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43-669: Iguanodontidae is a family of iguanodontians belonging to Styracosterna , a derived clade within Ankylopollexia . The clade is formally defined in the PhyloCode by Daniel Madzia and colleagues in 2021 as "the largest clade containing Iguanodon bernissartensis , but not Hadrosaurus foulkii ". Characterized by their elongated maxillae, they were herbivorous and typically large in size. This family exhibited locomotive dynamism; there exists evidence for both bipedalism and quadrupedalism within iguanodontid species, supporting

86-589: A 2024 analysis of Fonseca et al. Thescelosauridae Kulindadromeus Marginocephalia [REDACTED] Gideonmantellia Hypsilophodon [REDACTED] Tenontosauridae Rhabdodontoidea Anabisetia Diluvicursor Gasparinisaura Notohypsilophodon Elasmaria [REDACTED] Iyuku Dryosauridae CM 1949 Oblitosaurus Ankylopollexia [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Pubis (bone) The pubic bone

129-457: A diet that consisted of both gymnosperms and angiosperms , the latter of which co-evolved with the iguanodontids in the Cretaceous period. There is no consensus on the phylogeny of the group. Iguanodontidae is most frequently characterized as paraphyletic with respect to Hadrosauridae , although some researchers advocate for a monophyletic view of the family. The upper surface of

172-489: A non-avian dinosaur, rivaling that of modern mammals such as the domestic cow . They reached their apex of diversity and ecological dominance in the hadrosaurids (colloquially known as 'duck-bills'), before they were wiped out by the Cretaceous–Paleogene extinction event along with all other non- avian dinosaurs . Members are known worldwide. In 1870, Thomas Henry Huxley listed Iguanodontidae (coined by Cope

215-431: A portion of the inguinal falx (conjoined tendon of obliquus internus and transversus ), the lacunar ligament (Gimbernat's ligament), and the reflected inguinal ligament (triangular fascia). Medial to the pubic tubercle is the crest, which extends from this process to the medial end of the bone. It affords attachment to the inguinal falx, and to the rectus abdominis and pyramidalis . The point of junction of

258-418: A prominent tubercle, the pubic tubercle ( pubic spine ), which projects forward; the inferior crus of the subcutaneous inguinal ring (external abdominal ring), and the inguinal ligament (Poupart's ligament) are attached to it. Passing upward and laterally from the pubic tubercle is a well-defined ridge, forming a part of the pectineal line which marks the brim of the lesser pelvis : to it are attached

301-445: A shallow curve, in contrast to the straight ulna and radius . The ilium is thinner at the anterior end than it is at the posterior. Evidence suggests that these dinosaurs do not have plated, armored skin. In the past, Iguanodontidae became a waste-basket for any ornithopod that did not belong in either Hadrosauridae , or the now defunct Hypsilophodontidae . A number of studies suggest that Iguanodontidae as traditionally defined

344-410: A typical iguanodontid skull has a convex curve that extends from the snout to just past the orbit, where the skull flattens out to form a roughly level plane directly above the braincase. The antorbital fenestra , an opening in the skull anterior to the eye sockets, is reduced in size in iguanodontids. Their maxillae are roughly triangular, fairly flat, and sport thickened bony walls. An elongated maxilla

387-416: A year earlier ) as one of his three families of dinosaurs (alongside Megalosauridae and Scelidosauridae ), including within it the genera Iguanodon , Hypsilophodon , and Hadrosaurus , in addition to Cetiosaurus and tentatively Stenopelix . The term Ornithopoda was erected by Othniel Charles Marsh in 1881 as part of his then still ongoing investigation of the classification of Dinosauria. It

430-420: Is paraphyletic with respect to Hadrosauridae. That is, iguanodontids represent successive steps in the acquisition of advanced hadrosaurian characteristics, and in this view cannot be defined as a single distinct clade . Nevertheless, some researchers have found support for a monophyletic Iguanodontidae consisting of a handful of genera. Some other studies, however, fail to recover the group. The left cladogram

473-468: Is characteristic of the family. Iguanodontid dentaries are very long as well, and become increasingly thick towards the back of the skull. A pair of bony processes extending from the maxilla insert into the jugal and lacrimal , respectively. The iguanodontid jugal has particularly deep crevices that serve to mediate this contact. The lacrimal process constitutes the rostral margin of the reduced antorbital fenestra. Iguanodontids are generally limited to

