Biodiversity in deep time

More than 99% of species that are thought to have existed have gone extinct. This past biodiversity cannot be observed in the same manner as extant species; instead, researchers hoping to learn from Earth’s vast evolutionary history must rely on alternative sources of biodiversity data, such as the fossil record.

This historic record has noteworthy potential. Beyond documenting the varied forms and functions of species in deep time, past biodiversity records can also reveal responses to biogeographic change, ecosystem disruptions and mass extinction events. The most famous group documented in the fossil record, and perhaps the most studied, are the dinosaurs — the ruling reptiles of the Mesozoic. In this issue, Nature Reviews Biodiversity publishes a landmark Review of dinosaur palaeontology by Xu et al., synthesizing emerging knowledge about dinosaur origins, evolution and biology. This article follows our recently published Review from Park on the evolution and palaeontology of Cetacea, the clade that includes dolphins, whales and their earliest ancestors.

These Reviews showcase the valuable insights to be garnered from the fossil record, as well as discussing essential considerations for best practice use of these data. Each Review highlights cutting-edge techniques adapted for use with fossil data, including morphometrics, biogeographic climate modelling, high-resolution imaging and biomolecular analyses. Palaeontology is demonstrably a multidisciplinary science, drawing from and contributing to modern biodiversity science and beyond. For example, understanding how past species responded to climate perturbations can help to inform risk profiles for modern species at risk of extinction, many of which face ever-evolving challenges in the face of anthropogenically driven global change. However, the authors caution that the fossil record must be used carefully, with full consideration of its limitations. Palaeontology is a fossil-based discipline, but the preservation and discovery of fossils are not biologically or geographically uniform. Preservation is biased toward hard tissues, such as bones and teeth, and often relies on sedimentary environments rapidly burying dead organisms. The collection of fossils depends on field-based discovery and excavation, bringing logistic and economic challenges that vary with location.

Looking beyond its core scientific contributions, the fossil record has a usage that cannot be understated: the ability to inspire and educate. Fossils displayed in museums capture the imagination of the public, instilling a sense of wonder at a natural world that differs so greatly from the modern one, and with the capacity to educate and inspire new generations of biodiversity researchers.

Palaeontology is an essential component of the biodiversity science puzzle and is critical for understanding and addressing the origins of, maintenance of and threats to biodiversity that shape and inspire our publications as a journal.