 For example, Germanic languages are "Germanic" in that they share vocabulary and grammatical features that are not believed to have been present in the Proto-Indo-European language.These features are believed to be innovations that took place in Proto-Germanic, a descendant of Proto-Indo-European that was the source of all Germanic languages.Language families can be divided into smaller phylogenetic units, conventionally referred to as "branches" of the family because the history of a language family is often represented as a tree diagram.