023 review of Thyreophora rejects the traditional Ankylosauridae-Nodosauridae split, instead finding "nodosaurids" to be referrable to three separate families: Panoplosauridae, Polacanthidae, and Struthiosauridae. [9]

Ankylosauria

Sarcolestes

Paw Paw juvenile

Animantarx

Cedarpelta

Gargoyleosaurus

Polacanthidae
Ankylosauridae


Evolution

The origin of ankylosaurs is poorly understood, and only a few specimens from the Middle Jurassic are known. [10] The ancestry of ankylosaurs has long been sought among stegosaurs, the closest group to ankylosaurs compared to other dinosaurs. Currently, ankylosaurs are a close group of stegosaurs within the Eurypoda clade. [11] They are united by the presence of osteoderms in the skin, the narrow triangular skull of stegosaurs is similar to that of nodosaurids, and some similarity is found in the structure of the palate. [12] Since stegosaurs are known from the Middle Jurassic, [13] ankylosaurs are probably of the same age. They may have split up during the Aalenian period, more than 170 million years ago, but they were definitely in Africa by the Bathonian due to the presence of Spicomellus in Morocco. [14] There are no well-preserved remains of ankylosaurs of that age. An incomplete radius and ulna from the Isle of Skye in Scotland are known, the exact affiliation of which to ankylosaurs or stegosaurs is not established. [15] Most likely, ankylosaurs followed a different evolutionary path than stegosaurs, although it is unknown when and how they split off. In the latter, the osteoderms become raised, and the lateral protection disappears. [16] Ankylosaurs evolved towards the development of osteoderms on the surface of the skull, increased armor and further consolidation of the carapace, [17] which suggests that the ancestor of the carapace consisted of separate non-fused osteoderms. [18]

Paleobiology

Armour of the nodosaurid Edmontonia Edmontonia rugosidens armour AMNH 5381.jpg
Armour of the nodosaurid Edmontonia

Possible neonate-sized ankylosaur fossils have been documented in the scientific literature. [19]

Armor

All ankylosaurians had armor over much of their bodies, mostly scutes and nodules, with large spines in some cases. The scutes, or plates, are rectangular to oval objects organized in transverse (side to side) rows, often with keels on the upper surface. Smaller nodules and plates filled in the open spaces between large plates. In all three groups, the first two rows of plates tend to form a sort of half-ring around the neck; in nodosaurids, this comes from adjacent plates fusing with each other (and there is a third row as well), while ankylosaurids usually have the plates fused to the top of another band of bone. The skull has armor plastered on to it, including a distinctive piece on the outside-rear of the lower jaw.

Diet and feeding

Ankylosaurs were built low to the ground, typically one foot off the ground surface. They had small, triangular teeth that were loosely packed, similar to stegosaurs. The large hyoid bones left in skeletons indicates that they had long, flexible tongues. They also had a large, side secondary palate. This means that they could breathe while chewing, unlike crocodiles. Their expanded gut region suggests the use of fermentation to digest their food, using symbiotic bacteria and gut flora. Their diet likely consisted of ferns, cycads, and angiosperms. Mallon et al. (2013) examined herbivore coexistence on the island continent of Laramidia during the Late Cretaceous. It was concluded that ankylosaurs were generally restricted to feeding on vegetation at, or below, the height of 1 meter. [20]

Vocalization

In February 2023, scientists reported that the possible sounds ankylosaurs may have made were bird-like vocalizations based on a finding of a fossilized larynx from the ankylosaur Pinacosaurus grangeri . [21] [22]

See also

Related Research Articles

<span class="mw-page-title-main">Thyreophora</span> Extinct clade of dinosaurs

Thyreophora is a group of armored ornithischian dinosaurs that lived from the Early Jurassic until the end of the Cretaceous.

<i>Nodosaurus</i> Extinct genus of dinosaurs

Nodosaurus is a genus of herbivorous nodosaurid ankylosaurian dinosaur from the Late Cretaceous, the fossils of which are found exclusively in the Frontier Formation in Wyoming.

