A chemical formula contains information on the types and spatial arrangement of bonds in the chemical. It also tells you what elements are in the chemical, and how many atoms of each. The spatial arrangement is not necessarily very obvious from the formula, e.g. C2H5OH does not tell you much about the spatial arrangement of the bonds. A chemical formula contains information on the types and spatial arrangement of bonds in the chemical.
All modern amphibians are included in the subclass Lissamphibia, which is usually considered a clade, a group of species that have evolved from a common ancestor. The three modern orders are Anura (the frogs and toads), Caudata (or Urodela, the salamanders), and Gymnophiona (or Apoda, the caecilians).
By the end of the Ordovician, life was no longer confined to the seas. Plants had begun to colonize the land, closely followed in the Silurian by invertebrates, and in the Late Devonian by vertebrates. The early tetrapods of this time were amphibian-like animals that eventually gave rise to the reptiles and synapsids by the end of the Paleozoic. One of the earliest terrestrial tetrapod faunas known in the world is from Joggins, Nova Scotia.