Arthropod Groups Essay

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INTRODUCTION In this report, I present a summary of five major arthropod groups. The three groups chosen for this report are Trilobitomorpha, Crustacea and Insecta. Like my previous report, I have organized this report to provide a general summary of these groups, and also to examine a number of fossil specimens belonging to each group. For each group, ten specimens belonging to a specific sub-group (and a specific stratigraphic range when possible) were selected from the GB3D Type Fossils Database and examined in photograph or three-dimensional scan. For each group, unique and recurring characteristics among specimens were identified. When coherent, the respective stratigraphic context of the selected specimens was also considered.
Phylum Arthropoda Arthropods are bilateral animals with segmented exoskeletons. Segmentation of the exoskeleton occurs through a process known as sclerotization, whereby the cuticle thickens and hardens differentially throughout development. Arthropod segments are specialized to some extent, usually with paired appendages that have been modified to perform a specific task. Groups of similarly-specialized segments formed functional groups known as tagmata. (Robison and Kaesler, 1987) It has been argued that Arthropoda is polyphyletic, meaning that several distinct lineages evolved arthropod
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The selected specimens in this report were retrieved from the GB3D Type Fossils database by searching for [Taxon] and [3D Scans = True]. These results were refined through successive decrements in stratigraphic range until ten specimens of a single order and/or genera were returned. I downloaded a photograph or .ply file from GB3D in order to further investigate and illustrate the characteristics of each specimen. Collection localities for specimens of each respective group were plotted using Google

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