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Zhongjianichthys
''Zhongjianichthys rostratus'' is an extinct species basal chordate that lived in the Cambrian Period, approximately 518 million years ago, in what is now Southwest China. It is sometimes regarded as an early fish, and therefore as one of the first vertebrates in the global fossil record. The genus name, ''Zhongjianichthys'', is named after paleontologist Yang Zhongjian (1897-1979), who was widely honored as the "Father of Chinese Vertebrate Paleontology". Physical characteristics The eyes of ''Zhongjianichthys'' are located behind an antero-dorsal lobe of the head, and the mouth apparently did not have a jaw. It also lacked scales and had a thick skin. In fact, it is known to have had a thicker skin than other early chordates because, unlike ''Myllokunmingia'', which also lived in the Cambrian, no impressions of its myomeres have been found. The ventral fin is low in height, and runs much of the body's length. Although ''Zhonjianichthys'' appears more advanced than its relati ... [...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 538 and 485 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 it was later identified as a chordate. Subsequent discoveries 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 C ... [...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 radiation of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chordate
A chordate ( ) is a bilaterian animal belonging to the phylum Chordata ( ). All chordates possess, at some point during their larval or adult stages, five distinctive physical characteristics ( synapomorphies) that distinguish them from other taxa. These five synapomorphies are a notochord, a hollow dorsal nerve cord, an endostyle or thyroid, pharyngeal slits, and a post- anal tail. 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 inner mitochondrial membrane protease ATP23, which are exclusively shared by all vertebrates, tunicates and cephalochordates. These CSIs provide molecular means to reliably distinguish chordates from all other animals. Chordates are divided into three subphyla: Vertebrata (fish, amphibians, reptiles, birds and mammals), whose notochords are replaced by a cartilaginous/ bony axia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian Period
The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma. Most of the continents lay in the southern hemisphere surrounded by the vast Panthalassa, Panthalassa Ocean. The assembly of Gondwana during the Ediacaran and early Cambrian led to the development of new Convergent boundary, convergent plate boundaries and Volcanic arc, continental-margin arc magmatism along its margins that helped drive up global temperatures. Laurentia lay across the equator, separated from Gondwana by the opening Iapetus Ocean. The Cambrian marked a profound change in Life, life on Earth; prior to the Period, the majority of living organisms were small, Unicellular organism, unicellular and poorly preserved. Complex, multicellular organisms gradually became more common during the Ediacaran, but it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southwest China
Southwestern China () is a region in the People's Republic of China. It consists of five provincial administrative regions, namely Chongqing, Sichuan, Guizhou, Yunnan, and Xizang. Geography Southwestern China is a rugged and mountainous region, transitioning between the Tibetan Plateau to the west and the Chinese coastal hills (东南丘陵) and plains to the east. Key geographic features in the region include the Hengduan Mountains in the west, the Sichuan Basin in the northeast, and the karstic Yungui Plateau in the east. The majority of the region is drained by the Yangtze River, which forms the Three Gorges in the northeast of the region. The narrowest concept of Southwestern China consists of Sichuan, Chongqing, Yunnan, and Guizhou, while wider definitions often include Guangxi and western portions of Hunan. The official government definition of Southwestern China includes the core provinces of Sichuan, Chongqing, Yunnan, and Guizhou, in addition to the Tibet Autonomou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Record
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Though the fossil record is incomplete, numerous studies have demonstrated that there is enough information available to give a good understanding of the pattern of diversification of life on Earth. In addition, the record can predict and fill gaps such as the discovery of '' Tiktaalik'' in the arctic of Canada. Paleontology includes the study of fossils: their age, method of formation, and evolutionary significance. Specimens are sometimes considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years to 4.1 billion years old. Early edition, published online before print. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yang Zhongjian
Yang Zhongjian, also Yang Chung-chien (; 1 June 1897 – 15 January 1979), courtesy name Keqiang (), also known as C.C. (Chung Chien) Young, was a Chinese paleontologist and zoologist. He was one of China's foremost vertebrate paleontologists. He has been called the "Father of Chinese Vertebrate Paleontology". Biography Yang was born in Hua County, Shaanxi, China. He graduated from the Department of Geology of Peking University in 1923, and in 1927 received his doctorate from the University of Munich in Germany. In 1928 he worked for the Cenozoic Research Laboratory of the Geological Survey of China and took charge of excavations at the Peking Man Site at Zhoukoudian. He held professorial posts at the Geological Survey of China, Peking University, and Northwest University in Xi'an. Yang's scientific work was instrumental in the creation of China's Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, which today houses one of the most important collection ... [...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 mya and is thought to be a vertebrate, although this is not conclusively supported. The type 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. Some researchers have considered the other primitive chordate '' Haikouichthys'' to be synonymous with this taxon, but subsequent studies led by the British paleontologist Simon Conway Morris identified both genera to be distinct, separate taxa on the basis of different gill arrangement, the absence of branchial rays in ''Myllokunmingia'' and the myomeres ... [...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 fascia consisting of connective tissue, known as myosepta. Myomere counts are sometimes used for identifying specimens using meristics, since their number corresponds to the number of vertebrae in the adults. Myomere 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 (those of the "stomach" region) and related structures, while epaxial refers to more dorsal muscles (those of the "back"). The horizontal septum divides these two regions in vertebrates from cyclostomes (jawless lamprey and hagfish) to gnathostomes (jawed fish). In terrestrial chordates, which are gnathostomes themselves, the myomeres become fused as well ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is Cladogram#Homoplasies, homoplasy. The recurrent evolution of flight is a classic example, as flying pterygota, insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas ''homology (biology), homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different trai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maotianshan Shales
The Maotianshan Shales () are a series of Early Cambrian sedimentary deposits in the Chiungchussu Formation or Heilinpu Formation, famous for their '' Konservat Lagerstätten'', deposits known for the exceptional preservation of fossilized organisms or traces. The Maotianshan Shales form one of some forty Cambrian fossil locations worldwide exhibiting exquisite preservation of rarely preserved, non-mineralized soft tissue, comparable to the fossils of the Burgess Shale of British Columbia, Canada. They take their name from Maotianshan Hill () in Chengjiang County, Yunnan Province, China. The most famous assemblage of organisms are referred to as the Chengjiang biota for the multiple scattered fossil sites in Chengjiang. The age of the Chengjiang Lagerstätte is locally termed Qiongzhusian, a stage correlated to the late Atdabanian Stage in Siberian sequences of the middle of the Early Cambrian. The shales date to ≤. Along with the Burgess Shale, the Maotianshan Shales ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
