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Paciphacops Campbelli
''Paciphacops'' is a genus of trilobites within order Phacopida, suborder Phacopina. This genus is found primarily in the United States and Australia and is easily mistaken for the genera ''Phacops'' and ''Kainops'', which are also popular among collectors. One major difference between ''Paciphacops'' and ''Phacops'' is that the central raised area (or Trilobite#Cephalon, glabella) of the headshield (or cephalon (arthropod anatomy), cephalon) extends beyond the headshield's anterior margin. A major difference between ''Paciphacops'' and ''Kainops'' is the greater number of eye facets in ''Kainops''. The skin (or sclera) of the visual surface in ''Paciphacops'' is thickened and bulged compared to the edge of each lens. Species A subset of the currently valid species of ''Paciphacops'' is below. The geographic region designated below for each species does not necessarily represent the entire geographic range for each species. *''Paciphacops birdsongensis'', Tennessee. *''Paciphaco ... [...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 two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |