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).
Evolution of reptiles - First reptiles. 1  Reptiles first arose from amphibians in the swamps of the late Carboniferous. 2  The origin of the reptiles lies about 320â310 million years ago, in the swamps of the late Carboniferous period, when the first reptiles evolved from advanced reptiliomorph labyrinthodonts. The oldest known animal that may have been an amniote, a reptile rather than an amphibian, is Casineria (though it has also been argued to be a temnospondyl amphibian).