paleobiogeography

Paleobiogeography is the study of the geographic distribution of organisms through geological time, integrating fossil data with geographic and environmental context to understand how past distributions arose and changed. It sits at the intersection of paleontology, biogeography, and geology, and uses fossils, stratigraphy, paleoclimatic information, and plate tectonic reconstructions to reconstruct where ancient organisms lived and how they moved or became isolated.

Key concepts include vicariance, where geological barriers split populations, and dispersal, where organisms cross barriers. Endemism and provincialism describe distinct regional faunas, while extinction, immigration, and faunal exchange help explain shifts in distribution. Data sources include fossil occurrences with calibrated ages and paleolocation, sedimentary and paleoenvironmental indicators, isotopic data, and paleomagnetic and tectonic reconstructions that place continents and oceans in their ancient configurations.

Methodologically, paleobiogeographers test hypotheses about past range shifts, assemble biogeographic maps through time, and apply models that incorporate dispersal and vicariance events. They compare fossil distributions with phylogenetic trees to infer historical biogeographic patterns and to illuminate the tempo of faunal change.

Applications include tracing the historical distribution of major clades, explaining regional faunas through isolation and connections—such as distinct Australasian and South American mammal assemblages during certain intervals—and interpreting moments of large-scale faunal interchange linked to plate tectonics and climate change. Challenges arise from an incomplete fossil record, dating and sampling biases, and uncertainties in past plate configurations.

Overall, paleobiogeography seeks to explain how geographic context has shaped the evolution and distribution of life across deep time.