None of the extant speciation criteria seem testable across time, so the species distinction between an ancestor and its progeny seems difficult to navigate. Th

None of the extant speciation criteria seem testable across time, so the species distinction between an ancestor and its progeny seems difficult to navigate. This sort of event, of a species vanishing through the slow evolution of its progeny, is called "pseudoextinction" to distinguish from the other, true 'extinction' (the last surviving member of a lineage dies). In this case since we know that Neanderthal DNA lives on in its H. Sapiens descendants we can safely call this "pseudo" rather than a true extinction.