After noting that Amlicite and Lamanite bodies were tossed into the river, Mormon indicates how they were distinguished. The first method of distinguishing Amlicite (or even Nephite) bodies from Lamanites was that they had shaved their heads. While Mormon tells his readers that the Amlicites were distinguishable from Nephites because they had marked themselves with red on their foreheads, the Lamanites were easily seen because they had shaved their heads.
These two features suggest two different reasons for the differences. For the Lamanites, it may be that the shorn heads, if they were completely shorn, indicated that they were not going to be captured in battle. In Maya art, the act of capturing an enemy is represented by the victor grabbing hair that was pulled back. Were it a female, it might have been termed a ponytail, but this was worn higher on the head, and it is suspected that it was meant to represent corn tassels.
The Amlicite mark is probably confirmation that the meeting with the Lamanites was prearranged. If they were running toward the Lamanites with weapons in hand, the prearranged visual symbol would have told the Lamanites that these were not the enemy, even though they might appear to come in battle mode.