Ontogeny, Intraspecific Variation, and Systematics of the Late Cambrian Trilobite Dikelocephalus
نویسندگان
چکیده
منابع مشابه
A Cambrian peak in morphological variation within trilobite species.
Morphological variation within species is a raw material subject to natural selection. However, temporal change in morphological diversity has usually been studied in terms of variation among rather than within species. The distribution of polymorphic traits in cladistic character-taxon matrices reveals that the frequency and extent of morphological variation in 982 trilobite species are greate...
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Modularity of the cranidium of Crassifimbra? metalaspis, a Cambrian ptychoparioid trilobite, is investigated using landmark-based geometric morphometric methods to gain insight into the integration among morphogenetic processes responsible for shaping the head of an ancient arthropod. Of particular interest is the extent to which the structure of phenotypic integration was governed by direct in...
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Dedifferentiation, paedomorphosis, and the insertion and deletion of developmental stages make it impossible to deduce the genealogical hierarchy frum only ontogenetic transformation series. Like the outgroup criterion, ontogenetic character precedence is not theory-neutral and to use it to deduce genealogy requires certain assumptions. If scientists are going to use logically unbeatable theori...
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—Ontogenetic stages of trilobites have traditionally been recognized on the basis of the development of exoskeletal segmentation. The established protaspid, meraspid, and holaspid phases relate specifically to the development of articulated joints between exoskeletal elements. Transitions between these phases were marked by the first and last appearances of new trunk segment articulations. Here...
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Article history: The uppermost 43 cm of Dy Received 13 November 2007 Received in revised form 4 March 2008 Accepted 3 April 2008
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ژورنال
عنوان ژورنال: Smithsonian Contributions to Paleobiology
سال: 1994
ISSN: 0081-0266
DOI: 10.5479/si.00810266.79.1