Ecosystem Engineers Through Deep Time: Fossil Evidence of Beavers and Implications for Land Degradation and Development

ABSTRACT Beavers are major agents that shape and modify present‐day natural environments. This review aims to collate literature data on beaver occurrence across different regions in the past, based on fossil records and evidence from sediments, wood, and bone remains. The literature search was carried out using the Web of Science database, employing the keyword “beaver” alongside the names of geological periods spanning from the Oligocene to the Holocene. This review, based on 95 peer‐reviewed works, indicates a much greater diversity of species and ecological requirements of beavers in the past than the two currently occurring aquatic and terrestrial species, Castor fiber and Castor canadiensis . This indicates that beavers exerted a diverse range of environmental influences in the past. Some species were predominantly terrestrial and did not gnaw on trees, whereas others were fully aquatic, with the most recent forms becoming semiaquatic. The most significant environmental transformations began in the Early Pliocene, coinciding with the emergence of the beaver genus, Dipoides . This period also provides the clearest evidence in the form of wood‐bearing characteristic beaver tooth marks. The role of beavers as ecosystem engineers has been interrupted in the Anthropocene, following a marked decline in their populations. This decline has resulted from hunting and habitat destruction by human activity. However, present‐day observations, as well historical evidence suggest that contemporary semiaquatic beavers, by increasing water retention in valleys, may support efforts aimed at conserving organic soils (including the reduction of CO 2 emissions) and mitigating the negative effects of drought, and also influencing the increase of biodiversity.