2021-05-14

Prehistoric footprint fossils reveal the earliest known evidence of coastal mammals

By yqqlm yqqlm

Prehistoric footprint fossils reveal the earliest known evidence of coastal mammals

A study published in “Scientific Reports” In, geologist Anton Wroblewski and Applied Biodiversity Scientist Bonnie Gulas-Wroblewski of the Natural Resources Institute of Texas A&M University reported that they have found several sets of fossil footprints that may have come from brown bear-sized crestdons, which are known to be suckling The earliest evidence of animals gathering near the ocean.

Wroblewski said: “Fossils like footprints record the interaction between organisms and their environment, and they provide information that individual body fossils cannot provide. In this case, fossil traces show , 8 million years after the extinction of non-avian dinosaurs, large mammals use the marine environment regularly.”

Prehistoric footprint fossils reveal the earliest known evidence of coastal mammals(1)

Wroblewski found footprints in the Hannah Formation in Wyoming. These are huge animals left on the soft sediments and The imprint pressed on the surface of the ancient tidal flat. These footprints are now preserved in sandstone and are more than half a mile long. They were left by two different animals-one with four toes and the other with five toes. The footprints of these five-toeds are the same as those of the crestdon, which is a semi-aquatic mammal similar to a hippopotamus. The owner of the four-toed footprint is still a mystery.

“Palaeontologists have been working in this field for 30 years, but they have been looking for bones, leaf fossils, and pollen, so they didn’t notice footprints or traces,” Wroblewski said. It is reported that Wroblewski saw these footprints for the first time in September 2019. “When I found them, it was already evening, and the setting sun shone on them at the right angle, making them clearly visible on the sloping sandstone slab. At first, I couldn’t believe what I saw; for many years, I I walked through this outcrop without noticing them. When I saw the first few, I walked along the sandstone ridge and realized that they were part of a larger, wider trail,” Wroblewski continued. .

Prehistoric footprint fossils reveal the earliest known evidence of coastal mammals(2)

Plant fossils and pollen help researchers The age of these footprints is determined to be about 58 million years ago, and they are in the Paleocene period. Before this discovery, the earliest known evidence of mammalian interaction with the marine environment came from the Eocene about 9.4 million years later. Wroblewski pointed out that the Hanna Formation footprint is the first Paleocene mammalian footprint found in the United States and the fourth in the world-two sets of footprints were previously discovered in Canada, and another set was discovered in Svalbard, Norway. He said that this is also the world’s largest accumulation of mammalian footprints in the Paleocene Era, both in the representative range and in absolute numbers. At least two species have left their footprints.

Today’s large mammals gather near the marine environment for a variety of reasons-including protecting themselves from predators and insect bites, finding unique food, obtaining salt, etc. It may be limited in the tropical forests of North America in the Paleocene. Researchers say that ancient mammals may have similar reasons to go to the beach and enjoy a day.

Wroblewski said that this study shows that behavioral and evolutionary hypotheses based on isotopic, molecular, and body fossil data can be empirically tested with fossil traces. “There is no other evidence that directly records the behavior of extinct creatures preserved in their favorite habitat. There is still a lot of important information in the rock, which is waiting to be discovered when the light is right!”