Triceratops is a genus of herbivorous chasmosaurine ceratopsid dinosaur that first appeared during the late Maastrichtian stage of the Late Cretaceous period, about 68 million years ago in what is now North America. It is one of the last-known non-avian dinosaur genera, and became extinct in the Cretaceous–Paleogene extinction event 66 million years ago. The name Triceratops, which literally means 'three-horned face', is derived from the Greek words trí- meaning 'three', kéras meaning 'horn', and ṓps meaning 'face'.
Liriodendron is a genus of two species of characteristically large trees, deciduous over most of their populations, in the magnolia family (Magnoliaceae).
Pachycephalosaurus is a genus of pachycephalosaurid dinosaurs. The type species, P. wyomingensis, is the only known species, but some researchers argue that there might be a second species, P. spinifer. It lived during the Late Cretaceous Period of what is now North America. Remains have been excavated in Montana, South Dakota, Wyoming, and Alberta. It was a herbivorous creature which is primarily known from a single skull and a few extremely thick skull roofs, at 22 centimetres thick. More complete fossils have been found in recent years. Pachycephalosaurus was among the last non-avian dinosaurs before the Cretaceous–Paleogene extinction event. The genus Tylosteus has been synonymized with Pachycephalosaurus, as have the genera Stygimoloch and Dracorex in recent studies.
Thescelosaurus was a genus of small neornithischian dinosaur that appeared at the very end of the Late Cretaceous period in North America. It was a member of the last dinosaurian fauna before the Cretaceous–Paleogene extinction event around 66 million years ago. The preservation and completeness of many of its specimens indicate that it may have preferred to live near streams.
The Hell Creek Formation is an intensively studied division of mostly Upper Cretaceous and some lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The formation stretches over portions of Montana, North Dakota, South Dakota, and Wyoming. In Montana, the Hell Creek Formation overlies the Fox Hills Formation. The site of Pompeys Pillar National Monument is a small isolated section of the Hell Creek Formation. In 1966, the Hell Creek Fossil Area was designated as a National Natural Landmark by the National Park Service.
The Lance (Creek) Formation is a division of Late Cretaceous rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the latest Mesozoic vertebrate faunas. The Lance Formation is Late Maastrichtian in age, and shares much fauna with the Hell Creek Formation of Montana and North Dakota, the Frenchman Formation of southwest Saskatchewan, and the lower part of the Scollard Formation of Alberta.
Pectinodon is a genus of troodontid dinosaurs from the Late Cretaceous period (66 mya). It currently contains a single valid species, Pectinodon bakkeri, known only from teeth.
Edmontosaurus annectens is a species of flat-headed and duck-billed (hadrosaurid) dinosaur from the very end of the Cretaceous Period, in what is now North America. Remains of E. annectens have been preserved in the Frenchman, Hell Creek, and Lance Formations. All of these formations are dated to the late Maastrichtian stage of the Late Cretaceous Period, representing the last three million years before the extinction of the dinosaurs. E. annectens is also found in the Laramie Formation, and magnetostratigraphy suggests an age of 69-68 Ma for the Laramie Formation. Edmontosaurus annectens is known from numerous specimens, including at least twenty partial to complete skulls, discovered in the U.S. states of Montana, South Dakota, North Dakota, Wyoming and Colorado and the Canadian province of Saskatchewan. It had an extremely long and low skull and was a large animal, up to approximately 12 metres (39 ft) in length and 5.6 metric tons in average asymptotic body mass, and may have been even larger. E. annectens exhibits one of the most striking examples of the "duckbill" snout common to hadrosaurs. It has a long taxonomic history, and specimens have at times been classified in the genera Diclonius, Trachodon, Hadrosaurus, Claosaurus, Thespesius, Anatosaurus and Anatotitan, before being grouped together in Edmontosaurus.
The Fort Union Formation is a geologic unit containing sandstones, shales, and coal beds in Wyoming, Montana, and parts of adjacent states. In the Powder River Basin, it contains important economic deposits of coal, uranium, and coalbed methane.
The Prince Creek Formation is a geological formation in Alaska with strata dating to the Early Maastrichtian stage of the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.
