|
Acastoidea
Acastoidea is a superfamily of trilobites from the order Phacopida, suborder Phacopina. This superfamily is divided into two families, Acastidae and Calmoniidae. This superfamily is distinguishable from the Phacopidae in that eyes are closer to the glabella The glabella, in humans, is the area of skin between the eyebrows and above the nose. The term also refers to the underlying bone that is slightly depressed, and joins the two brow ridges. It is a cephalometric landmark that is just superior to ... and that the glabella has lobes, unlike the genera in Phacopidae. References Phacopina Arthropod superfamilies {{phacopida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phacopina
The Phacopina comprise a suborder of the trilobite order Phacopida. Species belonging to the Phacopina lived from the Lower Ordovician (Tremadocian) through the end of the Upper Devonian (Famennian).Moore, R.C. (ed.). Treatise on Invertebrate Paleontology. Part O – Arthropoda (Trilobitomorpha). 1959 The one unique feature that distinguishes Phacopina from all other trilobites are the very large, separately set lenses without a common cornea of the compound eye. Habitat As far as known, all Phacopina species were marine bottom-dwellers. Origin The Early Ordovician genus '' Gyrometopus'' (superfamily Dalmanitoidea, family Diaphanometopidae) is probably close to the common ancestor of the Phacopina. ''Gyrometopus'' is phacopid in appearance, but a rostral plate is present, unlike in other Phacopina. However, the rostral plate does not divide the cephalic doublure into a left and right section, but instead the rostral suture defines a semicircle in the frontal ¾ of the doublur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acastoidea
Acastoidea is a superfamily of trilobites from the order Phacopida, suborder Phacopina. This superfamily is divided into two families, Acastidae and Calmoniidae. This superfamily is distinguishable from the Phacopidae in that eyes are closer to the glabella The glabella, in humans, is the area of skin between the eyebrows and above the nose. The term also refers to the underlying bone that is slightly depressed, and joins the two brow ridges. It is a cephalometric landmark that is just superior to ... and that the glabella has lobes, unlike the genera in Phacopidae. References Phacopina Arthropod superfamilies {{phacopida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acastidae
Acastidae is a family of trilobites in the order Phacopida, suborder Phacopina The Phacopina comprise a suborder of the trilobite order Phacopida. Species belonging to the Phacopina lived from the Lower Ordovician ( Tremadocian) through the end of the Upper Devonian (Famennian).Moore, R.C. (ed.). Treatise on Invertebrate Pal ..., superfamily Acastoidea, containing the following genera: References Acastoidea Trilobite families {{Phacopida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calmoniidae
Calmoniidae is a family of trilobites from the order Phacopida, suborder Phacopina, superfamily Acastoidea. It contains the following genera: *''Anchiopella'' *''Andinacaste'' *'' Australocaste'' *'' Australops'' *'' Awaria'' *''Bainella'' *'' Belenops'' *'' Bouleia'' *''Calmonia'' *''Chiarumanipyge'' *'' Clarkeaspis'' *''Cryphaeoides'' *'' Curuyella'' *''Deltacephalaspis'' *'' Eldredgeia'' *'' Feistia'' *'' Hadrorachus'' *'' Jujuyops'' *''Kozlowskiaspis'' *'' Malvinella'' *'' Malvinocooperella'' *'' Metacryphaeus'' *''Morocconites ''Morocconites malladoides'' is an average size (about ) trilobite, which lived during the Devonian period, in what is now southern Morocco. This species is assumed to be a close relative of '' Acastoides''. The most conspicuous feature is the ve ...''Edgecombe, G.D. Morocconites Struve, 1989, A Devonian Acastine Trilobite (Calmoniidae: Acastinae. ''American Museum Novitates'', Number 299/ref> *'' Oosthuizenella'' *'' Palpebrops'' *'' Parabouleia'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phacopida
Phacopida ("lens-face") is an order of trilobites that lived from the Late Cambrian to the Late Devonian. It is made up of a morphologically diverse assemblage of taxa in three related suborders. Characteristics Phacopida had 8 to 19 thoracic segments and are distinguishable by the expanded glabella, short or absent preglabellar area, and schizochroal (Phacopina) or holochroal (Cheirurina and Calymenina) eyes. Schizochroal eyes are compound eyes with up to around 700 separate lenses. Each lens has an individual cornea which extended into a rather large sclera. The development of schizochroal eyes in phacopid trilobites is an example of post-displacement paedomorphosis. The eyes of immature holochroal Cambrian trilobites were basically miniature schizochroal eyes. In Phacopida, these were retained, via delayed growth of these immature structures (post-displacement), into the adult form. '' Eldredgeops rana'' (Phacopidae) and '' Dalmanites limulurus'' (Dalmanitidae) are tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walliserops
''Walliserops'' (named after Prof. O. Walliser of the University of Göttingen) is a genus of spinose phacopid trilobite, of the family Acastidae, found in Lower to Middle Devonian age rocks from the Anti-Atlas Mountains of Morocco. All species of ''Walliserops'' possess a three-pronged "trident" that protrudes from the glabella. ''Walliserops'' is most closely related to the genus '' Comura''. ''Walliserops'' was originally erected for a single species, ''W. trifurcatus''. Later, two other species were assigned: ''W. hammii'' & ''W. tridens''. All three currently described species come from the same strata near Foum Zguid in southern Morocco. Three as yet undescribed species are recorded from other locations. Early reports of "trident" trilobites and placement within the proposed new genus "''Parabolops''" ("parabola face") - long tridents being placed within "''P. neptunis''", short tridents placed within "''P. hammi''" - were pre-empted by the publication of the detailed an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phacopidae
Phacopidae is a family of phacopid trilobites that ranges from the Lower Ordovician to the Upper Devonian, with representatives in all paleocontinents. Description As in all Phacopina, the eyes (if present) consist of very large (0.5 mm in ''Phacops rana''), separately set lenses without a common cornea (so called schizochroal eyes). However, several phacopids have very few lenses, such as the species of the genera ''Cryphops'', ''Denckmannites'', ''Dienstina'', ''Eucryphops'', ''Nephranops'', and ''Plagiolaria'', or lack eyes altogether, like ''Afrops'', ''Dianops'', ''Ductina'', and ''Trimerocephalus''. The natural fracture lines (sutures) of the head run along the top edges of the compound eye. From the back of the eye these cut to the side of the head (proparian) and not to the back. In front of the eye, the right and left facial sutures connect in front of the inflated glabella and consequently the free cheeks (or librigenae) are yoked as a single piece. In some of the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glabella (trilobite Anatomy)
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 crustac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
