Othnielia (Othniel’s Dinosaur)
Othnielia (Othniel's Dinosaur)
Named By : Othniel Charles Marsh - 1877
Diet : Carnivore
Size : Estimated 2 meters long
Type of Dinosaur : Euornithopod
Type Species : O. rex (type)
Found in : USA
When it Lived : Late Jurassic, 154-142 million years ago
Othnielosaurus, a small animal of 2 meters (6.6 feet) in length and 10 kg (22 lb) in weight, was known as Othnielosaurus. Bipedal dinosaur, it had short forelimbs and longer hindlimbs. It also had large muscle attachment processes. The hands were small and had short fingers. The head was small from the partial skull and the skull of the possible specimen Barbara. It had small, leaf-shaped cheek teeth that were triangular in shape with small ridges along the front and back edges. The premaxillary teeth had less ornamentation. Othnielosaurus was similar to other hypsilophodonts and iguanodont grade ornithopods like Hypsilophodont, Thescelosaurus and Talenkauen. Thin plates were found along the ribs. These structures, called intercostal plates or cartilaginous, were originally cartilaginous.
Othnielosaurus was previously known as Nanosaurus and Laosaurus. It has been commonly regarded as a Hypsilophodont, ornithopod. This is a member of a small and fuzzy group of herbivorous dinosaurs that are small and run on their own. Robert Bakker and his colleagues challenged this view. In 1990. They described the new taxon Drinker nisti and split Othnielia in two species (O. rex, O. consors), and classified “othnieliids” as being more basal than hypsilophodontids. Recent analyses have suggested that a paraphyletic Hypsilophodontidae has been identified. However, Drinker is controversial as virtually nothing has been published about it since its original description. Othnielosaurus has been sometimes linked to other basal ornithopods, including Hexinlusaurus. Hexinlusaurus is considered by at least one author to have been a species Othnielia, O. multidens. Recent studies support the hypothesis that Othnielosaurus may be more basal than traditional hypsilophodonts. However, we can remove the genus of Ornithopoda as well as the larger Cerapoda group, which includes horned dinosaurs or domeheaded dinosaurs.
O.C. Marsh identified several genera and species in the late 19th-century that were recognized as hypsilophodonts and hypsilophodonts. These included Nanosaurus agilis, Laosaurus celer and L. consors. Thistaxonomy has been complicated and many revisions have been made over the years. Marsh published two different species of Nanosaurus in 1877. They were named based on partial remains taken from the Morrison Formation atGarden Park, Colorado. N. agilis was described in one paper, based upon YPM 1913. It had remains that included impressions of a dentary and postcranial bits such as an ilium and shin bones. Marsh also named N. rex, a different species, based on YPM1915 (also known as 1925 in Galton 2007, 2007), a complete thighbone. Both species were considered small animals (“fox-sized”) by Marsh. This genus was assigned to the now-defunct family Nanosauridae. On material collected from Como Bluff by Samuel Wendell Williston, Wyoming, he named the new species Laosaurus in the following year. L. celer was the first species to be named. It was based on portions of 11 vertebrae (YPM1875); L. gracilis was the second. This species was originally based upon a back centrum, a caudal centrum and a part of an ulna. A 1983 review by Peter Galton found that the specimen now has thirteen back, eight caudal centers, and portions of both hindlimbs. Marsh established L. consors in 1894, for YPM1882. It consists of a large part of an articulated skeleton, and at least one additional individual. The skull was not preserved completely, and the fact the vertebrae were only represented by centra suggests that it was a partially grown individual. Galton (1983), notes that a lot of the mounted skeletons were either plastered or painted. These animals were not subject to professional attention until the 1970s or 1980s when Peter Galton published a series on many of the “hypsilophodonts”. Jim Jensen and he described a partially skeleton in 1973 (BYU ESM 163 at Galton, 2007, missing the head, hands and tail of Nanosaurus (?). Other collectors had damaged the rex before he described it. He had already determined that Nanosaurus agilis was different than N. rex, and that the new skeleton was very different, so he named Othnielia N. rex. Although the 1977 reference was buried in a paper about the transcontinental species Dryosaurus, it did give Laosaurus consors to the new genus and L. gracilis as nomen nudum. Drinker’s publication further complicated the matter. Galton recently reevaluated Morrison Formation Ornithischians in 2007. He concluded that the femur upon which “Nanosaurus”, rex (and by extension Othnielia), is based was not diagnostic. He re-assigned the BYU Skelet to Laosaurus consors which is based more diagnostic material. Because the genus Laosaurus was also built on non-diagnostic material, Galton gave L. consors its own Genus, Othnielosaurus. In practical terms, Othnielosaurus consors is what was once known as Othnielia. Othnielia, which is not synonym for Othnielosaurus because they were based on different specimens, was renamed Othnielosaurus consors. The older name, however, retained the original femur. The current status of the different species is: Nanosaurus gigas is a possible basal odontopod, Othnielia is a dubious basal odontopod, Othnielia is a dubious basal odontopod, Othtielia is a tentatively valid taxon, Drinker nisti, L. consors, L. celer, and L. gracilis remain dubious.
Othnielosaurus, a smaller member of the Morrison Formation dinosaur fauna was compared to the giantsauropods. The Morrison Formation can be described as semiarid with distinct dry and wet seasons and flat floodplains. The vegetation ranged from river-lined gallery forests of conifers, treeferns, and rare trees to fern savannas containing rare trees. It is a great fossil hunting ground that holds fossils of green alga, fungi and mosses, horsetails and ferns, cycads as well as ginkgoes. Other fossils discovered include bivalves, snails, ray-finned fishes, frogs, salamanders, turtles, sphenodonts, lizards, terrestrial and aquatic crocodylomorphans, several species of pterosaur, numerous dinosaur species, and early mammals such as docodonts,multituberculates, symmetrodonts, and triconodonts. The Morrison is home to such dinosaurs as the Saurophaganax and Ceratosaurus theropods, Allosaurus and Torvosaurus, the Sauropods Brachiosaurus and Camarasaurus and Brontosaurus thesauropods Apatosaurus and Brachiosaurus and the Sauropods Apatosaurus and Brachiosaurus and the Ornithischians Camptosaurus and Dryosaurus and Stegosaurus and Dryosaurus and Dryosaurus and Dryosaurus and Dryosaurus and Dryosaurus and Dryosaurus. Othnielosaurus can be found in stratigraphic zones 2-5.
Othnielosaurus is usually interpreted as one of the hypsilophodonts, a small, swift herbivore. Bakker (1986), however, interpreted the related Nanosaurus to be an omnivore. Although this idea has received some support from the public, it is not supported in the official literature. To test this hypothesis, more skull remains will need to be described.