The Russian language and my own language have something in common - they are very rich and nuanced lexically, but not rich phonetically at all. There are even numerous parodies making fun of the Russian phonology because of that (e.g., this one).
I am curious as to whether the Russian language has always been that poor phonetically or got phonetically simplified over time. Languages indeed can get phonetically simplified: for example, the Turkish language had the voiced counterpart of the 'h' sound and has the corresponding letter, ğ, which nowadays has no own sound, and the English language is predicted to lose the 'th' sound by 2066.
My question is this: Are there any extinct Russian phonetic sounds? If so, what are some examples?
I will now make a few remarks to make my question more specific.
First of all, I am interested in sounds that ceased to exist rather than changed over time to survive as modified variants. For example, if people stopped pronouncing a certain sound in all words containing it, as happened with the Turkish ğ, then it is an extinct sound. Also, a sound is extinct if it got replaced in all words containing it by a different sound that had already been existing in the language as a separate sound. But if a sound just evolved, always staying as a separate sound and not becoming indistinguishable from any other sound of the language, then what it was in the past is not an extinct sound for the purposes of my question.
In other words, please consider sounds as evolutionists consider animal species. If an animal species evolved into something existing today, it is not extinct, even if it now looks very differently from how it looked before. But if it truly ceased to exist at a certain point of time, then it is extinct.
Second, I feel I need to define the Russian language, because there have been various Slavic ethnic groups living in what is now Russia. For the purposes of my question, let us define the Russian language as the language spoken by people who formed a linguistically uniform group living in the past thousand years in and around what is now Moscow, as well as by their ancestors, wherever they migrated to what is now Moscow from. In other words, just consider the Muscovite version of the language and trace back its history.
Third, I feel I should specify the history time frame, but instead I would like to ask you to just trace things back to the point at which you can find extinct sounds. My question is thus not a broad request for all extinct sounds; I just want some examples. The later the sound disappeared the better.
Finally, to illustrate what I am looking for, I would like to give a few examples of sounds absent in the Russian language:
th in English as well as dh and th in Albanian, i.e., voiced and voiceless interdental consonants,
ğ in Old Turkish, i.e., the voiced counterpart of h (звонкая аналогия русского звука х),
c in Turkish, i.e., the voiced counterpart of the Russian sound ч.
I want something like this, that is, something absent in modern Russian (albeit not necessarily sounding like any of the sounds listed above), but with evidence of previous existence in Russian.