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Stanleycaris Hirpex
''Stanleycaris'' is an extinct, monotypic genus of hurdiid radiodont from the middle Cambrian (Miaolingian). The type species is ''Stanleycaris hirpex''. ''Stanleycaris'' was described from the Stephen Formation near the Stanley Glacier and Burgess Shale locality of Canada, as well as Wheeler Formation of United States. The genus was characterized by the rake-like frontal appendages with robust inner spines. ''Stanleycaris'' was originally described only from frontal appendages and oral cone. However, in 2022, 268 specimens of ''Stanleycaris'', many of which were complete, were studied, making ''Stanleycaris'' a well documented radiodont. ''Stanleycaris'' had three eyes, a bizarre configuration previously unknown among other radiodont genera; yet this head anatomy supports early differentiation among arthropod head and trunk segmentation. The original description of the taxon appeared in an online supplement to the article published by Jean-Bernard Caron, Robert R. Gaines, M. G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the fossil record) after a period of apparent absence. More than 99% of all species that ever lived on Earth, amounting to over five billion species, are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryote globally, and possibly many times more if microorganisms, like bacteria, are included. Notable extinct animal species include non-avian dinosaurs, saber-toothed cats, dodos, m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2010 In Paleontology
Plants Angiosperms Molluscs Newly named bivalves Arthropods Fishes Amphibians Newly named amphibians Basal reptiles Newly named basal reptiles Ichthyopterygians Newly named ichthyopterygians Lepidosauromorphs Newly named plesiosaurs Newly named basal lepidosaurs Newly named lizards Newly named snakes Turtles Newly named turtles Archosauromorphs Newly named basal archosauromorphs Archosaurs Synapsids Newly named non-mammalian synapsids Mammals Other animals Footnotes Complete author list As science becomes more collaborative, papers with large numbers of authors are becoming more common. To prevent the deformation of the tables, these footnotes list the contributors to papers that erect new genera and have many authors. References {{Reflist, 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ganglion
A ganglion is a group of neuron cell bodies in the peripheral nervous system. In the somatic nervous system this includes dorsal root ganglia and trigeminal ganglia among a few others. In the autonomic nervous system there are both sympathetic and parasympathetic ganglia which contain the cell bodies of postganglionic sympathetic and parasympathetic neurons respectively. A pseudoganglion looks like a ganglion, but only has nerve fibers and has no nerve cell bodies. Structure Ganglia are primarily made up of somata and dendritic structures which are bundled or connected. Ganglia often interconnect with other ganglia to form a complex system of ganglia known as a plexus. Ganglia provide relay points and intermediary connections between different neurological structures in the body, such as the peripheral and central nervous systems. Among vertebrates there are three major groups of ganglia: *Dorsal root ganglia (also known as the spinal ganglia) contain the cell bodies of se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the cerebellum is 55–70 billion. Each neuron is connected by synapses to several thousand other neurons. These neurons typically communicate with one another by means of long fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells. Physiologically, brains exert centralized control over a body's other organs. They act on the rest of the body both by generating patterns of muscle activity and by driving the secretion of chemicals called hormones. This centralized control allows rapid and coordinated respon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Composition Of The Protocerebrum
The protocerebrum is the first segment of the panarthropod brain. Recent studies suggest that it comprises two regions. Region associated with the expression of ''six3'' ''six3'' is a transcription factor that marks the anteriormost part of the developing body in a whole host of Metazoa. In the panarthropod brain, the anteriormost (rostralmost) part of the germband expresses six3. This region is described as medial, and corresponds to the annelid prostomium. In arthropods, it contains the ''pars intercerebralis'' and ''pars lateralis''. ''six3'' is associated with the euarthropod labrum and the onychophoran frontal appendages (antennae). Region associated with the expression of ''orthodenticle'' The other region expresses homologues of orthodenticle, ''Otx'' or ''otd''. This region is more caudal and lateral, and bears the eyes. Orthodenticle is associated with the protocerebral bridge, part of the central complex, traditionally a marker of the prosocerebrum. In th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lyrarapax
