Instruct: Given a question, retrieve passages that can help answer the question.
Query: When did mososaurs live?
Mosasaurs (from Latin "Mosa" meaning the 'Meuse river', and Greek σαύρος "sauros" meaning 'lizard') are an extinct group of large marine reptiles containing 38 genera in total. Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. Mosasaurs probably evolved from an extinct group of aquatic lizards known as aigialosaurs in the Early Cretaceous. During the last 20 million years of the Cretaceous period (Turonian-Maastrichtian ages), with the extinction of the ichthyosaurs and pliosaurs, mosasaurs became the dominant marine predators. They became extinct as a result of the K-Pg event at the end of the Cretaceous period, about 66 million years ago.
"Sinosauropteryx" lived in what is now northeastern China during the early Cretaceous period. It was among the first dinosaurs discovered from the Yixian Formation in Liaoning Province, and was a member of the Jehol Biota. Well-preserved fossils of this species illustrate many aspects of its biology, such as its diet and reproduction.
Recent molecular phylogenetic studies suggest that most placental orders diverged late in the Cretaceous period, about 100 to 85 million years ago, but that modern families first appeared later, in the late Eocene and early Miocene epochs of the Cenozoic period. Fossil-based analyses, on the contrary, limit the placentals to the Cenozoic. Many Cretaceous fossil sites contain well-preserved lizards, salamanders, birds, and mammals, but not the modern forms of mammals. It is likely that they simply did not exist, and that the molecular clock runs fast during major evolutionary radiations. On the other hand, there is fossil evidence from of hoofed mammals that may be ancestors of modern ungulates.
Alamosaurus (; meaning "Ojo Alamo lizard") is a genus of titanosaurian sauropod dinosaurs, containing a single known species, Alamosaurus sanjuanensis, from the late Cretaceous Period of what is now southern North America. Isolated vertebrae and limb bones indicate that it reached sizes comparable to "Argentinosaurus" and "Puertasaurus", which would make it the largest dinosaur known from North America. Its fossils have been recovered from a variety of rock formations spanning the Maastrichtian age of the late Cretaceous period. Specimens of a juvenile "Alamosaurus sanjuanensis" have been recovered from only a few meters below the Cretaceous-Paleogene boundary in Texas, making it among the last surviving non-avian dinosaur species.
In the hall representing the Cretaceous period, which is the last period of the Mesozoic era from 145 to 66 million years ago, the displays relate to the biological and social habits of dinosaurs, reasons for their extinction by the end of the Cretaceous period, that are attributed to meteorite, volcanic eruptions and intense geographic and climatic changes. Evolution of birds inferred as theropods evolving from the non-avian dinosaurs are represented by the "Archaeopteryx" (a prehistoric bird) and dinosaurs such as the "Deinonychus" or the "Dromaeosaurus".
The Morrison Formation is a sequence of shallow marine and alluvial sediments which, according to radiometric dating, ranges between 156.3 million years old (Ma) at its base, to 146.8 million years old at the top, which places it in the late Oxfordian, Kimmeridgian, and early Tithonian stages of the Late Jurassic period. This formation is interpreted as a semiarid environment with distinct wet and dry seasons. The Morrison Basin where dinosaurs lived, stretched from New Mexico to Alberta and Saskatchewan, and was formed when the precursors to the Front Range of the Rocky Mountains started pushing up to the west. The deposits from their east-facing drainage basins were carried by streams and rivers and deposited in swampy lowlands, lakes, river channels and floodplains. This formation is similar in age to the Solnhofen Limestone Formation in Germany and the Tendaguru Formation in Tanzania. In 1877 this formation became the center of the Bone Wars, a fossil-collecting rivalry between early paleontologists Othniel Charles Marsh and Edward Drinker Cope.
Dimetrodon ( or , meaning "two measures of teeth") is an extinct genus of synapsids that lived during the Cisuralian (Early Permian), around 295–272 million years ago (Ma). It is a member of the family Sphenacodontidae. The most prominent feature of "Dimetrodon" is the large neural spine sail on its back formed by elongated spines extending from the vertebrae. It walked on four legs and had a tall, curved skull with large teeth of different sizes set along the jaws. Most fossils have been found in the southwestern United States, the majority coming from a geological deposit called the Red Beds of Texas and Oklahoma. More recently, fossils have been found in Germany. Over a dozen species have been named since the genus was first described in 1878.
