title: Postcranial osteogenesis of the helmeted water toad Calyptocephalella gayi (Neobatrachia: Calyptocephalellidae) with comments on the osteology of australobatrachians.
abstract: Calyptocephalella gayi is one of over 6,000 neobatrachians arranged into two main groups, Hyloides and Ranoides. Phylogenetically, C. gayi is placed in Australobatrachia, a Gondwanan clade that is either the most basal clade of Hyloides or the sister group of Hyloidea, depending on the cladistic hypothesis; as such, this species is a key taxon in the study of the early evolution of Neobatrachia. The ontogeny of the postcranial skeleton of C. gayi is described in this article. The description is based on pattern of chondrification and ossification of skeletal elements in a growth series of tadpoles, on juveniles and adult individuals. Particular attention was devoted to some developmental aspects and morphological traits of the adult skeleton. The body of Presacral Vertebra VIII is formed from three centers of ossification, in contrast to the usual two dorsolateral centers observed in the remaining vertebrae of C. gayi, as well as in most anuran taxa for which the development of the axial skeleton is known. Each half of the pelvic girdle arises from a single cartilaginous element. The early development of the autopodia of both the forelimb and hindlimb includes the presence of an additional chondral element, which occurs during the formation of Distal Carpal 5 and the transient formation of Distal Tarsal 4 before the latter is incorporated in the cartilaginous distal end of the fibular. Some osteological aspects of other australobatrachian anurans also are reviewed (e.g., presence of intervertebral discs) based on reports in the literature, as well as first hand observations. In the course of this study, it became evident that further osteological studies are needed to formulate a clear picture of the evolution of skeletal characters not only within Australobatrachia, but also within Neobatrachia.
authors.affiliation: Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia,", Av. Ángel Gallardo 470, C1405DJR, Ciudad Autónoma de Buenos Aires, Argentina.|CONICET, Av. Rivadavia 1917 (C1033AAJ) Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Paula
authors.initials: P
authors.lastname: Muzzopappa
authors.affiliation: Facultad de Ciencias Exactas y Naturales, Universidad Nacional de La Pampa, Uruguay 151, CP 6300, Santa Rosa, La Pampa, Argentina.
authors.forename: L Analía
authors.initials: LA
authors.lastname: Pugener
authors.affiliation: Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia,", Av. Ángel Gallardo 470, C1405DJR, Ciudad Autónoma de Buenos Aires, Argentina.|CONICET, Av. Rivadavia 1917 (C1033AAJ) Ciudad Autónoma de Buenos Aires, Argentina.|Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Laboratorio de Paleontología Evolutiva de Vertebrados, Universidad de Buenos Aires, Intendente Güiraldes 2160, C1428EGA, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Ana María
authors.initials: AM
authors.lastname: Báez
mesh_terms: D000293:Adolescent; D000818:Animals; D005075:Biological Evolution; D002025:Bufonidae / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development; D002356:Cartilage / Q000033:anatomy & histology; D005552:Forelimb / Q000033:anatomy & histology; D006614:Hindlimb / Q000033:anatomy & histology; D006801:Humans; D010012:Osteogenesis; D010388:Pelvis / Q000033:anatomy & histology; D010802:Phylogeny
keywords: Anura; Rana Grande Chilena; intervertebral discs; ontogeny; vertebral body ossification