Penguins International has been celebrating the Little Penguin as the Penguin of the Year for 2024 and how fortunate indeed, because a new tiny prehistoric penguin has been discovered! Named Pakudyptes hakataramea, the small early prehistoric penguin was similar in size to the Little Penguin (Eudyptula minor) that exists today. The name Pakudyptes comes from the Māori word for small, paku, and Greek word for diver, dyptes.
Three small penguin bones, including a humerus, ulna, and femur of Pakudyptes hakataramea, were discovered in South Canterbury, New Zealand in 1987 and sat in collections at the Geology Museum of the University of Otago until Dr. Tatsuro Ando and his team came along to process the collection 37 years later! Dr. Ando is a researcher that studies paleontology, comparative anatomy, and fossil histology and works at the Ashoro Museum of Paleontology in Japan. Dr. Ando worked alongside a team consisting of scientists and researchers at the University of Otago, New Zealand, and Okayama University of Science, Japan, to process the fossils, place them in the geologic time scale, and explore the evolution of penguin wings.
Why is it awesome that the femur, ulna, and radius were studied? Because these bones show the structures of the shoulder joint and elbow joint within the wing! The modern penguins we know of today have straight wings, not angled wings. In fact, Aptenodytes which includes both King and Emperor Penguins, have the straightest wings, and Spheniscus (Humboldt, Magellanic, Galápagos and Magellanic Penguins) the most angled. Scientists think the size or species (taxon) of penguin might have a correlation to the angle of their wings. The unique shape of penguin wings reflects food preferences and is relevant to diving depth (Haidr et al. 2023). The angled wing of Pakudyptes is different from modern penguins. Restrictions in the elbow joint makes the penguin wing a flipper that generates thrust by flapping motions, critical for hydrodynamics (Maeda et al. 2021, Hao et al. 2023, Ando et al. 2024). It turns out that modern penguins have a wider range of motion and more thrust than the Pakudyptes had.
How do they know that this adaptation shows a pivotal transition in penguin wing evolution? There are large gaps between prehistoric penguins from New Zealand and prehistoric penguins from South America. The Pakudyptes hakataramea fossil helps fill the gap of understanding! What Dr. Ando and his team found is that penguin wings evolved rapidly from the Late Oligocene (33.9 to 23 million years ago) to the Early Miocene (23.3 -16.3 million years ago). The Late Oligocene had many penguin species showing a rich diversity. Studying the Pakudyptes hakataramea fossil bone structure and movement reveals how the changes in bone structures over time enable the excellent swimming ability of modern penguins! The shape and structure of the bones show the angle of rotation of the wing or feathering angle, which plays a role in thrust generation in the propulsion mechanism in penguins, also known as hydrodynamics (Hao et al. 2023). The research also further confirms the importance of Zealandia in penguin evolution (Ando et al. 2024).
Citations:
Ando, T., Robinson, J., Loch, C., Nakahara, T., Hayashi, S., Richards, M.D., & Fordyce, R.E. (2024)
A new tiny fossil penguin from the Late Oligocene of New Zealand and the morphofunctional
transition of the penguin wing. Journal of the Royal Society of New Zealand, 1-22.
https://doi.org/10.1080/03036758.2024.2362283
Haidr NS. 2023. Ecomorphological variation of the penguin wing. Journal of
Morphology. 284(6):e21588. doi:10.1002/jmor.21588.
Hao Z, Yin B, Prapamonthon P, Yang G. 2023. Hydrodynamic performance of a penguin wing:
effect of feathering and flapping. Phys Fluids.
35:061907. https://pubs.aip.org/aip/pof/article/35/6/061907/2897344.
Maeda M, Harada N, Tanaka H. 2021. Hydrodynamics of gliding penguin flipper suggests the
adjustment of sweepback with swimming speeds. bioRxiv. 2021.05.24.445327.
doi:10.1101/2021.05.24.445327.
