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Emucaris Fava
''Emucaris fava'' is an extinct species of soft-shelled trilobite-like arthropod of the nektaspid order from the Lower Cambrian (Cambrian Stage 4) of South Australia. It is the only species classified under the genus ''Emucaris''. Etymology The generic name is derived from the Emu Bay Shale, the deposit where the species was collected, and the Latin word ' meaning shrimp. The specific name ''fava'' is from the Latin word for honeycomb, for the ornamentation on its pygidial axis. Description The outline of the dorsal exoskeleton of ''E. fava'' is pointed inverted egg-shaped, between and long and about 1⅔× as long as wide. The axis is up to 15% of the width of the body and only slightly raised. The semi-circular headshield (or cephalon) is about ½× as long as the tailshield (pygidium), and in between them four short thoracic body segments (somites). When disregarding the border, the pygidium of ''Emucaris'' is a triangle with a rounded termination, carrying a spine th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinct
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] |
Exoskeleton
An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the larger kinds of exoskeletons are known as " shells". Examples of exoskeletons within animals include the arthropod exoskeleton shared by chelicerates, myriapods, crustaceans, and insects, as well as the shell of certain sponges and the mollusc shell shared by snails, clams, tusk shells, chitons and nautilus. Some animals, such as the turtle, have both an endoskeleton and an exoskeleton. Role Exoskeletons contain rigid and resistant components that fulfill a set of functional roles in many animals including protection, excretion, sensing, support, feeding and acting as a barrier against desiccation in terrestrial organisms. Exoskeletons have a role in defense from pests and predators, support and in providing an attachment framework f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Arthropod 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] |
Kangaroo Island
Kangaroo Island, also known as Karta Pintingga (literally 'Island of the Dead' in the language of the Kaurna people), is Australia's third-largest island, after Tasmania and Melville Island. It lies in the state of South Australia, southwest of Adelaide. Its closest point to the mainland is Snapper Point in Backstairs Passage, which is from the Fleurieu Peninsula. The native population of Aboriginal Australians that once occupied the island (sometimes referred to as the Kartan people) disappeared from the archaeological record sometime after the land became an island following the rising sea levels associated with the Last Glacial Period around 10,000 years ago. It was subsequently settled intermittently by sealers and whalers in the early 19th century, and from 1836 on a permanent basis during the British colonisation of South Australia. Since then the island's economy has been principally agricultural, with a southern rock lobster fishery and with tourism growing in impo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emu Bay Shale
The Emu Bay Shale is a geological formation in Emu Bay, South Australia, containing a major Konservat-Lagerstätte (fossil beds with soft tissue preservation). It is one of two in the world containing Redlichiidan trilobites. The Emu Bay Shale is dated as Cambrian Series 2, Stage 4, correlated with the upper Botomian Stage of the Lower Cambrian. Its mode of preservation is the same as the Burgess shale, but the larger grain size of the Emu Bay rock means that the quality of preservation is lower. More than 50 species of trilobites, non-biomineralized arthropods, palaeoscolecids, a lobopodian, a polychaete, vetulicolians, nectocaridids, hyoliths, brachiopods, sponges, chancelloriids, and a chelicerate are known from the Emu Bay Shale. Description The Emu Bay Shale of Kangaroo Island, South Australia, is Australia's only known Burgess-Shale-type Konservat-Lagerstätte, and includes faunal elements such as ''Anomalocaris'', ''Tuzoia'', ''Isoxys'', and '' Wronascolex'', in commo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kangacaris
''Kangacaris'' is an extinct genus of soft-shelled trilobite-like arthropod of the nektaspid order from the Lower Cambrian (Botomian). ''K. zhangi'' is known from South Australia, and ''K. shui'' from South-West China. Etymology The generic name is derived from "Kanga", a contraction of Kangaroo Island, and Latin ' ("shrimp"). The specific name of the type species honors the Chinese palaeontologist Xingliang Zhang. Description The dorsal exoskeleton of ''Kangacaris'' is inverted egg-shaped, about long and wide. The axis is ⅓× as wide as the body and only slightly raised. The semi-circular headshield (or cephalon) is about ⅔× as long as the tailshield (pygidium), and in between them three short thoracic body segments (somites). The lateral margin of the pygidium is progressively angling towards the axis, ending in the slightest hint of a point. Twelve to thirteen furrows are most distinct on the axis, and becoming indiscernible near the border. The border of the ceph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Somite
