not until 1986 that Archosauria was defined as a crown-clade, restricting its use to more derived taxa.Cope's term was a Greek-Latin hybrid intended to refer to the cranial arches, but has later also been understood as "leading reptiles" or "ruling reptiles" by association with Greek ????? "leader, ruler".

The term "thecodont", now considered an obsolete term, was first used by the English paleontologist Richard Owen