<i>Ankylosaurus</i> Ankylosaurid dinosaur genus from the Late Cretaceous Period

Ankylosaurus is a genus of armored dinosaur. Its fossils have been found in geological formations dating to the very end of the Cretaceous Period, about 68–66 million years ago, in western North America, making it among the last of the non-avian dinosaurs. It was named by Barnum Brown in 1908; it is monotypic, containing only A. magniventris. The generic name means "fused" or "bent lizard", and the specific name means "great belly". A handful of specimens have been excavated to date, but a complete skeleton has not been discovered. Though other members of Ankylosauria are represented by more extensive fossil material, Ankylosaurus is often considered the archetypal member of its group, despite having some unusual features.

<i>Scelidosaurus</i> Genus of reptiles (fossil)

Scelidosaurus is a genus of herbivorous armoured ornithischian dinosaur from the Jurassic of England.

<i>Edmontonia</i> Extinct genus of dinosaurs

Edmontonia is a genus of panoplosaurin nodosaurid dinosaur from the Late Cretaceous Period. It is part of the Nodosauridae, a family within Ankylosauria. It is named after the Edmonton Formation, the unit of rock where it was found.

<i>Gastonia</i> (dinosaur) Ankylosaurian dinosaur genus from the Early Cretaceous period

Gastonia is a genus of herbivorous ankylosaurian dinosaur from the Early Cretaceous of North America, around 139 to 134.6 million years ago. It is often considered a nodosaurid closely related to Polacanthus. Gastonia has a sacral shield and large shoulder spikes.

<span class="mw-page-title-main">Ankylosauridae</span> Extinct family of dinosaurs

Ankylosauridae is a family of armored dinosaurs within Ankylosauria, and is the sister group to Nodosauridae. The oldest known Ankylosaurids date to around 122 million years ago and went extinct 66 million years ago during the Cretaceous–Paleogene extinction event. These animals were mainly herbivorous and were obligate quadrupeds, with leaf-shaped teeth and robust, scute-covered bodies. Ankylosaurids possess a distinctly domed and short snout, wedge-shaped osteoderms on their skull, scutes along their torso, and a tail club.

<i>Struthiosaurus</i> Extinct genus of dinosaurs

Struthiosaurus is a genus of nodosaurid dinosaurs, from the Late Cretaceous period (Santonian-Maastrichtian) of Austria, Romania, France and Hungary in Europe. It was a small dinosaur, measuring 2–3 m (6.6–9.8 ft) in length and weighing 300–400 kg (660–880 lb).

<span class="mw-page-title-main">Nodosauridae</span> Extinct family of dinosaurs

Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous period in what is now North America, South America, Europe, and Asia.

<i>Stegopelta</i> Extinct genus of dinosaurs

Stegopelta is a genus of struthiosaurin nodosaurid dinosaur. It is based on a partial skeleton from the latest Albian-earliest Cenomanian-age Lower and Upper Cretaceous Belle Fourche Member of the Frontier Formation of Fremont County, Wyoming, USA.

<i>Texasetes</i> Extinct genus of dinosaurs

Texasetes is a genus of ankylosaurian dinosaurs from the late Lower Cretaceous of North America. This poorly known genus has been recovered from the Paw Paw Formation near Haslet, Tarrant County, Texas, which has also produced the nodosaurid ankylosaur Pawpawsaurus.

<i>Cedarpelta</i> Extinct genus of reptiles

Cedarpelta is an extinct genus of basal ankylosaurid dinosaur from Utah that lived during the Late Cretaceous period in what is now the Mussentuchit Member of the Cedar Mountain Formation. The type and only species, Cedarpelta bilbeyhallorum, is known from multiple specimens including partial skulls and postcranial material. It was named in 2001 by Kenneth Carpenter, James Kirkland, Don Burge, and John Bird. Cedarpelta has an estimated length of 7 metres and weight of 5 tonnes (11,023 lbs). The skull of Cedarpelta lacks extensive cranial ornamentation and is one of the only known ankylosaurs with individual skull bones that are not completely fused together.

