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Zhongxiniscus
''Zhongxiniscus'' is a genus of primitive chordate from eastern Yunnan that lived during the Early Cambrian. Known from a single specimen, it had a small, broad and short, fish-like body that was roughly ten millimeters in length. It possessed S-shaped myomeres, numbering roughly seven per one millimeter of length. Two triangular fins are evident on the dorsal margin. Evolutionary relationships When compared to other Cambrian chordates like the possible cephalochordate ''Cathaymyrus'' and the two known vertebrates ''Haikouichthys'' and ''Myllokunmingia'', ''Zhongxiniscus'' resembles ''Cathaymyrus'' in having S-shaped myomeres, but is different in having a dorsal fin and a shorter body. ''Zhongxiniscus'' approaches in form to ''Haikouichthys'' and ''Myllokunmingia'' in its myomeres and its dorsal fin, but differs from the latter two having zigzag myomeres and fin rays, which ''Zhongxiniscus'' evidently lacks. For these reasons, ''Zhongxiniscus'' is tentatively considered to be an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Chordates
The Cambrian chordates are an extinct group of animals belonging to the phylum Chordata that lived during the Cambrian, between 485 and 538 million years ago. The first Cambrian chordate known is '' Pikaia gracilens'', a lancelet-like animal from the Burgess Shale in British Columbia, Canada. The discoverer, Charles Doolittle Walcott, described it as a kind of worm (annelid) in 1911, but was later realised to be a chordate. Since the discovery of other Cambrian fossils from the Burgess Shale in 1991, and from the Chengjiang biota of China in 1991, which were later found to be of chordates, several Cambrian chordates are known, with some fossils considered as putative chordates. The Cambrian chordates are characterised by the presence of segmented muscle blocks called myomeres and notochord, the two defining features of chordates. Before the full understanding of Cambrian fossils, chordates as members the most advanced phylum were believed to appear on Earth much later than the Cam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chordata
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 Bilateral symmetry, bilaterally symmetric, have a coelom, possess a circulatory system, and exhibit Metameric, 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 cep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Stage 3
Cambrian Stage 3 is the still unnamed third stage of the Cambrian. It succeeds Cambrian Stage 2 and precedes Cambrian Stage 4, although neither its base nor top have been formally defined. The plan is for its lower boundary to correspond approximately to the first appearance of trilobites, about million years ago, though the globally asynchronous appearance of trilobites warrants the use of a separate, globally synchronous marker to define the base. The upper boundary and beginning of Cambrian Stage 4 is informally defined as the first appearance of the trilobite genera ''Olenellus'' or '' Redlichia'' around million years ago. Naming The International Commission on Stratigraphy has not officially named the 3rd stage of the Cambrian. The stage approximately corresponds to the "Atdabanian", which is used by geologists working in Siberia. Biostratigraphy The oldest trilobite known is ''Lemdadella'' which appears at the beginning of the '' Fallotaspis'' zone. The Cambrian radiati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motility, able to move, can Sexual reproduction, reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of Cell (biology), cells, the blastula, during Embryogenesis, embryonic development. Over 1.5 million Extant taxon, living animal species have been Species description, described—of which around 1 million are Insecta, insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have Ecology, complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a Symmetry in biology#Bilate ... [...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] |
Myomere
Myomeres are blocks of skeletal muscle tissue arranged in sequence, commonly found in aquatic chordates. Myomeres are separated from adjacent myomeres by connective fascia (myosepta) and most easily seen in larval fishes or in the olm. Myomere counts are sometimes used for identifying specimens, since their number corresponds to the number of vertebrae in the adults. Location varies, with some species containing these only near the tails, while some have them located near the scapular or pelvic girdles. Depending on the species, myomeres could be arranged in an epaxial or hypaxial manner. Hypaxial refers to ventral muscles and related structures while epaxial refers to more dorsal muscles. The horizontal septum divides these two regions in vertebrates from cyclostomes to gnathostomes. In terrestrial chordates, the myomeres become fused as well as indistinct, due to the disappearance of myosepta. Shape The shape of myomeres varies by species. Myomeres are commonly zig-zag, " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalochordate
A cephalochordate (from Greek: κεφαλή ''kephalé'', "head" and χορδή ''khordé'', "chord") is an animal in the chordate subphylum, Cephalochordata. They are commonly called lancelets. Cephalochordates possess 5 synapomorphies, or primary characteristics, that all chordates have at some point during their larval or adulthood stages. These 5 synapomorphies include a notochord, dorsal hollow nerve cord, endostyle, pharyngeal slits, and a post-anal tail (see chordate for descriptions of each). The fine structure of the cephalochordate notochord is best known for the Bahamas lancelet, ''Asymmetron lucayanum''. Cephalochordates are represented in modern oceans by the Amphioxiformes and are commonly found in warm temperate and tropical seas worldwide. With the presence of a notochord, adult amphioxus are able to swim and tolerate the tides of coastal environments, but they are most likely to be found within the sediment of these communities. Cephalochordates are segmented mar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathaymyrus
''Cathaymyrus'' is a genus of Early Cambrian cephalochordate known from the Chengjiang locality in Yunnan Province, China. Both species have a long segmented body with no distinctive head. The segments resemble the v-shaped muscle blocks found in similar cephalochordates such as ''Amphioxus''. A long linear impression runs along the "back" of the body looking something like a chordate notochord. ''Cathaymyrus'' is related to ''Pikaia'', another cephalochordate from the Burgess Shale. See also *Maotianshan shales *''Haikouichthys'' *''Myllokunmingia ''Myllokunmingia'' is a genus of basal chordate from the Lower Cambrian Maotianshan shales of China 518 to 490 mya and is thought to be a vertebrate, although this is not conclusively proven. The species M. fengjiaoa is 28 mm long and 6&nbs ...'' References {{Taxonbar, from=Q19890829 Cambrian chordates Maotianshan shales fossils Cephalochordata Prehistoric chordate genera Cambrian genus extinctions ... [...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] |
Haikouichthys
''Haikouichthys'' is an extinct genus of craniate (animals with notochords and distinct heads) that lived 518 million years ago, during the Cambrian explosion of multicellular life. ''Haikouichthys'' had a defined skull and other characteristics that have led paleontologists to label it a true craniate, and even to be popularly characterized as one of the Prehistoric fish, earliest fishes. Cladistics, Cladistic analysis indicates that the animal is probably a basal chordate or a basal craniate; but it does not possess sufficient features to be included uncontroversially even in either stem group. It was formally described in 1999. Description ''Haikouichthys'' is about long and is narrower than ''Myllokunmingia'', another Wiktionary:putative#English, putative chordate that comes from the same beds. The holotype of ''Haikouichthys ercaicunensis'' was found in the Yuansshan member of the Maotianshan Shales, Qiongzhusi Formation in the 'Eoredlichia' Zone near Haikou at Ercaicun, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myllokunmingia
''Myllokunmingia'' is a genus of basal chordate from the Lower Cambrian Maotianshan shales of China 518 to 490 mya and is thought to be a vertebrate, although this is not conclusively proven. The species M. fengjiaoa is 28 mm long and 6 mm high. It is among the oldest possible craniates, found in the lower Cambrian Chengjiang (). It appears to have a skull and skeletal structures made of cartilage. There is no sign of biomineralization of the skeletal elements. The holotype was found in the Yuanshan member of the Qiongzhusi Formation in the Eoredlichia Zone near Haikou at Ercaicun, Kunming City, Yunnan, China. Only one species is known – ''Myllokunmingia fengjiaoa'' (Shu, Zhang & Han). Related creatures are ''Haikouichthys'' and '' Zhongjianichthys''. The animal has a distinct head and trunk with a forward sail-like (1.5 mm) dorsal fin and a ventral finfold (probably paired) further back. The maximum height of M. fengijaoa is at 6mm. The maximum height point i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrates
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] |
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