The Late Cretaceous Epoch spans from 100 million to 66 million years ago. The Late Cretaceous featured a cooling trend that would continue into the Cenozoic Era. Eventually, tropical ecology was restricted to the equator and areas beyond the tropic lines featured extreme seasonal changes of weather. Dinosaurs still thrived as new species such as "Tyrannosaurus", "Ankylosaurus", "Triceratops" and Hadrosaurs dominated the food web. Whether or not Pterosaurs went into a decline as birds radiated is debated, however many families survived until the end of the Cretaceous, alongside new species such as the gigantic "Quetzalcoatlus". Marsupials evolved within the large conifer forests as scavengers. In the oceans, Mosasaurs ruled the seas to fill the role of the ichthyosaurs, and huge plesiosaurs, such as "Elasmosaurus", evolved. Also, the first flowering plants evolved. At the end of the Cretaceous, the Deccan Traps and other volcanic eruptions were poisoning the atmosphere. As this was continued, it is thought that a large meteor smashed into Earth, creating the Chicxulub Crater creating the event known as the K-T Extinction, the fifth and most recent mass extinction event, during which 75% of life on Earth became extinct, including all non-avian dinosaurs. Every living thing with a body mass over 10 kilograms became extinct, and the age of the dinosaurs came to an end.
Pteranodon (; from Greek πτερόν ( pteron, "wing") and ἀνόδων (anodon, "toothless") is a genus of pterosaur that included some of the largest known flying reptiles, with wingspans over 8 meters (26 feet). They lived during the late Cretaceous geological period of North America in present-day Kansas, Alabama, Nebraska, Wyoming, and South Dakota. More fossil specimens of "Pteranodon" have been found than any other pterosaur, with about 1,200 specimens known to science, many of them well preserved with nearly complete skulls and articulated skeletons. It was an important part of the animal community in the Western Interior Seaway.
Hurum, Zhe-Xi Luo, and Kielan-Jaworowska suggested in 2006 that the spurs on the ankles of Mesozoic mammals (such as "Catopsbaatar") were homologous with those of monotremes, and were a basal (or "primitive") feature lost by later therian mammals. The male platypus uses the spur to deliver venom from a gland, but it is unknown if the extinct groups were venomous as well. Mesozoic mammals were mostly small (with exceptions such as the fox-sized "Repenomamus") and, although they were too small to be prey for large theropod dinosaurs, smaller theropods, large lizards, crocodiles, and birds could have fed on them. For example, mammal jaws have been found in the abdomen of a specimen of the small theropod "Sinosauropteryx"; the jaws belonged to "Zhangheotherium", which also had spurs, and the multituberculate "Sinobaatar". Since dinosaurs dominated Earth during the Mesozoic, this period has been called the "dark ages" of mammalian history. The spur, which would have been more effective if venomous, was probably used as a defensive weapon by small, early mammals. It could also have been used during intraspecific competition or predation.
The pelvic bones of "Catopsbaatar" specimen PM120/107 may not have been fused because fusion occurred late in development, because it was a sexually dimorphic feature only occurring in males (unfused pelvic bones might have enabled expansion of the birth canal in females), or pelvic fusion may be a taxonomic difference between "Catopsbaatar" and other multituberculates. Unlike with other mammals, the pelvis of multituberculates was very narrow; in other genera where the pelvis is known, each half of the pubis and ischium were fused together, forming a keel. The length and rigidity of the keel indicate that the pelvis could not have spread during birth. Because there would be little space for the passage of an egg (egg-laying monotremes have wide ischial archs), Kielan-Jaworowska suggested in 1979 that multituberculates were viviparous (gave live birth) and that the newborns were extremely small—similar to those of marsupials.
An intertwined subject to the taxonomy which has been noted and studied has been the size and ontogeny (growth and development) of the individuals represented. Individuals of multiple sizes are represented in the sample, but overall they represent smaller animals than the hadrosaurs known from Asian and North American species. Despite this, a small number of individuals falling into the adult size ranges of other hadrosaurs are indicated by isolated elements, such as femurs. Multiple hypotheses have been put forward to explain this: firstly, juvenile individuals may have been the dominant life stage living in the area where the bonebed was preserved, due to ecological differences over lifespan; secondly, it's possible they represent dwarfed animals dominating the environment relative to rare a larger species; lastly, it's possible the large individuals were comparative giants of a single dwarfed species, near the extreme end of individual variation in the species. The 2015 analysis of hadrosaur dentaries from the Pyrenees found two morphotypes to be present in the bonebed, so they favored the second hypothesis. The more in-depth 2018 study used histological analysis in order to assess the age of different individuals, using tibiae. Of the several tibiae tested, four (between long) were identified as juveniles between the ages of one and three based on comparisons to tissue patterns in other ornithopods, and three more were found to likely be juveniles based on similarities to the former four. The eighth ( long) and ninth ( long) were found to belong to an early adult and subadult individual respectively. A femur was found to share subadult growth features with the subadult tibia. Three tibiae (, , and around respectively) were found to belong to adult individuals. Growth trajectory was found to be consistent between the tibiae, supporting the idea that the site represents a large variety of age stages of a single species.
