page_title: Beckwithia (arthropod)
section_title: Description
hierarchical_section_title: Beckwithia (arthropod) / Description
caption_attribution_description: English: A cephalon of Beckwithia typa, an arthropod, Class Merostomata, Family Aglaspididae, 25 mm along the midline, collected in the Weeks Formation, Utah, USA, from the Middle Cambrian
context_page_description: Beckwithia is an extinct genus of average to large size, soft bodied basal chelicerate arthropods that lived during the late Middle and Upper Cambrian on the former paleocontinent Laurentia, in what are now Utah and Wisconsin. It has an inverted egg-shape, with a semi-circular head, 11 abdominal segments and a tail spine. It is a typical member of the group Aglaspidida.
context_section_description: The outline of the exoskeleton of Beckwithia is an inverted egg-shape with a stout sword-like tail spine or telson. The dorsal shield covering the cephalothorax (or prosoma) is semi-circular, with the margin curving smoothly from the front to an acute, but rather small genal spine at the outside and the back. The front and side margin is bordered by a flatted and undecorated zone of almost constant length/width. The area within that band is densely covered in pustules. Two distinctly raised eyes that are circular to oval are located at the outer rim of what could be compared to a trilobite glabella, with a strongly effaced outline and lobes. The abdomen (or opisthosoma) consists of 11 segments (or possibly sometimes 10 or 12) perpendicular to the midline, that terminate to the sides in small spines that angle to the back. Each segment carries a spine at midline too that is directed backward, a character that distinguishes Beckwithia from other Aglaspidid genera. Only one species, Beckwithia typa, is currently recognized.
caption: A cephalon of Beckwithia typa, 25 mm
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