A new species of Ice Age toad has been discovered in Los Angeles

Researcher Alberto Cruz was examining the bones of ancient amphibians and reptiles held in the museum when he noticed an unusual fragment. It was part of the lower spine, connected to the pelvis.

At first, the scientist assumed that the bone’s strange shape might have been the result of disease or injury. However, a comparison with modern spadefoot toads revealed that the find differed significantly from all known species.

To verify this, Cruz studied the shape and dimensions of the bones from La Brea and compared them with 80 specimens from museum collections in Los Angeles and at the University of California, Berkeley. As a result, the researchers concluded that the bone belonged to a distinct, previously unknown species.

Details

The material was discovered as far back as the 1950s, but the La Brea amphibian collection had not been reviewed in detail for nearly 30 years.

This shows that new species can be discovered not only during excavations. Sometimes important finds are already lying in museum storerooms, but their significance only becomes clear after re-examination and comparison with modern animals.

Spea labreae became the first new species of extinct amphibian to be described based on material from La Brea. According to the museum, prior to this, only one other extinct Pleistocene amphibian species was known in North America — a fossil tree frog from Florida.

The La Brea Tar Pits are best known for the remains of mammoths, giant sloths and sabre-toothed cats. However, small frogs, toads and lizards can provide scientists with just as much information about the past.

Such animals do not usually stray far from their habitats and react quickly to changes in temperature, humidity and vegetation. Their presence or absence therefore helps us to understand what the environment was like during a particular period.

The fragile bones of amphibians are rarely preserved. The La Brea tar pits create unusual conditions in which even very small remains can survive to the present day.

Other unusual toads also lived in Los Angeles

During the same research, scientists discovered the remains of a Mexican burrowing toad at La Brea for the first time. Today, this species is not found in Los Angeles, and its nearest populations live some 2,500 kilometres to the south — in Mexico.

Such a significant shift in range illustrates just how drastically the region’s natural environment changed following the end of the Ice Age. Together with the extinction of Spea labreae, this discovery helps to reconstruct the history of the local environment.

Why this is important

Scientists are not claiming that the new species went extinct specifically because of global warming or any other specific climate change. It is impossible to determine the exact cause of extinction from a single bone.

However, the discovery confirms that ancient Los Angeles was home to amphibians that are no longer found in the region today. Studying such animals allows us to gain a better understanding of how different species responded to environmental changes in the past.

Source

Study: Alberto Cruz et al. A new extinct Pleistocene species of spadefoot toad and comments on the paleoecology and paleobiogeography of anurans from Rancho La Brea, California.

Journal: Journal of Vertebrate Palaeontology, 2026.