Scientists Closing in on Answers About ‘Lost’ Prehistoric Cats of Natural Bridge Caverns

October 1, 2024

Last January, a team of cavers led by a paleontologist from The University of Texas at Austin rappelled into two deep chambers at Natural Bridge Caverns to retrieve rare fossil finds: the bones of two small prehistoric cats, each about the size of a housecat.

A year later, the bones of the Natural Bridge Cats are beginning to reveal their secrets.

Researchers have determined their age – about 11,500 years old – and have successfully extracted fragments of ancient DNA. They have also determined the cats are not a common bobcat, as was previously proposed, but likely a species of Neotropical cat, such as an ocelot, margay or jaguarundi.

“This puts these cats into a Neotropical group, which are all endangered today. Only ocelots are left in Texas,” said John Moretti, a doctoral student at the UT Jackson School of Geosciences leading the research. “This gets us into a really interesting group of cats – including a species that is now possibly extinct.”

Although the researchers don’t yet know what species of small cat slinked through the cave’s passageways thousands of years ago, they are closing in on answers.

Moretti is working with UT Assistant Professor Melissa Kemp, who is part of the Jackson School and the College of Natural Sciences, to apply state-of-the-art methods to prepare the ancient DNA fragments for sequencing that can definitively identify the cats. He is also conducting a systematic comparison of the bones from the Natural Bridge Cats to bones from Neotropical cats living today.

Discovering the cats’ identity could reverberate beyond the Texas cavern and popular tourist destination. The Natural Bridge Cats could serve as a literal skeleton key – providing a reference that could help with identifying the bones of ancient small cats around the world.

“They are prompting us to revisit questions about old specimens that have just been sitting on the shelf,” said Moretti. “Without them, there’s not an impetus to wrestle with these problems.”

The remains of the Natural Bridge Cats were found in two chambers called the Dungeon and the Inferno Room which are almost a mile from the current entrance of the cavern and 200 feet underground. Portions of the Dungeon cat were discovered in 1963 and brought to the UT collections for study and safe keeping.

But in 2022, cavers discovered more cat bones in the Dungeon and a brand-new cat specimen in the Inferno Room. The openings into those two pit-like chambers are surrounded by small muddy pawprints that indicate it’s possible the cats fell into the chambers from above – and couldn’t get out.

“For decades, we’ve wondered about these bones – then we discovered the second cat. We have so many questions, including how these cats could have gotten so deep in the cave,” said Brad Wuest, president and CEO of Natural Bridge Caverns. “Discovery and exploration is at the heart of everything we do here at the caverns. Being involved with John and the team at UT Austin in this process of understanding more about the Natural Bridge Cats has been both rewarding and fascinating.”

In January 2023, Moretti led a recovery mission to bring the cats back to the surface after thousands of years underground. Research over the past year has helped to uncover some of the cats’ secrets.

Moretti matched the newly discovered bones in the Dungeon to the specimen sitting in the UT collections the past 60 years, showing that the two sets of bones came from the same skeleton. And two different dating techniques have placed the age of the cats in the ballpark of about 11,500 years ago. Radiocarbon dating on collagen extracted from the bones has the specimen at slightly older than that age. Uranium-thorium dating led by Jackson School scientists Staci Lowey and Alex Janelle on flowstone covering part of the specimen has it slightly younger.

But most important for figuring out the identity of the ancient cats is the successful extraction of ancient DNA. As expected, the DNA is in rough shape after spending thousands of years in a cave. But Moretti is hopeful about eventually being able to get a species identification.

“Like bones and other organic materials, DNA breaks down over time into smaller and smaller pieces,” Moretti said. “There’s still information stored in those fragments but it takes a lot of work to reconstruct and read the genetic code again.”

The DNA and collagen samples came from the Dungeon cat. The Inferno Room cat did not have DNA or collagen preserved. But based on the bones, Moretti thinks that what’s learned about one cat can be applied to the other.

“They’re the same shape and size,” Moretti said. “I feel confident that what we learn about the age and molecular identity of one skeleton is applicable to the other.”

Having two ancient cats of the same kind found together – not to mention, with pawprints nearby – is incredibly rare. The cat from the Dungeon is the most complete specimen of a small Neotropical cat from the last ice age in North America. And together the two specimens make up a nearly complete skeleton with all its major parts in place.

If the Natural Bridge Cats can be definitively identified as a certain species, their bones could help with classifying other ancient cat fossils – which are notoriously few in number and look very similar to one another.

For example, the bones brought back from the Dungeon in 1963 were identified in the UT collection as belonging to a bobcat until the additional bones brought back by Moretti disproved that.

The new bones are also raising interest around an old hypothesis that the Dungeon specimen is an extinct species of margay called a ‘river cat.’ The hypothesis was proposed by Lars Werdelin, a world-renowned expert on extinct cats based out of the Swedish Museum of Natural History, who examined the bones while conducting a national survey of small wildcat fossils in 1985.

Moretti is closely comparing the bones of the Natural Bridge Cats to skeletons from margays and other Neotropical cats on loan to UT from other institutions to identify what’s natural variation versus a distinguishing anatomical feature.

The research team is also deploying a custom-built imaging device designed to capture high-resolution, 3D images of the cat tracks. Data obtained from those images will provide a way of testing if those ancient paw prints were made by the Dungeon and Inferno Room cats.

But until the DNA sequencing results are in, he expects the Natural Bridge Cats – who are now together in the UT collections – to continue keeping their identity a secret.