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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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ductina Vietnamica 2 Frontal
''Ductina'' is a genus of extinct, small to average sized, eyeless Phacopida, phacopid Trilobita, trilobite, that lived during the Devonian. Description The body of ''Ductina'' is small to average (up to ), 1ΒΌ to 2 times as long as wide, blunted oval. Body without any adornment. The headshield (or Cephalon (arthropod head), cephalon) is 2 to 3 times as wide as it is long in the direction of the axis (or sagittally). The cephalic axis (or Cephalon (arthropod head), glabella) is strongly widening forward with shallow furrows, the front curving downward to end at an approximate straight angle to the plain of the axis. Another shallow furrow (the occipital furrow), with left and right a deep pit (apodemal pit), crosses to the back of the glabella to define a narrow band (or Cephalon (arthropod head)#Trilobites, occipital ring), and just in front left and right a small lobe is defined by shallow furrows and a deep pits. The back of the cephalon is often broken, obscuring the featur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |