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Mandibulata
The clade Mandibulata constitutes one of the major subdivisions of the phylum Arthropoda, alongside Chelicerata. Mandibulates include the crustaceans, myriapods (centipedes and millipedes, among others), and all true insects. The name "Mandibulata" refers to the mandibles, a modified pair of limbs used in food processing, the presence of which are characteristic of most members of the group. The mandibulates are divided between the extant groups Myriapoda (millipedes and centipedes, among others) and Pancrustacea (including crustaceans and hexapods, the latter group containing insects). Molecular phylogenetic studies suggest that the living arthropods are related as shown in the cladogram below. Crustaceans do not form a monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod
Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metamerism (biology), metameric) Segmentation (biology), segments, and paired jointed appendages. In order to keep growing, they must go through stages of moulting, a process by which they shed their exoskeleton to reveal a new one. They form an extremely diverse group of up to ten million species. Haemolymph is the analogue of blood for most arthropods. An arthropod has an open circulatory system, with a body cavity called a haemocoel through which haemolymph circulates to the interior Organ (anatomy), organs. Like their exteriors, the internal organs of arthropods are generally built of repeated segments. They have ladder-like nervous systems, with paired Anatomical terms of location#Dorsal and ventral, ventral Ventral nerve cord, nerve cord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hymenocarina
Hymenocarina is an Order (biology), order of extinct marine arthropods known from the Cambrian. They possess bivalved carapaces, typically with exposed posteriors. Members of the group are morphologically diverse and had a variety of ecologies, including as filter feeders and as predators. Recent research has generally considered them to be stem or crown group members of Mandibulata, due to the presence of Mandible (arthropod mouthpart), mandibles in well-preserved species. Taxonomy Hymenocarines are characterized by the combination of the following characters: bivalved, convex carapace covering Cephalothorax, cephalothoracic (combined head and thorax) region; cephalothorax bearing multisegmented antennae (though as an exception antennae are absent in ''Odaraia'') and rounded Mandible (arthropod mouthpart), mandibles and likely Maxilla (arthropod mouthpart), maxillae, post maxillae limbs with spiny, subdivided basis and Arthropod leg, endopods (lower, leg-like parts) with well-d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chelicerata
The subphylum Chelicerata (from Neo-Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. Chelicerates include the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, ticks, and mites, among many others), as well as a number of extinct lineages, such as the eurypterids (sea scorpions) and chasmataspidids. Chelicerata split from Mandibulata by the mid-Cambrian, as evidenced by stem-group chelicerates like Habeliida and '' Mollisonia'' present by this time. The surviving marine species include the four species of xiphosurans (horseshoe crabs), and possibly the 1,300 species of pycnogonids (sea spiders), if the latter are indeed chelicerates. On the other hand, there are over 77,000 well-identified species of air-breathing chelicerates, and there may be about 500,000 unidentified species. Like all arthropods, chelicerates have segmented bodies with jointed limbs, all covered in a cuti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pancrustacea
Pancrustacea is the clade that comprises all crustaceans and all hexapods (insects and relatives). This grouping is contrary to the Atelocerata hypothesis, in which Hexapoda and Myriapoda are sister taxa, and Crustacea are only more distantly related. As of 2010, the Pancrustacea taxon was considered well accepted, with most studies recovering Hexapoda within Crustacea. The clade has also been called Tetraconata, referring to having a four-part cone in the ommatidium. The term "Tetraconata" is preferred by some scientists in order to avoid confusion with the use of "pan-" to indicate a clade that includes a crown group and all of its stem group representatives. Molecular studies A monophyletic Pancrustacea has been supported by several molecular studies, in most of which the subphylum Crustacea is paraphyletic with regard to hexapods (that is, that hexapods, including insects, are derived from crustacean ancestors). This means that within Pancrustacea, only some members are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mandible (arthropod Mouthpart)
250px, The mandibles of a bull ant The mandible (from or mandĭbŭ-lum, a jaw) of an arthropod is a pair of mouthparts used either for biting or cutting and holding food. Mandibles are often simply called jaws. Mandibles are present in the extant subphyla Myriapoda (millipedes and others), Crustacea and Hexapoda (insects etc.). These groups make up the clade Mandibulata, which is currently believed to be the sister group to the rest of arthropods, the clade Arachnomorpha (Chelicerata and Trilobita). Unlike the chelicerae of arachnids, mandibles can often be used to chew food. Mandibulates also differ by having antennae, and also by having three distinct body regions: head, thorax and abdomen. (The cephalothorax (or prosoma) of chelicerates is a fusion of head and thorax.) Insects Insect mandibles are as diverse in form as their food. For instance, grasshoppers and many other plant-eating insects have sharp-edged mandibles that move side to side. Most butterflies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Myriapoda
Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. Although molecular evidence and similar fossils suggests a diversification in the Cambrian Period, the oldest known fossil record of myriapods dates between the Late Silurian and Early Devonian, with '' Pneumodesmus'' preserving the earliest known evidence of air-breathing on land. Other early myriapod fossil species around the similar time period include '' Kampecaris obanensis'' and '' Archidesmus'' sp. The phylogenetic classification of myriapods is still debated. The scientific study of myriapods is myriapodology, and those who study myriapods are myriapodologists. Anatomy Myriapods have a single pair of antennae and, in most cases, simple eyes. Exceptions are the two classes of symphylans and pauropods, the millipede order Polydesmida and the centipede order Geophilomorpha, which are all ey ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marrellomorpha
Marrellomorpha are an extinct group of arthropods known from the Cambrian to the Early Devonian. They lacked mineralised hard parts, so are only known from areas of exceptional preservation, limiting their fossil distribution. The best known member is '' Marrella'', with thousands of specimens found in the Cambrian aged Burgess Shale of Canada. Taxonomy The group is divided up into two major orders, Marrellida and Acercostraca. Marrellida is recognised by the possession of head shields with two or three pairs of elongate spine-like projections, and three attached pairs of uniramous (single-branched) appendages, while Acercostraca generally have large ovoid carapaces that cover the entire upper half of the body, and five pairs of uniramous appendages attached to the head section. Both groups have unbranched antennae and a segmented trunk with biramous (divided into two branches) appendages. Recent research has suggested the previously enigmatic Cambrian trilobite-like arthrop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thylacocephala
The Thylacocephala (from the Greek or ', meaning " pouch", and or ' meaning "head") are group of extinct probable mandibulate arthropods, that have been considered by some researchers as having possible crustacean affinities. As a class they have a short research history, having been erected in the early 1980s. They typically possess a large, laterally flattened carapace that encompasses the entire body. The compound eyes tend to be large and bulbous, and occupy a frontal notch on the carapace. They possess three pairs of large raptorial limbs, and the abdomen bears a battery of small swimming limbs. Their size ranges from ~15 mm to potentially up to 250 mm. Inconclusive claims of thylacocephalans have been reported from the lower lower Cambrian ('' Zhenghecaris''), but later study considered that genus as radiodont or arthropod with uncertain systematic position. The oldest unequivocal fossils are Upper Ordovician and Lower Silurian in age. As a group, the Thylacocephala s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambropodus
''Cambropodus'' is a genus of Cambrian arthropod from the Wheeler Shale of Utah. It contains one species, ''Cambropodus gracilis''. Description ''Cambropodus'' is only known from a partial specimen preserving what seems to be the front end of the body. It preserves nine pairs of appendages, all uniramous and likely used for walking, which bear some similarity to the legs of Scutigeromorpha. Due to their flexibility, they likely had between four and six podomeres, although the exact amount is unclear. The head also preserves two long antenniform structures. However, unlike myriapods, ''Cambropodus'' has no specialised head limbs, and instead the first two limb pairs are very similar to the rest. On the head, the limbs are more laterally attached, however they become more ventrally attached on the body. The complete animal is estimated to be roughly 2 cm long, with at least 15 pairs of appendages. The gut is preserved as a light stripe down the middle of the fossil, with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crustacean
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthropods including decapods (shrimps, prawns, crabs, lobsters and crayfish), seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods (insects and entognathans) emerged deep in the Crustacean group, with the completed pan-group referred to as Pancrustacea. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans ( oligostracans and multicrustaceans). The 67,000 described species range in size from '' Stygotantulus stocki'' at , to the Japanese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fuxianhuiida
Fuxianhuiida is an extinct clade of arthropods from the Cambrian of China. All currently known species are from Cambrian Series 2 aged deposits in Yunnan, Yunnan Province, including the Maotianshan Shales, Chengjiang biota. Although historically suggested to be members of the arthropod stem group recent research has suggested that they may be closely related to Mandibulata, mandibulates. Many specimens are known with exceptional soft tissue preservation, including preserved guts and Nervous tissue, neural tissue, which given their Basal (phylogenetics), basal phylogenetic position makes them important in understanding the evolution of Arthropoda as a whole. They reach a size of up to 15 cm, and are interpreted as Benthic zone, benthic predators and scavengers. The Fuxianhuiid exoskeleton is unmineralised, and the number of Tergum, tergites ranges from 15 to over 40. The Cephalon (arthropod head), cephalon is covered by a head shield and contains stalked eyes connected by the S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Odaraia
''Odaraia'' is an extinct genus of bivalved Hymenocarina, hymenocarine arthropod with a single known species ''Odaraia alata'', found in the Middle Cambrian Burgess Shale in British Columbia, Canada. History of research and taxonomy The genus and species were first described by Charles Doolittle Walcott, Charles Walcott in 1912. It was placed into its own family, Odaraiidae by Simonetta and Delle Cave in 1975,Simonetta AM, Delle Cave L . 1975 The Cambrian non-trilobite arthropods from the Burgess Shale of British Columbia: a study of their comparative morphology, taxonomy and evolutionary significance. ''Palaeontogr. Ital.'' which has been used to include other genera of bivalved Cambrian arthropods. The species was redescribed by Derek Briggs 1981, and again redescribed in 2024 by Izquierdo-López and Caron. While originally ''Odaraia'' and other odaraiids have been interpreted as Basal (phylogenetics), basal euarthropods not closely related to any living arthropod group, the co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
