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Multituberculates
Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the Middle Jurassic, and reached a peak diversity during the Late Cretaceous and Paleocene. They eventually declined from the mid Paleocene onwards, disappearing from the known fossil record in the late Eocene. They are the most diverse order of Mesozoic mammals with more than 200 species known, ranging from mouse-sized to beaver-sized. These species occupied a diversity of ecological niches, ranging from burrow-dwelling to squirrel-like arborealism to jerboa-like hoppers. Multituberculates are usually placed as crown mammals outside either of the two main groups of living mammals—Theria, including placentals and marsupials, and MonotremataAgustí-Antón 2002, pp 3-4—but usually as closer to Theria than to monotremes. They are considered to be clos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Catopsbaatar
''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 epoch, 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 last is the genus' most complete specimen. ''Catopsbaatar'' was a member of the family Djadochtatheriidae. The skull of ''Catopsbaatar'' was up to long and, as in other multituberculates, proportionally large. The external appearance of these animals' heads may have been similar to those of rodents. The skull ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Plagiaulacida
Plagiaulacida is a group of extinct multituberculate mammals. Multituberculates were among the most common mammals of the Mesozoic, "the age of the dinosaurs". Plagiaulacids are a paraphyletic grouping, containing all multituberculates that lie outside of the advanced group Cimolodonta. They ranged from the Middle Jurassic Period to the early Late Cretaceous of the northern hemisphere. During the Cenomanian, they were replaced by the more advanced cimolodontans. Kielan-Jaworowska and Hurum (2001) divides “Plagiaulacida” into three informal lineages, the paulchoffatiids, the plagiaulicids, and the allodontids. Allodontid line The Allodontid line may be a superfamily, Allodontoidea. Both allodontids and paulchoffatiids (below) were among the most basal of the plagiaulacids. The Allodontid line contains: The family Allodontidae is known from two genera from the Upper Jurassic Morrison Formation of North America. The family Zofiabaataridae contains a single genus, '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Plagiaulacoid
A plagiaulacoid is a type of blade-like, most often serrated, tooth present in various mammal groups, usually a premolar. Among modern species it is present chiefly on diprotodontian marsupials (specifically, Potoroidae, '' Bettongia'' and '' Burramys''), which have both the upper and lower first premolars converted into serrated blades. However, various other extinct groups also possessed plagiaulacoids. These would be multituberculates, some "Plesiadapiformes" such as '' Carpolestes'' and various metatherians such as '' Epidolops'' and various early diprotodontians. In many of these only a lower premolar became converted into a blade, while the upper premolars showed less specialisation. The various independent development of these teeth is considered a good example of convergent evolution. Multituberculates in particular probably own the most specialised of all plagiaulacoids. In early taxa, all lower premolars became plagiaulacoids, forming a "saw"-like arrangement. However, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''palaiós'' meaning "old" and the Eocene Epoch (which succeeds the Paleocene), translating to "the old part of the Eocene". The epoch is bracketed by two major events in Earth's history. The K–Pg extinction event, brought on by an asteroid impact and possibly volcanism, marked the beginning of the Paleocene and killed off 75% of living species, most famously the non-avian dinosaurs. The end of the epoch was marked by the Paleocene–Eocene Thermal Maximum (PETM), which was a major climatic event wherein about 2,500–4,500 gigatons of carbon were released into the atmosphere and ocean systems, causing a spike in global temperatures and ocean acidification. In the Paleocene, the continents of the Northern Hemisphere were still connected v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations containing land animal fossils include the Forest Marble Formation in England, the Kilmaluag Formation in Scotland,British Geological Survey. 2011Stratigraphic framework for the Middle Jurassic strata of Great Britain and the adjoining continental shelf: research report RR/11/06 British Geological Survey, Keyworth, Nottingham. the Daohugou Beds in China, the Itat Formation in Russia, and the Isalo III Formation of western Madagascar. Paleogeography During the Middle Jurassic Epoch, Pangaea began to separate into Laurasia and Gondwana, and the Atlantic Ocean formed. Eastern Laurasia was tectonically active as the Cimmerian plate continued to collide with Laurasia's southern coast, completely closing the Paleo-Tethys Ocean. A subd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Vertebrate Palaeontology (Benton)
