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Crassigyrinus
''Crassigyrinus'' (from , 'thick' and , 'tadpole') is an extinct genus of carnivorous stem tetrapod from the Early Carboniferous Clackmannan Group of Scotland and possibly Greer, West Virginia. Discovery The type specimen was originally described as ''Macromerium scoticum'' and lacked a complete skull. With subsequent discoveries, ''Crassigyrinus'' is now known from three skulls, one of which is in articulation with a fairly complete skeleton, and two incomplete lower jaws. ''Crassigyrinus'' grew up to 2 meters in length, coupled with tiny limbs and unusually large jaws. ''Crassigyrinus'' is taxonomically enigmatic, having confused paleontologists for decades with its apparent fish-like and tetrapod features.Chapter on ''Crassigyrinus'' from ''Gaining ground: the origin and evolution of te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crassigyrinus Cranial Drawings
''Crassigyrinus'' (from , 'thick' and , 'tadpole') is an extinct genus of carnivorous stem tetrapod from the Early Carboniferous Clackmannan Group of Scotland and possibly Greer, West Virginia. Discovery The type specimen was originally described as ''Macromerium scoticum'' and lacked a complete skull. With subsequent discoveries, ''Crassigyrinus'' is now known from three skulls, one of which is in articulation with a fairly complete skeleton, and two incomplete lower jaws. ''Crassigyrinus'' grew up to 2 meters in length, coupled with tiny limbs and unusually large jaws. ''Crassigyrinus'' is taxonomically enigmatic, having confused paleontologists for decades with its apparent fish-like and tetrapod features.Chapter on ''Crassigyrinus'' from ''Gaining ground: the origin and evolution of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrapod
A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetrapoda (). Tetrapods include all Neontology#Extant taxa versus extinct taxa, extant and Extinction, extinct amphibians and amniotes, with the latter in turn Evolution, evolving into two major clades, the Sauropsida, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids (extinct pelycosaur, "pelycosaurs", therapsids and all extant mammals, including Homo sapiens, humans). Hox gene mutations have resulted in some tetrapods becoming Limbless vertebrate, limbless (snakes, legless lizards, and caecilians) or two-limbed (cetaceans, sirenians, Bipedidae, some lizards, kiwi (bird), kiwis, and the extinct moa and elephant birds). Nevertheless, they still qualify as tetrapods through their ancestry, and some retain a pair of ves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Labyrinthodontia
"Labyrinthodontia" (Greek, 'maze-toothed') is an informal grouping of extinct predatory amphibians which were major components of ecosystems in the late Paleozoic and early Mesozoic eras (about 390 to 150 million years ago). Traditionally considered a subclass of the class Amphibia, modern classification systems recognize that labyrinthodonts are not a formal natural group (clade) exclusive of other tetrapods. Instead, they consistute an evolutionary grade (a paraphyletic group), ancestral to living tetrapods such as lissamphibians (modern amphibians) and amniotes (reptiles, mammals, and kin). "Labyrinthodont"-grade vertebrates evolved from lobe-finned fishes in the Devonian, though a formal boundary between fish and amphibian is difficult to define at this point in time. "Labyrinthodont" generally refers to extinct four-limbed tetrapods with a large body size and a crocodile-like lifestyle. The name describes the pattern of infolding of the dentin and enamel of the teeth, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyostega
''Ichthyostega'', from Ancient Greek ἰχθύς (''ikthús''), meaning "fish", and στέγη (''stégē''), meaning "roof", is an Extinction, extinct genus of limbed tetrapodomorpha, tetrapodomorphs from the Devonian, Late Devonian of what is now Greenland. It was among the earliest four-limbed vertebrates ever in the fossil record and was one of the first with weight-bearing adaptations for terrestrial locomotion. ''Ichthyostega'' possessed lungs and limbs that helped it navigate through shallow water in swamps. Although ''Ichthyostega'' is often labelled a 'tetrapod' because of its limbs and fingers, it evolved long before true crown group tetrapods and could more accurately be referred to as a stegocephalian or stem tetrapod. Likewise, while undoubtedly of amphibian build and habit, it is not a true member of the group in the narrow sense, as the first modern amphibians (members of the group Lissamphibia) appeared in the Triassic Period. Until finds of other early stegocephal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboniferous
