Page "Language family" Paragraph 9

Sometimes, however, a proto-language can be identified with a historically known language.

For instance, dialects of Old Norse are the proto-language of Norwegian, Swedish, Danish, Faroese and Icelandic.

Likewise, the Appendix Probi depicts Proto-Romance, a language almost unattested due to the prestige of Classical Latin, a highly stylised literary register not representative of the speech of ordinary people.