<p>Organisms inherently preserve ancestral information within their bodies, proving evidence of evolutionary processes. Selenium, the least abundant essential element in the Earth’s crust, has emerged as a limiting factor in the development of animal reproductive systems. By integrating selenium concentration information from plants and animals, this study demonstrates that the decline in Earth’s surface selenium abundance may be associated with the origin and extinction of vertebrate species. Coal-derived selenium abundance data indicate that surface selenium may have been continuously lost, with depletion rates consistent with a natural decay process that could contribute to periodic vertebrate extinctions. The conserved selenium levels in animal germ cells imply that animals require selenium more strictly than plants, potentially imposing certain boundary conditions and constraints on the evolution of vertebrate reproductive systems (origin of new species). The syntheses here suggest that the biogeochemistry of selenium, broadly defined, provides new information and insight into the coevolution of vertebrate species and environment.</p>