'' Lyrarapax'' is a radiodont genus of the family Amplectobeluidae that lived in the early Cambrian period 520 million years ago. Its neural tissue indicates that the radiodont frontal appendage is protocerebral, resolving parts of the arthropod head problem and showing that the frontal appendage is homologous to the antennae of Onychophorans and labrum of euarthropods. Its fossilized remains were found in Yunnan Yunnan , () is a landlocked province in 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 C ... in southwestern China. A second species was described in 2016, differing principally in the morphology of its frontal appendages. Taxonomy The scientific name "''Lyrarapax''" is a compound word of the Latin "lyra" (lyre) and "rapax" (predator), and is named after the outline of the body of this genus, which resembles a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peytoia
''Peytoia'' is a genus of hurdiid radiodont that lived in the Cambrian period, containing two species, ''Peytoia nathorsti'' from the Miaolingian of Canada and ''Peytoia infercambriensis'' from Poland, dating to Cambrian Stage 3. Its two frontal appendages had long bristle-like spines, it had no fan tail, and its short stalked eyes were behind its large head. 108 specimens of ''Peytoia'' are known from the Greater Phyllopod bed, where they comprise 0.21% of the community. ''Peytoia nathorsti'' and its junior synonym ''Laggania cambria'' played a major role in the discovery of the radiodont body plan. Initially interpreted as a jellyfish and a sea cucumber respectively, they were eventually shown to be the mouthparts and body of a single animal, which bore ''Anomalocaris''-like appendages. ''Peytoia infercambriensis'' is the geologically oldest known radiodont species. Classification ''Peytoia'' belongs to the clade Hurdiidae, and is closely related to the contemporary genus ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ommatidium
The compound eyes of arthropods like insects, crustaceans and millipedes are composed of units called ommatidia (singular: ommatidium). An ommatidium contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The outer part of the ommatidium is overlaid with a transparent cornea. Each ommatidium is innervated by one axon bundle (usually consisting of 6–9 axons, depending on the number of rhabdomeres) and provides the brain with one picture element. The brain forms an image from these independent picture elements. The number of ommatidia in the eye depends upon the type of arthropod and range from as low as 5 as in the Antarctic isopod ''Glyptonotus antarcticus'', or a handful in the primitive Zygentoma, to around 30,000 in larger Anisoptera dragonflies and some Sphingidae moths. Description Ommatidia are typically hexagonal in cross-section and approximately ten times longer than wide. The diameter is largest at the surface, tapering toward the in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compound Eye
A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color. The image perceived by this arthropod eye is a combination of inputs from the numerous ommatidia, which are oriented to point in slightly different directions. Compared with single-aperture eyes, compound eyes have poor image resolution; however, they possess a very large view angle and the ability to detect fast movement and, in some cases, the polarization of light. Because a compound eye is made up of a collection of ommatidia, each with its own lens, light will enter each ommatidium instead of using a single entrance point. The individual light receptors behind each lens are then turned on and off due to a series of changes in the light intensity during movement or when an object in moving, creating a flic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
20220715 Radiodonta Brain Interpretations
__NOTOC__ Year 715 ( DCCXV) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. The denomination 715 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Byzantine Empire * May – Emperor Anastasios II is deposed in an army mutiny, and succeeded by Theodosius III, a tax-collector from the ''theme'' of Opsikion (modern Turkey). After a six-month siege, Theodosius and his troops take Constantinople; Anastasios is forced to abdicate the throne, and retires to a monastery in Thessaloniki ( Macedonia). Europe * September 26 – Battle of Compiègne: Ragenfrid, mayor of the palace of Neustria and Burgundy (appointed by King Dagobert III), defeats Theudoald in the first battle of the Frankish civil war, following the death of Pepin II (of Herstal). * Dagobert III dies of an illness and is succeeded by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amplectobeluidae
''Amplectobeluidae'' is a clade of Cambrian radiodonts. Definition In 2014, ''Amplectobeluidae'' was defined as the most inclusive clade including '' Amplectobelua symbrachiata'' but not ''Anomalocaris canadensis'', ''Tamisiocaris borealis'', or ''Hurdia victoria''. Description Amplectobeluids could be recognized by frontal appendages with well-developed first distal endite, which forming a pincer-like structure that presumably better suited for a grasping function. Complete body fossils of amplectobeluids are only known by ''Amplectobelua'' and ''Lyrarapax'', both showing combination of characters resembling ''Anomalocaris'' (i.e. streamlined body; small head with ovoid sclerites; well-developed swimming flaps; a pair of caudal furcae). Another distinctive features only known in amplectobeluid genera were pairs of gnathobase-like structures (known by ''Amplectobelua'' and ''Ramskoeldia''), or an oral cone with combination of tetraradial arrangement and scale-like nodes (known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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