The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the Permian Period, Ma. It is the fifth and penultimate period of the Paleozoic era and the fifth period of the Phanerozoic eon (geology), eon. In North America, the Carboniferous is often treated as two separate geological periods, the earlier Mississippian (geology), Mississippian and the later Pennsylvanian (geology), Pennsylvanian. The name ''Carboniferous'' means "coal-bearing", from the Latin ("coal") and ("bear, carry"), and refers to the many coal beds formed globally during that time. The first of the modern "system" names, it was coined by geologists William Conybeare (geologist), William Conybeare and William Phillips (geologist), William Phillips in 1822, based on a study of the British rock succession. Carboniferous is the per ... [...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 nutrition and energy requirements are met by consumption of animal tissues (mainly muscle, fat and other soft tissues) as food, whether through predation 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 (bears), 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 gia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Class (biology)
In biological classification, class () is a taxonomic rank, as well as a taxonomic unit, a taxon, in that rank. It is a group of related taxonomic orders. Other well-known ranks in descending order of size are domain, kingdom, phylum, order, family, genus, and species, with class ranking between phylum and order. History The class as a distinct rank of biological classification having its own distinctive name – and not just called a ''top-level genus'' ''(genus summum)'' – was first introduced by French botanist Joseph Pitton de Tournefort in the classification of plants that appeared in his '' Eléments de botanique'' of 1694. Insofar as a general definition of a class is available, it has historically been conceived as embracing taxa that combine a distinct ''grade'' of organization—i.e. a 'level of complexity', measured in terms of how differentiated their organ systems are into distinct regions or sub-organs—with a distinct ''type'' of construction, whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eusthenopteron
''Eusthenopteron'' (from 'stout', and 'wing' or 'fin') is an extinct genus of prehistoric marine lobe-finned fish known from several species that lived during the Late Devonian period, about 385 million years ago. It has attained an iconic status from its close relationship to tetrapods. Early depictions of animals of this genus show them emerging onto land, but paleontologists now think that ''Eusthenopteron'' species were strictly aquatic animals, though this is not completely known.M. Laurin, F. J. Meunier, D. Germain, and M. Lemoine 2007A microanatomical and histological study of the paired fin skeleton of the Devonian sarcopterygian ''Eusthenopteron foordi'' ''Journal of Paleontology'' 81: 143–153. The genus was first described by J. F. Whiteaves in 1881, as part of a large collection of fishes from Miguasha, Quebec, Canada. Some 2,000 ''Eusthenopteron'' specimens have been collected from Miguasha, one of which was the object of intensely detailed study and severa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lobe-finned Fish
Sarcopterygii (; )—sometimes considered synonymous with Crossopterygii ()—is a clade (traditionally a class or subclass) of vertebrate animals which includes a group of bony fish commonly referred to as lobe-finned fish. These vertebrates are characterised by prominent muscular limb buds (lobes) within their fins, which are supported by articulated appendicular skeletons. This is in contrast to the other clade of bony fish, the Actinopterygii, which have only skin-covered bony spines supporting the fins. The tetrapods, a mostly terrestrial clade of vertebrates, are now recognized as having evolved from sarcopterygian ancestors and are most closely related to lungfishes. Their paired pectoral and pelvic fins evolved into limbs, and their foregut diverticulum eventually evolved into air-breathing lungs. Cladistically, this would make the tetrapods a subgroup within Sarcopterygii and thus sarcopterygians themselves. As a result, the phrase "lobe-finned fish" normally refe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acanthostega
''Acanthostega'', from Ancient Greek ἄκανθα (''ákantha''), meaning "spine", and στέγη (''stégē''), meaning "roof", is an extinct genus of stem tetrapoda, stem-tetrapod, among the first vertebrates, vertebrate animals to have recognizable Limb (anatomy), limbs. It appeared in the late Devonian period (Famennian age) about 365 million years ago, and was anatomically intermediate between lobe-finned fishes and those that were able to come onto land. Discovery The fossilized remains are generally well preserved, with the famous fossil by which the significance of this species was discovered being found by Jennifer A. Clack in East Greenland in 1987, though fragments of the skull had been discovered in 1933 by Gunnar Säve-Söderbergh and Erik Jarvik. Description The ''Acanthostega'' Polydactyly in stem-tetrapods, had eight digits on each hand (the number of digits on the feet is unclear) linked by webbing. It lacked wrists, and was generally poorly adapted for wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
