Not sure this statement is true if "more closely related" is understood as shorter combined time between the two species from their most recent common ancestor. Hummingbirds and brachiosaurs had a more recent common ancestor than brachiosaurs and triceratopses (albeit probably still quite close to the dawn of dinosaurs in the Late Triassic ), but the latter pair lived closer in time to the common ancestor of all dinosaurs (while hummingbirds are from the Oligocene).