No more frogs dating
The arrangement of pectoral elements and the number of vertebrae are some guides, but the degree of vertebral articulation and the arrangement of the bones in the leg have not been found to be reliable indicators.
The early proto-frogs developed from temnospondylid ancestors in which some of the elements of their vertebrae remained separate.
The Salientia (Latin salere (salio), "to jump") are a stem group including modern frogs in the order Anura and their close fossil relatives the "proto-frogs" (e.g., Triadobatrachus and Czatkobatrachus).
It dates back to the Early Triassic, about 250 million years ago.The families Alytidae, Pipidae, and Pelobatidae are ecologically isolated, the harlequin frogs, restricted to a neotropical range in Central and South America, and the Ranidae and Bufonidae probably radiated from tropical regions of Africa and Asia.