Dinosaur fans will already be familiar with the ichthyosaurus, a prehistoric marine reptile that resembled a dolphin in appearance. Well it now seems that one of its close relatives, named Hupehsuchus, fed much like a modern-day baleen whale.
Although baleen whales are enormous, they feed entirely on tiny creatures such as krill and plankton.
They do so by first taking in a huge mouthful of seawater, with pleated skin on the underside of their jaw expanding to hold as much as possible. When they subsequently force that water back out, it passes through plates along the sides of their mouth known as baleen. Made of keratin, these plates have bristles along the edge that act as a sieve, trapping the concentrated krill and whatnot inside the whale’s mouth.
Led by Zichen Fang of the Wuhan Center of China Geological Survey, an international team of scientists has discovered that Hupehsuchus utilized a similar technique.
The creature – which was not related to whales – reached about 1 meter (3.3 ft) in length, and lived in what is now China approximately 248 million years ago. Paleontologists have known of its existence for many years, but the new understanding of its feeding habits is based on the analysis of two recently unearthed fossilized skulls.
“These were more complete than earlier finds and showed that the long snout was composed of unfused, strap-like bones, with a long space between them running the length of the snout,” said the Wuhan Center’s Prof. Long Chen, director of the study. “This construction is only seen otherwise in modern baleen whales where the loose structure of the snout and lower jaws allows them to support a huge throat region that balloons out enormously as they swim forward, engulfing small prey.”
Additionally, like those of baleen whales, the skulls lacked teeth but did have a series of grooves running the length of the jaws. In whales, those grooves support the baleen plates. And while no such actual plates were found on the Hupehsuchus skulls, this could likely be because the type of keratin of which they were made didn’t fossilize well.
A paper on the research, which also involved scientists from the University of Bristol, was recently published in the journal BMC Ecology and Evolution.
Source: University of Bristol