This new Ice Age toad lived only in LA. Why the discovery matters

Ice-Age discoveries are still happening at the La Brea Tar Pits while the museum is closed for renovations.

And for the first time in Los Angeles, researchers have found a new species of extinct amphibian, according to a study released Wednesday in the Journal of Vertebrate Paleontology.

The little amphibian is a type of spadefoot toad — which technically aren’t toads but have the word in the common name. The researchers have affectionately named it Spea labreae (spay-ah lah-bray-eye) — a nod to the location where it was discovered.

How they found the amphibian

Spea labreae is now one of only two amphibians found from this era in North America. The other is a tree frog in Florida.

The study’s lead author, José Alberto Cruz, discovered the spadefoot while reviewing a collection of bones that had been barely touched since they were excavated from Rancho La Brea in 1929.

This incomplete sacro-urostyle bone (base of the spine that connects to the hips) is the holotype specimen used to describe the new species, Spea labreae.

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Courtesy La Brea Tar Pits

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At first, he said, he thought the sample came from a sick or injured amphibian in the already known spadefoot family. But as he compared the bones, he realized that couldn’t explain the differences in what he saw.

“[I thought,] 'Oh my god, this is a new species that is [being kept] in a drawer,'” he said. “And now it’s in the light to the world.”

This was Cruz's first discovery of an extinct species. He said he measured the bones to determine the size. According to his research, it was a bit larger than today's spadefoots. (Reporter’s note: Sorry to anyone who was hoping for it to be huge, like I was.)

As for the name, Spea labreae may seem self-explanatory, but there’s another reason.

“ The team [is] amazing,” he said. “All the people inside, the curators, the collection managers, the excavation lab — all the people are great.”

Why the discovery matters for climate change

Amphibians are incredibly sensitive to climate changes and need water. Because of that, researchers can learn more about what conditions were like during the Ice Age, such as precipitation and temperature, just from a frog's presence.

“ The birds, they can fly. If the conditions are very bad, they move,” he said. “But in the case of toads, frogs … they can’t move a lot.”

Co-author Emily Lindsey, a  vertebrate paleontologist at the La Brea Tar Pits, said the new discovery could offer insights about a much colder, wetter L.A. region.

Reconstructions of the dark Spea labreae at the center and right in the La Brea Tar Pits, compared with Spea hammondii (light spadefoot, left), which is the species in L.A. today. The Mexican burrowing toad is at the bottom.

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Artwork by Arturo Dávalos

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Courtesy La Brea Tar Pits

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“ If we’re trying to understand what Los Angeles looked like during the Ice Age, these are some of our best clues that can give us information about that,” she said.

For Spea labreae, L.A. is its only known home so far. But researchers also found the first record of the Mexican burrowing toad here, which today is only found in southern Mexico.

Lindsey said something big may have happened that made the toad move, such as climate changes during the late Ice Age or the arrival of humans.

Although the new discoveries won’t be in a dedicated exhibit when the museum reopens, they will be incorporated into the format.

“ Toads are definitely going to be represented in the new museum,” Lindsey said, “along with insects, songbirds, pack rats and all of the other plants and animals that make up an ecosystem.”