Linnaeus contributed the hierarchical classification system of organisms into domains, kingdoms, phyla, classes, orders, families, genera, and species based on their morphological and evolutionary features. He constructed one of the first phylogenetic trees to classify living species into the domains of prokaryotes, archaea, and eukaryotes as well as the kingdoms of plants and animals. Modern taxonomy is based on Linnaeus' approach of using shared morphological and evolutionary traits to group organisms on the phylogenetic tree.