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Ankylopollexia
Ankylopollexia is an extinct clade of ornithischian dinosaurs that lived from the Late Jurassic to the Late Cretaceous. It is a derived clade of iguanodontian ornithopods and contains the subgroup Styracosterna. The name stems from the Greek word, "ankylos", mistakenly taken to mean stiff, fused (in fact the adjective means bent or curved; used of fingers, it can mean hooked), and the Latin word, "pollex", meaning thumb. Originally described in 1986 by Sereno, a most likely synapomorphic feature of a conical thumb spine defines the clade.
First appearing around 156 million years ago, in the Jurassic, Ankylopollexia became an extremely successful and widespread clade during the Cretaceous, and were found around the world. The group died out at the end of the Maastrichtian. They grew to be quite large, comparable to some carnivorous dinosaurs and they were universally herbivorous.
Ankylopollexians varied greatly in size over the course of their evolution.[citation needed]. Jurassic genus Camptosaurus was small, no more than 5 metres (16 ft) in length and half a tonne in weight. The largest known ankylopollexian, dating to the late Campanian age (around 70 million years ago), belonged to the hadrosaurid family, and is named Shantungosaurus. It was around 14.7 metres (48 ft) to 16.6 metres (54 ft) in length and weighed, for the largest individuals, up to 16 tonnes (18 short tons).
Primitive ankylopollexians tended to be smaller as compared to the larger, more derived hadrosaurs. There are, however, exceptions to this trend. A single track from a large ornithopod, likely a relative of Camptosaurus, was reported from the Lourinhã Formation, dating to the Jurassic in Portugal. The corresponding animal had an estimated hip height of around 2.8 metres (9.2 ft), much larger than the contemporary relative Draconyx. The primitive styracosternan Iguanacolossus was named for its distinct robustness and large size, likely around 9 metres (30 ft) in length.[citation needed] Regarding hadrosaurs, one of the more basal members of Hadrosauroidea, the Chinese genus Bolong, is estimated to have been around 200 kilograms (440 lb). Another exception of this trend is Tethyshadros, a more derived genus of Hadrosauroidea. Estimated to have weighed 350 kilograms (770 lb), Tethyshadros have been found only on certain islands in Italy. Its diminutive size is explained by insular dwarfism. In addition a 44 cm scapula belonging to an ankylopollexian has been found in the Lourinhã Formation the length of the scapula indicates an animal similar in size to Camptosaurus.
About 157 million years ago, Ankylopollexia and Dryosauridae are believed to have split into separate evolutionary branches. Originally named and described in 1986 by Paul Sereno, Ankylopollexia would receive a phylogenetic definition in a later paper by Sereno in 2005. In the 1986 paper, the groups Camptosauridae and Styracosterna were used to define the clade, but in the 2005 paper, a phylogenetic definition was given: the last common ancestor of the species Camptosaurus dispar and Parasaurolophus walkeri and all its descendants. Ankylopollexia would receive a formal PhyloCode definition as "the smallest clade containing Camptosaurus dispar and Iguanodon bernissartensis". This clade contains the two subclades Camptosauridae and Styracosterna, which are both defined using Camptosaurus dispar and Iguanodon bernissartensis, creating a node-stem triplet with Ankylopollexia.
The cladogram below follows the phylogenetic analysis of Bertozzo et al. (2017).
The neurobiology of ankylopollexians has been studied as far back as 1871, when a well preserved cranium (specimen NHMUK R2501) discovered in September 1869 from the Wealden Group on the Isle of Wight and tentatively referred to the genus Iguanodon was described by John Hulke. He noted that due to the lesser correlation of the shape of the brain and wall of cranial cavity in reptiles, any deduction of the shape of the brain of the animal would be approximate. The referral of this skull was reinforced in a later study, published in 1897. It was here inquired that the brain of the dinosaur may have been more closely associated to the cavity than that of modern reptiles, and so an endocast was created and studied. This was not the first endocast of an ankylopolloxian brain, for in 1893, the skull of a Claosaurus annectens (today referred to the genus Edmontosaurus) was used by Othniel Charles Marsh to create a cast of the brain cavity. Some basics remarks were made, including the small size of the organ, but interpreting minute features of the organ was noted to be difficult. The 1897 paper noted the similarity of the two endocasts.
Hadrosaurs have been noted as having the most complex brains among ankylopollexians, and indeed among ornithischian dinosaurs as a whole. The brains of a large variety of taxa have been studied. John Ostrom, would, in 1961, provide what was then the most extensive and detailed review and work on hadrosaur neuro-anatomy. This area of hadrosaur study was in its infancy at this point, and only the species known today as Edmontosaurus annectens, Edmontosaurus regalis, and Gryposaurus notabilis (at that time thought to be a synonym of its relative Kritosaurus) had specimens suitable at the time to be examined (Lambeosaurus was listed as having a briefly described braincase, but this was a mistake originating in Lull and Wright (1942)). Ostrom supported the view that the brains of hadrosaurs and other dinosaurs would've likely only filled a portion of the cranial cavity, therefore hindering the ability to learn from endocasts, but noted they were still useful. He noted, similar to Marsh, noted the small predicted size of the organ, but also that it was significantly developed. A number of similarities to the brains of modern reptiles were noted.
