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37-599: Ankylosauridae ( / ˌ æ ŋ k ɪ l oʊ ˈ s ɔː r ɪ d iː / ) 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

74-518: A "strongly curved" back (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. Ankylosauria and Stegosauria together form the two major subgroups of Thyreophora , a group of armoured dinosaurs distinct from ornithopods and marginocephalians . Historically used for forms lacking large vertical plates, Kenneth Carpenter proposed in 1997

111-607: A distinctly domed and short snout, wedge-shaped osteoderms on their skull, scutes along their torso, and a tail club. Ankylosauridae is exclusively known from the Northern Hemisphere, with specimens found in North America, Europe, and Asia. The first discoveries within this family were of the genus Ankylosaurus , by Peter Kaiser and Barnum Brown in Montana in 1906. Brown went on to name Ankylosauridae and

148-546: A part of the genus Stegopelta , and Brown himself placed it within the suborder Stegosauria. It has previously been interpreted that variation in ankylosaurid tail club shape is due to sexual dimorphism , which assumes that tail club morphology has a sex-linked intraspecific function. This is possible if the tail club was used for agonistic behaviour. However, a sexual dimorphism theory would predict roughly equal numbers of individuals with two distinct sizes of tail clubs. Obvious sexual dimorphism has not been documented, but if

185-630: A phylogenetic analysis of Ankylosauridae consisting of Gastonia , Cedarpelta , Chuanqilong , other basal ankylosaurids, and a number of derived ankylosaurids. Their phylogeny includes some uncertain phylogenetic relationships, between Ankylosaurus , Anodontosaurus , Scolosaurus , and Ziapelta . Lesothosaurus Scelidosaurus Stegosauria Minmi paravertebra Gargoyleosaurus More derived nodosaurids Gastonia Ahshislepelta Aletopelta Liaoningosaurus Cedarpelta Chuanqilong Gobisaurus Shamosaurus Ankylosauria Ankylosauria

222-1045: A same-definition junior synonym of Ankylosauria. The clade Euankylosauria was named by Soto-Acuña and colleagues in 2021 in their description of a unique basal ankylosaur Stegouros to represent the grouping uniting ankylosaurids and nodosaurids, to the exclusion of their newly discovered clade Parankylosauria . This clade is formally defined in the PhyloCode as "the largest clade containing Ankylosaurus magniventris and Nodosaurus textilis , but not Stegouros elengassen ". Scelidosaurus Stegosauria Kunbarrasaurus Antarctopelta Stegouros Cedarpelta Dongyangopelta Gargoyleosaurus Gastonia Hylaeosaurus Mymoorapelta Panoplosaurus Peloroplites Polacanthus Hoplitosaurus Sauroplites Taohelong Nodosaurinae Aletopelta Chuanqilong Liaoningosaurus Gobisaurus Shamosaurus Ankylosaurinae A 2023 review of Thyreophora rejects

259-461: A set of synonyms or homonyms will be considered accepted (generally the one registered first; see below). The PhyloCode only governs the naming of clades , not of paraphyletic or polyphyletic groups, and only allows the use of specimens , species , and apomorphies as specifiers (anchors). Unlike rank-based nomenclatural codes ( ICN , ICZN , ICNB ), the PhyloCode does not require

296-469: A singular structure called a "synsacrum complex". There is a complete fusion between centra, neural arches, zygapophyses, and sometimes neural spines. In 2017, Victoria M. Arbour and David C. Evans described a new genus of ankylosaurine that preserved extensive soft tissues along the body. This animal, named Zuul after its resemblance to the Ghostbusters monster, is also the first ankylosaur from

333-565: A tail club were included in Kenneth Carpenter's 2001 phylogeny of Ankylosauridae. Daniel Madzia and colleagues in 2021 formally defined Ankylosauridae in the PhyloCode as "the largest clade containing Ankylosaurus magniventris , but not Nodosaurus textilis ". The basal subfamily Shamosaurinae is formally defined as "the largest clade containing Gobisaurus domoculus and Shamosaurus scutatus , but not Ankylosaurus magniventris ". This definition ensures that Shamosaurinae

370-674: 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

407-603: Is associated with the International Society for Phylogenetic Nomenclature (ISPN). The companion volume, Phylonyms , establishes 300 taxon names under PhyloCode , serving as examples for those unfamiliar with the code. RegNum is an associated online database for registered clade names. The PhyloCode regulates phylogenetic nomenclature by providing rules for deciding which associations of names and definitions are considered established, which of those will be considered homonyms or synonyms, and which one of

