| Liomesaspis Temporal range: Late Carboniferous–Early Permian, | |
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| Fossils of Liomesaspis laevis (A, B) and Liomesaspis birtwelli (C) | |
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| Genus: | Liomesaspis |
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Liomesaspis is an extinct genus of xiphosuran, related to the modern horseshoe crab. It lived from the late Carboniferous to the Early Permian.
The subphylum Chelicerata constitutes one of the major subdivisions of the phylum Arthropoda. Chelicerates include the sea spiders, horseshoe crabs, and arachnids, as well as a number of extinct lineages, such as the eurypterids and chasmataspidids.
A transitional fossil is any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group. This is especially important where the descendant group is sharply differentiated by gross anatomy and mode of living from the ancestral group. These fossils serve as a reminder that taxonomic divisions are human constructs that have been imposed in hindsight on a continuum of variation. Because of the incompleteness of the fossil record, there is usually no way to know exactly how close a transitional fossil is to the point of divergence. Therefore, it cannot be assumed that transitional fossils are direct ancestors of more recent groups, though they are frequently used as models for such ancestors.
Teleoceras is an extinct genus of rhinocerotid. It lived in North America during the Miocene and Pliocene epochs during the Hemingfordian to the end of Hemphillian from around 17.5 to 4.9 million years ago. It grew up to lengths of 13 feet long.
Menoceras is a genus of extinct, small rhinocerotids endemic to most of southern North America and ranged as far south as Panama during the early Miocene epoch. It lived from around 30.7—19.7 Ma, existing for approximately 11 million years.
Xiphosura is an order of arthropods related to arachnids. They are more commonly known as horseshoe crabs. They first appeared in the Hirnantian. Currently, there are only four living species. Xiphosura contains one suborder, Xiphosurida, and several stem-genera.
Sivatherium is an extinct genus of giraffid that ranged throughout Africa and Eurasia. The species Sivatherium giganteum is, by weight, one of the largest giraffids known, and also one of the largest ruminants of all time.
Diarthrognathus is an extinct genus of tritheledontid cynodonts, known from fossil evidence found in South Africa and first described in 1958 by A.W. Crompton. The creature lived during the Early Jurassic period, about 200 million years ago. It was carnivorous and small, slightly smaller than Thrinaxodon, which was under 50 centimetres (20 in) long.
Pezosiren portelli, also known as the "walking manatee", is a basal sirenian from the early Eocene of Jamaica, 50 million years ago. The type specimen is represented by a Jamaican fossil skeleton, described in 2001 by Daryl Domning, a marine mammal paleontologist at Howard University in Washington, DC. It is believed to have had a hippopotamus-like amphibious lifestyle, and is considered a transitional form between land and sea mammals.
Brachydiastematherium transylvanicum is the westernmost species of brontothere, with the first fossils of it being found in Transylvania, Romania. In comparison with other brontothere fossils, it is suggested that B. transylvanicum would have had an elongated head, not unlike Dolichorhinus, and be about 2 meters at the withers.
Leptauchenia is an extinct goat-like genus of terrestrial herbivore belonging to the oreodont family Merycoidodontidae, and the type genus of the tribe Leptaucheniini. The genus was endemic to North America during the Late Oligocene to Early Miocene and lived for approximately 17.6 million years.
Leptaucheniinae was a taxon of small, goat-like oreodonts with proportionally big heads found throughout North America during the Late Oligocene. Because skeletons of Leptauchenia and Sespia have been found by the literal thousands, they are often quoted as being the most numerous fossil mammals in North America during the Late Oligocene. They had high-crowned, hypsodont teeth which were used to chew gritty vegetation.
Cormocyon is an extinct genus of borophagine canid native to North America. It lived from the Oligocene to the Early Miocene, 30.8—20.6 Mya, existing for about 10.2 million years. It is regarded as a primitive, transitional member of the Borophagini tribe.
Paliguana is an extinct genus of lizard-like lepidosauromorph reptile. It is known from a single somewhat poorly preserved skull around 3 centimetres (1.2 in) in length from the earliest Triassic Katberg Formation in the upper Lystrosaurus Assemblage Zone of South Africa. It is currently the earliest known lepidosauromorph.
Austrolimulus fletcheri is an extinct xiphosuran, related to the modern horseshoe crab. The holotype and only known specimen is from Middle Triassic-aged strata of Brookvale, New South Wales of Australia.
Oligobunis is an extinct genus of mustelids, which existed during the Miocene epoch.
Synziphosurina is a paraphyletic group of chelicerate arthropods previously thought to be basal horseshoe crabs (Xiphosura). It was later identified as a grade composed of various basal euchelicerates, eventually excluded from the monophyletic Xiphosura sensu stricto and only regarded as horseshoe crabs under a broader sense. Synziphosurines survived at least since early Ordovician to early Carboniferous in ages, with most species are known from the in-between Silurian strata.
Floridaceras is an extinct genus of rhinocerotid of the Miocene epoch, endemic to North America, living from around ~20.6–16.3 Ma, existing for approximately 4.3 million years.
Donald Ross Prothero is an American geologist, paleontologist, and author who specializes in mammalian paleontology and magnetostratigraphy, a technique to date rock layers of the Cenozoic era and its use to date the climate changes which occurred 30–40 million years ago. He is the author or editor of more than 30 books and over 300 scientific papers, including at least 5 geology textbooks.
Radinskya is an extinct perissodactyl-like mammal from the Paleocene of China. It is named after palaeontologist and perissodactyl expert Leonard Radinsky who died prematurely in 1985.
The Paleobiology Database (PBDB) is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms.
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