Baleen whales (mysterious animals) are the largest animals on Earth. How they achieved such enormous sizes is still debated, and research to date has focused primarily on when they grew, rather than where they grew. was. Paleontologists now report on the remains of a toothless baleen whale (chaeomysticete) from South Australia. At an estimated length of 9 meters, it is the largest baleen whale from the early Miocene. Analysis of body size over time shows that ancient baleen whales in the Southern Hemisphere were larger than those in the Northern Hemisphere.
It was previously thought that the onset of the Ice Age in the Northern Hemisphere about 3 million years ago triggered the evolution of truly gigantic baleen whales.
The new study, led by Dr James Rule of Monash University and the Natural History Museum in London, reveals that this evolutionary size jump did, in fact, occur as early as 20 million years ago, and in the exact opposite direction in the southern hemisphere. I made it.
The major discovery came from a study of 16- to 21-million-year-old fossils held in Museum Victoria’s collection.
This specimen, the anterior end of the lower jaw of a large edentulous baleen whale, was discovered in 1921 on a cliff face on the banks of the Murray River in South Australia, but was largely unrecognized in collections.
In their study, Dr. Ruhl and colleagues explain how whales evolved to be larger in the southern hemisphere rather than the northern hemisphere, and that whales have been larger in the southern hemisphere throughout their evolutionary history (about 20 million to 30 million years). It was shown that
The discovery highlights the vital importance of the Australian and wider Southern Hemisphere fossil record in putting together a global picture of whale evolution.
The Murray River whale fossil confounds that theory, although previous leading theories were based primarily on fossils found in the northern hemisphere.
“The Southern Hemisphere, and Australia in particular, has always been overlooked as a frontier for fossil whale discovery,” says Dr Eric Fitzgerald, a palaeontologist at Museums Victoria Research Institute.
“Like the Murray River whale, the fossil whale discoveries in the south have shaken up whale evolution, giving us a more accurate, truly global picture of what was happening in the oceans in ancient times. .”
Researchers have discovered that the tip of a baleen whale’s jaw can expand depending on its body size.
They estimated the baleen whale to be about 9 meters long.
“The largest whales alive today, such as the blue whale, reach the length of a basketball court,” Dr. Ruhl said.
“About 19 million years ago, Murray River whales were nine meters long, already a third of this length. So baleen whales were well on their way to becoming ocean giants.”
of result will appear in Proceedings of the Royal Society B.
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James P. Rule other. 2023. A huge baleen whale emerges from its cold cradle in the south. Procedure R. Soc. B 290 (2013): 20232177; doi: 10.1098/rspb.2023.2177
Source: www.sci.news
