Skeletogenesis in anurans: cranial and postcranial development inmetamorphic and postmetamorphic stages of Leptodactylus bufonius (Anura: Leptodactylidae)

Abstract

Osteological studies of anurans generally have focused on the descriptions of adults and larval chondrocrania, including developmental series of chondrocrania. Thus, the changes occurring during postmetamorphic stages have largely been overlooked. Herein, we describe cranial and postcranial skeletogenesis, and change in skull shape through the metamorphic and postmetamorphic development of Leptodactylus bufonius. Several elements, particularly those of the cranium, are already ossified at metamorphic climax; among these elements are the frontoparietals, prootics, premaxillae, maxillae, squamosals, pterygoids, neopalatines, angulosplenials, dentaries, mentomeckelians, and the mesosternum. Determining the exact timing of ossification of some elements is difficult because variation in their development may result from extrinsic factors. The otic region and that of the jaw closure undergo the greatest changes in shape, which may imply functional constraints. The development of many skeletal elements is still incomplete at metamorphosis; thus, the changes occurring postmetamorphically are crucial to achieving the configuration and function of an adult skeleton.