Literaturdatenbank
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Bramble, D. M., Hutchison, H. J., & Legler, J. M. (1974). Kinosternid shell kinesis: structure, function and evolution. Copeia, 1974(2), 456–475.
Added by: Admin (09 May 2010 16:30:52 UTC) |
| Resource type: Journal Article BibTeX citation key: Bramble1974a View all bibliographic details  |
Categories: General Keywords: Kinosternidae, Kinosternon, Kinosternon leucostomum, Kinosternon scorpioides, Morphologie = morphology, Schildkröten = turtles + tortoises Creators: Bramble, Hutchison, Legler Collection: Copeia |
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| Abstract |
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The structural, functional and behavioral correlates of shell kinesis have been established for the Recent genera (Staurotypus, Claudius, Sternotherus, Kinosternon) of kinosternid turtles. This information together with new paleontological data has been used to formulate an interpretive model (scenario) for the evolution of shell kinesis within the Kinosternidae. Anterior plastral kinesis has evolved independently in the Staurotypinae and Kinosterninae. In each group a mobile plastron originated to open the front of the shell. This function appears to be correlated with relatively large head size, durophagy and a defense behavior in which the jaws gape widely while the head is retracted into the shell. This primitive form of shell kinesis is displayed by modern Staurotypus and Sternotherus. In Claudius, kinesis involves pivoting of the entire (but reduced) plastron about ligamentous plastro-carapacial junctions. Though mechanically quite different, shell kinesis in Claudius has apparently evolved from a Staurotypus-like condition. In Kinosternon the ancestral opening mechanism has been converted to a closing mechanism. This reversal of function is associated with a secondary reduction in relative head size, a shift away from durophagous feeding, and a change in defense tactics. Kinosternon is convergent with emydine box turtles in that the neck retractor musculature (M. retrahens capitis collique) is used to elevate the anterior plastron. Kinesis of the posterior plastron in Kinosternon may also have begun as a means of opening the shell. The method of closing the posterior lobe is mechanically like that of emydid box turtles except that in Kinosternon the M. attrahens pelvium (rather than M. testoiliacus) is the chief adductor muscle. A special form of midline kinesis permits an exceptionally tight seal between the posterior plastron and carapace in some of the more terrestrial species (K. scorpioides, K. leucostomum). Relative plastral development and kinesis within Kinosternon appears to be strongly influenced by local environmental conditions, especially the permanence of the aquatic habitat.
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