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Cristozoa
Cristozoa (also known as crest animals) is a grouping of animals possessing a neural crest and derivatives. It includes all the Craniata, as well as their immediate precraniate precursors. The precraniate crest animals, such ''Haikouella'' and ''Yunnanozoon'', are all extinct and found only in Early Cambrian strata of Yunnan Yunnan , () is a landlocked Provinces of China, province in Southwest China, the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is ... (southwestern China). References Deuterostome unranked clades {{chordate-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yunnanozoon
''Yunnanozoon lividum'' (Yunnan + Greek ζῷον ''zôion'', ''lividum''; "livid animal of Yunnan") is an extinct species of possible vertebrate or chordate from the Lower Cambrian, Chengjiang biota of Yunnan province, China. It is thought of as a deuterostome suspected of being either a hemichordate or chordate. In 2022, a study reanalyzed fossils of ''Yunnanozoon'' and found it to be one of the earliest members of the vertebrate family tree. ''Yunnanozoon'' is similar to the form ''Haikouella'', which is almost certainly a chordate. Still, there are anatomical differences from ''Haikouella'', including a smaller stomach and much larger (1 mm) pharyngeal teeth. It is by no means certain whether Yunannozoon possessed features such as a heart, gills, etc., which are seen in well-preserved specimens of ''Haikouella''. ''Yunnanozoon'' somewhat resembles the Middle Cambrian ''Pikaia'' from the Burgess shale of British Columbia in Canada. Thirteen pairs of symmetrically arra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haikouella
''Haikouella'' is an agnathan chordate from the Lower Cambrian Maotianshan Shales of Chengjiang County in Yunnan Province, China. An analysis in 2015 placed ''Haikouella'' as a junior synonym of ''Yunnanozoon,'' another Maotianshan shale Cambrian chordate''.'' It is similar to the form ''Yunnanozoon'', which is possibly a hemichordate. Still, there are anatomical differences from ''Yunnanozoon'', including a larger stomach and smaller (0.1 mm) pharyngeal teeth. ''Haikouella'' does not have bones or a movable jaw, but it otherwise resembles vertebrates. ''Haikouichthys'' and ''Myllokunmingia'', which seem to share significant fish-like characters, have been found in the same beds. Suspected hemichordates are also known from these deposits as well as from the Middle Cambrian Burgess Shale of British Columbia. Other than possible fish scales/plates from the Upper Cambrian of Wyoming, these Chinese fish-like chordates are one of the only known pre-Ordovician craniates. ''Haikou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described. Vertebrates comprise such groups as the following: * jawless fish, which include hagfish and lampreys * jawed vertebrates, which include: ** cartilaginous fish (sharks, rays, and ratfish) ** bony vertebrates, which include: *** ray-fins (the majority of living bony fish) *** lobe-fins, which include: **** coelacanths and lungfish **** tetrapods (limbed vertebrates) Extant vertebrates range in size from the frog species ''Paedophryne amauensis'', at as little as , to the blue whale, at up to . Vertebrates make up less than five percent of all described animal species; the rest are invertebrates, which lack vertebral columns. The vertebrates traditionally include the hagfish, which do no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclostomata
Cyclostomi, often referred to as Cyclostomata , is a group of vertebrates that comprises the living jawless fishes: the lampreys and hagfishes. Both groups have jawless mouths with horny epidermal structures that function as teeth called ceratodontes, and branchial arches that are internally positioned instead of external as in the related jawed fishes. The name Cyclostomi means "round mouths". It was named by Joan Crockford-Beattie. Possible external relationships This taxon is often included in the paraphyletic superclass Agnatha, which also includes several groups of extinct armored fishes called ostracoderms. Most fossil agnathans, such as galeaspids, thelodonts, and osteostracans, are more closely related to vertebrates with jaws (called gnathostomes) than to cyclostomes. Cyclostomes seem to have split off before the evolution of dentine and bone, which are present in many fossil agnathans, including conodonts. Biologists disagree on whether cyclostomes are a c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petromyzontiformes
Lampreys (sometimes inaccurately called lamprey eels) are an ancient extant lineage of jawless fish of the order Petromyzontiformes , placed in the superclass Cyclostomata. The adult lamprey may be characterized by a toothed, funnel-like sucking mouth. The common name "lamprey" is probably derived from Latin , which may mean "stone licker" ( "to lick" + "stone"), though the etymology is uncertain. ''Lamprey'' is sometimes seen for the plural form. There are about 38 known extant species of lampreys and five known extinct species. Parasitic carnivorous species are the most well-known, and feed by boring into the flesh of other fish to suck their blood; but only 18 species of lampreys engage in this micropredatory lifestyle. Of the 18 carnivorous species, nine migrate from saltwater to freshwater to breed (some of them also have freshwater populations), and nine live exclusively in freshwater. All non-carnivorous forms are freshwater species. Adults of the non-carnivorous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ostracoderm
