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Paleontologists with the Smithsonian National Museum of Natural History have discovered a previously unknown prehistoric species – a 270-million-year-old amphibian with wide eyes and a cartoonish grin – and its name is a nod to an iconic froggy celebrity.
Kermit the Frog meets Kermitops for free, the latest ancient amphibian to be identified after examining a tiny fossil skull that had not been studied in the Smithsonian’s fossil collection for 40 years, according to a paper published Thursday in the Zoological Journal of the Linnean Society.
Predating the dinosaurs, Kermitops are believed to have roamed the lower Clear Fork Formation of Texas during the Early Permian Era 298.9 million to 272.3 million years ago. The ancient amphibian’s skull, measuring just over an inch (about 2.5 centimeters) long, has large oval eye sockets and – due to its slightly crushed state – a faint smile that the researchers said was reminiscent of the Muppet icon to them.
The discovery of the new amphibian species could provide some answers to how frogs and salamanders evolved to get their special characteristics today, the authors wrote in the paper.
“One thing Kermitops really shows is that the origin of modern amphibians is a little more complicated than some of the research has made it out to be,” said study co-author Arjan Mann, a postdoctoral paleontologist at the Smithsonian’s National Museum of Natural History. .
“And that really means that people need to keep studying these things because just looking at museum collections, like this fossil, can change our thinking about evolutionary hypotheses of living descendants.” The fossil was discovered for the first time in 1984 by the late Nicholas Hotton III, a museum paleontologist who had excavated fossils from the Red Beds in Texas, an area known to be rich in Permian-age remains.
Kermitops, not a frog
The fossil was discovered for the first time in 1984 by the late Nicholas Hotton III, a museum paleontologist who had excavated fossils from the Red Beds in Texas, an area known to be rich in Permian-age remains.
Researchers have found a large treasure at the site, including the remains of ancient reptiles, amphibians and synapsids, the predecessors of mammals. The resulting collection included so many finds, paleontologists were unable to study some specimens, including the newly named Kermitops. That changed in 2021, when the skull caught the eye of Mann, then a postdoctoral fellow, who was sifting through the Texas collection to see if any significant specimens had been overlooked.
“Not only was (the skull) well prepared by someone, but it had features that distinguished it from anything else in the group that I had ever seen,” Mann said. In early 2023, Calvin So, lead author of the new paper and a doctoral student at George Washington University, began studying the skull for a doctoral paper.
Kermitops is not classified as a frog because the prehistoric amphibian does not have the same characteristics and anatomy that can be found in modern frogs, So said. But the researchers determined that the specimen is from the temnospondyls group, which is believed to be the most common ancestor of all liosamphibians – a category that includes frogs, salamanders and caecilians, Mann added.
The researchers noted several features that the ancient amphibian shares with its modern relatives, including a similar location of the eardrum at the back of the skull, a small opening between the nostrils that produces sticky mucus to help frogs catch their prey , and even evidence of bicuspid, pedicellate teeth unique to amphibians and found in most modern amphibian species.
Features of the ancient amphibian
The presence of teeth and other modern features of this prehistoric species can help researchers better understand the evolutionary transition that amphibians went through to get their unique features, such as teeth, today. A June 2021 study found that some species of frogs lost teeth repeatedly throughout their lineages.
“This work is significant because it provides an even more distinctive early relative of our modern amphibians,” said David Blackburn, co-author of that 2021 study and curator of amphibians and reptiles at the Florida Museum of Natural History at the University of Florida. . , via email.
“In the last 20 to 30 years many new species have been discovered and described among distant relatives, and each discovery tends to reshape our knowledge of the evolutionary tree,” Blackburn added.
But Kermitops had many different features from its modern relatives. The creature’s robust skull had extra bones and features that actually disappeared with evolution, and its long chin paired with a short region of the skull behind the eyes was unique to the species, probably helping insects to catch
The fossil’s features, a mix of modern and prehistoric features, reinforce previous suggestions that the evolution of amphibians was complex, said Marc Jones, curator of fossil reptiles at London’s Natural History Museum.
“It also adds to the diversity of Early Permian animals that are likely to be the evolutionary cousins of modern amphibians. It highlights the need for more Late Permian fossils,” Jones said via email, adding that he appreciated the amphibian’s name. “He’s not a frog but then technically Kermit. He has five fingers and a lizard frill.”
Preservation of small fossils
The early fossil record for lysoamphibians is considered fragmentary, according to a news release from the Smithsonian Institution, and is largely due to the creatures’ small size and delicate bone composition, making the fossils difficult to preserve and get later, So said .
“Today we see only a small percentage of all the things that have been alive in the history of the Earth,” Marson added. “And one of the conditions that significantly improves the preservation of a fossil is its size, because if it is larger, it will be more resistant to some of the erosive forces that we experience such as wind erosion and water erosion.”
In addition, although prehistoric species are generally considered to be large, Kermitops could help fill the gap in amphibian evolution, explaining how some of today’s critters got their small size.
The skull of Kermitops is similar in size to that of another well-known Early Permian amphibian, Gerobatrachus, which had a skull about an inch long (2.5 centimeters). But many frogs today have bodies shorter than that length, Blackburn said.
“You may wonder, ‘Were there no very small vertebrates in the past, like today’s small species?’ My bet is yes, they were there, but our ability to find them in the fossil record is very difficult,” Blackburn added.
So they said they hoped the species name would draw attention to the remarkable discoveries paleontologists make by studying museum collections of prehistoric fossils – including those smaller than dinosaurs.
“We wanted to name it Kermitops because we wanted to draw attention to this unique, tiny fossil that most people wouldn’t notice if you put it next to a Tyrannosaurus in the gallery,” said So.
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