Suspensory behavior in the context of Climbing

Brachiation (from "brachium", Latin for "arm"), or arm swinging, is a form of arboreal locomotion in which primates swing from tree limb to tree limb using only their arms. During brachiation, the body is alternately supported under each forelimb. This form of locomotion is the primary means of locomotion for the small gibbons and siamangs of southeast Asia. Gibbons in particular use brachiation for as much as 80% of their locomotor activities. Some New World monkeys, such as spider monkeys and muriquis, were initially classified as semibrachiators and move through the trees with a combination of leaping and brachiation. Some New World species also practice suspensory behaviors by using their prehensile tail, which acts as a fifth grasping hand. Evidence has shown that the extinct ape Proconsul from the Miocene of East Africa developed an early form of suspensory behaviour, and was therefore referred to as a probrachiator.

Upon further observations and more in depth understandings of the anatomy and behaviour of primates, the terms semibrachiator and probrachiator have largely fallen out of favour within the scientific community. Currently, researchers classify gibbons and siamangs as the only true brachiators and classify the great apes as modified brachiators. All other brachiation behaviours that do not meet either of these classifications are referred to as forearm suspensory postures and locomotion.

Danuvius guggenmosi is an extinct species of great ape that lived 11.6 million years ago during the Middle–Late Miocene in southern Germany. It is the sole member of the genus Danuvius. The area at this time was probably a woodland with a seasonal climate. A male specimen was estimated to have weighed about 31 kg (68 lb), and two females 17 and 19 kg (37 and 42 lb). Both genus and species were described in November 2019.

It is the first-discovered Late Miocene great ape with preserved long bones which could be used to reconstruct the limb anatomy and thus the locomotion of contemporary apes. Its discoverer, paleoanthropologist Madelaine Böhme, says Danuvius had adaptations for both hanging in trees (suspensory behavior) and walking on two legs (bipedalism)—whereas, among present-day great apes, humans are better adapted for the latter and the others the former. Danuvius thus had a method of locomotion unlike any previously known ape called "extended limb clambering", she says, walking directly along tree branches as well as using arms for suspending itself. The last common ancestor between humans and other apes possibly had a similar method of locomotion. However, paleoanthropologist Scott Williams and others say the fragmentary remains do not differ enough from other fossil apes to provide such a clue to the origins of bipedalism.