Definitely not enough to draw an accurate timeline, but enough for educated guesses. As you say, guestimates shift with major discoveries, but not quite as much

Definitely not enough to draw an accurate timeline, but enough for educated guesses. As you say, guestimates shift with major discoveries, but not quite as much as pop-science press would have you think. This species is now the oldest known australopithecine, by a hair. It is a contemporary and possible ancestor of afarensis. It's true that we don't know (and probably won't because it's too old for DNA) if these fossils just represent diversity in a species, subspecies or several species. We do know that they're similar to each other. We also know that they existed 4mya. Divergence from chimps is thought to have happened around 6-7mya (also controversial, and subject to change). So... all the australopithecines at that time were probably genetically compatible, considering apes slow breeding and how long it takes most large mammals to completely speciate. Considering how different they are from chimps and similar they are to each other, it's a decent guess that they are closely related. We know that the genus had at least 5 types/subspecies/species, 6 if we include habilis. Baboons occupy a similar niche to australopithecines. There are 5 closely related species. They hybridize often, but still maintain these separate species/types, probably because it's adaptive in their respective ecosystems. It's meaningful that australopithecines had a similar pattern. An interesting side point is that there's some speculation that baboons emerged once australopithecines (inc habilis) declined, homo (erectus) emerged and the ecological niche became free. So yes, we can't tell exactly which of these extremely closely related types represent distinct "species" and which of these is our immediate ancestor. But, that's more semantics than substance. We have pretty strong evidence that early homo was an australopithecine type, within a closely related (recently emerged) genus.. and that there was probably a lot of hybridization within the genus. There's a lot to the difference between definitive knowledge and no knowledge.