Studies On The Os Nasocavorum Of Order Anura And Anatomy And Comparison Of The Skeletal System Of Three Kinds Of Frogs

We found an unknown small bone when observing the skeleton ofHylarana(Odorrana) margaretae, then we observed H. livida, Rana guentheri, inwhich the similar bone structure was found too. And we consult concerned recordsabout this structure,Wu guan-fu reported it firstly in the paper of "Study onSkeletal System of Rana rugosa Temmick et Schegel". We observed 58 species intotal, including all families of Anura in China, such as Bombinidae, Megophryidae,Bufonidae, Hylidae, Microhylidae, Dicroglossidae, Ranidae, Rhacophoridae, etc.The result is that, all species we observed have os nasocavorum, which is locatedthe identical position, So the bone is the Homologous structure to the skeleton ofAnura. But we don't kown its fuction.There are three styles according to the location of os nasocavorum:①it lies onthe naris, such as Bombina orientalis boulenger;②it is under the naris, such asBufo gargarizans Contor, B. minshanicus Boulenger;③it lies on nasal cavity.It could be divided into 6 styles based on the modality, that's styleⅠ, styleⅡ,styleⅢstyleⅣ, styleⅤ, styleⅥ, From styleⅠto styleⅤ, the modality of os nasocanorum to this 5 styles is different, which we could distinguish easily, thesestyles correspond to Bombinidae, Megophryidae, Bufonidae, Hylidae, Microhylidae.StyleⅥincludes species of Ranidae, Rhacophoridae and Dicroglossinae, inwhich the modality is simple, except L.rugulosa and Paa boulengeri Günther.We observed H.margaretae, L.limnocharis and R.rugosa(Amphibia; Anura;),and the result is that: the three types of frogs are the same in the arcus maxillaris,Lower jaw, apparatus hyoideus, cartilage laryngo-trachealis and skeletonappendiculare; The Centrum of the eighth vertebrae is amphicoelous, so thevertebral column is dipasiocoela typically; H.margaretae and R.rugosa arearcifery, but L.limnocharis shows the incomplete arcifery, and left of osepicoracoideum overlaps on the edge of the right of os epicoracoideum at the center;the omosternum of H.margaretae is complete, the base of omosternum ofL. limnocharis is divided into two branches, and the base of omosternum of R.rugosais not complete; on the metasternum, L.limnocharis is complete, R.rugosa is notcomplete, and the base of H.margaretae is divided into two branches; Os nasaleand os nasocavorum of the three types are different, os sphenethmoidale ofH.margaretae is the same as R. rugosa, which is different from L. limnocharis. Underthe subarticular tubercles of palms and pes, H.margaretae is very big, which is anunattached small bone in L. limnocharis.