 Anura is divided into three suborders that are broadly accepted by the scientific community , but the relationships between some families remain unclear . Future molecular studies should provide further insights into their evolutionary relationships . The suborder Archaeobatrachia contains four families of primitive frogs . These are Ascaphidae , Bombinatoridae , Discoglossidae and Leiopelmatidae which have few derived features and are probably paraphyletic with regard to other frog lineages . The six families in the more evolutionarily advanced suborder Mesobatrachia are the fossorial Megophryidae , Pelobatidae , Pelodytidae , Scaphiopodidae and Rhinophrynidae and the obligatorily aquatic Pipidae . These have certain characteristics that are intermediate between the two other suborders . Neobatrachia is by far the largest suborder and includes the remaining families of modern frogs , including most common species . 96 % of the over 5 @,@ 000 extant species of frog are neobatrachians . 