The somites (outdated term: primitive segments) are a set of bilaterally paired blocks of paraxial mesoderm that form in the embryonic stage of somitogenesis, along the head-to-tail axis in segmented animals. In vertebrates, somites subdivide into the dermatomes, myotomes, sclerotomes and syndetomes that give rise to the vertebrae of the vertebral column, rib cage, part of the occipital bone, skeletal muscle, cartilage, tendons, and skin (of the back). The word ''somite'' is sometimes also used in place of the word '' metamere''. In this definition, the somite is a homologously-paired structure in an animal body plan, such as is visible in annelids and arthropods. Development The mesoderm forms at the same time as the other two germ layers, the ectoderm and endoderm. The mesoderm at either side of the neural tube is called paraxial mesoderm. It is distinct from the mesoderm underneath the neural tube which is called the chordamesoderm that becomes the notochord. The pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the creature's body, each of which is in turn composed of multiple segments. The human thorax includes the thoracic cavity and the thoracic wall. It contains organs including the heart, lungs, and thymus gland, as well as muscles and various other internal structures. Many diseases may affect the chest, and one of the most common symptoms is chest pain. Etymology The word thorax comes from the Greek θώραξ ''thorax'' "breastplate, cuirass, corslet" via la, thorax. Plural: ''thoraces'' or ''thoraxes''. Human thorax Structure In humans and other hominids, the thorax is the chest region of the body between the neck and the abdomen, along with its internal organs and other contents. It is mostly protected and supported by the rib cage, spi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trilobite
Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period () and they flourished throughout the lower Paleozoic before slipping into a long decline, when, during the Devonian, all trilobite orders except the Proetida died out. The last extant trilobites finally disappeared in the mass extinction at the end of the Permian about 252 million years ago. Trilobites were among the most successful of all early animals, existing in oceans for almost 270 million years, with over 22,000 species having been described. By the time trilobites first appeared in the fossil record, they were already highly diversified and geographically dispersed. Because trilobites had wide diversity and an easily fossilized exoskeleton, they left an extensive fossil record. The stu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalon (arthropod Head)
The cephalon is the head section of an arthropod. It is a tagma, i.e., a specialized grouping of arthropod segments. The word cephalon derives from the Greek κεφαλή (kephalē), meaning "head". Insects In insects, ''head'' is a preferred term. The insect head consists of five segments, including three (the labial, maxillary and mandibular) necessary for food uptake, which are altogether known as the gnathocephalon and house the suboesophageal ganglion of the brain, as well as the antennal segment, and an ocular segment, as well as a non segmented fused section of the head where the archicerebrum is housed known as the acron. See also arthropod head problem. Chelicerates and crustaceans In chelicerates and crustaceans, the cephalothorax is derived from the fusion of the cephalon and the thorax, and is usually covered by a single unsegmented carapace. In relation with the arthropod head problem, phylogeny studies show that members of the Malacostraca class of cru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dorsal (anatomy)
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and anatomical axes. The meaning of terms that are used can change depending on whether an organism is bipedal or quadrupedal. Additionally, for some animals such as invertebrates, some terms may not have any meaning at all; for example, an animal that is radially symmetrical will have no anterior surface, but can still have a description that a part is close to the middle ("proximal") or further from the middle ("distal"). International organisations have determined vocabularies that are often used as standard vocabularies for subdisciplines of anatom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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