<i>Mymoorapelta</i> Extinct genus of ornithischian dinosaur

Mymoorapelta is a nodosaurid ankylosaur from the Late Jurassic Morrison Formation of western Colorado and central Utah, USA. The animal is known from a single species, Mymoorapelta maysi, and few specimens are known. The most complete specimen is the holotype individual from the Mygatt-Moore Quarry, which includes osteoderms, a partial skull, vertebrae, and other bones. It was initially described by James Kirkland and Kenneth Carpenter in 1994. Along with Gargoyleosaurus, it is one of the earliest known nodosaurids.

<i>Panoplosaurus</i> Extinct genus of dinosaurs

Panoplosaurus is a genus of armoured dinosaur from the Late Cretaceous of Alberta, Canada. Few specimens of the genus are known, all from the middle Campanian of the Dinosaur Park Formation, roughly 76 to 75 million years ago. It was first discovered in 1917, and named in 1919 by Lawrence Lambe, named for its extensive armour, meaning "well-armoured lizard". Panoplosaurus has at times been considered the proper name for material otherwise referred to as Edmontonia, complicating its phylogenetic and ecological interpretations, at one point being considered to have existed across Alberta, New Mexico and Texas, with specimens in institutions from Canada and the United States. The skull and skeleton of Panoplosaurus are similar to its relatives, but have a few significant differences, such as the lumpy form of the skull osteoderms, a completely fused shoulder blade, and regularly shaped plates on its neck and body lacking prominent spines. It was a quadrupedal animal, roughly 5 m (16 ft) long and 1,600 kg (3,500 lb) in weight. The skull has a short snout, with a very domed surface, and bony plates directly covering the cheek. The neck had circular groups of plates arranged around the top surface, both the forelimb and hindlimb were about the same length, and the hand may have only included three fingers. Almost the entire surface of the body was covered in plates, osteoderms and scutes of varying sizes, ranging from large elements along the skull and neck, to smaller, round bones underneath the chin and body, to small ossicles that filled in the spaces between other, larger osteoderms.

Dracopelta is a monospecific genus of ankylosaur dinosaur from Portugal that lived during the Late Jurassic in what is now the Lourinhã Formation. The type and only species is Dracopelta zbyszewskii, which is represented by a partial skeleton including unpublished material.

<span class="mw-page-title-main">Polacanthinae</span> Extinct subfamily of dinosaurs

Polacanthinae is a subfamily of ankylosaurs, most often nodosaurids, from the Late Jurassic through Early Cretaceous of Europe and potentially North America and Asia. The group is defined as the largest clade closer to Polacanthus foxii than Nodosaurus textilis or Ankylosaurus magniventris, as long as that group nests within either Nodosauridae or Ankylosauridae. If Polacanthus, and by extent Polacanthinae, falls outside either family-level clade, then the -inae suffix would be inappropriate, and the proper name for the group would be the informally defined Polacanthidae.

<span class="mw-page-title-main">Genasauria</span> Extinct clade of dinosaurs

Genasauria is a clade of extinct beaked, primarily herbivorous dinosaurs. Paleontologist Paul Sereno first named Genasauria in 1986. The name Genasauria is derived from the Latin word gena meaning ‘cheek’ and the Greek word saúra (σαύρα) meaning ‘lizard.’ It is hypothesized that Genasauria had diverged from Lesothosaurus by the Early Jurassic. Cranial features that characterize Genasauria include a medial offset of the maxillary dentition, a sprout-shaped mandibular symphysis, moderately sized coronoid process, and an edentulous anterior portion of the premaxilla. A distinguishing postcranial feature of Genasauria is a pubic peduncle of the ilium that is less robust than the ischial peduncle. Genasauria is commonly divided into Neornithischia and Thyreophora. Neornithischia is characterized by asymmetrical distributions of enamel covering the crowns of the cheek teeth, an open acetabulum, and a laterally protruding ischial peduncle of the ilium. Neornithischia includes ornithopods, pachycephalosaurs, and ceratopsians. Thyreophora is characterized by body armor and includes stegosaurs, ankylosaurs, Scelidosaurus, and Scutellosaurus.

