The Convention on Biological Diversity’s (CBD) Aichi Target 19 provides a specific mandate for developing and sharing an advanced biodiversity knowledge base. While the GBIF network has collected hundreds of millions of records, gaps and biases do remain. This study assessed nearly 200 million GBIF-mediated occurrences of terrestrial vertebrates to identify such gaps and biases. The results show that Asia, Africa, and South America have large areas with no records. By superimposing the occurrences on expert-curated maps, the researchers estimate the level of completeness and find that this is highly correlated with record density, except in very species-rich areas such as the American and African tropics. The strongest limiting factor of data completeness is related to digitization and mobilization rather than actual collection. National research funding and GBIF participation are consistently strong factors in determining completeness.