The supplementary materials for the article "Accelerated modern human-induced species losses: Entering the sixth mass extinction" provide additional data and tables to support the research. Table S1 defines IUCN categories used to assess modern extinction rates. Table S2 estimates modern extinction rates since 1500 and 1900. The data on contemporary extinctions (1500 to present) include species classified as extinct (EX), extinct in the wild (EW), and possibly extinct (PE). These species were obtained from the IUCN and verified through their website. The background extinction rate for mammals was determined by analyzing fossil and modern extinction data, resulting in a rate of 2 extinctions per million species-years, which is double previous estimates. The study compares recent extinction rates with background rates, using two estimates: a highly conservative rate (only EX species) and a more inclusive rate (EX, EW, and PE species). The results indicate that current extinction rates are significantly higher than background rates, suggesting we are entering the sixth mass extinction. The list of extinct vertebrates since 1500, according to IUCN (2014), includes numerous amphibians, fishes, and other species. These data support the conclusion that human-induced species losses are accelerating, leading to a potential sixth mass extinction.The supplementary materials for the article "Accelerated modern human-induced species losses: Entering the sixth mass extinction" provide additional data and tables to support the research. Table S1 defines IUCN categories used to assess modern extinction rates. Table S2 estimates modern extinction rates since 1500 and 1900. The data on contemporary extinctions (1500 to present) include species classified as extinct (EX), extinct in the wild (EW), and possibly extinct (PE). These species were obtained from the IUCN and verified through their website. The background extinction rate for mammals was determined by analyzing fossil and modern extinction data, resulting in a rate of 2 extinctions per million species-years, which is double previous estimates. The study compares recent extinction rates with background rates, using two estimates: a highly conservative rate (only EX species) and a more inclusive rate (EX, EW, and PE species). The results indicate that current extinction rates are significantly higher than background rates, suggesting we are entering the sixth mass extinction. The list of extinct vertebrates since 1500, according to IUCN (2014), includes numerous amphibians, fishes, and other species. These data support the conclusion that human-induced species losses are accelerating, leading to a potential sixth mass extinction.