<span class="mw-page-title-main">Timeline of ankylosaur research</span>

This timeline of ankylosaur research is a chronological listing of events in the history of paleontology focused on the ankylosaurs, quadrupedal herbivorous dinosaurs who were protected by a covering bony plates and spikes and sometimes by a clubbed tail. Although formally trained scientists did not begin documenting ankylosaur fossils until the early 19th century, Native Americans had a long history of contact with these remains, which were generally interpreted through a mythological lens. The Delaware people have stories about smoking the bones of ancient monsters in a magic ritual to have wishes granted and ankylosaur fossils are among the local fossils that may have been used like this. The Native Americans of the modern southwestern United States tell stories about an armored monster named Yeitso that may have been influenced by local ankylosaur fossils. Likewise, ankylosaur remains are among the dinosaur bones found along the Red Deer River of Alberta, Canada where the Piegan people believe that the Grandfather of the Buffalo once lived.

<span class="mw-page-title-main">Parankylosauria</span> Extinct group of dinosaurs

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.

References

  1. 1 2 Soto-Acuña, Sergio; Vargas, Alexander; Kaluza, Jonatan; Leppe, Marcelo; Botelho, Joao; Palma-Liberona, José; Gutstein, Carolina; Fernández, Roy; Ortiz, Hector; Milla, Verónica; Aravena, Bárbara; Manríquez, Leslie M. E.; Alarcón-Muñoz, Jhonatan; Pino, Juan Pablo; Trevisan, Cristine; Mansilla, Héctor; Hinojosa, Luis Felipe; Muñoz-Walther, Vicente; Rubilar-Rogers, David (2021). "Bizarre tail weaponry in a transitional ankylosaur from subantarctic Chile". Nature. 600 (7888): 259–263. Bibcode:2021Natur.600..259S. doi:10.1038/s41586-021-04147-1. PMID   34853468. S2CID   244799975.
  2. 1 2 3 4 5 Madzia, D.; Arbour, V.M.; Boyd, C.A.; Farke, A.A.; Cruzado-Caballero, P.; Evans, D.C. (2021). "The phylogenetic nomenclature of ornithischian dinosaurs". PeerJ. 9: e12362. doi: 10.7717/peerj.12362 . PMC   8667728 . PMID   34966571.
  3. ↑ Osborn, H. F. (1923). "Two Lower Cretaceous dinosaurs of Mongolia." American Museum Novitates, 95: 1–10.
  4. 1 2 Ben Creisler, Dinosauria Translation and Pronunciation Guide. Archived 2011-11-11 at the Wayback Machine
  5. ↑ Brown, B. 1908. The Ankylosauridae, a new family of armored dinosaurs from the Upper Cretaceous. American Museum of Natural History Bulletin 24: 187—201.
  6. ↑ Carpenter, K., 1997, "Ankylosauria" pp. 16-20 in: P.J. Currie and K. Padian (eds.), Encyclopedia of Dinosaurs, Academic Press, San Diego
  7. ↑ Carpenter, K. (2001). "Phylogenetic Analysis of the Ankylosauria". In Carpenter, Kenneth (ed.). The Armored Dinosaurs. Indiana University Press. p. 455. ISBN   0-253-33964-2.
  8. ↑ Norman, D.B. (2021). "Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships". Zoological Journal of the Linnean Society. 191 (1): 1–86. doi:10.1093/zoolinnean/zlaa061.
