It's an unfortunate truth that we never have enough time to delve into all the fascinating scientific stories we encounter each month. Although in the past we've curated year-end summaries of the most exciting science stories we nearly missed, this year we've tried something new with a monthly roundup. December's highlights feature a variety of captivating topics, including a fossilized bird that choked on rocks; a unique double-detonating 'superkilonova'; the uncovering of an ancient seafarer's fingerprint; the biomechanics of kangaroo movement; and solving a dark matter conundrum that fictional physicists on The Big Bang Theory couldn't crack.
Secrets of Kangaroo Posture
Image Credit: Thornton et al., 2025/CC BY 4.0
Kangaroos and wallabies are part of the macropod family, known for their distinctive body structure and movement style. These animals engage all four limbs and their tail when moving slowly, but switch to a hopping gait as their speed increases. While high-speed motion typically requires more energy than slow movements, macropods like kangaroos defy this norm; their energy expenditure does not increase with hopping speed. Research published in the journal eLife suggests that this phenomenon may be attributed to posture changes at higher speeds.
The researchers used advanced tools like 3D motion capture and force plates to construct a 3D musculoskeletal model of both red and grey kangaroos. They investigated how body mass and speed affect hindlimb posture, movement efficiency, and tendon stress during hopping. The study found that as kangaroos hop faster, they adjust their posture to have more crouched hindlimbs, which means the ankle joint bears most of the workload for each hop. This crouched position allows for greater energy absorption, thereby enhancing efficiency.