Herto Man refers to the 160,000- to 154,000-year-old human remains ("Homo sapiens") discovered in 1997 from the Upper Herto Member of the Bouri Formation in the Afar Triangle, Ethiopia. The discovery of Herto Man was especially significant at the time as it fell within a long gap in the fossil record between 300 and 100 thousand years ago, and at its description in 2003, it represented the oldest dated "H. sapiens" remains. In the original description paper, these 12 (at minimum) individuals were described as falling just outside the umbrella of "anatomically modern human". Thus, Herto Man was classified into a new subspecies as "H. s. idaltu" ( "elder"). It supposedly represented a transitional morph between the more archaic ""H. (s.?) rhodesiensis" and "H. s. sapiens" (that is, a stage in a chronospecies). Subsequent researchers have rejected this classification. The validity of such subspecies is difficult to justify because of the vague definitions of "species" and "subspecies", especially when discussing a chronospecies, as the exact end-morphology and start-morphology of the ancestor and descendant species are inherently unresolvable.