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516-406: Is made up of a body , superior ramus , and inferior ramus ( Latin : branch ). The left and right coxal bones join at the pubic symphysis . It is covered by a layer of fat – the mons pubis . The pubis is the lower limit of the suprapubic region . In the female, the pubis is anterior to the urethral sponge . The body of pubis has: The body forms the wide, strong, middle and flat part of

559-494: Is often listed as an infraorder within a suborder Ornithopoda, though Benton (2004) lists Ornithopoda as an infraorder and does not rank Iguanodontia. Traditionally, iguanodontians were grouped into the superfamily Iguanodontoidea and family Iguanodontidae . However, phylogenetic studies show that the traditional "iguanodontids" are a paraphyletic grade leading up to the hadrosaurs (duck-billed dinosaurs). Groups like Iguanodontoidea are sometimes still used as unranked clades in

602-399: Is thought that iguanodontids were primarily quadrupedal but could optionally walk on two limbs. The ossification of tendons along the neural arches may have played a role in facilitating the dynamic pedality of iguanodontids, as the ossified tendons could help withstand the additional stress incurred on the backbone by standing upright. Some research suggests that organism size plays a role in

645-512: Is usually given the rank of Suborder, within the order Ornithischia. While ranked taxonomy has largely fallen out of favour among dinosaur paleontologists, some researchers have continued to employ such a classification, though sources have differed on what its rank should be. Benton (2004) placed it as an infraorder within the suborder Cerapoda (originally named as an unranked clade ), while others, such as Ibiricu et al. 2010, have retained it at its traditional ranking of suborder. Iguanodontia

688-511: The Greek ornithos , ornis ("bird") and pous , podos ("feet"); this is in reference to members’ characteristic birdlike feet. They were also characterized as lacking in body armour, not developing a horny beak , having an elongated pubis (that eventually extended past the ilium ), and having a missing hole in the lower jaw (a Mandibular fenestra ). A variety of ornithopods, and related ornithischians , had thin cartilaginous plates along

731-831: The Hypsilophodontidae is problematic. The group previously consisted of all non- iguanodontian bipedal ornithischians, but a phylogenetic reappraisal has shown such species to be paraphyletic . As such, the hypsilophodont family is currently represented only by Hypsilophodon . Later ornithopods became larger, but never rivalled the incredible size of the long-necked, long-tailed sauropods that they partially supplanted. The very largest, such as Shantungosaurus , were as heavy as medium-sized sauropods (up to 23 metric tons /25 short tons ), but never grew much beyond 15 metres (50 feet). Historically, most indeterminate ornithischian bipeds were lumped in as ornithopods. Most have since been reclassified. Ornithopoda

774-410: The cervical vertebrae have ribs attached. The initial set are linear; the rest are two-headed. Tendons along the neural arches were ossified , limiting mobility in the backbone in exchange for reinforcement. A similar ossification is seen in the tail. Iguanodontids have a rod-shaped pubis that extends parallel to the ischium . The paired sternal bones are often hatchet-shaped. The humerus has

817-409: The inferior ramus of the ischium below the obturator foramen . Non- placental mammals possess osteological projections of the pubis known as epipubic bones. These evolved first among derived cynodonts , and evolved as a means of support for muscles flexing the thigh, facilitating the development of an erect gait. However, these prevent the expansion of the torso, preventing pregnancy and forcing

860-506: The theropods , to help them balance as they ran on their hind legs. Later ornithopods became more adapted to grazing on all fours; their spines curved, and came to resemble the spines of modern ground-feeders, such as the bison . As they became more adapted to eating while bent over, they became facultative quadrupeds; still running on two legs, and comfortable reaching up into trees, but spending most of their time walking or grazing on all fours. The taxonomy of dinosaurs previously ascribed to

903-645: The European Hypsilophodon and three American taxa he named himself, Camptonotus , Laosaurus , and Nanosaurus . Camptonotus was in 1885 renamed to Camptosaurus , as the original name was pre-occupied by a cricket ; the associated family followed suit, becoming Camptosauridae. In Iguanodontidae, only found in Europe, he included Iguanodon and Vectisaurus . In Hadrosauridae, he included Hadrosaurus , Cionodon , and tentatively Agathaumas . Ornithopoda means "bird feet", from

