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Eokinorhynchus
''Eokinorhynchus'' is a Fortunian (earliest Cambrian) ecdysozoan known from three fossils. It is interpreted as a stem-group Kinorhynch Kinorhyncha ( grc, κινέω, kīnéō, I move, ' "snout") is a phylum of small marine invertebrates that are widespread in mud or sand at all depths as part of the meiobenthos. They are also called mud dragons. Modern species are or less, ..., which would make it by far the earliest and indeed only reported member of this group from the fossil record. References Kinorhyncha Prehistoric protostome genera Cambrian genus extinctions {{Cambrian-animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinorhynch
Kinorhyncha ( grc, κινέω, kīnéō, I move, ' "snout") is a phylum of small marine invertebrates that are widespread in mud or sand at all depths as part of the meiobenthos. They are also called mud dragons. Modern species are or less, but Cambrian forms could reach . Anatomy Kinorhynchs are limbless animals, with a body consisting of a head, neck, and a trunk of eleven segments. They are the only members of Ecdysozoa, except from the panarthropoda, with a segmented body. Juveniles have eight or nine segments, depending on genus, with the last two or three being added later during growth. Like other ecdysozoans they do not have external cilia, but instead have a number of spines along the body, plus up to seven circles of spines around the head. These spines are used for locomotion, withdrawing the head and pushing forward, then gripping the substrate with the spines while drawing up the body. The body wall consists of a thin syncitial layer, which secretes a toug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinorhyncha
Kinorhyncha ( grc, κινέω, kīnéō, I move, ' "snout") is a phylum of small marine invertebrates that are widespread in mud or sand at all depths as part of the meiobenthos. They are also called mud dragons. Modern species are or less, but Cambrian forms could reach . Anatomy Kinorhynchs are limbless animals, with a body consisting of a head, neck, and a trunk of eleven segments. They are the only members of Ecdysozoa, except from the panarthropoda, with a segmented body. Juveniles have eight or nine segments, depending on genus, with the last two or three being added later during growth. Like other ecdysozoans they do not have external cilia, but instead have a number of spines along the body, plus up to seven circles of spines around the head. These spines are used for locomotion, withdrawing the head and pushing forward, then gripping the substrate with the spines while drawing up the body. The body wall consists of a thin syncitial layer, which secretes a tough ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fortunian
The Fortunian age marks the beginning of the Phanerozoic Eon, the Paleozoic Era, and the Cambrian Period. It is the first of the two stages of the Terreneuvian series. Its base is defined as the first appearance of the trace fossil ''Treptichnus pedum'' million years ago. The top of the Fortunian which is the base of the Stage 2 of the Cambrian has not been formally defined yet, but will correspond to the appearance of an Archeocyatha species or "Small shelly fossils" approximately million years ago. The name Fortunian is derived from a part of the Burin Peninsula, the town of Fortune near the GSSP and Fortune Bay. GSSP The type locality (GSSP) of the Fortunian stage is in Fortune Head, at the northern edge of the Burin Peninsula, Newfoundland, Canada (). This GSSP coincides with the base of the Terreneuvian series, the Precambrian-Cambrian boundary and the beginning of the Phanerozoic. The outcrops show a carbonate-siliciclastic succession which is mapped as the Chapel Island F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecdysozoa
Ecdysozoa () is a group of protostome animals, including Arthropoda (insects, chelicerata, crustaceans, and myriapods), Nematoda, and several smaller phyla. They were first defined by Aguinaldo ''et al.'' in 1997, based mainly on phylogenetic trees constructed using 18S ribosomal RNA genes. A large study in 2008 by Dunn ''et al.'' strongly supported the Ecdysozoa as a clade, that is, a group consisting of a common ancestor and all its descendants. The group is also supported by morphological characters, and includes all animals that grow by ecdysis, moulting their cuticle. The group was initially contested by a significant minority of biologists. Some argued for groupings based on more traditional taxonomic techniques, while others contested the interpretation of the molecular data. Etymology The name ''Ecdysozoa'' stems etymologically . Characteristics The most notable characteristic shared by ecdysozoans is a three-layered cuticle (four in Tardigrada) composed of orga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
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''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Protostome Genera
Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared 5000 years ago. It took thousands of years for writing systems to be widely adopted, with writing spreading to almost all cultures by the 19th century. The end of prehistory therefore came at very different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. In the early Bronze Age, Sumer in Mesopotamia, the Indus Valley Civilisation, and ancient Egypt were the first civilizations to develop their own scripts and to keep historical records, with their neighbors following. Most other civilizations reached the end of prehistory during the following Iron Age. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
