But the suggestion that these fossils prove an evolving lineage of Homo erectus in Asia and Africa, Berger said, is "taking the available evidence too far."
Berger led the team that discovered Australopithecus sediba, a possible human ancestor that lived around 2 million years ago in South Africa. He criticized the authors of the new study for not comparing the fossils at Dmanisi to A. sediba or to more recent fossils found in East Africa.
Lordkipanidze said he and colleagues consider A. sediba to be earlier and more primitive than the Dmanisi hominids, and that there's "no doubt" the Georgian fossils belong to the Homo genus.
But the selectivity of fossils compared to them in this study may have artificially biased the results toward the researchers' hypotheses, Berger said.
Ian Tattersall, curator emeritus at the American Museum of Natural History's anthropology division, said in an e-mail that there's "no way this extraordinarily important specimen is Homo erectus," if the skull fragment discovered in Trinil, Java, Indonesia, defines the features of the Homo erectus group.
The New York museum's Hall of Human Origins takes visitors on a tour through human evolutionary history, showing distinct Homo species reflected in major fossil finds such as Turkana Boy (Homo ergaster) and Peking man (Homo erectus).
The Dmanisi discovery may find a place there too, but it's probably not going to result in relabeling other species, Tattersall said.
"Right now I certainly wouldn't change the Hall -- except to add the specimen, which really is significant," he said.
There is an area of about 50,000 square meters at Dmanisi still to be excavated, so Skull 5 may have even more company.
Follow Elizabeth Landau on Twitter at @lizlandau.