Spea labreae: Unknown Ice Age Amphibian Found at La Brea

For more than 70 years, small bones recovered from the famous La Brea tar pits sat in a scientific collection, attracting far less attention than mammoths and sabre-toothed cats. When palaeontologist Alberto Cruz decided to re-examine them, he made an unexpected find: an unknown Ice Age amphibian species, now named Spea labreae.

How did an unknown species remain hidden for decades?

Cruz was not searching for a new species when he began reviewing amphibians and reptiles held in the La Brea collections. One bone displayed unusual features and, at first, he thought the differences might have resulted from disease or an injury suffered by the animal rather than from an unknown species.

However, after repeatedly comparing the material with known spadefoot toads, that explanation became less convincing. Cruz said he examined numerous specimens before becoming convinced that he had made a discovery. The study by J. Alberto Cruz and Emily Lindsey, published in 2026 in the Journal of Vertebrate Paleontology, formally described Spea labreae.

What could a single bone reveal?

The holotype, the specimen used as the defining reference for the species, consists of a fragment of the sacro-urostyle, a skeletal area close to the base of the spine. Although it may seem limited, particular bone shapes allow detailed comparisons. The researchers also assessed other specimens to establish whether the differences occurred consistently.

• The material had remained in scientific collections for decades before being recognised as a new species.
• The species was named Spea labreae after the renowned La Brea fossil site.
• The study compared the fossils with modern specimens to confirm consistent anatomical differences.
• The discovery is the first extinct amphibian species described from Rancho La Brea fossils.

The find is particularly unusual because frog, toad and salamander skeletons are fragile and often do not survive fossilisation. According to La Brea Tar Pits itself, asphalt deposits provide exceptional conditions for preserving small remains that would normally vanish from the fossil record.

Why is a small frog so important to scientists?

Large mammals may dominate Ice Age reconstructions, but amphibians provide a different kind of evidence. Because they are highly sensitive to temperature, water availability and vegetation changes, their presence or absence helps palaeontologists examine the environments in which they lived.

Cruz explained that environmental shifts capable of changing vegetation and climate affect these animals directly. As a result, Spea labreae could help reconstruct changes that took place in southern California at the end of the Pleistocene. The study specifically explored how climatic and geographical changes influenced the distribution of these amphibians.

Watch the video shared by the 9NEWS YouTube channel announcing the discovery of the new species.

Did the same collection contain another surprise?

The review also identified fossils from the genus Rhinophrynus, the Mexican burrowing toad, at La Brea. Interestingly, members of this group do not currently live in the Los Angeles area. According to the museum, its modern populations occur around 2,500 kilometres further south, illustrating how animal distributions have changed.

This geographical difference offers an important clue to environmental transformations after the Ice Age. The scientific paper concludes that climate changes during deglaciation, together with the geography of the south-western United States, probably helped alter the distribution of these groups over thousands of years.

How many discoveries might still be in museum drawers?

La Brea has been studied for more than a century and contains the largest known collection of late Pleistocene asphalt fossils. Even so, Emily Lindsey, curator and director of excavations at the site's research centre, stressed that new discoveries are still emerging. In her view, the case clearly shows that much remains to be found.

The story of Spea labreae demonstrates that a palaeontological discovery does not always begin with a new excavation. Sometimes, the next unknown animal is already catalogued in a museum, waiting for someone to ask the right question. These old collections are worth watching, because a small drawer may hold a species lost for thousands of years.