EOSC 326 Study Guide - Diplichnites, Rusophycus, Paraphyly
3 May 2012
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It is composed of calcium carbonate and is divided into three parts: cephalon, thorax, and pygidium. The glabella can contain ridges called glabellar furrows. The glabella"s function is hypothesized to contain egg sacs or act as a digestive chamber. Thorax: this is the animal"s body, it contained between 2 and 61 articulating segments. It houses the joined, paired limbs. Trilobite eyes are compound, meaning they contained multiple lenses. In each lens, the main optical axis (c- axis) is perpendicular to the surface of the eye. Each eye contains from 1 to 15,000 individual lenses of 100 m in diameter. The entire eye is covered with a single membrane. Individual black or white dots are assembled to form an image; double refraction meant fuzzy images were produced. This allowed these species of trilobites to see clear, focused images. They could also see 3d images. Schizochroal eyes can be see in trilobites from ordovician to devonian age: unusual eye adaptations:
