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Lancian
The Lancian was a North American faunal stage of the Late Cretaceous. It was the final stage of the Cretaceous period in North America, lasting from approximately 70.6 to 66 million years ago. Geology Terrestrial sedimentary strata from the Judithian to the Lancian are generally regressive throughout the entire sequence, so the preserved changes in fossil communities represent not only phylogenetic changes but ecological zones from the submontane habitats to near-sea level coastal habitats. Paleobiogeography By the Lancian, the crested hadrosaurs are no longer the dominant inhabitant of any province of western North America; the only remaining species was ''Hypacrosaurus''. Lehman records three surviving chasmosaurs, ''Triceratops,'' ''Torosaurus'' and '' Nedoceratops'', with the possibility of the recently discovered '' Ojoceratops, Regaliceratops and'' ''Bravoceratops''. It has recently been suggested that ''Triceratops'' and ''Torosaurus'' may be synonymous, though this is st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triceratops
''Triceratops'' ( ; ) is a genus of Chasmosaurinae, chasmosaurine Ceratopsia, ceratopsian dinosaur that lived during the late Maastrichtian age of the Late Cretaceous Period (geology), period, about 68 to 66 million years ago on the island continent of Laramidia, now forming western North America. It was one of the last-known non-avian dinosaurs and lived until the Cretaceous-Paleogene extinction event, Cretaceous–Paleogene extinction event 66 million years ago. The name ''Triceratops'', which means 'three-horned face', is derived from the Ancient Greek, Greek words () meaning 'three', () meaning 'horn', and () meaning 'face'. Bearing a large bony neck frill, frill, three horns on the skull, and a large, four-legged body, exhibiting convergent evolution with bovines and rhinoceroses, ''Triceratops'' is one of the most recognizable of all dinosaurs and the best-known ceratopsian. It was also one of the largest, measuring around long and weighing up to . It shared the la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edmontosaurus Annectens
''Edmontosaurus annectens'' (meaning "connected lizard from Edmonton"), often colloquially and historically known as ''Anatosaurus'' (meaning "duck lizard"), is a species of flat-headed Saurolophinae, saurolophine hadrosaurid dinosaur from the late Maastrichtian Geologic time scale, age at the very end of the Cretaceous Period (geology), period, in what is now western North America. Remains of ''E. annectens'' have been preserved in the Frenchman Formation, Frenchman, Hell Creek Formation, Hell Creek, and Lance Formations. All of these formations are dated to the late Maastrichtian age of the Late Cretaceous period, which represents the last three million years before the Cretaceous–Paleogene boundary, extinction of the non-avian dinosaurs (between 68 and 66 million years agoHoltz, Thomas R. Jr. (2012) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'Winter 2011 Appendix./ref>). ''E. annectens'' is also found in the Laramie Formation, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alamosaurus
''Alamosaurus'' (; meaning "Ojo Alamo lizard") is a genus of titanosaurian sauropod dinosaurs containing a single known species, ''Alamosaurus sanjuanensis'', from the Maastrichtian age of the Late Cretaceous period in what is now southwestern North America. It is the only known titanosaur to have inhabited North America after the nearly 30-million year absence of sauropods from the North American fossil record and probably represents an immigrant from South America. Adults would have measured around long, tall at the shoulder and weighed up to , though some specimens indicate a larger body size. Isolated vertebrae and limb bones suggest that it could have reached sizes comparable to ''Argentinosaurus'' and '' Puertasaurus'', which would make it the absolute largest dinosaur known from North America. Its fossils have been recovered from a variety of rock formations spanning the Maastrichtian age. Specimens of a juvenile ''Alamosaurus sanjuanensis'' have been recovered from o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quetzalcoatlus
''Quetzalcoatlus'' () is a genus of azhdarchid pterosaur that lived during the Maastrichtian age of the Late Cretaceous in North America. The Type (biology), type specimen, recovered in 1971 from the Javelina Formation of Texas, United States, consists of several wing fragments and was species description, described as ''Quetzalcoatlus northropi'' in 1975 by Douglas A. Lawson, Douglas Lawson. The Generic name (biology), first part of the name refers to the Aztec serpent god of the sky, Quetzalcōātl, while the specific name, second part honors Jack Northrop, designer of a flying wing, tailless fixed-wing aircraft. The remains of a second species were found between 1972 and 1974, also by Lawson, around from the ''Q. northropi'' locality. In 2021, these remains were assigned to the name ''Quetzalcoatlus lawsoni'' by Brian Andres and (posthumously) Wann Langston Jr., Wann Langston Jr, as part of a series of publications on the genus. ''Quetzalcoatlus northropi'' has gained fame a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Faunal Stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries. Rock series are divided into stages, just as geological epochs are divided into ages. Stages are divided into smaller stratigraphic units called chronozones or substages, and added together into superstages. The term faunal stage is sometimes used, referring to the fact that the same fauna (animals) are found throughout the layer (by definition). Definition Stages are primarily defined by a consistent set of fossils ( biostratigraphy) or a consistent magnetic polarity (see paleomagnetism) in the rock. Usually one or more index fossils that are common, found worldwide, easily recognized, and limited to a single, or at most a few, stages are used to define the stage's bottom. Thus, f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Denversaurus
''Denversaurus'' (meaning "Denver lizard") is a genus of panoplosaurin nodosaurid dinosaur from the late Maastrichtian of Late Cretaceous Western North America. Although at one point treated as a junior synonym of '' Edmontonia'' by some taxonomists, current research indicates that it is its own distinct nodosaurid genus. Discovery and naming In 1986, the paleontologists Kenneth Carpenter and Brent Breithaupt described DMNH 468 which was a specimen of a late Maastrichtian nodosaurid, tentatively assigned to '' Edmontonia'' sp., discovered from the lower Hell Creek Formation of South Dakota. In 1988, Robert Thomas Bakker decided to split the genus ''Edmontonia''. The species ''Edmontonia rugosidens'' was made into a separate genus named ''Chassternbergia'' and DMNH 468 was designated as a holotype of a new genus and species. The type species of this genus was ''Denversaurus schlessmani''. The generic name referred to the Denver Museum of Natural History at Denver, Colorado ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Cretaceous
The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 Megaannum#SI prefix multipliers, Ma to 100.5 Ma. Geology Proposals for the exact age of the Barremian–Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining Anoxic event#Cretaceous, early Aptian Oceanic Anoxic Event 1a (OAE1a) was dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java Plateau, Ontong Java-Manihiki Plateau, Manihiki-Hikurangi Plateau, Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. The Onto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avisaurus
''Avisaurus'' (meaning "bird lizard") is a genus of enantiornithine avialan from the Late Cretaceous of North America. Discovery ''Avisaurus archibaldi'' was discovered in the Late Cretaceous Hell Creek Formation of North America (Maastrichtian, from c.70.6-66 million years ago), making it one of the last enantiornithids. It was collected in 1975 in the UCMP locality V73097, in Garfield County, Montana, USA. The holotype is represented by a single fossil of a tarsometatarsus in the collection of the University of California Museum of Paleontology. It has the catalog number UCMP 117600. The species name honors J. David Archibald, its discoverer, from The University of California, Berkeley. It was initially described as the left tarsometatarsus of a non-avian theropod by Brett-Surman and Paul in 1985. It was later redescribed as the right tarsometatarsus of an enantiornithine bird by Chiappe in 1992.Chiappe, Luis M. (1992) "Enantiornithine (Aves) Tarsometatarsi and the Avian Affinit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nodocephalosaurus
''Nodocephalosaurus'' (meaning "knob headed lizard") is a monospecific genus of ankylosaurid dinosaur from New Mexico that lived during the Late Cretaceous (late Campanian to early Maastrichtian stage, 73.49 to 73.04 Ma) in what is now the De-na-zin member of the Kirtland Formation. The type and only species, ''Nodocephalosaurus kirtlandensis'', is known only from a partial skull. It was named in 1999 by Robert M. Sullivan. ''Nodocephalosaurus'' has an estimated length of 4.5 metres (15 feet) and weight of 1.5 tonnes (3,306 lbs).Paul, G.S., 2016, ''The Princeton Field Guide to Dinosaurs 2nd Edition'', Princeton University Press It is closely related and shares similar cranial anatomy to '' Akainacephalus''. Discovery and naming In 1995, a partial skull of an ankylosaur was discovered weathering out of a grey mudstone a few hundred metres west of a new ''Parasaurolophus'' site in the De-na-zin member of the Kirtland Formation, New Mexico. Robert M. Sullivan and Thomas E. Willi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoceratopsian
Ceratopsia or Ceratopia ( or ; Greek: "horned faces") is a group of herbivorous, beaked dinosaurs that thrived in what are now North America, Asia and Europe, during the Cretaceous Period, although ancestral forms lived earlier, in the Late Jurassic of Asia. The earliest known ceratopsian, '' Yinlong downsi'', lived between 161.2 and 155.7 million years ago.Holtz, Thomas R. Jr. (2011) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'Winter 2010 Appendix./ref> The last ceratopsian species, '' Triceratops prorsus'', became extinct during the Cretaceous–Paleogene extinction event, . ''Triceratops'' is by far the best-known ceratopsian to the general public. It is traditional for ceratopsian genus names to end in "''-ceratops''", although this is not always the case. One of the first named genera was '' Ceratops'' itself, which lent its name to the group, although it is considered a ''nomen dubium'' today as its fossil remains have no disti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anagenesis
Anagenesis is the gradual evolution of a species that continues to exist as an interbreeding population. This contrasts with cladogenesis, which occurs when branching or splitting occurs, leading to two or more lineages and resulting in separate species. Anagenesis does not always lead to the formation of a new species from an ancestral species. When speciation does occur as different lineages branch off and cease to interbreed, a core group may continue to be defined as the original species. The evolution of this group, without extinction or species selection, is anagenesis. Hypotheses One hypothesis is that during the speciation event in anagenetic evolution, the original populations increases quickly, and then racks up genetic variation over long periods of time by mutation and recombination in a stable environment. Other factors, such as selection or genetic drift will have such a significant effect on genetic material and physical traits that a species can be acknowl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bearpaw Transgression
Bearpaw or Bear Paw may refer to: * Bearpaw (brand), a brand of footwear, including sheepskin boots, slippers and casual shoes * Bear-paw poppies, the genus of the poppy family Papaveraceae * Mikołaj "Bearpaw" Potocki (1595–1651), Polish nobleman * Bearpaw Mountain, a summit in Washington state *Bear Paw Mountains, mountain range in the U.S. state of Montana *Bearpaw Formation, a rock formation in the U.S. state of Montana, as well as the Canadian provinces of Alberta and Saskatchewan, named for the Bear Paw Mountains in Montana * Bear's Paw, a mountain in the U.S. state of North Carolina *a type of snowshoe *Bear Paws, a family of cookies manufactured by Dare Foods, a Canada-based food manufacturing company *'' Cotyledon tomentosa'', a species of flowering plant in the family Crassulaceae, native to South Africa, a subspecies of which is known as bear's paw, See also *Battle of Bear Paw The Battle of Bear Paw (also sometimes called Battle of the Bears Paw or Battle of the B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
