A recent review conducted by researchers from the University of Bristol and the University of Uppsala challenges the common belief that hopping is the primary mode of locomotion for kangaroos throughout their evolutionary history. The study reveals that extinct kangaroo species exhibited a wide range of locomotion patterns, including quadrupedal bounding, climbing, and slower hopping. The researchers suggest that the high-speed endurance hopping observed in modern kangaroos was likely uncommon or even absent in their ancestors. Instead, many extinct species adopted alternative forms of movement, such as bipedal striding.
The comprehensive analysis, published in Alcheringa: An Australasian Journal of Palaeontology, examines the fossil evidence of kangaroo locomotion and their relatives over the past 25 million years. The study presents new analyses of limb bone and ankle bone metrics, providing support for previous hypotheses regarding locomotor differences.
Contrary to popular belief, the review emphasizes that being a successful large kangaroo does not solely depend on endurance hopping. The fossil record demonstrates that some extinct kangaroo species possessed diverse locomotory capabilities. While most kangaroos today, both small and large, utilize hopping gaits to some extent, the research reveals that several extinct kangaroos employed different modes of locomotion.
The earliest recognized kangaroo types from the late Oligocene to the middle Miocene primarily employed quadrupedal bounding, climbing, and slower speed hopping as their primary modes of locomotion. These early forms were small-bodied, weighing below 12kg. Larger-bodied kangaroos weighing over 20kg did not appear until the late Miocene, coinciding with increasing aridity and the spread of open vegetated habitats.
Hopping becomes problematic at larger body sizes, leading some later kangaroo species to develop specialized anatomies for efficient higher-speed hopping at body sizes exceeding 35kg. Although modern large kangaroos are known for their spectacular hopping abilities, they do not surpass 100kg in weight, with most individuals weighing under 70kg. Many extinct kangaroo species were physically too large to hop, exceeding these size limits.
Lead author Professor Christine Janis from Bristol’s School of Earth Sciences emphasizes the need to appreciate the diversity of large kangaroos that existed as recently as 50 thousand years ago, suggesting that the habitat in Australia at that time differed from today. Modern large hopping kangaroos, which are the exception in kangaroo evolution, represent a distinct lineage.
While hopping originated early in kangaroo evolution, primarily in small-bodied forms, the emergence of larger-sized kangaroos in the late Miocene presented various options. Some species specialized in large-bodied endurance hopping, similar to the ancestors of modern kangaroos, while others adopted alternative forms of locomotion at higher speeds.
The protemnodons, closely related to modern large kangaroos, likely relied on a quadrupedal type of locomotion, rarely utilizing hopping. On the other hand, the sthenurine short-faced kangaroos, a lineage that diverged from all modern kangaroos approximately 15 million years ago, adopted bipedal striding at all speeds.
The new data presented in the study on the length of the tibia (shin bone) and calcaneum (ankle bone) further support these earlier hypotheses regarding locomotor differences in these two extinct kangaroo groups. The absence of a long calcaneal heel, which helps resist rotational forces during hopping, suggests a more erect limb posture rather than the crouched posture required for hopping in sthenurines.
Professor Janis concludes that the assumption that increasing aridity favored hopping kangaroos after the Miocene period is overly simplistic. Kangaroos have employed various gait modes throughout their evolutionary history, and the fast endurance hopping of modern kangaroos should not be considered the pinnacle of evolution. The extinction of similar animals that moved differently contributes to the perception of modern endurance-hopping kangaroos as unique. In a light-hearted tone, Professor Janis suggests the need for a rival Australian airline that covers shorter distances than QANTAS, featuring a motif of a striding sthenurine.
Reference: “Myth of the QANTAS leap: perspectives on the evolution of kangaroo locomotion” by Christine M. Janis, Adrian M. O’Driscoll, and Benjamin P. Kear, 25 May 2023, Alcheringa: An Australasian Journal of Palaeontology.
DOI: 10.1080/03115518.2023.2195895
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Frequently Asked Questions (FAQs) about Kangaroo locomotion
Q: What does the study reveal about kangaroo locomotion?
A: The study reveals that kangaroo locomotion is more diverse than commonly believed. Extinct kangaroo species displayed various movement patterns, including quadrupedal bounding, climbing, and slower hopping, challenging the notion that hopping is the primary mode of locomotion for all kangaroos.
Q: Were there alternative forms of movement adopted by kangaroos?
A: Yes, many extinct kangaroo species adopted alternative forms of movement. Some utilized bipedal striding, while others moved about on all four limbs. This suggests that hopping was not the exclusive mode of locomotion for all kangaroos throughout their evolutionary history.
Q: Did the study find any evidence of high-speed endurance hopping in extinct kangaroos?
A: The study suggests that high-speed endurance hopping, commonly observed in modern kangaroos, was likely rare or absent in most extinct kangaroo species. Only a few large-bodied lineages, such as the direct ancestors of modern kangaroos, exhibited this form of locomotion.
Q: How does the fossil record support the findings of the study?
A: The fossil evidence, including analyses of limb bone and ankle bone metrics, supports the hypotheses regarding the locomotor differences between modern and extinct kangaroo species. The length and structure of these bones provide insights into the varied locomotion modes employed by different kangaroo lineages.
Q: What implications does the study have for understanding kangaroo evolution?
A: The study challenges the notion that hopping is the pinnacle of kangaroo evolution. It highlights the diversity of locomotion modes employed by kangaroos in the past and emphasizes that modern large hopping kangaroos are exceptions rather than the norm. The research provides a deeper understanding of the evolutionary history of kangaroo locomotion.
More about Kangaroo locomotion
- Alcheringa: An Australasian Journal of Palaeontology: Link
- University of Bristol: Link
- University of Uppsala: Link
- QANTAS: Link
3 comments
wow, the fossil record reveals a whole new side of kangaroo history. they were so much more diverse than we thought. makes you wonder what else we might be missing about other animals. fascinating stuff!
interesting research! shows that our assumptions about kangaroo evolution were a bit off. they didn’t all hop all the time. diverse ways of getting around. science is amazing!
this study challenges what we thought we knew about kangaroo locomotion. diversity is the key, and hopping is not the be-all and end-all. keeps us questioning and learning. love it when science surprises us!