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Ontogeny of a new species of Paraparchites (Ostracoda) from the Lower Permian Speiser Shale in Kansas
Published online by Cambridge University Press: 20 May 2016
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Both ontogeny and sexual dimorphism of the Ostracoda are important for understanding their evolution. The purpose of this study is to evaluate the ontogeny and possible sexual dimorphism, of the ostracode species Paraparchites punctatus n. sp. by assessing size, shape, and ornamentation at the stages of its growth for which we were able to obtain specimens: adults and five or six instars. Brooks's rule suggests that with each molt crustaceans double their volume (Brooks, 1886; Teissier, 1960; see also Przibram, 1931). The degree of adherence to Brooks's rule during ontogeny bears on the importance of heterochrony in evolution. The new species follows Brooks's rule rather closely. Another aspect of morphology investigated herein is sexual dimorphism: although many ostracodes have sexually dimorphic valves and carapaces, this is not true of all species of Paraparchites Ulrich and Bassler, 1906, and some other major groups (Scott, 1959; Moore, 1961).
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