Theropoda - Wikipedia. Not to be confused with Pteropoda, marine gastropods. Theropoda ( or . Theropods were ancestrally carnivorous, although a number of theropod groups evolved to become herbivores, omnivores, piscivores, and insectivores. Theropods first appeared during the Carnian age of the late Triassicperiod 2. Ma). In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by 1. Biology. Strict carnivory has always been considered the ancestral diet for theropods as a group, and a wider variety of diets was historically considered a characteristic exclusive to the avian theropods (birds). However, discoveries in the late 2.
Fossilized specimens of early theropods known to scientists in the 1. For example, a Compsognathus longipes fossil was found with a lizard in its stomach, and a Velociraptor mongoliensis specimen was found locked in combat with a Protoceratops andrewsi (a type of ornithischian dinosaur). The first confirmed non- carnivorous fossil theropods found were the therizinosaurs, originally known as segnosaurs. First thought to be prosauropods, these enigmatic dinosaurs were later proven to be highly specialized, herbivorous theropods. Carnivorous. Carnivores are animals whose main method of getting food is to kill and eat other animals, or to scavenge their dead flesh. Typically, the word brings to. Published: 27 January 2011 (GMT+10). How many times have you come across all these fun facts about snakes for kids? These interesting facts include snake diet, habitat, reproduction and behavior. Therizinosaurs possessed large abdomens for processing plant food, and small heads with beaks and leaf- shaped teeth. Further study of maniraptoran theropods and their relationships showed that therizinosaurs were not the only early members of this group to abandon carnivory. Several other lineages of early maniraptors show adaptations for an omnivorous diet, including seed- eating (some troodontids) and insect- eating (many avialans and alvarezsaurs). Oviraptorosaurs, ornithomimosaurs and advanced troodontids were likely omnivorous as well, and some early theropods (such as Masiakasaurus knopfleri and the spinosaurids) appear to have specialized in catching fish. Some theropods, such as Baryonyx, Lourinhanosaurus, ornithomimosaurs, and birds, are known to use gastroliths, or gizzard- stones. The majority of theropod teeth are blade- like, with serration on the edges. Others are pachydont or phyllodont depending on the shape of the tooth or denticles. The morphology of the teeth is distinct enough to tell the major families apart. An investigation in July 2. Feathers or feather- like structures are attested in most lineages of theropods. However, outside the coelurosaurs, feathers may have been confined to the young, smaller species, or limited parts of the animal. Many larger theropods had skin covered in small, bumpy scales. In some species, these were interspersed with larger scales with bony cores, or osteoderms. This type of skin is best known in the ceratosaur Carnotaurus, which has been preserved with extensive skin impressions. More fully feathered theropods, such as dromaeosaurs, usually retain scales only on the feet. Some species may have mixed feathers elsewhere on the body as well. Scansoriopteryx preserved scales near the underside of the tail. Since its discovery, however, a number of other giant carnivorous dinosaurs have been described, including Spinosaurus, Carcharodontosaurus, and Giganotosaurus. This was based on evidence that theropods were the only dinosaurs to get continuously smaller, and that their skeletons changed four times as fast as those of other dinosaur species. In modern birds, the body is typically held in a somewhat upright position, with the upper leg (femur) held parallel to the spine and with the forward force of locomotion generated at the knee. Scientists are not certain how far back in the theropod family tree this type of posture and locomotion extends. During this period, theropods such as carnosaurs and tyrannosaurids were thought to have walked with vertical femurs and spines in an upright, nearly erect posture, using their long, muscular tails as additional support in a kangaroo- like tripodal stance. Studies of limb bone articulation and the relative absence of trackway evidence for tail dragging suggested that, when walking, the giant, long- tailed theropods would have adopted a more horizontal posture with the tail held parallel to the ground. Some studies support a traditional vertically oriented femur, at least in the largest long- tailed theropods. Theropod endocrania can also be reconstructed from preserved brain cases without damaging valuable specimens by using a computed tomography scan and 3. D reconstruction software. These finds are of evolutionary significance because they help document the emergence of the neurology of modern birds from that of earlier reptiles. An increase in the proportion of the brain occupied by the cerebrum seems to have occurred with the advent of the Coelurosauria and . This trait was, however, not universal: spinosaurids had well developed forelimbs, so also did many coelurosaurs. One genus, Xuanhanosaurus, has