If you are seriously interested in the question, may I recommend a book called, IIRC, Principles of Diachronic Syntax, by David Lightfoot. Although not stated in these terms, this book advances a thesis that there may well be a kind of punctuated evolution of languages.
I may be doing it an injustice, but my recollection, nearly 25 years old, is that by way of example he claimed that the English modals underwent a fairly major reorganization between the years 1550 and 1600. Before 1500 English, like French and German, had a special class of verbs called modals, but by 1600 and continuing to the present day, English has a new syntactic category called modals that are not verbs for a number of reasons. Before 1550, the periphrasitc expressions such as, “be about to be”, “be able to be”, “have to be” didn’t exist since we had “will”, “can”, and “must” to cover those semantic areas, but after 1600, we didn’t. In French and German, it is perfectly acceptable to say, “Je doit pouvoir” and “Ich muss koennen”, but in English you have to say, “I must be able to”, not “I must can”. There were other changes in the verb that took place at the same time (see Lightfoot’s book for more details).
A more obvious example is that in the years from 1066 to around 1400, English became a new language. This was partly because of a massive infusion of new words from French, but even more because it changed from a fairly hrighly inflected language to one that has basically only 4 inflections (three of which consist in adding an “s”). Obviously, there are historical reasons for this, but it is still an example of punctuated evolution. Biological evolution too, is frequently punctuated by major enviromental changes.