At a Glance
- Researchers discovered, based on a fossil found near the Florida-Georgia border, that tegu lizards once lived in North America during the Middle Miocene Climatic Optimum around 15 million years ago.
- The newly identified species, Wautaugategu formidus, provides the first evidence that these lizards, now invasive in Florida, naturally inhabited the region during a warmer prehistoric period.
- Advanced machine learning and 3D imaging helped scientists identify the fossil vertebra and determine its exact placement in the lizard’s spine, confirming the species’ identity.
- The warm climate and high sea levels during the Miocene likely facilitated the temporary migration of these lizards from South America to North America.
- This discovery highlights how shifts in climate have historically influenced animal migration and demonstrates the value of modern technology in understanding ancient ecosystems.
A groundbreaking discovery by researchers at the Florida Museum of Natural History has revealed that prehistoric tegu lizards once roamed North America during the Middle Miocene Climatic Optimum, around 15 million years ago. This discovery, whose results were published in the Journal of Paleontology, was made after scientists analyzed a single vertebra fossil found in a clay mine near the Florida-Georgia border. The fossil puzzled scientists for years and was identified as belonging to a new tegu species, Wautaugategu formidus. This marks the first evidence of tegu lizards, native to South America, existing in North America.
Tegus, now famously known for their invasions in Florida, was initially introduced to the U.S. via the pet trade and quickly became an invasive species. However, a recent study suggests that these reptiles had a much earlier presence in the region. The discovery of W. formidus highlights that during a warm period in Earth’s history, the climate was favorable enough for these lizards to migrate from South America into North America. Scientists believe the warm climate and higher sea levels made the southeastern U.S. an ideal environment for these lizards, though their presence was short-lived.
The research team used advanced technology to analyze the fossil. They employed a new machine-learning technique to compare the fossil vertebra with other known tegu species, pinpointing its location within the lizard’s spine. With the help of artificial intelligence and 3D imaging, scientists quickly identified the species. They named it W. formidus, with “formidus” meaning “warm” to reflect the heat of the period that allowed these lizards to thrive. This discovery opens the door for more research into the migration patterns of ancient species and their interaction with changing climates.
The fossil of W. formidus offers new insight into ancient ecosystems and the movement of species between continents. As global temperatures fluctuated, the conditions that once allowed tegu lizards to thrive in North America were no longer sustainable, leading to their eventual disappearance. Scientists hope that further exploration and fossil discoveries illuminate this unique historical period. The study also showcases the power of combining traditional paleontology with modern technology to speed up fossil identification and expand our understanding of ancient life.
References
- Bowser, B. & Florida Museum of Natural History. (2025, May 12). From prehistoric resident to runaway pet: First tegu fossil found in the US. Phys.Org; Florida Museum of Natural History. https://phys.org/news/2025-05-prehistoric-resident-runaway-pet-tegu.html
- Bourque, J. R., & Stanley, E. L. (2025). A tegu-like lizard (Teiidae, tupinambinae) from the middle miocene climatic optimum of the southeastern united states. Journal of Paleontology, 1–15. https://doi.org/10.1017/jpa.2024.89