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444-782: Is based on phylogeny (i.e., ancestry and descent) and uses specifiers (e.g., species, specimens, apomorphies) to indicate actual organisms . The formula of the definition indicates an ancestor. The defined taxon, then, is that ancestor and all of its descendants. Thus, the content of a phylogenetically defined taxon relies on a phylogenetic hypothesis. The following are examples of types of phylogenetic definition (capital letters indicate specifiers): Other types of definition are possible as well, taking into account not only organisms' phylogenetic relations and apomorphies but also whether or not related organisms are extant . The following table gives examples of phylogenetic definitions of clades that also have ranks in traditional nomenclature. When all

481-492: Is only valid when both Gobisaurus and Shamosaurus form a clade to the exclusion of Ankylosaurus . In a study done in 2004 by Vickaryous et al., Gargoyleosaurus , Gastonia , and Minmi were recorded as basal ankylosaurids, with the rest of the ankylosaurids filled out with Gobisaurus , Shamosaurus , and ankylosaurines from China, Mongolia, and North America. In 2012, Thompson et al. undertook an analysis of almost all known valid ankylosaurs and outgroup taxa at

518-593: The Northern Hemisphere ( North America , Europe and Asia ), but the more basal Parankylosauria are known from southern Gondwana ( South America , Australia and Antarctica ) during the Cretaceous. Ankylosauria was first named by Henry Fairfield Osborn in 1923. In the Linnaean classification system, the group is usually considered either a suborder or an infraorder. It is contained within

555-577: The PhyloCode is still small, and the publication of PhyloCode literature stagnated in the mid-2010s, before accelerating after publication of Phylonyms in 2020 and of the launch of the Bulletin of Phylogenetic Nomenclature , which is a journal dedicated to the publication of nomenclatural acts (especially definition of taxon names) valid under the PhyloCode . To be valid under the PhyloCode, taxon names and associated definitions should be registered in

592-499: The PhyloCode . 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

629-580: The Judith River Formation. Barnum Brown and Peter Kaisen discovered the first ankylosaurid genus, Ankylosaurus , in 1906 in the Hell Creek Beds in Montana. The fossil material they found was a portion of the skull, two teeth, some vertebrae, a distorted scapula, ribs and more than thirty osteoderms. Reconstruction of the specimen was initially met with skepticism by those who believed it to be at least very close to, or completely

666-544: The clubs of one sex are much larger, then there would be a bias for preservation and discovery towards that sex. In 1978, W.P. Coombs, Jr. classified almost all valid species of Ankylosauria within either Nodosauridae or Ankylosauridae. This was a pivotal study and described many characters of ankylosaurs in the earliest phylogenetic analyses of the group. Later in 1998, Paul Sereno formally defined Ankylosauridae as all ankylosaurs more closely related to Ankylosaurus than to Panoplosaurus . Ankylosaurs not known to possess

703-418: The definitional foundations of the alternative systems. Note that the PhyloCode does not govern the names of species, whose rules of availability, typification, etc., remain regulated by the requisite traditional Code of Nomenclature. The PhyloCode is controversial and has inspired considerable criticism from some taxonomists. While inaugurated decades ago, the number of supporters for widespread adoption of

740-407: The first informal definition of the group, as all ornithischians closer to Ankylosaurus than Stegosaurus . 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

777-409: The group Thyreophora , which also includes the stegosaurs , armored dinosaurs known for their combination of plates and spikes. 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

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814-453: The most important use of RegNum will be the decision of which one of a number of synonyms or homonyms will be considered accepted: the one with the lowest registration number, except in cases of conservation. (Condensed from the PhyloCode' s Preface. ) The PhyloCode grew out of a workshop at Harvard University in August 1998, where decisions were made about its scope and content. Many of

851-455: The neck, as opposed to the sister group, nodosaurids, which have three. Nodosauridae and Ankylosauridae also share the unique attribute of abundant structural fibres in both primary and secondary bone. Ankylosaurids also have an S-shaped narial passage. The most distinguishing feature of ankylosaurids is the presence of a tail club . It is made out of modified interlocking distal caudal vertebrae and enlarged, bulbous osteoderms. The "handle" of

888-420: The publication of the companion volume, Phylonyms , in 2020. The theoretical foundation of the PhyloCode was developed in a series of papers by de Queiroz and Gauthier , which was foreshadowed by earlier suggestions that a taxon name could be defined by reference to a part of a phylogenetic tree . Whenever possible, the writers of the PhyloCode used the draft BioCode , which attempted to unify

925-496: The rank-based approach into a single code, as a model. Thus, the organization of the PhyloCode , some of its terminology, and the wording of certain rules are derived from the BioCode . Other rules are derived from one or more of the rank-based codes, particularly the botanical and zoological codes. However, many rules in the PhyloCode have no counterpart in any code based on taxonomic ranks because of fundamental differences in

