Celtis occidentalis
Early Oligocene (Orellan)
Brule Formation
Pennington County, SD, USA

Set of 3 fossilized hackberry seeds. Each about 0.2 inches

Seed,

Celtis is the plant genus that includes hackberry trees.  These seeds actually come from a terrestrial vertebrate-bearing bed with few other kinds of plant fossils being found there.

The Early Oligocene was a time of cooler climates as the world began to look more like it does today.  The continents were nearing their modern positions.  Many modern mammal families had appeared but were still represented by early forms.  Some archaic groups of the Eocene were still present as well.