Journal ArticleDOI
Ultrastructural morphology of the shell and shell membrane of eggs of common snapping turtles (Chelydra serpentina).
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The calcareous layer begins to detach from the shell membrane about half‐way through incubation, and changes in shell morphology attending this detachment indicate that snapping turtles may use the shell as a source of calcium during embryogenesis.Abstract:
Common snapping turtles (Chelydra serpentina) lay nearly spherical, flexible-shelled eggs having an outer mineral layer composed of calcium carbonate in the aragonite form. The mineral layer is arranged into loosely organized groups of nodular shell units, with numerous spaces (or pores) between adjacent shell units. Shell units are structurally complex, consisting of an inner tip that is morphologically distinct from the main body of the shell unit. Contained within an intact shell unit at the interface of the tip and the main part of the shell unit is the central plaque, an apparent modification of the shell membrane that may serve to nucleate calcification of shell units during shell formation. The tips of shell units are firmly attached to a single, multilayered shell membrane throughout much of incubation. The calcareous layer begins to detach from the shell membrane about half-way through incubation, and changes in shell morphology attending this detachment indicate that snapping turtles may use the shell as a source of calcium during embryogenesis. The arrangement of the mineral layer into groups of shell units, the large number of spaces between shell units, and little or no interlocking of crystallites of adjacent shell units apparently are factors contributing to the ability of these eggs to swell as they absorb water.read more
Citations
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Journal ArticleDOI
Contemporary and Fossil Chelonian Eggshells
TL;DR: Although fossil turtle eggs were first reported over 100 years ago, their shell structure is still poorly understood and the fossil record is probably limited to the most easily preserved rigid-shelled eggs.
Book ChapterDOI
Egg envelopes in vertebrates
TL;DR: In this paper, the authors summarize the available information about the origin, structure, composition, and function of the acellular envelopes that enclose vertebrate eggs and encourage a broader, more unified perspective of the apparent evolutionary homologies of animal egg envelopes.
Journal ArticleDOI
Patterns and Possible Significance of Water Exchange by Flexible-Shelled Eggs of Painted Turtles (Chrysemys picta)
TL;DR: Turtle hatching from eggs exposed to relatively wet conditions were larger than hatchlings emerging from eggs incubated in slightly drier settings, and turtles exposed to wet substrates had longer incubation periods and higher hatching success than eggs exposure to drier substrates.
Journal ArticleDOI
Turtles as diapsid reptiles
TL;DR: This paper reviews the neontological character evidence for turtle relationships and shows that most, but not all, of these characters are invalid in the reconstruction of turtle relationships within Amniota.
Journal ArticleDOI
Influence of Hydration of the Environment on Eggs and Embryos of the Terrestrial Turtle Terrapene ornata
TL;DR: The relativelyLarge eggs of Terrapene ornata may represent the one adaptation of this species for development in terrestrial conditions, because large eggs of other turtles are more likely to hatch following incubation in a stressful hydric environment than are smaller eggs laid by conspecifics.
References
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Book
Elements of X-ray diffraction
TL;DR: In this article, the authors present a chemical analysis of X-ray diffraction by Xray Spectrometry and phase-diagram Determination of single crystal structures and phase diagrams.
Book
Turtles of the United States
Carl H. Ernst,Roger W. Barbour +1 more
TL;DR: Turtles of the United State as discussed by the authors is a popular children's book about turtles in the United States, which is based on the Turtles of the USA. http://www.turtlesoftheusa.org/
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