962-472: The role of the advisory group that oversaw the earlier stages of development of the PhyloCode. The Second International Phylogenetic Nomenclature Meeting took place from June 28, 2006, to July 2, 2006, at Yale University ( New Haven , Connecticut , U.S.). The Third International Phylogenetic Nomenclature Meeting took place from July 21, 2008, to July 22, 2008, at Dalhousie University ( Halifax , Nova Scotia , Canada). The PhyloCode went into effect with

999-618: The rules of the PhyloCode are organized as articles, which in turn are organized as chapters. Each article may also contain notes, examples, and recommendations. Once implemented, the PhyloCode will be associated with a registration database , called RegNum , which will store all clade names and definitions that will be considered acceptable. It is hoped that this will provide a publicly usable tool for associating clade names with definitions, which could then be associated with sets of subtaxa or specimens through phylogenetic tree databases (such as TreeBASE ). As currently planned, however,

1036-448: The specifiers in a node-based definition are extant specimens or species, as in the following definition of Mammalia, a crown group is defined. (The traditional definition of Mammalia is less restrictive, including some fossil groups outside of the crown group.) PhyloCode has gone through several revisions. As of November 2023 , the current version is 6, released on the website on June 8, 2020. As with other nomenclatural codes,

1073-406: The subfamily Ankylosaurinae in 1908. Ankylosaurids are stout, solidly built, armoured dinosaurs. They possess accessory ossifications on cranial bones that cover some skull openings and form wedge-shaped, horn-like structures. Along the ankylosaurid torso are scute rows, which are filled in with smaller ossicles to create a fused shield of armour. Only two collars of armour plates can be found on

1110-448: The tail club involves the vertebrae, and requires elongated prezygapophyses to overlap at least half of the preceding vertebral centrum length. These distal caudal vertebrae also lack transverse processes and neural spines, and therefore tend to be longer than they are wide; the reverse is true for proximal caudal vertebrae. Derived ankylosaurids possess a fusion of posterior dorsal, sacral, and sometimes anterior caudal vertebrae, which forms

1147-1059: The time. They based their resulting phylogeny on characters representing cranial, post-cranial, and osteodermal anatomy, and details of synapomorphies for each recovered clade. This study placed Gargoyleosaurus and Gastonia within basal Nodosauridae, and put Cedarpelta and Liaoningosaurus as basal ankylosaurids. Huayangosaurus taibaii Stegosaurus armatus Nodosauridae Minmi paravertebra Liaoningosaurus paradoxus Cedarpelta bilbeyhallorum Gobisaurus domoculus Shamosaurus scutatus Zhongyuansaurus luoyangensis Tsagantegia longicranialis Shanxia tianzhensis "Crichtonsaurus" benxiensis Dyoplosaurus acutosquameus Pinacosaurus mephistocephalus Ankylosaurus magniventris Euoplocephalus tutus Minotaurasaurus ramachandrani Pinacosaurus grangeri Nodocephalosaurus kirtlandensis Talarurus plicatospineus Tianzhenosaurus youngi Saichania chulsanensis Tarchia gigantea In 2016, Arbour and Currie have presented

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1184-576: The traditional Ankylosauridae-Nodosauridae split, instead finding "nodosaurids" to be referrable to three separate families: Panoplosauridae , Polacanthidae , and Struthiosauridae . Sarcolestes Paw Paw juvenile Animantarx Cedarpelta Gargoyleosaurus Hoplitosaurus Niobrarasaurus Polacanthus Texasetes Patagopelta Hylaeosaurus Gastonia burgei Gastonia lorriemcwhinneyae Peloroplites Sauropelta Tatankacephalus Invictarx Silvisaurus PhyloCode The PhyloCode

1221-416: The two subclades Nodosauridae and Ankylosauridae , creating the new clade Ankylosauromorpha for all taxa closer to Ankylosaurus than Stegosaurus . 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

1258-403: The use of ranks , although it does optionally allow their use. The rank-based codes define taxa using a rank (such as genus , family , etc.) and, in many cases, a type specimen or type subtaxon . The exact content of a taxon, other than the type, is not specified by the rank-based codes. In contrast, under phylogenetic nomenclature, the content of taxa are delimited using a definition that

1295-453: 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". 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

1332-689: The workshop participants, together with several other people who subsequently joined the project, served as an advisory group. In April 2000, a draft was made public on the web and comments were solicited from the scientific community. A second workshop was held at Yale University in July 2002, at which some modifications were made in the rules and recommendations of the PhyloCode . Other revisions have been made from time to time as well. The First International Phylogenetic Nomenclature Meeting, which took place from July 6, 2004, to July 9, 2004, in Paris , France ,

1369-478: Was attended by about 70 systematic and evolutionary biologists from 11 nations. This was the first open, multi-day conference that focused entirely on phylogenetic nomenclature, and it provided the venue for the inauguration of a new association, the International Society for Phylogenetic Nomenclature (ISPN). The ISPN membership elects the Committee on Phylogenetic Nomenclature (CPN), which has taken over

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