Sagittal keels occur in several early human species, most noticeably in " Homo erectus " and occasionally in " Homo heidelbergensis ".
22.
Palaeoanthropologists generally agree that " Homo erectus " and " Homo heidelbergensis " have immigrated into Europe, debated remain migration routes and chronology.
23.
But their discoverers suggest either late Homo erectus or Homo heidelbergensis _ two early human species found in Europe during the Paleolithic era.
24.
Prolonged presence has been attested for " Homo antecessor " ( or " Homo erectus antecessor ", " Homo heidelbergensis " and Neanderthals.
25.
The scientists raised the possibility that these hominids were related to the later Homo heidelbergensis, which is thought to be ancestral to the Neanderthals.
26.
Rightmire said he saw no reason yet to reconsider his idea that Homo heidelbergensis was the last common ancestor of Neanderthals and modern humans.
27.
Later, the related species " Homo heidelbergensis " ( the common ancestor of both Neanderthals and " Homo sapiens " ) used it extensively.
28.
They could be considered a primitive form of Homo heidelbergensis, but a new species might be named in the future if the sample is enlarged.
29.
Based on the age of the tracks, they have been tentatively ascribed to the hominid " Homo heidelbergensis ", a probable ancestor of the Neanderthals.
30.
Eventually, in 1993 the project unearthed remains belonging to a " Homo heidelbergensis ", which proved to be the earliest known hominin in Europe at that time.