also been claimed to have been quadrupedal because of its comparatively robust forelimbs, but this is no longer thought to be likely. Some basal theropods (Herrerasaurus, Eoraptor) had four digits, and also a reduced metacarpal V. Ceratosaurians usually had four digits, while most tetanurans had three. The spinosaurids could have used their powerful forelimbs to hold fish. Some small coelurosaurus (dromaeosaurids, scansoriopterygids) are believed to have used their forelimbs to climb in trees. In humans, pronation is achieved by motion of the radius relative to the ulna (the two bones of the forearm). In saurischian dinosaurs, however, the end of the radius near the elbow was actually locked into a groove of the ulna, preventing any movement. Movement at the wrist was also limited in many species, forcing the entire forearm and hand to move as a single unit with little flexibility. This was also true of more basal theropods, such as herrerasaurs and dilophosaurs. Coelurosaurs showed a shift in the use of the forearm, with greater flexibility at the shoulder allowing the arm to be raised towards the horizontal plane, and to even greater degrees in flying birds. However, in coelurosaurs, such as ornithomimosaurs and especially dromaeosaurs, the hand itself had lost most flexibility, with highly inflexible fingers. Dromaeosaurs and other maniraptorans also showed increased mobility at the wrist not seen in other theropods, thanks to the presence of a specialized half- moon shaped wrist bone (the semi- lunate carpal) that allowed the whole hand to fold backward towards the forearm in the manner of modern birds. Molnar published a survey of pathologies in theropod dinosaur bone. He found pathological features in 2. Pathologies were found in theropods of all body size although they were less common in fossils of small theropods, although this may be an artifact of preservation. They are very widely represented throughout the different parts of theropod anatomy. The most common sites of preserved injury and disease in theropod dinosaurs are the ribs and tail vertebrae. Despite being abundant in ribs and vertebrae, injuries seem to be . The lack of preserved injuries in these bones suggests that they were selected by evolution for resistance to breakage. The least common sites of preserved injury are the cranium and forelimb, with injuries occurring in about equal frequency at each site. Most pathologies preserved in theropod fossils are the remains of injuries like fractures, pits, and punctures, often likely originating with bites. Some theropod paleopathologies seem to be evidence of infections, which tended to be confined only to small regions of the animal's body. Evidence for congenital malformities have also been found in theropod remains. Such discoveries can provide information useful for understanding the evolutionary history of the processes of biological development. Unusual fusions in cranial elements or asymmetries in the same are probably evidence that one is examining the fossils of an extremely old individual rather than a diseased one. Dinosaur swim tracks are considered to be rare trace fossils, and are among a class of vertebrate swim tracks that also include those of pterosaurs and crocodylomorphs. The study described and analyzed four complete natural molds of theropod foot prints that are now stored at the Huaxia Dinosaur Tracks Research and Development Center (HDT). These dinosaur footprints were in fact claw marks, which suggest that this theropod was swimming near the surface of a river and just the tips of its toes and claws could touch the bottom. The tracks indicate a coordinated, left- right, left- right progression, which supports the proposition that theropods were well- coordinated swimmers. The herrerasaurs existed during the early late Triassic (Late Carnian to Early Norian). They were found in North America and South America and possibly also India and Southern Africa. The herrerasaurs were characterised by a mosaic of primitive and advanced features. Some paleontologists have in the past considered the herrerasaurians to be members of Theropoda, while other theorized the group to be basal saurischians, and may even have evolved prior to the saurischian- ornithischian split. Cladistic analysis following the discovery of Tawa, another Triassic dinosaur, suggests the herrerasaurs likely were early theropods. The Coelophysoidea were a group of widely distributed, lightly built and potentially gregarious animals. They included small hunters like Coelophysis and (possibly) larger predators like Dilophosaurus. These successful animals continued from the Late Carnian (early Late Triassic) through to the Toarcian (late Early Jurassic). Although in the early cladistic classifications they were included under the Ceratosauria and considered a side- branch of more advanced theropods. They competed alongside their more anatomically advanced tetanuran relatives and—in the form of the abelisaur lineage—lasted to the end of the Cretaceous in Gondwana. The Tetanurae are more specialised again than the ceratosaurs.
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