Osteology of the Myobatrachine Frog Arenophryne rotunda Tyler (Anura: Leptodactylidae) and Comparisons with other Myobatrachine Genera

Abstract

Cranial and post-cranial osteology of the headfirst-burrowing Australian myobatrachine frog, Arenophryne rotunda, are described and compared with the genera Myobatrachus, Pseudophryne, Uperoleia and Ranidella. Some anatomical features, such as the position of the nasal bones, the form of the occipital condyles and the orientation of the coracoids, are considered to be burrowing adaptations, whilst other features reflect phylogenetic affinities. The highly paedomorphic nature of the skull is unique among the genera examined.

A Glimpse at the Ontogeny of the Fossil Neobatrachian FrogCalyptocephalella canquelifrom the Deseadan (Oligocene) of Patagonia, Argentina

“…Most of the described Austra− lian australobatrachians have slender frontoparietals, which are not in contact to one another along the midline or with the nasals even in adults. However, frontoparietals do meet me− dially in adults of some taxa (e.g., Adelotus brevis, Lech− riodus fletcheri, Myxophies fasciolatus, Uperoleia rugosa, Uperoleia laevigata ;Parker 1940;Stephenson 1964;Lynch 1971;Davies 1984Davies , 1989, but their ontogeny is unknown, except for Uperoleia laevigata. In this latter species the frontoparietals meet along the midline after the end of the metamorphosis (Davies 1989).…”

Postcranial osteogenesis of the helmeted water toad Calyptocephalella gayi (Neobatrachia: Calyptocephalellidae) with comments on the osteology of australobatrachians

“…obs.). The omosternum was reported as absent in the fossorial species Myobatrachus gouldi and Arenophryne rotunda , as well as Pseudophryne guentheri (Tyler, ; Davies, ). The presence of an omosternum seems to be variable in Pseudophryne , according to the aforementioned data and observations.…”

“…Parker () and Heyer and Liem () agreed that the vertebral bodies of the latter genus lack notochordal pits, whereas the condyles are firmly ankylosed to the centra. Davies () mentioned that free intervertebral discs occur in Arenophryne rotunda during its ontogeny, and Littlejohn et al (:12) reported that “…the majority of [Limnodynastinae] genera have free intervertebral discs as subadults” and that “…[in Myobatrachinae] the vertebrae are procoelous with free intervertebral discs in many cases persisting in the adult.” Also Talavera () indicated that species of Myobatrachidae together with those of Pelobatidae and Megophryidae are the only anurans having free condyles in at least some period of their life cycles.…”

Burrowing behavior of Dermatonotus muelleri (Anura, Microhylidae) with reference to the origin of the burrowing behavior of Anura

“…Dasypops schirchi Microhylidae Emerson (1976) Myersiella microps Microhylidae Emerson (1976) Asterophrynae Microhylidae Davies (1984) Copiula spp. Microhylidae Davies (1984) Choerophryne Microhylidae Davies (1984) Oxydactyla stenodactyla Microhylidae Zweifel (2000) Oxydactyla alpestris Microhylidae Zweifel (2000) Oxydactyla coggeri Microhylidae Zweifel (2000) Myobatrachus goeldii Myobatrachidae Littlejohn et al (1993) A. rotunda Myobatrachidae Tyler (1989) Species and family names follow Frost et al (2006) H. marmoratus, a forelimbs-head-first burrower, whereas the burrowing speed of Gliphoglossus molossus, a hindlimbs-first burrower, was only 5.9 cm/min.…”

“…Our analysis indicated that the hindlimbs-first burrowing behavior appears to be basal for anurans. Anuran evolution was primarily directed by saltatory locomotion (Gans and Parsons 1965;Duellman and Trueb 1986;Carroll 2007), and hindlimbs-first and snout-head-first burrowing require fewer modifications to anurans' muscular and skeletal structures than forelimbs-head-first burrowing (Emerson 1976(Emerson , 1994Davies 1984;Freitas 2001). Some fossil anurans show skeletal adaptations for hindlimbs burrowing, and it is likely that they could avoid high daytime temperatures and periods of dryness by constructing a burrow in which they could estivate (Henrici and Haynes 2006).…”