The various Turkic languages share a common ancestor. Though no surviving examples of this language have been found (that is to say, it is unattested), linguistic reconstruction allows for insight to be gained about how the language worked and operated.
Yet, there are lexical descriptions about Proto-Turkic, but little is known about its grammar and morphology. Some linguists like András Roná-Tas in his chapter The reconstruction of Proto-Turkic and the genetic question, have described the grammar of Proto-Turkic. However, his reconstructions have Common Turkic features like -z- in place of -ŕ- (like rat but palatalized with y as in young), and he said that:
... But Proto-Turkic can only be reconstructed by taking the Kipchak languages, thus also Proto-Kipchak, into consideration.—András Roná-Tas, "The reconstruction of Proto-Turkic and the genetic question", The Turkic Languages (1998)
- It is not recommended to use this book as a reference in Wikipedia article as it represents original researches of two users.