Brachychampsa is an extinct genus of alligatoroid, possibly a basal caiman. Specimens have been reported from New Mexico, Colorado, Wyoming, Montana, North and South Dakota, New Jersey, and Saskatchewan, though only those from Montana, Utah, and New Mexico are based on material sufficient to justify the referral. One specimen has been reported from the Darbasa Formation of Kazakhstan, although the species status is indeterminate for the fossil. The genus first appeared during the late Campanian stage of the Late Cretaceous and became extinct during the late Maastrichtian stage of the Cretaceous. Brachychampsa is distinguished by an enlarged fifth maxillary tooth in the upper jaw.
Sphenodiscus is an extinct genus of acanthoceratacean ammonite. The genus has been found from many continents and is thought to have had a large global distribution during the Maastrichtian stage of the Late Cretaceous. It was one of the last ammonoids to have evolved before the entire subclass became extinct during the Paleocene, which was directly after the Cretaceous–Paleogene extinction event.
This is an overview of the fossil flora and fauna of the Maastrichtian-Danian Hell Creek Formation.
Gamerabaena is an extinct genus of baenid turtle which existed in North Dakota during the late Cretaceous Period. It is known from a single fragmentary skull that was found in the Maastrichtian-age Hell Creek Formation. It contains the species Gamerabaena sonsalla. Gamerabaena is similar to the genus Palatobaena, but it differs in its lack of a posterior expansion of the triturating surface, a somewhat rectangular skull, and a wide angle between the maxillae. Gamerabaena also has a lingual ridge on the inner side of the jaw that is not seen in Palatobaena.
The Klondike Mountain Formation is an Early Eocene (Ypresian) geological formation located in the northeast central area of Washington state. The formation is comprised of volcanic rocks in the upper unit and volcanic plus lacustrine (lakebed) sedimentation in the lower unit. the formation is named for the type location designated in 1962, Klondike Mountain northeast of Republic, Washington. The formation is a lagerstätte with exceptionally well-preserved plant and insect fossils has been found, along with fossil epithermal hot springs.
Acheroraptor is an extinct genus of dromaeosaurid theropod dinosaur known from the latest Maastrichtian Hell Creek Formation of Montana, United States. It contains a single species, Acheroraptor temertyorum. A. temertyorum is one of the two geologically youngest known species of dromaeosaurids, the other being Dakotaraptor, which is also known from Hell Creek. A basal cousin of Velociraptor, Acheroraptor is known from upper and lower jaw material.
Anzu is a monospecific genus of caenagnathid dinosaur from North Dakota, South Dakota and Montana that lived during the Late Cretaceous in what is now the Hell Creek Formation. The type species and only species, Anzu wyliei is known from numerous skeletons that preserve cranial and postcranial elements. It was named in 2014 by Matthew C. Lamanna, Hans-Dieter Sues, Emma R. Schachner, and Tyler R. Lyson.
This timeline of hadrosaur research is a chronological listing of events in the history of paleontology focused on the hadrosauroids, a group of herbivorous ornithopod dinosaurs popularly known as the duck-billed dinosaurs. Scientific research on hadrosaurs began in the 1850s, when Joseph Leidy described the genera Thespesius and Trachodon based on scrappy fossils discovered in the western United States. Just two years later he published a description of the much better-preserved remains of an animal from New Jersey that he named Hadrosaurus.
Dakotaraptor is a potentially chimaeric genus of large dromaeosaurid theropod dinosaur that lived in North America during the Late Cretaceous period. The remains have been found in the Maastrichtian stage of the Hell Creek Formation, dated to the very end of the Mesozoic era, making Dakotaraptor one of the last surviving dromaeosaurids. The remains of D. steini were discovered in a multi-species bonebed. Elements of the holotype and referred specimens were later found to belong to trionychid turtles, and further analysis of potential non-dromaeosaurid affinities of the holotype and referred material have not yet been conducted. Phylogenetic analyses of D. steini place it in a variety of positions in the Dromaeosauridae.
This article contains papers in paleobotany that were published in 2016.
