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| Reconstruction of Spea labreae, (dark spadefoots, center) in La Brea Tar Pits compared with Spea hammondii (light spadefoot, left), the species currently present in the area, and the presence of the Mexican burrowing toad (Rhinophrynidae, bottom). Cruz & Lindsey, 2026 Artwork by Arturo Dávalos |
ABSTRACT
Fossil amphibians hold great promise for paleoecological, paleoclimatological, and biogeographic studies because of their extreme sensitivity to environmental conditions. However, the study of fossil amphibians to date has been limited, because the fragility of frog, toad, and salamander skeletons means that diagnostic elements are rarely preserved in the fossil record. One unique locality that preserves a robust record of Quaternary amphibians is Rancho La Brea in Los Angeles, California, U.S.A. Here, we describe the amphibian fauna from the Hancock Collection of Rancho La Brea, which contains fossils from ∼45,000 years before present through the Holocene. We document previously unrecognized taxa from this locality, including the Mexican burrowing toad Rhinophrynus sp. and a new species of spadefoot toad, Spea labreae, sp. nov. Using osteological comparison material, we calculate the size of this new species of Spea, which is larger than the extant species in this genus. We analyze the current distribution and fossil record of the genus Spea and the family Rhinophrynidae, documenting changes in geographic ranges of these taxa during the Quaternary. These changes likely resulted from the interplay of deglacial climate changes and topographic complexity in the American Southwest, and may help to predict amphibian responses to climate changes impacting the region today.
Class AMPHIBIA, Linnaeus, 1767
Order ANURA Rafinesque, 1815
Family SCAPHIOPODIDAE Cope, 1865
Genus SPEA Cope, 1866
SPEA LABREAE, sp. nov.
Etymology—The specific epithet refers to La Brea, Spanish for ‘the tar’ which gave rise to the name of Rancho La Brea, the locality where this species is found.
Locality, Horizon, and Age—Pit A, Rancho La Brea, Los Angeles, California, Late Pleistocene–Holocene.
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| Reconstruction of Spea labreae, (dark spadefoots, center and right) in La Brea Tar Pits compared with Spea hammondii (light spadefoot, left), the species currently present in the area, and the presence of the Mexican burrowing toad (Rhinophrynidae, bottom). Artwork by Arturo Dávalos. |
J. Alberto Cruz and Emily L. Lindsey. 2026. A New extinct Pleistocene Species of Spadefoot Toad and comments on the Paleoecology and Paleobiogeography of Anurans from Rancho La Brea, California. Journal of Vertebrate Paleontology. e2689465. DOI: doi.org/10.1080/02724634.2026.2689465 [04 Aug 2026]
