|
Apodous
Many vertebrates are limbless, limb-reduced, or apodous, with a body plan consisting of a head and vertebral column, but no adjoining limbs such as legs or fins. Jawless fish are limbless but may have preceded the evolution of vertebrate limbs, whereas numerous reptile and amphibian lineages – and some eels and eel-like fish – independently lost their limbs. Larval amphibians, tadpoles, are also often limbless. No mammals or birds are limbless, but some feature partial limb-loss or limb reduction. Examples The jawless fish (hagfish and lamprey) do not have appendage-like fins. They may not have lost them, but rather, simply retained the form that vertebrates had before the evolution of limbs. There are also a number of fish with elongated bodies that have no fins or reduced appendage-like fins, for example eels and swamp eels. Reptiles have on a number of occasions evolved into limbless forms – snakes, amphisbaenians, and legless lizards (limb loss in lizards has evol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrate
Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebrata with some 65,000 species, by far the largest ranked grouping in the phylum Chordata. The vertebrates include mammals, birds, amphibians, and various classes of fish and reptiles. The fish include the jawless Agnatha, and the jawed Gnathostomata. The jawed fish include both the Chondrichthyes, cartilaginous fish and the Osteichthyes, bony fish. Bony fish include the Sarcopterygii, lobe-finned fish, which gave rise to the tetrapods, the animals with four limbs. Despite their success, vertebrates still only make up less than five percent of all described animal species. The first vertebrates appeared in the Cambrian explosion some 518 million years ago. Jawed vertebrates evolved in the Ordovician, followed by bony fishes in the Devonian. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipes (lizard)
''Bipes'' is a genus of amphisbaenians (or worm lizards) found only in Mexico, the sole living member of the family (biology), family Bipedidae. They are carnivorous, Fossorial, burrowing reptiles, but unlike other species of amphisbaenians, they possess two stubby forelimbs placed far forward on the body. They also retain an almost complete pectoral girdle. The shovel-like limbs are used to scrape away soil while burrowing, in a manner similar to a mole (animal), mole. Evidence for their occurrence in the United States is reviewed by Somma (1993). References Further reading *Pierre André Latreille, Latreille PA (1801). ''In'': Charles-Nicolas-Sigisbert Sonnini de Manoncourt, Sonnini CS, Latreiile PA (1801). ''Histoire naturelle des reptiles, avec figures desinées d'après nature; Tome II. Premiere partie. Quadrupèdes et bipèdes ovipares''. Paris: Crapalet. 332 pp. (''Bipes'', pp. 90–96.) *Edward Harrison Taylor, Taylor EH (1951). "Concerning Oligocene Amphisbaenid Re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossorial
A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamanders. Among invertebrates, many molluscs (e.g., clams), insects (e.g., beetles, wasps, bees), and arachnids (e.g. spiders) are fossorial. Prehistoric evidence The physical adaptation of fossoriality is widely accepted as being widespread among many Prehistory, prehistoric Phylum, phyla and Taxon, taxa, such as bacteria and early eukaryotes. Furthermore, fossoriality has evolved independently multiple times, even within a single Family (biology), family. Fossorial animals appeared simultaneously with the colonization of land by arthropods in the late Ordovician period (over 440 million years ago). Other notable early burrowers include ''Eocaecilia'' and possibly ''Dinilysia''. The oldest example of burrowing in synapsids, the lineag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Finless Porpoise
''Neophocaena'' is a genus of porpoise native to the Indian and Pacific oceans, as well as the freshwater habitats of the Yangtze River basin in China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after .... They are commonly known as finless porpoises. Genetic studies indicate that ''Neophocaena'' is the most basal living member of the porpoise family. There are three species in this genus: Description The finless porpoises are the only porpoises to lack a true dorsal fin. Instead there is a low ridge covered in thick skin bearing several lines of tiny tubercles. In addition, the forehead is unusually steep compared with those of other porpoises. With fifteen to twenty-one teeth in each jaw, they also have, on average, fewer teeth than other porpoises, although there is some o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elephant Birds
Elephant birds are extinct flightless birds belonging to the order Aepyornithiformes that were native to the island of Madagascar. They are thought to have gone extinct around 1000 CE, likely as a result of human activity. Elephant birds comprised three species, one in the genus '' Mullerornis'', and two in '' Aepyornis.'' ''Aepyornis maximus'' is possibly the largest bird to have ever lived, with their eggs being the largest known for any amniote. Elephant birds are palaeognaths (whose flightless representatives are often known as ratites), and their closest living relatives are kiwi (found only in New Zealand), suggesting that ratites did not diversify by vicariance during the breakup of Gondwana but instead convergently evolved flightlessness from ancestors that dispersed more recently by flying. Discovery Elephant birds have been extinct since at least the 17th century. Étienne de Flacourt, a French governor of Madagascar during the 1640s and 1650s, mentioned an ostrich-li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kiwi (bird)
Kiwi are flightless birds endemism, endemic to New Zealand of the Order (biology), order Apterygiformes. The five extant species fall into the family Apterygidae and genus ''Apteryx''. Approximately the size of a domestic chicken, kiwi are the smallest ratites (which also include ostriches, emus, rhea (bird), rheas, cassowary, cassowaries and the extinct elephant birds and moa). DNA sequence comparisons have yielded the conclusion that kiwi are much more closely related to the extinct Malagasy elephant birds than to the moa with which they shared New Zealand. There are five recognised species, four of which are currently listed as Vulnerable species, vulnerable, and Little spotted kiwi, one of which is Near-threatened species, near threatened. All species have been negatively affected by historic Deforestation in New Zealand, deforestation, but their remaining habitat is well protected in large forest reserves and national parks. At present, the greatest threat to their surviva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sirenians