  9. ↑ Raven, T. J.; Barrett, P. M.; Joyce, C. B.; Maidment, S. C. R. (2023). "The phylogenetic relationships and evolutionary history of the armoured dinosaurs (Ornithischia: Thyreophora)". Journal of Systematic Palaeontology. 21 (1). 2205433. Bibcode:2023JSPal..2105433R. doi:10.1080/14772019.2023.2205433. S2CID   258802937.
  10. ↑ Arbour, V. M., Currie, P. J. 2016. Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs. Journal of Systematic Palaeontology 14 (5): 385—444.
  11. ↑ Norman, D. B., Witmer, L. M. and Weishampel, D. B. 2004. Basal Thyreophora. Pр. 335—342. In D. B. Weishampel, P. Dodson, and H. Osmolska (eds.), The Dinosauria. Berkeley: University of California Press.
  12. ↑ T.A. Tumanova, 1987, "Pantsirnyye dinozavry Mongolii", Trudy Sovmestnaya Sovetsko-Mongol'skaya Paleontologicheskaya Ekspeditsiya 32: 1-80.
  13. ↑ "PBDB".
  14. ↑ Maidment, Susannah C. R.; Strachan, Sarah J.; Ouarhache, Driss; Scheyer, Torsten M.; Brown, Emily E.; Fernandez, Vincent; Johanson, Zerina; Raven, Thomas J.; Barrett, Paul M. (2021-09-23). "Bizarre dermal armour suggests the first African ankylosaur". Nature Ecology & Evolution. 5 (12): 1576–1581. Bibcode:2021NatEE...5.1576M. doi:10.1038/s41559-021-01553-6. ISSN   2397-334X. PMID   34556830. S2CID   237616095.
  15. ↑ Clark, N.D.L. 2001. A thyreophoran dinosaur from the early Bajocian (Middle Jurassic) of the Isle of Skye, Scotland. Scottish Journal of Geology, 37: 19—26.
  16. ↑ Coombs, W. P. 1978. The families of the ornithischian dinosaur order Ankylosauria. Journal of Paleontology 21: 143—170.
  17. ↑ Maryanska, T. 1977. Ankylosauridae (Dinosauria) from Mongolia. Palaeontologia Polonica, 37: 85—151.
  18. ↑ T.A. Tumanova, 1987, "Pantsirnyye dinozavry Mongolii", Trudy Sovmestnaya Sovetsko-Mongol'skaya Paleontologicheskaya Ekspeditsiya 32: 1-80.
  19. ↑ Tanke, D.H. and Brett-Surman, M.K. 2001. Evidence of Hatchling and Nestling-Size Hadrosaurs (Reptilia:Ornithischia) from Dinosaur Provincial Park (Dinosaur Park Formation: Campanian), Alberta, Canada. pp. 206-218. In: Mesozoic Vertebrate Life—New Research Inspired by the Paleontology of Philip J. Currie. Edited by D.H. Tanke and K. Carpenter. Indiana University Press: Bloomington. xviii + 577 pp.
  20. ↑ Mallon, Jordan C; David C Evans; Michael J Ryan; Jason S Anderson (2013). "Feeding height stratification among the herbivorous dinosaurs from the Dinosaur Park Formation (upper Campanian) of Alberta, Canada". BMC Ecology. 13 (1): 14. Bibcode:2013BMCE...13...14M. doi: 10.1186/1472-6785-13-14 . PMC   3637170 . PMID   23557203.
  21. ↑ Wilke, Carolyn (24 February 2023). "What Sounds Did Dinosaurs Make? - A new study of a fossilized ankylosaur suggests it could have uttered birdlike calls". The New York Times . Retrieved 26 February 2023.
  22. ↑ Yoshida, Junki; Kobayashi, Yoshitsugu; Norell, Mark a. (15 February 2023). "An ankylosaur larynx provides insights for bird-like vocalization in non-avian dinosaurs". Communications Biology . 152 (1): 152. doi:10.1038/s42003-023-04513-x. PMC   9932143 . PMID   36792659.
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