See upright indriid lemurs & sifakas leaping, similarities to hylobatid upright sitting posture, leaping, fur coat, sleeping in tree forks (not bowl nests), coloration patterns; differences due to dry forest lemurs (no liana vines) vs rainforest hylobatids (liana vines) allowing slow => fast brachiation. Neither wade yet both have long legs and backs vs great apes.

The extraordinary athletic performance of leaping gibbons
Anthony J Channon ... Evie E Vereecke 2011 doi org/10.1098/rsbl.2011.0574

The distance that animals leap depends on their take-off angle & velocity.
The velocity is generated by mechanical work during the push-off phase of standing-start leaps.
Gibbons are capable of exceptional leaping performance, crossing gaps in the forest canopy >10 m,
yet they possess none of the adaptations possessed by specialist leapers synonymous with maximizing mechanical work.

To understand this impressive performance, we recorded leaps of the gibbons >3.7 m.
Gibbons perform more mass-specific work (35.4 J/kg) than reported for any other species to date:
they accelerate to 8.3 m/s in a single movement, redefining our estimates of work performance by animals.
This energy (enough for a 3.5 m vertical leap) is 60 % higher than that achieved by galagos (renowned for their remarkable leaping performance).
The gibbons' unusual morphology facilitates a division of labour among the hind- & fore-limbs & trunk,
this results in modest power requirements vs more specialized leapers