Ape Quartet #4: Orphaned book by Eliot Schrefer

Before humans, and before human history, there were the apes.
Snub is a young gorilla, living in the heart what will eventually be known as Africa. She is jealous of her mother's new baby . . . and restless in her need to explore. When a natural disaster shakes up her family, Snub finds herself as the guardian of her young sibling . . . and lost in a reshaped world.
Snub may feel orphaned, but she is not alone. There are other creatures stalking through the woods -- a new form of predator, walking on two legs. One of their kind is also orphaned, and is taken in by Snub. But the intersection of the human world and the gorilla world will bring both new connections and new battles.
In his boldest work yet, two-time National Book Award finalist Eliot Schrefer shows us a riveting, heartbreaking early encounter between ape and man -- told from the ape's point of view. It is a journey unlike any other in recent literature.