The structure of claws in digging mammals depends on the type of soil and especially on the mode of digging. Similar adaptations to usage of claws are not infrequently realized in different morphological ways. Claws can be adapted to loosening of soil, moving it aside, and to destroying walls of termite nests. A sharp cutting edge, required for loosening of soil, may be formed differently depending on the working trajectory of the claws. If the claws move vertically during digging (Meles), the laminacornea becomes equally thick on both sides of the phalanx. If the working trajectory has some sideward inclination, the lateral part of the lamina cornea grows more intensively, while the terminal phalanx may be symmetrical (Prometheomys, Myospalax, Geomys) or asymmetrical (Chlamyphorus, Chrysochloris, Notoryctes) in cross-section. In the case of a horizontal working path, the claw is flattened and has sharp lateral edges (Tachyglossus). Claws adapted to the destruction of termite nests are strengthened either by bifurcation of the terminal phalanx with formation of a corneous I-beam (Manis), or by subdivision of the lamina solearis into a denser dorsal layer and a softer ventral one (Myrmecophaga), The claws adapted to moving the soil apart are flatand have no sharp edges (Talpidae). Attempts to correlate the claw shape with the animal's biology while neglecting the claw function are criticized.
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