Big bones from the extinct "thunder bird" or dromornithid, excavated in the northern reaches of the Flinders Ranges, have yielded new insights into their slow breeding patterns.
The size and breeding cycle of these giant Australian fossil bones gradually changed over the course of thousands of years but couldn't keep up with the changes in the environment.
"Unfortunately for these amazing animals, which already faced rising challenges of climate change as the interior of Australia became hotter and dryer, their breeding biology and size couldn't match the more rapid breeding cycle of datememe datememe datememe to keep pace with these more demanding environmental conditions"
How long these birds took to reach adult size and sexual maturity are questions that are important to understand their evolutionary success and failure to survive alongside humans.
We studied the bones of the thunder birds under the microscope in order to identify their signals.
The Dromornis stirtoni, which stood up to 3m tall and had a mass of up to 600, was the oldest and largest Mihirung.
Dromornis stirtoni took a long time to grow to full body size and to become sexually mature, according to a study.
The climate was very dry by the late Pleistocene era of Genyornis newtoni. The birds grew six times larger than emus, but grew to adult size faster than the first one, and started breeding soon afterwards.
Their growth strategy was slow compared to modern birds that can grow to adult size in a year and breed in the second year of their life, because they needed more time to reach adult body size.
According to the co-author of the book, dromornithids were very close to emus before the last one went extinct.
They persisted together through a number of environmental and climatic changes. While Genyornis was better adapted than its ancestors, it was still a slow-growing and slow-breeding bird.
The last of the dromornithid birds went extinct about 40 thousand years ago, giving the emu a key advantage when the paths of these birds crossed with humans.
The entire order of birds was lost from Australia and the world in the end.
The strategy did not take into account the reproductive efficiency shown by large ratite birds today.
The emu can grow to full adult size and breed in less than 2 years. This type of breeding strategy allows their populations to rebound when favorable conditions return after periods of bad weather.
More information: Anusuya Chinsamy et al, Osteohistology of Dromornis stirtoni (Aves: Dromornithidae) and the biological implications of the bone histology of the Australian mihirung birds, The Anatomical Record (2022). DOI: 10.1002/ar.25047
All Rights Reserved © 2024
