A Theoretical Morphologic Analysis of Ecomorphologic Variation in Archimedes Helical Colony Form

Other| December 01, 2002 A Theoretical Morphologic Analysis of Ecomorphologic Variation in Archimedes Helical Colony Form GEORGE R. McGHEE, Jr.; GEORGE R. McGHEE, Jr. 1Department of Geological Sciences, Wright-Rieman Laboratories, Rutgers University, New Brunswick, NJ 08903 Search for other works by this author on: GSW Google Scholar FRANK K. McKINNEY FRANK K. McKINNEY 2Department of Geology, Appalachian State University, Boone, NC 28608 Search for other works by this author on: GSW Google Scholar PALAIOS (2002) 17 (6): 556–570. https://doi.org/10.1669/0883-1351(2002)017<0556:ATMAOE>2.0.CO;2 Article history accepted: 12 May 2002 first online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation GEORGE R. McGHEE, FRANK K. McKINNEY; A Theoretical Morphologic Analysis of Ecomorphologic Variation in Archimedes Helical Colony Form. PALAIOS 2002;; 17 (6): 556–570. doi: https://doi.org/10.1669/0883-1351(2002)017<0556:ATMAOE>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyPALAIOS Search Advanced Search Abstract In this contribution theoretical morphospace techniques are demonstrated to be particularly useful in the analysis of ecomorphologic variation; that is, the detection of repetitive morphologies that consistently reoccur in similar environments. Although at least six distinct species of Archimedes occurred in the mid-Carboniferous shallow seas of North America, the distribution of a sample of 116 of their helical colony morphologies within theoretical morphospace forms two clouds of points that correspond to two paleoenvironmental settings: basinal versus back-shoal. It is argued that the distribution of the two Archimedes ecomorphologic colony types in morphospace is a function of the vertical extent of the quiet-water zone above the sea floor in back-shoal versus basinal environments, and not of differences in colony-type feeding efficiencies. It also is argued that the observed tendency of back-shoal colonies to form geographically distinct morphologic populations in morphospace is a function of their clonal mode of reproduction, in contrast to the more commonly sexually-reproducing basinal colonies.Theoretical morphospace analyses also can reveal species that do not show ecomorphologic variation in colony form. The unusual species Archimedes laxus, which occurs in both basinal and back-shoal environments, occupies its own unique position within the theoretical morphospace, a position that is displaced from and does not overlap the regions of morphospace occupied by other colonies, either basinal or back-shoal. Consideration of the unique aspects of this species' morphology leads to the suggestion that A. laxus may have had a rapid growth, weed-like mode of life that was quite different from typical Archimedes colonies. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.