Ostracoderms () are the armored jawless fish of the Paleozoic Era. The term does not often appear in classifications today because it is paraphyletic (excluding jawed fishes) (may also be polyphyletic if anaspids are closer to cyclostomes) and thus does not correspond to one evolutionary lineage. However, the term is still used as an informal way of loosely grouping together the armored jawless fishes. An innovation of ostracoderms was the use of gills not for feeding, but exclusively for respiration. Earlier chordates with gill precursors used them for both respiration and feeding. Ostracoderms had separate pharyngeal gill pouches along the side of the head, which were permanently open with no protective operculum. Unlike invertebrates that use ciliated motion to move food, ostracoderms used their muscular pharynx to create a suction that pulled small and slow moving prey into their mouths. Swiss anatomist Louis Agassiz received some fossils of bony armored fish from Scotland ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gnathostomata
Gnathostomata (; from Greek: (') "jaw" + (') "mouth") are the jawed vertebrates. Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all living vertebrates, including humans. In addition to opposing jaws, living gnathostomes have true teeth (a characteristic which has subsequently been lost in some), paired appendages (pectoral and pelvic fins, arms, legs, wings, etc.), the elastomeric protein of elastin, and a horizontal semicircular canal of the inner ear, along with physiological and cellular anatomical characters such as the myelin sheaths of neurons, and an adaptive immune system that has the discrete lymphoid organs of spleen and thymus, and uses V(D)J recombination to create antigen recognition sites, rather than using genetic recombination in the variable lymphocyte receptor gene. It is now assumed that Gnathostomata evolved from ancestors that already possessed a pair of both pectoral and pelvic fins. Until recently these ancestors, know ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neural Crest
Neural crest cells are a temporary group of cells unique to vertebrates that arise from the embryonic ectoderm germ layer, and in turn give rise to a diverse cell lineage—including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons and glia. After gastrulation, neural crest cells are specified at the border of the neural plate and the non-neural ectoderm. During neurulation, the borders of the neural plate, also known as the neural folds, converge at the dorsal midline to form the neural tube. Subsequently, neural crest cells from the roof plate of the neural tube undergo an epithelial to mesenchymal transition, delaminating from the neuroepithelium and migrating through the periphery where they differentiate into varied cell types. The emergence of neural crest was important in vertebrate evolution because many of its structural derivatives are defining features of the vertebrate clade. Underlying the development of neural crest is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Craniata
A craniate is a member of the Craniata (sometimes called the Craniota), a proposed clade of chordate animals with a skull of hard bone or cartilage. Living representatives are the Myxini (hagfishes), Hyperoartia (including lampreys), and the much more numerous Gnathostomata (jawed vertebrates).Campbell & Reece 2005 p. 676 Formerly distinct from vertebrates by including hagfish, molecular and anatomical research in the 21st century has led to the reinclusion of hagfish as vertebrates, making living craniates synonymous with living vertebrates. The clade was conceived largely on the basis of the Hyperoartia (lampreys and kin) being more closely related to the Gnathostomata (jawed vertebrates) than the Myxini (hagfishes). This, combined with an apparent lack of vertebral elements within the Myxini, suggested that the Myxini were descended from a more ancient lineage than the vertebrates, and that the skull developed before the vertebral column. The clade was thus composed of the Myx ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yunnan
Yunnan , () is a landlocked Provinces of China, province in Southwest China, the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is Kunming. The province borders the Chinese provinces of Guizhou, Sichuan, autonomous regions of Guangxi, and Tibet Autonomous Region, Tibet as well as Southeast Asian countries: Vietnam, Laos, and Myanmar. Yunnan is China's fourth least developed province based on disposable income per capita in 2014. Yunnan is situated in a mountainous area, with high elevations in the northwest and low elevations in the southeast. Most of the population lives in the eastern part of the province. In the west, the altitude can vary from the mountain peaks to river valleys by as much as . Yunnan is rich in natural resources and has the largest diversity of plant life in China. Of the approximately 30,000 species of Vascular plant, higher plants in China, Yu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chordates
A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These five synapomorphies include a notochord, dorsal hollow nerve cord, endostyle or thyroid, pharyngeal slits, and a post-anal tail. The name “chordate” comes from the first of these synapomorphies, the notochord, which plays a significant role in chordate structure and movement. Chordates are also bilaterally symmetric, have a coelom, possess a circulatory system, and exhibit metameric segmentation. In addition to the morphological characteristics used to define chordates, analysis of genome sequences has identified two conserved signature indels (CSIs) in their proteins: cyclophilin-like protein and mitochondrial inner membrane protease ATP23, which are exclusively shared by all vertebrates, tunicates and cephalochordates. These CSIs prov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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