J. Whittaker: Weighed 884 points from 16 sites in CA plus 1 NV Anasazi, 1 NB 18th C Apache, 1 ND protohistoric, 1 SD protohistoric, 1 MO Archaic, 1 MO Hopewell. Finds bimodality: less than 3.49 gm, and more than 4.5 gm (only 33 = 3.7% fall between). Suggests small point tradition reflects bow and arrow, late sites, while large point tradition is atlatl, earlier sites. Notes contradictory evidence: Browne 1938 and his own experiments with atlatl show small points, no points, large points all work on both arrow and dart. Late metal arrow points also heavier, but early ones fit pattern. Some sites with both sizes may have atlatl and bow coexisting. [Widely cited, perhaps a good rule of thumb, but no more than that. Would like to know what else he tried with atlatls.]