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946-530: The animal to give birth to larval young (the modern marsupial "joeys" and monotreme "puggles"). Placentals are unique among all mammals, including other eutherians , in having lost epipubic bones and having been able to develop proper pregnancy . In some groups, remnants of these pre-pubic bones can be found as os penises . The clade Dinosauria is divided into the Saurischia and Ornithischia based on hip structure , including importantly that of

989-438: The body forms part of the wall of the lesser pelvis and joints to the origin of a part of the obturator internus muscle. The superior pubic ramus is the upper of the two rami. It forms the upper edge of the obturator foramen . It extends from the body to the median plane where it joins with the ramus of the opposite side. It consists of an inner flattened part and a narrow outer prismoid portion. The upper border presents

1032-435: The crest with the medial border of the bone is called the angle; to it, as well as to the symphysis , the superior crus of the subcutaneous inguinal ring is attached. The medial border is articular; it is oval, and is marked by eight or nine transverse ridges, or a series of nipple-like processes arranged in rows, separated by grooves; they serve for the attachment of a thin layer of cartilage, which intervenes between it and

1075-414: The determination of pedality, where larger organisms are more likely to choose to walk on all fours than their smaller counterparts. Iguanodontids are low-browsing herbivores that fed extensively on gymnosperms like ferns and horsetails , especially during the early Cretaceous period. These dinosaurs were very effective as herbivores due in part to their combination of bilateral dental occlusion with

1118-443: The ground than gymnosperms; their proliferation provided a wealth of easily accessible food for the members of Iguanodontidae. [REDACTED] [REDACTED] [REDACTED] [REDACTED] Iguanodontia Ornithopoda ( / ˌ ɔːr n ə ˈ θ ɒ p ə d ə / ) is a clade of ornithischian dinosaurs , called ornithopods ( / ˈ ɔːr n ə θ ə ˌ p ɒ d z , ɔːr ˈ n ɪ θ -/ ). They represent one of

1161-518: The idea that individual organisms were capable of both locomoting exclusively with their hind limbs and locomoting quadrupedally. Iguanodontids possess hoof-like second, third, and fourth digits, and in some cases, a specialized thumb spike and an opposable fifth digit. Their skull construction allows for a strong chewing mechanism called a transverse power stroke . This, paired with their bilateral dental occlusion, made them extremely effective as herbivores. Members of Iguanodontidae are thought to have had

1204-502: The iguanodontid forelimb are close together. In some cases, it is possible that digits three and four were bound into a single structure by layers of skin, a specialized adaptation for quadruped locomotion. In addition, the wrist bones are fused into a block, and the thumb bones are fused into a spike-like point. In Iguanodon , the fifth digit is long, flexible, and opposable. On the hind limb, digits two, three, and four are wide and short, with blunt claws that resemble hooves . All of

1247-424: The interpubic fibrocartilaginous lamina. The lateral border presents a sharp margin, the obturator crest, which forms part of the circumference of the obturator foramen and affords attachment to the obturator membrane . The inferior pubic ramus is a part of the pelvis and is thin and flat. It passes laterally and downward from the medial end of the superior ramus; it becomes narrower as it descends and joins with

1290-456: The jaw. They have a thick layer of enamel over the lip-facing (labial) surface of the crown, a robust primary ridge beginning at the base of the crown, and a denticulate margin. Most members of the family have maxillary tooth crowns lanceolate in shape. The labial surface of the teeth has some grooves, while the tongue-facing (lingual) surface is smooth. Iguanodontids have lost their premaxillary teeth. The second, third, and fourth digits of

1333-408: The most successful groups of herbivorous dinosaurs during the Cretaceous . The most primitive members of the group were bipedal and relatively small-sized, while advanced members of the subgroup Iguanodontia became quadrupedal and developed large body size. Their major evolutionary advantage was the progressive development of a chewing apparatus that became the most sophisticated ever developed by

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1376-415: The outside of the ribs; in some cases, these plates mineralized and were fossilized. The function of these intercostal plates is unknown. They have been found with Hypsilophodon , Nanosaurus , Parksosaurus , Talenkauen , Thescelosaurus , and Macrogryphosaurus to date. The early ornithopods were only about 1 metre (3 feet) long, but probably very fast. They had a stiff tail, like

1419-537: The paraphyletic nature of Hypsilophodontidae . A 2017 study which named and described Burianosaurus noted that the type species Iguanodon bernissartensis must be part of the definition, and that the 2005 definition would, in their analysis, include a far larger group than intended (including Marginocephalia ). They proposed an entirely new, node-based definition: the last common ancestor of Iguanodon bernissartensis , Dryosaurus altus , Rhabdodon priscus , and Tenontosaurus tilletti . In 2021, Iguanodontia