On occasion, the bone of a fossilised predator is preserved well enough to retain recognizable proteins that belong to the species it consumed when alive. Stable isotope analysis of these proteins has shown that "Smilodon" preyed mainly on bison and horses, and occasionally ground sloths and mammoths, while "Homotherium" often preyed on young mammoths and other grazers such as pronghorn antelope and bighorn sheep when mammoths were not available.
Josephoartigasia monesi, an extinct species of South American caviomorph rodent, is the largest rodent known, and lived from about 4 to 2 million years ago during the Pliocene to early Pleistocene. The species is one of two in the genus "Josephoartigasia", the other being "J. magna". "J. monesi" is sometimes called the giant pacarana, after its closest living relative, the pacarana ("Dinomys branickii") in the family Dinomyidae. The species may have weighed a ton, considerably larger than any living rodent.
Tsintaosaurini is a tribe of basal lambeosaurine hadrosaurs native to Eurasia. It currently contains only "Tsintaosaurus" (from Shandong, east China) and "Pararhabdodon" (from Spain and France).
"Koutalisaurus", also known from late Cretaceous Spain and formerly referred to "Pararhabdodon" 
, may also be a tsintaosaurin because of its association with the latter genus; some recent work also suggests it may indeed be referrable to "Pararhabdodon".
During the upper Triassic period, about 210 million years ago, the region around Frick was a dry lowland with flat hills and small depressions. During the rainy season, the depressions filled with water and dinosaurs congregated around the ponds. When they died, their bodies were covered by the mud in the ponds and fossilized, creating rich fossil beds in Frick. The first Plateosaurus fossils were discovered in 1961 and further excavations during the following decades have discovered numerous fossils. In 2006, the only Coelophysoidea (a small flesh-eating dinosaur species) fossil in Switzerland, was found by an amateur paleontologist in Frick.
Catopsbaatar is a genus of multituberculate, an extinct order of rodent-like mammals. It lived in what is now Mongolia during the late Campanian age of the Late Cretaceous Period, about 72 million years ago. The first fossils were collected in the early 1970s, and the animal was named as a new species of the genus "Djadochtatherium " in 1974, "D. catopsaloides". The specific name refers to the animal's similarity to the genus "Catopsalis". The species was moved to the genus "Catopsalis" in 1979, and received its own genus ("Catopsbaatar", Greek and Mongolian for "visible hero") in 1994. Five skulls, one molar, and one skeleton with a skull are known; the latter is the genus' most complete specimen. "Catopsbaatar" was a member of the family Djadochtatheriidae.
The first publicized discovery of a partial fossil mosasaur skull in 1764 by quarry workers in a subterranean gallery of a limestone quarry in Mount Saint Peter, near the Dutch city of Maastricht, preceded any major dinosaur fossil discoveries, but remained little known. However, a second find of a partial skull drew the Age of Enlightenment's attention to the existence of fossilized animals that were different from any known living creatures. When the specimen was discovered between 1770 and 1774, Johann Leonard Hoffmann, a surgeon and fossil collector, corresponded about it with the most influential scientists of his day, making the fossil famous. The original owner, though, was Godding, a canon of Maastricht cathedral.
Rhizosmilodon is an extinct genus of saber-tooth cat of the subfamily Machairodontinae that lived during the Early Pliocene and was discovered in the U.S. state of Florida. Comparable in size to a medium-sized modern jaguar at about 165 lb. in weight, fossils of "Rhizosmilodon" are known only from Florida. The best specimens for this species are its lower jaw and teeth, which carry intermediate characteristics between advanced forms such as "Smilodon" and primitive forms such as "Paramachairodus". It was likely an ambush predator, preying on animals such as deer, tapirs and horses.
