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Symmetrodont
Symmetrodonta is a group of Mesozoic mammals and mammal-like synapsids characterized by the triangular aspect of the molars when viewed from above, and the absence of a well-developed talonid. The traditional group of 'symmetrodonts' ranges in age from the latest Triassic to the Late Cretaceous, but most research in the last 20-30 years has concluded that they are not a true taxonomic group, but include several unrelated branches of the mammal tree. Despite this, the name is still used informally by some researchers for convenience, usually restricted to the spalacotheriids and zhangheotheriids Martin, T., 2018. 6. Mesozoic mammals—early mammalian diversity and ecomorphological adaptations. In Mammalian evolution, diversity and systematics (pp. 199-300). De Gruyter.. There are some symmetrodonts with acutely-triangulated molar cusps (“acute-angled symmetrodonts”) that seem to form a true monophyletic group, and lasted from the Early Cretaceous to the Campanian, although Zha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chronoperates
''Chronoperates'' (meaning "time wanderer" in Greek) is an extinct genus of mammal whose remains have been found in a late Paleocene deposit in Alberta, Canada. It is represented by the type species ''Chronoperates paradoxus'' and known only from a partial left lower jaw. It was first identified in 1992 as a non-mammalian cynodont, implying a ghost lineage of over 100 million years since the previously youngest known record of non-mammalian cynodonts, which at that time was in the Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ... period (some non-mammalian cynodonts are now known to have persisted until the Early Cretaceous). Subsequent authors have challenged this interpretation, particularly as the teeth do not resemble any known non-mammalian cynodonts. ''Chronoperat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zhangheotherium
''Zhangheotherium'' is a genus of symmetrodont, an extinct order of mammals. Previously known from only the tall pointed crowned teeth, ''Zhangheotherium'', described from Liaoning Province, China, fossils in 1997, is the first symmetrodont known from a complete skeleton. It was dated to between 145 and 125 million years ago in the Cretaceous. A single species, ''Zhangheotherium quinquecuspidens'', is known. Symmetrodonts and other archaic mammals such as multituberculates and monotremes are still being debated on their taxonomical relationships. ''Zhangheotherium'' has many primitive characteristics. Among them is a spur at the foot, seen today in the modern platypus. In addition, it walked with a reptilian sprawl, like monotremes and many Mesozoic mammals such as ''Jeholodens'' and ''Repenomamus ''Repenomamus'' (Latin: "reptile" (reptilis), "mammal" (mammalis)) is a genus of opossum- to badger-sized gobiconodontid mammal containing two species, ''Repenomamus robustus'' and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zhangheotheriids
Zhangheotheriidae is a possibly paraphyletic family of " symmetrodont" mammals that is currently known from Early Cretaceous deposits in China and Russia. Five genera are currently recognized, '' Anebodon'', '' Kiyatherium'', '' Maotherium'', '' Origolestes'', and ''Zhangheotherium ''Zhangheotherium'' is a genus of symmetrodont, an extinct order of mammals. Previously known from only the tall pointed crowned teeth, ''Zhangheotherium'', described from Liaoning Province, China, fossils in 1997, is the first symmetrodont known ...''. References Symmetrodonta Prehistoric mammal families Early Cretaceous mammals of Asia {{cretaceous-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zhangheotheriidae
Zhangheotheriidae is a possibly paraphyletic family of " symmetrodont" mammals that is currently known from Early Cretaceous deposits in China and Russia. Five genera are currently recognized, '' Anebodon'', '' Kiyatherium'', '' Maotherium'', '' Origolestes'', and ''Zhangheotherium ''Zhangheotherium'' is a genus of symmetrodont, an extinct order of mammals. Previously known from only the tall pointed crowned teeth, ''Zhangheotherium'', described from Liaoning Province, China, fossils in 1997, is the first symmetrodont known ...''. References Symmetrodonta Prehistoric mammal families Early Cretaceous mammals of Asia {{cretaceous-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zhangheotherium Quinquecuspidens
''Zhangheotherium'' is a genus of symmetrodont, an extinct order of mammals. Previously known from only the tall pointed crowned teeth, ''Zhangheotherium'', described from Liaoning Province, China, fossils in 1997, is the first symmetrodont known from a complete skeleton. It was dated to between 145 and 125 million years ago in the Cretaceous. A single species, ''Zhangheotherium quinquecuspidens'', is known. Symmetrodonts and other archaic mammals such as multituberculates and monotremes are still being debated on their taxonomical relationships. ''Zhangheotherium'' has many primitive characteristics. Among them is a spur at the foot, seen today in the modern platypus. In addition, it walked with a reptilian sprawl, like monotremes and many Mesozoic mammals such as '' Jeholodens'' and '' Repenomamus''. Recent studies show that it led a possibly scansorial Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spalacotheriidae
