In terms of cranial kinesis, the anuran skull can be classified as rhynchokinetic and/or pleurokinetic. Moreover, the level of ossification of the skull varies from cartilaginous to largely ossified, adding to the disparity in anuran cranial morphology (Paluh et al., 2020). The anuran skulls may further diversify in shape and ossification level during juvenile and adult growth (Ponssa & Vera Candioti, 2012). However, the skull morphologies of adults may be affected by diet specialisation of larvae (Herrel et al., 2019, and references therein). During metamorphosis an extensive tissue remodelling takes place, including the de novo formation of skull bones, and the full (adult) complement of cranial bones does not form until after metamorphosis is complete (Hanken & Gross, 2005 Kerney et al., 2012). The existence of distinct developmental stages (aquatic larvae and metamorphosed juveniles and adults) requires distinct functional adaptations. Additional functional support is provided by the palatine that stabilises and connects the upper jaw to the braincase (Roček, 2003 Trueb, 1973 Trueb et al., 1993). the structure that connects the jaw to the braincase. The quadrate (an element of the viscerocranium) articulates to the lower jaw and together with the pterygoid and squamosal it forms the suspensorium, i.e. Laterally the ventral arm of squamosal bone reaches the quadrate and its upper arm (the otic ramus) reaches the otic region of the braincase. The neurocranium consist of the sphenethmoid and paired prootics and exoccipitals (Fig. The dermal complement consists of the dorsal roofing bones (paired nasals and frontoparietals) and the ventral palatal bones (paired vomers, palates and pterygoids and medial parasphenoid). ![]() The bones of all three skull complements (neurocranium, dermatocranium and viscerocranium) are largely reduced. Anurans have a broad, dorsoventrally flattened and fenestrated skull, with a posterior position of the jaw articulation joints. The description of the anuran skull morphology is necessarily general, due to the remarkable diversity and variation in the development of skull skeletal elements (Hanken & Hall, 1984 Herrel et al., 2019 Smirnov, 1990, 1994 Trueb, 1973, 1985 Trueb & Alberch, 1985 Weisbecker & Mitgutsch, 2010). As here applied to anuran amphibians it refers to just the mobility of the upper jaw and the palate relative to the braincase (Iordansky, 1989). Cranial kinesis denotes the mobility between cranial elements, not including the articulation of the lower jaw (e.g. ![]() Another property of the vertebrae skull that can be directly related with feeding is cranial kinesis. For several groups it has been shown that skull shape reflects selection pressures from functional requirements, such as food intake, in mammals (Galatius et al., 2020 Van Cakenberghe et al., 2002 Wroe & Milne, 2007), birds (Felice et al., 2019), snakes (Andjelković et al., 2016 Klaczko et al., 2016) and frogs (Paluh et al., 2020). The skull form (size and shape) may be constrained by development and by descent and by a variety of mechanical demands imposed by its functional role in perception, food gathering and vocalisation as well as locomotion and defence (Hanken & Hall, 1993). The vertebrate skull is an anatomically and developmentally complex skeletal structure with multiple functions. At the population level, this variation supports an efficient exploitation of the habitat and may promote morphological adaptation in a changing environment. Overall, the results suggest that developmental plasticity produces high variation in ossification and cranial kinesis, affecting individuals’ feeding performances. However, sample sizes are mostly small and intraspecific variation is high, which might compromise the analyses. We also found that skull shape and inferred kinetic properties of the skull are highly variable across the Bufonini tribe. High variation in the amount of bone ossification was recorded in both species, ranging from scarcely ossified and loosely connected bones to highly ossified and firmly connected bones. ![]() In either species, females have a shorter snout and a higher and wider skull at the jaw articulation point that is positioned more posteriorly, in comparison with conspecific males. spinosus is shorter and higher, with a ventral arm of the squamosal bone and the jaw articulation point positioned perpendicular to the braincase, in comparison with a more lateral position in B. The species significantly diverge in skull shape. spinosus with micro-computed tomography and geometric morphometrics and compared the results with published data for related species in a phylogenetic context. We examined the cranial morphology and cranial kinesis of the common toads Bufo bufo and B.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |