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Ptychopariina
Ptychopariina is an extinct suborder of trilobites of the order Ptychopariida.Swinnerton HH, 1915. Suggestions for a Revised Classification of trilobites. ''Geological Magazine''. Also known as the ''primitive Ptychopariida'', they are a notably wide and varied taxon. Some of the representative genera include ''Elrathia'', '' Densonella'', '' Norwoodia'', '' Tricrepicephalus'', '' Conocoryphe'', and '' Modocia''. Description Specialization Specialization or Specialized may refer to: Academia * Academic specialization, may be a course of study or major at an academic institution or may refer to the field in which a specialist practices * Specialty (medicine), a branch of medical ... is common in the Ptychopariina, which has made it difficult for authors to develop a single type that can distinguish Ptychopariina from other clades. The thorax tends to be relatively long, with the pygidium generally smaller in size than the thorax. References External links''Ptychopariid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ptychopariida
Ptychopariida is a large, heterogeneous order of trilobite containing some of the most primitive species known. The earliest species occurred in the second half of the Lower Cambrian, and the last species did not survive the Ordovician–Silurian extinction event. Trilobites have facial sutures that run along the margin of the glabella and/or fixigena to the shoulder point where the cephalon meets the thorax. These sutures outline the cranidium, or the main, central part of the head that does not include the librigena (free cheeks). The eyes are medial along the glabella on the suture line (and some species have no eyes). The fossils of the moults of trilobites can often be told from the fossils of the actual animals by whether the librigena are present. (The librigena, or cheek spines, detach during moulting.) In ptychopariids, short bladelike genal spines are often present on the tips of the librigena. The thorax is large and is typically made up of eight or more segments. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henry Hurd Swinnerton
Henry Hurd Swinnerton (1875–1966) was a British geologist. He was professor of geology at University College Nottingham from 1910 to 1946. Swinnerton was educated at the Royal College of Science, and earned a doctorate in zoology (D.Sc.) from the University of London in July 1902. In the 1930s Swinnerton was a member of the Fenland Research Committee, contributing valuable knowledge of the geomorphology of the Lincolnshire coast. In 1937 he served as President of the Lincolnshire Naturalists' Union; he gave his Presidential address on "The Problem of the Lincoln Gap". In 1942 he was awarded the Murchison Medal of the Geological Society of London. Selected bibliography *Swinnerton H.H. (1910) ''Nottinghamshire'', Cambridge County Geographies Cambridge County Geographies is a book series published by Cambridge University Press. Volumes *Aberdeenshire by Mackie, Alexander *Argyllshire and Buteshire by MacNair, Peter (wikisource) *Ayrshire by Foster, John *Banffshire by Barclay ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tricrepicephalus
''Tricrepicephalus'' is an extinct genus of ptychopariid trilobites of the family Tricrepicephalidae with species of average size. Its species lived from 501 to 490 million years ago during the Dresbachian faunal stage of the late Cambrian Period. Fossils of ''Tricrepicephalus'' are widespread in Late Cambrian deposits in North America, but is also known from one location in South-America. ''Tricrepicephalus'' has an inverted egg-shaped exoskeleton, with three characteristic pits in the fold that parallels the margin of the headshield just in front of the central raised area. The articulating middle part of the body has 12 segments and the tailshield carries two long, tubular, curved pygidial spines that are reminiscent of earwig's pincers that rise backwards from the plain of the body at approximately 30°. Description The outline of the exoskeleton of ''Tricrepicephalus'' is an inverted egg shaped though almost ovate, widest at the tip of the genal spines and 1.2× as long ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, the equivalent Latin term ''cladus'' (plural ''cladi'') is often used in taxonomical literature. The common ancestor may be an individual, a population, or a species (extinct or extant). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over the last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic. Some of the relationships between organisms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological properties, its behavior, and the products of behavior. An organism's phenotype results from two basic factors: the expression of an organism's genetic code, or its genotype, and the influence of environmental factors. Both factors may interact, further affecting phenotype. When two or more clearly different phenotypes exist in the same population of a species, the species is called polymorphic. A well-documented example of polymorphism is Labrador Retriever coloring; while the coat color depends on many genes, it is clearly seen in the environment as yellow, black, and brown. Richard Dawkins in 1978 and then again in his 1982 book ''The Extended Phenotype'' suggested that one can regard bird nests and other built structures such as cad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Generalist And Specialist Species
A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources (for example, a heterotroph with a varied diet). A specialist species can thrive only in a narrow range of environmental conditions or has a limited diet. Most organisms do not all fit neatly into either group, however. Some species are highly specialized (the most extreme case being monophagous, eating one specific type of food), others less so, and some can tolerate many different environments. In other words, there is a continuum from highly specialized to broadly generalist species. Description Omnivores are usually generalists. Herbivores are often specialists, but those that eat a variety of plants may be considered generalists. A well-known example of a specialist animal is the monophagous koala, which subsists almost entirely on eucalyptus leaves. The raccoon is a generalist, because it has a natural range that includes most of North ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conocoryphe
''Conocoryphe'' is a genus of primarily eyeless trilobites belonging to the family Conocoryphidae. They lived during the Middle Cambrian period, about 505 million years ago. These arthropods lived on the sea bottom (epifaunal) and lived off dead particulate organic matter (a lifestyle called detritivorous). Distribution Cambrian of the Czech Republic, France, Spain, Turkey, United States (Wisconsin). Taxonomy ''Conocephalites'' Barrande, 1852 was introduced as a replacement for ''Conocephalus'' Zenker, 1833, which was unavailable since Thunberg (1815 ) had previously used the name for a genus of conehead bushcricket. Barrande, however, was unaware that ''Conocoryphe'' had already been proposed by Hawle and Corda in 1847. Type species ''Trilobites sulzeri'' (Schlotheim, 1823 = ''Conocoryphe sulzeri sulzeri'' (Schlotheim, 1823); ''Conocoryphe latifrons'' Hawle & Corda, 1847 HAWLE, I. and CORDA, A. J. C. 1847. Podrom einer Monographie der bo Èhmischen Trilobiten. ''Abha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norwoodia
''Norwoodia'' is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived from 501 to 490 million years ago during the Dresbachian faunal stage In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convent ... of the late Cambrian Period. References Ptychoparioidea Ptychopariida genera Cambrian trilobites Cambrian trilobites of North America Paleozoic life of Yukon {{Ptychopariida-stub Cambrian genus extinctions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elrathia
''Elrathia'' is a genus of trilobite belonging to Ptychopariacea known from the mid-Cambrian of Laurentia (North America). ''E. kingii'' is one of the most common trilobite fossils in the USA locally found in extremely high concentrations within the Wheeler Formation in the U.S. state of Utah. ''E. kingii'' has been considered the most recognizable trilobite. Commercial quarries extract ''E. kingii'' in prolific numbers, with just one commercial collector estimating 1.5 million specimens extracted in a 20-year career. 1950 specimens of ''Elrathia'' are known from the Greater Phyllopod bed, where they comprise 3.7% of the community. Etymology Even though the generic name ''Elrathia'' was first published in the combination ''E. kingii'', a species from the House Range, Utah, the name, itself, is derived from Elrath, Cherokee County, Alabama. Description ''E. kingii'' is a medium-sized trilobite with a smooth sub-ovate carapace that is tapered towards the rear. Thorax is usua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