Spalacotheriidae is a family of extinct mammals belonging to the paraphyletic group 'Symmetrodonta'. They lasted from the Early Cretaceous to the Campanian in North America, Europe, Asia and North Africa. Spalacotheriids are characterised by having molar teeth with three molar cusps sitting at acute angles to one another.Martin, T., 2018. 6. Mesozoic mammals—early mammalian diversity and ecomorphological adaptations. In Mammalian evolution, diversity and systematics (pp. 199-300). De Gruyter. The shape of their teeth as well as their long lower jaw indicate a carnivorous/insectivorous diet. A sub-group of Spalacotheriidae, the spalacolestines, lack a Meckelian groove in the jaw, indicating that they had a modern ear anatomy. Genera * ''Akidolestes'' * '' Infernolestes'' * ''Spalacotherium'' * ''Symmetrolestes ''Symmetrolestes'' is an extinct genus of small spalacotheriid mammal from the Early Cretaceous period of Japan. The genus contains one species known as ''S. parv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molar (tooth)
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth", from ''mola'', millstone and ''dens'', tooth. Molars show a great deal of diversity in size and shape across mammal groups. The third molar of humans is sometimes vestigial. Human anatomy In humans, the molar teeth have either four or five cusps. Adult humans have 12 molars, in four groups of three at the back of the mouth. The third, rearmost molar in each group is called a wisdom tooth. It is the last tooth to appear, breaking through the front of the gum at about the age of 20, although this varies from individual to individual. Race can also affect the age at which this occurs, with statistical variations between groups. In some cases, it may not even erupt at all. The human mouth contains upper (maxillary) and lower (mandib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Talonid
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth", from ''mola'', millstone and ''dens'', tooth. Molars show a great deal of diversity in size and shape across mammal groups. The third molar of humans is sometimes vestigial. Human anatomy In humans, the molar teeth have either four or five cusps. Adult humans have 12 molars, in four groups of three at the back of the mouth. The third, rearmost molar in each group is called a wisdom tooth. It is the last tooth to appear, breaking through the front of the gum at about the age of 20, although this varies from individual to individual. Race can also affect the age at which this occurs, with statistical variations between groups. In some cases, it may not even erupt at all. The human mouth contains upper (maxillary) and lower (mandibul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spalacotheriids
Spalacotheriidae is a family of extinct mammals belonging to the paraphyletic group 'Symmetrodonta'. They lasted from the Early Cretaceous to the Campanian in North America, Europe, Asia and North Africa. Spalacotheriids are characterised by having molar teeth with three molar cusps sitting at acute angles to one another.Martin, T., 2018. 6. Mesozoic mammals—early mammalian diversity and ecomorphological adaptations. In Mammalian evolution, diversity and systematics (pp. 199-300). De Gruyter. The shape of their teeth as well as their long lower jaw indicate a carnivorous/ insectivorous diet. A sub-group of Spalacotheriidae, the spalacolestines, lack a Meckelian groove in the jaw, indicating that they had a modern ear anatomy. Genera * ''Akidolestes'' * '' Infernolestes'' * ''Spalacotherium'' * ''Symmetrolestes'' * Spalacolestinae ** '' Aliaga'' ** '' Heishanlestes'' ** '' Lactodens'' ** '' Shalbaatar'' ** '' Spalacolestes'' ** '' Spalacotheridium'' ** '' Spalacotheroides' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnivorous
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other soft tissues) whether through hunting or scavenging. Nomenclature Mammal order The technical term for mammals in the order Carnivora is ''carnivoran'', and they are so-named because most member species in the group have a carnivorous diet, but the similarity of the name of the order and the name of the diet causes confusion. Many but not all carnivorans are meat eaters; a few, such as the large and small cats (felidae) are ''obligate'' carnivores (see below). Other classes of carnivore are highly variable. The Ursids, for example: While the Arctic polar bear eats meat almost exclusively (more than 90% of its diet is meat), almost all other bear species are omnivorous, and one species, the giant panda, is nearly exclusively herbivorous. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insectivorous
A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores were amphibians. When they evolved 400 million years ago, the first amphibians were piscivores, with numerous sharp conical teeth, much like a modern crocodile. The same tooth arrangement is however also suited for eating animals with exoskeletons, thus the ability to eat insects is an extension of piscivory. At one time, insectivorous mammals were scientifically classified in an order called Insectivora. This order is now abandoned, as not all insectivorous mammals are closely related. Most of the Insectivora taxa have been reclassified; those that have not yet been reclassified and found to be truly related to each other remain in the order Eulipotyphla. Although individually small, insects exist in enormous numbers. Insects make up ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theria
Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. Characteristics Therian mammals give birth (''see viviparity'') to live young without a shelled egg. This is possible thanks to key proteins called syncytins which allow exchanges between the mother and its offspring through a placenta, even rudimental ones such as in marsupials. Genetic studies have suggested a viral origin of syncytins through the endogenization process. The marsupials and the placental mammals evolved from a common therian ancestor that gave live birth by suppressing the mother's immune system. While the marsupials continued to give birth to an underdeveloped fetus after a short pregnancy, the ancestors of placental mammals gradually evolved a prolonged pregnancy. Therian mammals no longer have the coracoid bone, con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
