270 million year old fossil ‘Kermit the Frog’ found in museum collection

An early amphibian was named after the largest living (species) frog: Kermit. The species, given the scientific title Kermitops congratulations, preceded true frogs and is considered by the scientists who described it to be a proto-amphibian important to the development of this important animal order.

K. free was described from a fossil skull kept at the Smithsonian’s National Museum of Natural History since 1984. The skull was found in 270-million-year-old rocks from north-central Texas. George Washington University doctoral student Calvin So led the writing of the description, and after confirming that it was a previously unknown species, gave the name. While many chose names of scientific mentors or names associated with where a fossil was found, So and co-authors opted for something with broader appeal.

Nine years after scientists discovered a living frog that looked exactly like the famous Muppet and inexplicably named it Hyalinobatrachium dianae, So he took the opportunity to set things right. Kermit has previously been honored with a generic name, Hensonbatrachus kermitibut this is his first generation.

“The use of the name Kermit has significant implications for how we can bring the science done by paleontologists in museums to the general public,” So said in a statement. “Because this animal is a distant relative of modern-day amphibians, and Kermit is a modern-day amphibian icon, it was the perfect name for it.”

The word ‘ops’ in the name comes from the Greek for ‘face’, as it was the unusual shape of the skull with large eyes that reminded So of Kermit.

K. free had a skull only 3 inches long and 2 inches wide; the dimensions of the rest of his body are unknown. Then, as now, life would have been dangerous for a being of this size. The same Red Beds in which Smithsonian curator Nicholas Hotton found the fossil also revealed larger reptiles and synapsids, the ancestors of mammals, many of which would have been frog-eating.

The Kermitops fossil compared to a modern frog skull.  Kermit's ear is at the bottom.  Like modern frogs, it is covered by an external tympanum or eardrum.  In the center right, bony shingles can be seen in the eyelid that would have protected the eye.

The Kermitops fossil compared to a modern frog skull. Kermit’s ear is at the bottom. Like modern frogs, it is covered by an external tympanum or eardrum. In the center right, bony shingles can be seen in the eyelid that would have protected the eye.

Image credits: Brittany M. Hance, Smithsonian.

There is a huge backlog of fossil discoveries waiting to be described, into which Kermit, the ancestral amphibian, fell – until he was rescued by So, at the suggestion of Dr Arjan Mann.

A lot of K. freeThe species’ features are common to other amphibiamiforms of the period, but a few are unique, most notably a distinct fontanelle in the upper jaw.

Calvin So holds Kermitop's skull in the palm of his hand, unlike the traditional interaction.

Calvin So holds Kermitop’s skull in the palm of his hand, unlike the traditional interaction.

Image credits: Phillip R Lee

Based on the shape of its skull, K. free It is believed to have fed on caterpillar-like insects, a reasonable precursor to Kermit’s stated fly diet. The authors suspect that it looked more like a modern salamander than a frog, but that it could be an ancestor of both.

It is not surprising that amphibians do not exhibit fossilization as well as species with sturdier bones. So little is known about their ancestors. Kermitops an important development.

“Paleontology has always been more than just dinosaurs, and there are still a lot of cool evolutionary stories and mysteries waiting to be answered. We just have to keep looking,” Mann said.

Maybe being honored in this way will make Kermit feel like it’s a little easier being green. It also leaves open the possibility that if a slightly younger and smaller species is found, it could be called Robin. If only Jim Henson had lived through it – but at least he had a sea slug.

The scientific description, including the name, is published in the Zoological Journal of the Linnean Society.

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