Baleen whales, the majestic giants of the sea, have long been recognized for their unique filter-feeding technique.
Utilizing the sturdy keratin baleen plates in their mouths, these marine mammals engulf massive quantities of water and sift out minute organisms like krill and plankton for sustenance.
However, recent fossil discoveries suggest that this feeding strategy might not be as modern as once thought.
A collaborative team of scientists from the United Kingdom and China has uncovered a collection of extraordinary fossils belonging to an ancient reptile group that seems to have employed filter feeding approximately 250 million years ago.
Published on August 7 in the journal BMC Ecology and Evolution, their findings challenge the prevailing notion that filter feeding was exclusive to contemporary marine creatures.
While whales are perhaps the most well-known filter feeders, other present-day animals, such as basking sharks, also employ similar techniques.
Until now, the fossil record provided scant evidence of filter feeding among ancient marine reptiles from the Mesozoic Era (approximately 252 to 66 million years ago).
This new study introduces two fossilized skulls, both belonging to an early marine reptile named Hupehsuchus nanchangensis.
This creature, measuring around three feet in length, inhabited China some 248 million years ago during the Early Triassic period.
The intense competition for sustenance during this period might have spurred the development of a specialized feeding system in H. nanchangensis.
Dr. Michael Benton, a study co-author and vertebrate paleontologist from the University of Bristol, remarked, “This was a time of turmoil, only three million years after the huge end-Permian mass extinction, which had largely eliminated all life.
It’s amazing to see how quickly these big marine reptiles sprang on the scene and fundamentally altered the marine ecosystems at the time.”
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Revealing Ancient Filter Feeding: Rewriting Evolutionary Timelines
Examining the well-preserved specimens, the research team compared their shape and dimensions to 130 skulls of various aquatic animals.
Astonishingly, the Hupehsuchus skulls exhibited characteristics consistent with filter feeding. Notably, the reptiles possessed soft structures resembling an expandable throat region, enabling them to intake copious water containing small prey.
Similar to baleen whales, the skulls showcased structures that filtered food as it moved forward.
The resemblance to present-day baleen whales extended to grooves and notches along the jaws of the Hupehsuchus skulls, a feature shared with these modern marine mammals.
Intriguingly, these whales possess keratin strips in their mouths instead of teeth, a similarity echoed in the ancient reptiles.
Further analysis revealed that the mostly complete fossilized skulls had elongated snouts composed of unfused, strap-like bones – a distinctive feature observed only in baleen whales.
This unique adaptation facilitates their consumption of krill.
Dr. Zichen Fang, a study co-author and paleontologist from the Wuhan Center of China Geological Survey, marveled at these discoveries.
“The hupehsuchians were a distinctive group in China and near cousins of ichthyosaurs. They have been recognized for 50 years, but not much is known about their way of life.”
Due to its limited swimming agility, H. nanchangensis was likely a leisurely swimmer.
This attribute suggests that its feeding method might have resembled that of today’s bowhead and right whales, which skim the ocean’s surface with mouths agape, straining sustenance from the water.
These revelations represent a captivating example of convergent evolution, where similar adaptations arise independently in different species.
The ancient reptile’s filter-feeding strategy not only enriches our understanding of evolution but also redefines the timeline of this remarkable feeding technique.
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Source: Popular Science