''Vertebrate Palaeontology'' is a basic textbook on vertebrate paleontology by Michael J. Benton, published by Blackwell's. It has so far appeared in four editions, published in 1990, 1997, 2005, and 2015. It is designed for paleontology graduate courses in biology and geology as well as for the interested layman. The book is widely used, and has received excellent reviews: *"This book is a ′must′ for a biology or geology student and researcher concerned by palaeontology. It perfectly succeeds in showing how palaeobiological information is obtained". Review of 3rd edition, ''Zentrallblatt fur Geologie und Palaontologie'', 2007. *"One anticipates that Benton's ''Vertebrate Palaeontology'' will become the 'industry standard', and as such it should occupy space on the shelves of all involved in undergraduate teaching". Ivan Sansom, School of Earth Sciences, University of Birmingham. Review of the 2nd edition for the Micropalaeontological Society. *"... his expertise in a ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Euharamiyida
Euharamiyida also known as Eleutherodontida, is clade of early mammals or mammal-like cynodonts from the Middle Jurassic to Early Cretaceous of Eurasia and possibly North America. The group is sometimes considered a sister group to Multituberculata, or part of an earlier divergence within the synapsid line. It is disputed whether or not they are related to the Haramiyids from the Late Triassic, such as '' Haramiyavia''. The morphology of their teeth indicates that they were herbivorous or omnivorous. Some members of the group are known to be arboreal, including gliding forms similar to modern flying squirrels or colugos. Evolution The position of euharamyidans is contested. They are either considered crown group mammals as members of Allotheria, related to multituberculates, or they are considered to stem-group mammals within the Mammaliaformes. The position is often dependent on the relationships of euharamiyids to the Late Triassic haramiyids such as '' Haramiyavia'' and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Gondwanatheria
Gondwanatheria is an extinct group of mammaliaforms that lived in parts of Gondwana, including Madagascar, India, South America, Africa and Antarctica during the Upper Cretaceous through the Paleogene (and possibly much earlier, if '' Allostaffia'' is a member of this group). Until recently, they were known only from isolated teeth, a few lower jaws, two partial skulls and one complete cranium. They are generally considered to be closely related to the multituberculates and likely the euharamiyidians, well known from the Northern Hemisphere, with which they form the clade Allotheria. Classification For several decades the affinities of the group were not clear, being first interpreted as early xenarthrans, or "toothless" mammals similar to the modern anteater. A variety of studies have placed them as allotheres related to multituberculates, possibly even true multituberculates, closer to cimolodonts than " plagiaulacidans" are. However, a more recent study recovered th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Diastema (dentistry)
A diastema (plural diastemata, from Greek διάστημα, space) is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars. More colloquially, the condition may be referred to as gap teeth or tooth gap. In humans, the term is most commonly applied to an open space between the upper incisors (front teeth). It happens when there is an unequal relationship between the size of the teeth and the jaw. Diastemata are common for children and can exist in adult teeth as well. In humans Causes 1. Oversized Labial Frenulum: Diastema is sometimes caused or exacerbated by the action of a labial frenulum (the tissue connecting the lip to the gum), causing high mucosal attachment and less attached keratinized tissue. This is more prone to recession or by tongue thrusting, which can push the teeth apart. 2. Periodontal Disease: Periodontal disease, also known as gum disease, can result in bone los ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Allotheria
Allotheria (meaning "other beasts", from the Greek , '–other and , '–wild animal) is an extinct branch of successful Mesozoic mammals. The most important characteristic was the presence of lower molariform teeth equipped with two longitudinal rows of cusps. Allotheria includes Multituberculata, Gondwanatheria (which may be part of Multituberculata, as the sister group to Cimolodonta), and probably Haramiyida, although some studies show them to be more basal mammaliaforms rather than true mammals, therefore differing from true allotheres significantly. Allotheres also had a narrow pelvis, indicating that they gave birth to tiny helpless young like marsupials or laid eggs and gave milk to feed their young like monotremes do. This is a feature of all non-placental mammals. Interpretations When he first identified Allotheria in 1880, Othniel Marsh regarded this group as an order within Marsupialia. However, in 1997 McKenna and Bell classified Allotheria as an infraclass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Taeniolabis NT Small
''Taeniolabis'' ("banded incisor") is a genus of extinct multituberculate mammal from the Paleocene of North America. Description It is the largest known member of the extinct order Multituberculata, as well as the largest non-therian mammal: ''T. taoensis'', a species known from Danian deposits in the Denver Formation of Colorado, possibly exceeds 100 kg. Taxonomy It is within the suborder of Cimolodonta and is a member of the superfamily Taeniolabidoidea. The genus was named by Edward Drinker Cope in 1882. Species have also been placed with the genera ''Catopsalis'' and ''Polymastodon''. The species ''Taeniolabis lamberti'' was named by N.B. Simmons in 1987. It has been found in the Puercan (Paleocene)-age Tullock Formation of Montana. It is not quite as large as ''T. taoensis'', but still a hefty size for a multituberculate. The species ''Taeniolabis taoensis'' was named by Cope E.D. in 1882. It is also known as ''Catopsalis pollux'' (Cope, 1882); ''Polymastodo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |