This is the second book in the Tales from Avalon series - loosely connected stories that might tell something of Earth's history before the dawn of time as we know it.

Genesis: To Outrun a Nova tells a story about an attempt made by the Mersian empire as their sun goes nova. They must relocate. Unfortunately, they didn't count on bringing certain other species to Earth with them.

This is how an original colonization effort might have gone given the hectic nature of getting citizens on the ground and ready for their new home. Mistakes happen.