Outgroups

An outgroup is a phylogenetic taxon which is determined to be distantly enough related from the remaining taxa that comprise the ingroups. It must be closely related to the same lineage and thus possess a common ancestor with the ingroups, but it must possess enough differences to deem it an outgroup. Outgroups can be determined based on scientific data gained from morphology, paleontology, embryology, and gene sequencing.