The time between Noah's flood and Peleg's tectonics was when the dispersal from Babel took place. From Babel small family groups spread out, figuratively speaking, to the ends of the Earth.
The Sons of Noah
Lemurs and Birds
"First lemurs; some modern groups of birds". Modern is a concept in the evolution narrative. The Paleocene is recent, therefore according to the narrative anything different about it can be called modern. It's meaningless.