Um, where did you get that birthdate for Elijah? I've seen it posted as about 1750, which would make him plenty old enough to have two kids by Selena. (On the other hand, early census records make him look closer to 1770 in birth date.) SOMEBODY named Elijah Tyner seems to have married a Selina Roger, but maybe it was a different fellow:
EFFINGHAM COUNTY, GEORGIA MARRIAGES
Tyner, Elijah marr Rogers, Selina 02/15/1774
Tyner, Jackson marr Pace, Sarah Ann 12/16/1832
Tyner, John C. marr Curry, Mary 12/18/1815
Tyner, Jonathan marr Harris, Ann 11/05/1819
Tyner, Jordan marr Stokes, Mary 09/10/1820
Tyner, Lucian marr Highsmith, Anna 02/11/1824
Tyner, Simeon marr Southwell, Ester Ann 04/20/1827
Have you tried contacting the posters of those family trees? They might modify the tree, or they might produce a Bible record that clears everything up--either way, asking them (politely) about the age problem wouldn't hurt.