1462-418: The pelvic girdle formed where the ischium , ilium , and pubis all meet, and into which the head of the femur inserts. The orientation and position of the acetabulum is one of the main morphological traits that caused dinosaurs to walk in an upright posture with their legs directly underneath their bodies. The prepubic process is a bony extension of the pubis that extends forward from the hip socket and toward

1505-412: The possession of single replacement tooth at each position, although exceptions exist. The most primitive example bears positions for 13 maxillary and 14 dentary teeth. More derived forms have a larger number of positions per row. For example, I. bernissartensis is able to accommodate up to 29 maxillary and 25 dentary teeth. Iguanodontids exhibit contact between maxillary and dentary teeth upon closure of

1548-442: The pubic bone. The bodies of the left and right pubic bones join at the pubic symphysis . The rough upper edge is the pubic crest , ending laterally in the pubic tubercle . This tubercle , found roughly 3 cm from the pubic symphysis, is a distinctive feature on the lower part of the abdominal wall ; important when localizing the superficial inguinal ring and the femoral canal of the inguinal canal . The inner surface of

1591-421: The pubis. An opisthopubic pelvis is a condition where the pubic bone extends back towards the tail of the animal, a trait that is also present in birds. In a propubic pelvis, however, the pubic bone extends forward towards the head of the animal, as can be seen in the typical saurischian pelvic structure pictured below. The acetabulum , which can be thought of as a "hip-socket", is an opening on each side of

1634-470: The scientific literature, though many traditional "iguanodontids" are now included in the more inclusive group Hadrosauroidea . Iguanodontia was originally phylogenetically defined, by Paul Sereno , in 1998, as the most inclusive group containing Parasaurolophus walkeri but not Hypsilophodon foxii . Later, in 2005, he amended the definition to include Thescelosaurus neglectus as a secondary external specifier, alongside Hypsilophodon , accounting for

1677-463: The transverse power stroke of their chewing mechanism. Additionally, iguanodontids lack a rigid secondary palate , which helps to mitigate torsional stresses during occlusion, a feature that enhanced their ability to break down plant matter. Additionally, the iguanodontids co-evolved with the radiation of angiosperms in the Cretaceous period. Angiosperms typically develop more rapidly and lower to

1720-508: Was considered one of the four definite orders of dinosaurs, the others being Theropoda , Sauropoda , and Stegosauria ( Hallopoda was considered a possible fifth). He subdivided the order into three families: Camptonotidae , Iguanodontidae , and Hadrosauridae ; the former was a new name, whereas the latter two were carried over from the nomenclatures of Huxley and Edward Drinker Cope respectively. Within Camptonotidae he included

1763-590: Was given a formal definition under the PhyloCode : "The smallest clade containing Dryosaurus altus , Iguanodon bernissartensis , Rhabdodon priscus , and Tenontosaurus tilletti , provided that it does not include Hypsilophodon foxii ." Under this revised definition, Iguanodontia is limited to its traditionally included species, and if it were found to include hypsilophodonts, which were not traditionally considered iguanodontians, it would become an invalid grouping. The slightly less inclusive clade Dryomorpha

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1806-558: Was named by Paul Sereno in 1986 and given a formal definition in the PhyloCode as "the smallest clade containing Dryosaurus altus and Iguanodon bernissartensis ". This group includes basal members such as Hesperonyx , members of the family Dryosauridae , and the derived clade Ankylopollexia . In 2021, Ornithopoda was given a formal definition under the PhyloCode : "The largest clade containing Iguanodon bernissartensis but not Pachycephalosaurus wyomingensis and Triceratops horridus ." The cladogram below follows

1849-634: Was recovered in a 2015 analysis that supports a monophyletic Iguanodontidae, whereas the right cladogram from 2012 study finds the group to be paraphyletic: Camptosaurus Batyrosaurus Ouranosaurus Hadrosauroidea Barilium Iguanodon Mantellisaurus Proa Bolong Jinzhousaurus Camptosaurus Uteodon Hippodraco Theiophytalia Iguanacolossus Lanzhousaurus Kukufeldia Barilium Iguanodon Mantellisaurus Hadrosauroidea Fossilized footprints provide evidence for both quadrupedality and bipedality within iguanodontids. It

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