A long-overlooked fossil in a well-known Los Angeles collection has revealed something unexpected.
Scientists at the La Brea Tar Pits and Museum say the specimen belongs to a previously unknown extinct spadefoot toad from the ice age, making it only the second amphibian from that period ever identified in the United States.
What happened?
For decades, the La Brea Tar Pits' amphibian and reptile collection included delicate fossils that had received little study. Among them was the specimen now named Spea labreae, as the Los Angeles Times and 9 News reported.
Before this, the only known U.S. ice age amphibian was Hyla baderi, an extinct tree frog from Florida.
Dr. Alberto Cruz — the study's lead author and then a postdoctoral fellow at the museum — noticed one fossil looked different while he was reexamining older material.
His first suspicion was that the specimen showed evidence of disease or injury. A closer look led to a different conclusion: it represented a species that had not been identified before.
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To test that idea, Cruz compared La Brea material with 80 specimens from the Herpetology Collection at the Natural History Museum of Los Angeles County and UC Berkeley's Museum of Vertebrate Zoology.
"I thought: 'Oh my gosh, this is a new species,'" Cruz said.
Why does it matter?
Part of what makes the discovery stand out is how rarely amphibians appear in the fossil record.
Because their skeletons are so fragile, they often decay before they can be preserved. When fossils do survive, though, they can help scientists track how nearby environments changed over time.
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That kind of evidence is especially valuable in Southern California, since amphibians usually stay within fairly limited ranges and respond quickly to changes in habitat, moisture, and temperature.
"If you change the environment, you change the vegetation, the climate is warmer or colder, it affects these animals directly," Cruz said, according to the LA Times.
That sensitivity gives researchers another tool for piecing together conditions in the Los Angeles area near the end of the last ice age and for understanding how ecosystems react to climate shifts.
In a museum news release, researchers said, "While the toad may be much smaller than the mammoths and saber-toothed cats that made the Tar Pits famous, this discovery has a big impact on our understanding of the climate at the end of the last ice age."
What's being done?
Its publication in the Journal of Vertebrate Paleontology also highlights the continued work underway at the Samuel Oschin Global Center for Ice Age Research at the La Brea Tar Pits during the museum's renovation.
The study is a reminder that major discoveries do not always depend on newly unearthed fossils. Sometimes they come from revisiting specimens that have been sitting in collections for years.
The same research also recorded another first involving the Mexican burrowing toad, Rhinophrynus. The species is still alive today, but researchers said its nearest known population is now in southern Mexico, roughly 1,550 miles away.
Together, those results show how dramatically animal ranges can shift over long periods.
More broadly, the find highlights the public importance of museums and conservation science. Learning about past biodiversity can help shape future habitat protection in places dealing with hotter conditions and ecological stress.
"This material is originally from the 1950s, but when you study it again, you can find gold in these specimens," Cruz said, per the LA Times.
Emily Lindsey, curator and excavation site director at the La Brea Tar Pits' center, summed it up simply: "There's definitely more to come."
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