From Genome: The Autobiography of a Species in 23 Chapters:

[T]he remarkable truth is that we come from a long line of failures.  We are apes, a group that almost went extinct fifteen million years ago in competition with the better-designed [note: I take serious issue with this phrasing] monkeys.  We are primates, a group of mammals that almost went extinct forty-five million years ago in competition with the better-designed rodents.  We are synapsid tetrapods, a group of reptiles that almost went extinct 200 million years ago in competition with the better-designed dinosaurs.  We are descended from limbed fishes, which almost went extinct 360 million years ago in competition with the better-designed ray-finned fishes.  We are chordates, a phylum that survived the Cambrian era 500 million years ago by the skin of its teeth in competition with the brilliantly successful arthropods.  Our ecological success came against humbling odds.