A remarkable breakthrough from the Florida Museum of Natural History has unveiled that tegus, a group of large lizards currently labeled invasive in Florida, have a deep prehistoric footprint in southeastern North America. While the charismatic Argentine black and white tegus are well known for their introduction through the pet trade in the 1990s, this new research reveals their distant ancestors once roamed these lands millions of years ago. This revelation upends established beliefs about the geographic history of tegus and highlights the unexpected complexity of species dispersal in the Miocene epoch.
The journey to this scientific breakthrough began decades ago with a single, diminutive fossil vertebra about half an inch in size, discovered in early 2000 from a clay mine situated near the Florida-Georgia border. Despite its modest size, the fossil resisted identification for nearly 20 years, confounding paleontologists who debated whether it belonged to a lizard, a snake, or another reptile. It wasn’t until Jason Bourque, a fossil preparator and vertebrate paleontology specialist, revisited the specimen that the pieces began to fit together. Bourque’s meticulous examination hinted that the specimen bore a striking resemblance to tegu vertebrae, an insight that catalyzed further inquiry.
What followed was a fusion of traditional paleontology and cutting-edge technology. Recognizing the limitations of relying solely on expert morphological comparisons, Bourque collaborated with Edward Stanley, director of the museum’s digital imaging laboratory, to apply a novel machine learning approach to fossil identification. Using high-resolution CT scans, Stanley captured three-dimensional data on every anatomical nuance—the bumps, holes, and furrows—of the fossil vertebra. This 3D morphometric data was then analyzed alongside over 100 vertebrae from extant tegus and related lizard species, sourced from the museum’s openVertebrate (oVert) project, an expansive repository of vertebrate 3D images.
By implementing an automatic landmarking system devised by Arthur Porto, the museum’s curator of artificial intelligence for natural history and biodiversity, the research team bypassed the usual painstaking manual measurements. Porto’s algorithm adeptly recognized corresponding landmarks across the comparative vertebrae datasets, enabling precise shape analysis to pinpoint the fossil’s taxonomic identity. The result was unequivocal: the fossil vertebra belonged to a previously unidentified tegu species, which the researchers named Wautaugategu formidus. The genus name “Wautauga” references the local forest near the fossil site, inspiring a poetic connection to the "land beyond," while “formidus,” Latin for “warm,” alludes to the warm climatic conditions of its time.
The fossil dates back to the Middle Miocene Climatic Optimum (around 15 million years ago), a period characterized by elevated global temperatures and significantly higher sea levels. At this time, much of modern Florida lay submerged beneath shallow seas, with the terrestrial landscape concentrated near ancient coastal ridges where the fossil was found. Tegus, known for their terrestrial habits but also capable swimmers, may have exploited these warm conditions to expand their range northward from ancestral South American origins into what is now southeastern United States territory. This discovery effectively extends the known biogeographic range of prehistoric tegus far beyond current confines.
Yet, this prehistoric colonization was ephemeral. The absence of any tegus in fossil records before or after this thermal peak suggests Wautaugategu formidus was a transient experimental dispersal lineage, thriving only during the Middle Miocene’s warm span. The subsequent global cooling likely sealed their fate, as tegus’ reproductive physiology—highly dependent on temperature—would not have been sustainable in the cooler climates that followed. The cold may have limited egg incubation success, drastically reducing population viability and leading to local extinction.
This singular vertebra, small yet monumental, opens new avenues of inquiry into vertebrate dispersal dynamics and paleoclimatic influence on reptilian evolution. Bourque expresses keen interest in expanding fieldwork along the ancient coastal ridges near the Florida-Georgia boundary, hoping to uncover additional fossils that might flesh out the enigmatic existence of prehistoric tegus in North America. Such discoveries could illuminate evolutionary patterns and regional ecosystem transformations through geological epochs.
Beyond the paleontological implications, the study underscores the profound role of interdisciplinary research, particularly the integration of artificial intelligence and 3D imaging to accelerate fossil identification. Stanley emphasizes the significance of leveraging machine learning to reduce reliance on outdated manual assessments that demand decades of expert knowledge, a bottleneck that has left countless fossil collections unexamined. This technological synergy promises to revolutionize the speed, scale, and accessibility of paleontological research worldwide.
Moreover, the museum’s openVertebrate project exemplifies the power of open-access digital repositories in biodiversity science. By cataloging thousands of 3D vertebrate images, it facilitates global collaboration and comparative analyses previously impossible due to specimen scarcity and geographical limitations. In utilizing such resources, the Florida Museum’s team illustrates how digital natural history assets enhance and democratize scientific discovery on a scale matched to the challenges posed by the vast fossil record.
Ecologically, the story of Wautaugategu formidus offers valuable context for understanding the modern tegu invasion crisis. Today’s Argentine black and white tegus, introduced as pets, grow large and thrive in Florida’s subtropical environment, where they disrupt native ecosystems severely. The paradox of tegus’ ancient presence and modern invasive status invites reflection on how climate cycles, human activity, and species adaptability interplay to shape contemporary biodiversity.
The identification of Wautaugategu formidus also invites a recalibration of evolutionary timelines within Teiidae, shedding light on their diversification patterns correlated with Miocene climate fluctuations. The discovery encourages reexamination of fossil collections worldwide using similar advanced morphometric and machine learning methods, raising the prospect that other “mystery boxes” of fossil bones may harbor unknown species awaiting rediscovery.
Ultimately, this study exemplifies how a single bone, small enough to fit on a finger, can rewrite the history of an entire lineage and transform our understanding of ancient ecosystems. The melding of paleontological perseverance with innovative digital techniques points toward a new era, where unlocking the secrets of Earth’s past becomes more efficient, comprehensive, and revelatory.
Subject of Research: Tegus in the Middle Miocene Southeastern United States; paleontology and evolutionary biology of Teiidae lizards
Article Title: A tegu-like lizard (Teiidae, Tupinambinae) from the Middle Miocene Climatic Optimum of the southeastern United States
News Publication Date: 17-Apr-2025
Web References:
https://doi.org/10.1017/jpa.2024.89
https://www.floridamuseum.ufl.edu/overt/
https://www.floridamuseum.ufl.edu/science/florida-museum-hires-first-curator-of-artificial-intelligence-for-natural-history-and-biodiversity/
References:
Bourque, J., Stanley, E., Porto, A. (2025). A tegu-like lizard (Teiidae, Tupinambinae) from the Middle Miocene Climatic Optimum of the southeastern United States. Journal of Paleontology. DOI:10.1017/jpa.2024.89
Image Credits: Photo courtesy of Kevin Blackwell / Amphibian Foundation
Keywords: Reptiles, Paleontology, Invasive species, Climate change, Fossils
