Tiny toad, big discovery: New ice age amphibian found in La Brea Tar Pits collection

Researchers in Los Angeles have made a ribbiting new discovery at the La Brea Tar Pits and Museum — an extinct amphibian from the ice age.

The spadefoot toad, or Spea labreae, is one of only two ice age amphibians to have been found in the U.S. The other is an extinct species of tree frog in Florida, according to the museum’s news release.

“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,” the news release read.

The discovery of the spadefoot toad was made two years ago but published recently in the Journal of Vertebrate Paleontology and marks one of several discoveries made at the Samuel Oschin Global Center for Ice Age Research at the La Brea Tar Pits, where the museum is undergoing renovation.

Unearthing the spadefoot toad wasn’t the result of a targeted search — it happened by accident, much like many of history’s greatest finds.

Dr. Alberto Cruz, the lead author, was reviewing the rarely studied collections of amphibians and reptiles as a postdoctoral fellow at the La Brea Tar Pits when he noticed an amphibian that looked different from the others.

At first glance, he thought he was looking at a specimen that had been sick or injured rather than a new species. Upon closer inspection, he realized that wasn’t the case.

To identify the spadefoot toad, Cruz said he examined the bones of amphibians found at the Tar Pits, a collection that hadn’t been analyzed in nearly 30 years. He then compared the collection with the 80 specimens at the Herpetology Collection at the Los Angeles County Natural History Museum and the Museum of Vertebrate Zoology at the University of Berkeley.

“I thought: ‘Oh my gosh, this is a new species,’” he said. “This material is originally from the 1950s, but when you study it again, you can find gold in these specimens. It’s very cool.”

Researchers say amphibians provide a window into the past because they don’t travel far during their lifetimes and are sensitive to climate change. When their fossils are discovered, it helps scientists piece together how local environments changed over time.

“If you change the environment, you change the vegetation, the climate is warmer or colder, it affects these animals directly,” Cruz said.

The miracle behind Cruz’s discovery is that amphibians such as frogs, toads and salamanders rarely make it into the fossil records because of their fragile skeletons.

Emily Lindsey, curator and excavation site director at the La Brea Tar Pits’ center, said the discovery of the ice age toad is an example of the ongoing discoveries being made at the museum.

“There’s definitely more to come,” she said.

Also detailed in the Journal of Vertebrate Paleontology is the first record of another amphibian: the Mexican burrowing toad —Rhinophrynus. The species, which still exists, once inhabited the Southwestern region including Los Angeles. Researchers note that its closest known population is now roughly 1,550 miles away in southern Mexico.