A new species of Ice Age toad discovered at La Brea Tar Pits: The spadefoot toad Spea labreae

A new species of Ice Age toad, Spea labreae, has been identified in the fossilized remains recovered from the La Brea Tar Pits in Los Angeles. The discovery marks the first time a new species of extinct amphibian has been documented from the Pleistocene era in North America since a tree frog from Florida was described over a century ago. The toad, which lived alongside megafauna such as mammoths and saber-toothed cats, offers valuable insights into the climatic conditions of the late Ice Age. Researchers at the Samuel Oschin Global Center for Ice Age Research at La Brea Tar Pits made the discovery while examining the museum’s extensive collection of understudied amphibian and reptile fossils. The newly identified species, Spea labreae, belongs to the spadefoot toad family and is distinguished by unique skeletal features that set it apart from existing species. The holotype specimen consists of an incomplete sacro-urostyle bone, the base of the spine connecting to the hips, which was used to formally describe the new species in the Journal of Vertebrate Paleontology. Dr. Alberto Cruz, the study’s lead author, initially suspected that the specimen might represent a diseased or injured individual due to its unusual characteristics. However, after thorough comparison with modern spadefoot toads, he concluded that it represented a previously unknown species. Cruz, who works as a research associate at La Brea Tar Pits and a scientist for Mexico’s CIPAQ institute, noted that the discovery underscores the potential for uncovering new species even in well-studied fossil sites. “This material is originally from the 1950s, but when you study it again, you can find gold in these specimens,” Cruz remarked. His work highlights the importance of revisiting historical collections with fresh perspectives and advanced analytical techniques. Dr. Emily Lindsey, curator and excavation site director at the Samuel Oschin Center, echoed this sentiment, emphasizing that the Tar Pits continue to yield surprising findings despite decades of research. Amphibians, particularly small species like S. labreae, serve as critical indicators of past environmental conditions. Unlike larger mammals, which are often the focus of paleontological studies, amphibians exhibit limited mobility and are highly responsive to shifts in temperature and humidity. Their presence or absence in the fossil record can reveal subtle yet significant changes in climate and ecosystem dynamics. This makes them invaluable tools for reconstructing ancient climates. The fragility of amphibian skeletons means that few specimens survive the fossilization process, especially in non-asphaltic environments. The La Brea Tar Pits, however, provide an exceptional setting for preserving such delicate remains due to the sticky asphalt that rapidly entombs organisms upon death. As a result, the discovery of S. labreae represents a rare and remarkable addition to the fossil record. Cruz suggests that the Tar Pits may hold many more undocumented species waiting to be uncovered. The high sensitivity of amphibians to environmental fluctuations implies that numerous extinct species could have existed without leaving behind sufficient evidence. “If you change the environment, you change the vegetation, the climate is warmer or colder, it affects these animals directly,” he explained. The identification of S. labreae adds another layer to the complex tapestry of life that once thrived in the region. While the tar pits are renowned for their megafaunal remains, the continued unearthing of smaller, less conspicuous species illustrates the diversity of life during the Ice Age. As research continues, it is likely that more hidden chapters of Earth’s prehistoric past will emerge from the depths of the La Brea Tar Pits.