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Ankylopollexia
Ankylopollexia is an extinct clade of ornithischian dinosaurs that lived from the Late Jurassic to the Late Cretaceous. It is a derived clade of iguanodontian ornithopods and contains the subgroup Styracosterna. The name stems from the Greek word, "ankylos", mistakenly taken to mean stiff, fused (in fact the adjective means bent or curved; used of fingers, it can mean hooked), and the Latin word, "pollex", meaning thumb. Originally described in 1986 by Sereno, a most likely synapomorphic feature of a conical thumb spine defines the clade.
First appearing around 156 million years ago, in the Jurassic, Ankylopollexia became an extremely successful and widespread clade during the Cretaceous, and were found around the world. The group died out at the end of the Maastrichtian. They grew to be quite large, comparable to some carnivorous dinosaurs and they were universally herbivorous.
Ankylopollexians varied greatly in size over the course of their evolution.[citation needed]. Jurassic genus Camptosaurus was small, no more than 5 metres (16 ft) in length and half a tonne in weight. The largest known ankylopollexian, dating to the late Campanian age (around 70 million years ago), belonged to the hadrosaurid family, and is named Shantungosaurus. It was around 14.7 metres (48 ft) to 16.6 metres (54 ft) in length and weighed, for the largest individuals, up to 16 tonnes (18 short tons).
Primitive ankylopollexians tended to be smaller as compared to the larger, more derived hadrosaurs. There are, however, exceptions to this trend. A single track from a large ornithopod, likely a relative of Camptosaurus, was reported from the Lourinhã Formation, dating to the Jurassic in Portugal. The corresponding animal had an estimated hip height of around 2.8 metres (9.2 ft), much larger than the contemporary relative Draconyx. The primitive styracosternan Iguanacolossus was named for its distinct robustness and large size, likely around 9 metres (30 ft) in length.[citation needed] Regarding hadrosaurs, one of the more basal members of Hadrosauroidea, the Chinese genus Bolong, is estimated to have been around 200 kilograms (440 lb). Another exception of this trend is Tethyshadros, a more derived genus of Hadrosauroidea. Estimated to have weighed 350 kilograms (770 lb), Tethyshadros have been found only on certain islands in Italy. Its diminutive size is explained by insular dwarfism. In addition a 44 cm scapula belonging to an ankylopollexian has been found in the Lourinhã Formation the length of the scapula indicates an animal similar in size to Camptosaurus.
About 157 million years ago, Ankylopollexia and Dryosauridae are believed to have split into separate evolutionary branches. Originally named and described in 1986 by Paul Sereno, Ankylopollexia would receive a phylogenetic definition in a later paper by Sereno in 2005. In the 1986 paper, the groups Camptosauridae and Styracosterna were used to define the clade, but in the 2005 paper, a phylogenetic definition was given: the last common ancestor of the species Camptosaurus dispar and Parasaurolophus walkeri and all its descendants. Ankylopollexia would receive a formal PhyloCode definition as "the smallest clade containing Camptosaurus dispar and Iguanodon bernissartensis". This clade contains the two subclades Camptosauridae and Styracosterna, which are both defined using Camptosaurus dispar and Iguanodon bernissartensis, creating a node-stem triplet with Ankylopollexia.
The cladogram below follows the phylogenetic analysis of Bertozzo et al. (2017).
The neurobiology of ankylopollexians has been studied as far back as 1871, when a well preserved cranium (specimen NHMUK R2501) discovered in September 1869 from the Wealden Group on the Isle of Wight and tentatively referred to the genus Iguanodon was described by John Hulke. He noted that due to the lesser correlation of the shape of the brain and wall of cranial cavity in reptiles, any deduction of the shape of the brain of the animal would be approximate. The referral of this skull was reinforced in a later study, published in 1897. It was here inquired that the brain of the dinosaur may have been more closely associated to the cavity than that of modern reptiles, and so an endocast was created and studied. This was not the first endocast of an ankylopolloxian brain, for in 1893, the skull of a Claosaurus annectens (today referred to the genus Edmontosaurus) was used by Othniel Charles Marsh to create a cast of the brain cavity. Some basics remarks were made, including the small size of the organ, but interpreting minute features of the organ was noted to be difficult. The 1897 paper noted the similarity of the two endocasts.
Hadrosaurs have been noted as having the most complex brains among ankylopollexians, and indeed among ornithischian dinosaurs as a whole. The brains of a large variety of taxa have been studied. John Ostrom, would, in 1961, provide what was then the most extensive and detailed review and work on hadrosaur neuro-anatomy. This area of hadrosaur study was in its infancy at this point, and only the species known today as Edmontosaurus annectens, Edmontosaurus regalis, and Gryposaurus notabilis (at that time thought to be a synonym of its relative Kritosaurus) had specimens suitable at the time to be examined (Lambeosaurus was listed as having a briefly described braincase, but this was a mistake originating in Lull and Wright (1942)). Ostrom supported the view that the brains of hadrosaurs and other dinosaurs would've likely only filled a portion of the cranial cavity, therefore hindering the ability to learn from endocasts, but noted they were still useful. He noted, similar to Marsh, noted the small predicted size of the organ, but also that it was significantly developed. A number of similarities to the brains of modern reptiles were noted.