Of Eorl: The line thought broken

[Urwen]

Eorl was the father of the Rohirrim, who all had golden hair. But where they did they get their golden hair from? House of Hador would be an obvious answer, but how? Tuor only had one son, and there is no indication that Earendil is an ancestor of Rohirrim in any way. That leaves his cousins, but all three of them died.

But there is an unknown variable there: Tolkien never explicitly stated that Nienor and her child died, only that they jumped into the river. And the river took them to a hidden place, where Nienor lived long enough to bear a child before dying.

That child is Eorl's ancestor.