The Sirenia (), commonly referred to as sea cows or sirenians, are an order (biology), order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The extant Sirenia comprise two distinct family (biology), families: Dugongidae (the dugong and the now extinct Steller's sea cow) and Trichechidae (manatees, namely the Amazonian manatee, West Indian manatee, and African manatee, West African manatee) with a total of four species. The Protosirenidae (Eocene sirenians) and Prorastomidae (terrestrial sirenians) families are extinct. Sirenians are classified in the clade Paenungulata, alongside the elephants and the hyraxes, and evolved in the Eocene 50 million years ago (mya). The Dugongidae Genetic divergence, diverged from the Trichechidae in the late Eocene or early Oligocene (30–35 mya). Sirenians grow to between in length and in weight. The recently extinct Steller's sea cow was the largest known sirenian to ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cetacea
Cetacea (; , ) is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel themselves through the water with powerful up-and-down movements of their tail, which ends in a paddle-like fluke, using their flipper-shaped forelimbs to steer. While the majority of cetaceans live in marine environments, a small number reside solely in brackish water, brackish or fresh water. Having a cosmopolitan distribution, they can be found in some rivers and all of Earth's oceans, and many species migrate throughout vast ranges with the changing of the seasons. Cetaceans are famous for cetacean intelligence, their high intelligence, complex social behaviour, and the enormous size of some of the group's members. For example, the blue whale reaches a maximum confirmed length of and a weight of 173 tonne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adelospondyli
Adelospondyli is an Order (biology), order of elongated, presumably aquatic, Carboniferous amphibians (''Sensu, sensu lato''). They have a robust skull roofed with solid bone, and Orbit (anatomy), orbits located towards the front of the skull. The limbs were almost certainly absent, although some historical sources reported them to be present. Despite the likely absence of limbs, adelospondyls retained a large part of the bony shoulder girdle. Adelospondyls have been assigned to a variety of groups in the past. They have traditionally been seen as members of the subclass Lepospondyli, related to other unusual early Tetrapod, tetrapods such as "Microsauria, microsaurs", "Nectridea, nectrideans", and Aistopoda, aïstopods. Analyses such as Ruta & Coates (2007) have offered an alternate classification scheme, arguing that adelospondyls were actually far removed from other lepospondyls, instead being Crown group#Stem groups, stem-tetrapod Stegocephalia, stegocephalians closely related ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lysorophia
Lysorophia is an order (biology), order of fossorial Carboniferous and Permian Tetrapod, tetrapods within the Recumbirostra. Lysorophians resembled small snakes, as their bodies are extremely elongate. There is a single family (biology), family, the Molgophidae (previously known as Lysorophidae). Currently there are around five genus, genera included within Lysorophia, although many may not be valid. Description The skull is heavily built but with large lateral openings to accommodate jaw musculature, with small Orbit (anatomy), orbits restricted to the anterior edge of the large Fenestra (anatomy), fenestrae. The intertemporal, supratemporal, postfrontal, and jugal bones of the skull have disappeared. The mandibles are short and robust with a small number of large triangular teeth. Although it was initially thought that the maxilla and premaxilla were freely movable, detailed anatomical studies show that this is not the case. The braincase is extremely robust, suggesting that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aïstopoda
Aistopoda (Greek for "[having] not-visible feet") is an order of highly specialised snake-like stegocephalians known from the Carboniferous and Cisuralian, Early Permian of Europe and North America, ranging from tiny forms only , to nearly in length. They first appear in the fossil record in the Mississippian age, Mississippian period and continue through to the Cisuralian, Early Permian. The skull is small but very specialised, with large Orbit (anatomy), orbits, and large Fenestra (anatomy), fenestrae. The primitive form ''Ophiderpeton'' has a pattern of dermal bones in the skull similar in respects to the temnospondyls. But in the advanced genus ''Phlegethontia'' the skull is very light and open, reduced to a series of struts supporting the braincase against the lower jaw, just as in Ophidia, snakes, and it is possible that the aistopods filled the same ecological niches in the Paleozoic that snakes do today. They had an extremely elongated body, with up to 230 vertebrae. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphiumidae
''Amphiuma'' is a genus of aquatic salamanders from the United States, the only Extant taxon, extant genus within the family (biology), family Amphiumidae . They are colloquially known as amphiumas. They are also known to fishermen as "conger eels" or "Congo snakes", which are zoology, zoologically incorrect designations or misnomers, since amphiumas are actually salamanders (and thus amphibians), and not fish, nor reptiles and are not from Congo Basin, Congo. ''Amphiuma'' exhibits one of the largest complements of DNA in the living world, around 25 times more than a human. Taxonomy Numerous phylogenetic studies have indicated that amphiumas form a clade with the families Torrent salamander, Rhyacotritonidae (torrent salamanders) and Plethodontidae (lungless salamanders), with an especially close relationship to Plethodontidae. Despite this possible relationship, the two families must have still diverged very early on. The genus ''Proamphiuma'' from the Cretaceous is the earlies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
