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Spalacotheriid
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 ''Spalacotherium'' is a genus of extinct mammal from the Early Cretaceous of Europe. The type species ''Spalacotherium tricuspidens'' was originally named by Richard Owen in 1854, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. parvus'', the type fossil (which is only fossil known) is from fluvial deposits located in the Dinosaur Quarry in the Kitadani Formation, near the city of Katsuyama which lies alongside valley of the Sugiyamagawa River. It was described by Tsubamoto and Rougier in 2004 keeping the Holotype at the National Science Museum, Tokyo, Japan. Description The type specimen (NSM PV 20562, holotype) is known from a fragmentary right jaw with the first incisor and five postcanine teeth preserved. ''Symmetrolestes'' is more derived than zhangheotheriids as it had acute−angled molariform teeth with completely developed shearing surfaces, taller crowns on it teeth and more complete cingulids. It differs from other spalacotheriids due to the fact it had fewer molariform teeth, a higher number of premolariform teeth and gradual tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Akidolestes
''Akidolestes'' is an extinct genus of mammals from the family Spalacotheriidae, spalacotheriid. Although Akidolestes do not have any modern relatives, they are early mammal, mammals related to Theria, therians (the subclass containing marsupials and placentals). They belong to a group of Theriiformes, theriiform mammals known as the Spalacotheriidae, Spalacotherioidea. However, unlike other members of this Taxonomic rank, superfamily, ''Akidolestes'' have a few prototherian features. The genus name, ''Akidolestes'', is derived from ''akido'', Greek for point, and ''lestes'', Greek for thief. Akido- refers to the pointed Rostrum (anatomy), snout and -lestes is a common suffix for fossil mammals. The specific epithet, ''cifelli'', is in honor of Richard L. Cifelli, a prominent researcher in prehistoric mammals. An ''Akidolestes'' fossil preserved with a complete post-cranium and a partial skull was discovered in the Yixian Formation of Liaoning, China. The holotype of ''Akidol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yaverlestes
''Yaverlestes gassoni'' is an extinct mammal which dates to the early Cretaceous period, 130 million years ago. It is part of the Wessex Formation from the Isle of Wight, England. The holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ..., BMNH M 54386, is a partial jaw discovered near Yaverland. The genus name, ''Yaverlestes'', is derived from ''Yaverland'', the location of its discovery, and ''lestes'', Greek for thief. The specific epithet, ''gassoni'', is in honour of Brian Gasson, its discoverer. References Early Cretaceous mammals of Europe Prehistoric mammal genera {{cretaceous-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symmetrodonta
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] |
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 145 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 carbon isotope 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. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
