Paleoanthropologists found 17 ancient skulls in the Atapuerca Mountains of northern Spain, suggesting they belong to an unknown species that has characteristics of Neanderthals, as well as early members of the hominid lineage.
The facial bones and teeth of these people, who lived 430,000 years ago, resemble those of Neandertals, which are known from much younger fossils.
Sima fossils suggest these hominins were part of the Neanderthal lineage, but not necessarily direct ancestors. Other ancient humans in Europe do not exhibit the suite of Neanderthal-like features seen in the Sima fossils suggesting more than one evolutionary lineage appears to have coexisted on that continent at the time.
The Atapuerca team suggests that the bones be reclassified as a new, still unnamed species that was an ancestor of Neanderthals, but not modern humans.
Know all about this studdy here: http://news.sciencemag.org/archaeology/2014/06/fossils-put-new-face-ancestors-neandertals