Smilodon is a genus of the extinct machairodont subfamily of the felids. It is one of the most famous prehistoric mammals, and the best known saber-toothed cat. Although commonly known as the saber-toothed tiger, it was not closely related to the tiger or other modern cats. "Smilodon" lived in the Americas during the Pleistocene epoch (2.5 mya–10,000 years ago). The genus was named in 1842, based on fossils from Brazil. Three species are recognized today: S. gracilis, S. fatalis, and S. populator. The two latter species were probably descended from "S. gracilis", which itself probably evolved from "Megantereon". The hundreds of individuals obtained from the La Brea Tar Pits in Los Angeles constitute the largest collection of "Smilodon" fossils.
The Middle Stone Age (or MSA) was a period of African prehistory between the Early Stone Age and the Later Stone Age. It is generally considered to have begun around 280,000 years ago and ended around 50–25,000 years ago. The beginnings of particular MSA stone tools have their origins as far back as 550–500,000 years ago and as such some researchers consider this to be the beginnings of the MSA. The MSA is often mistakenly understood to be synonymous with the Middle Paleolithic of Europe, especially due to their roughly contemporaneous time span, however, the Middle Paleolithic of Europe represents an entirely different hominin population, "Homo neanderthalensis", than the MSA of Africa, which did not have Neanderthal populations. Additionally, current archaeological research in Africa has yielded much evidence to suggest that modern human behavior and cognition was beginning to develop much earlier in Africa during the MSA than it was in Europe during the Middle Paleolithic. The MSA is associated with both anatomically modern humans ("Homo sapiens") as well as archaic "Homo sapiens", sometimes referred to as "Homo helmei". Early physical evidence comes from the Gademotta Formation in Ethiopia, the Kapthurin Formation in Kenya and Kathu Pan in South Africa.
"Sinosauropteryx" was a small theropod with an unusually long tail and short arms. The longest known specimen reaches up to in length, with an estimated weight of It was a close relative of the similar but older genus "Compsognathus", both genera belonging to the family Compsognathidae. Only one species of "Sinosauropteryx" has been named: "S. prima", meaning "first" in reference to its status as the first feathered non-avialian dinosaur species discovered. Three specimens have been described. The third specimen previously assigned to this genus represents either a second, as-yet unnamed species or a distinct, related genus.
The presence of young mosasaurs in the formation suggests that mosasaurs were viviparous and gave birth hundreds of miles out to sea, as Niobrara was in the middle of the Western Interior Seaway at the time. Juveniles would have been vulnerable to predation by the many large mid-ocean predators, so it is likely that mosasaurs lived in groups rather than solitarily. Also, viviparous species tend to have much fewer offspring than egg-laying ones, so if there were few young that were born, they were most likely to have sought protection within groups in order to reach adulthood and thereby maintain the population of mosasaurs.
This timeline of mosasaur research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, and taxonomic revisions of mosasaurs, a group of giant marine lizards that lived during the Late Cretaceous Epoch. Although mosasaurs went extinct millions of years before humans evolved, humans have coexisted with mosasaur fossils for millennia. Before the development of paleontology as a formal science, these remains would have been interpreted through a mythological lens. Myths about warfare between serpentine water monsters and aerial thunderbirds told by the Native Americans of the modern western United States may have been influenced by observations of mosasaur fossils and their co-occurrence with creatures like "Pteranodon" and "Hesperornis".
Suchomimus (meaning "crocodile mimic") is a genus of spinosaurid theropod dinosaur that lived between 125 to 112 million years ago in what is now Niger, during the Aptian to early Albian stages of the Early Cretaceous Period. The animal was named and described by Paul Sereno and colleagues, based on a partial skeleton from the Erlhaz Formation. Its long and shallow skull, similar to that of a crocodile, earns it its genus name, while the species Suchomimus tenerensis alludes to the locality of its first remains, the Ténéré Desert. Some palaeontologists consider the animal to be an African species of the European spinosaurid "Baryonyx", "B. tenerensis". "Suchomimus" might also be a junior synonym of the contemporaneous spinosaurid "Cristatusaurus lapparenti", although the latter taxon is based on much more fragmentary remains.
Mesosaurs ("middle lizards") were a group of small aquatic reptiles that lived during the early Permian period, roughly 299 to 270 million years ago. Mesosaurs were the first known aquatic reptiles, having apparently returned to an aquatic lifestyle from more terrestrial ancestors. However, just how terrestrial mesosaur ancestors had become remains uncertain; recent research cannot establish with confidence if the first amniotes were fully terrestrial, or only amphibious. Most authors consider mesosaurs to have been aquatic, although adult animals may have been amphibious, rather than completely aquatic, as indicated by their moderate skeletal adaptations to a semi-aquatic lifestyle. Similarly, their affinities are uncertain; they may be either the most basal sauropsids, or among the most basal parareptiles.