It is one class of Vertebrate,Chordata.On its growing process,Amphibia may be developed by metamorphosis.The larva living in water breathe with branchia,while the adult living on the land mainly breathe with lung.It is generally accepted that Amphibia was evolved from the Osteichthyes.Because the skeleton of amphibian is thin,it is hard to turn intofossil,so that the Amphinbian fossils are very rare.Among the Amphibian discovered fossils in China,the cost famous one was the Rana basaltica fossil unearthed from Miocene stratum in Linqu,Shandong.