Archaeopterygidae

Archaeopteryx (; ), sometimes referred to by its German name, "''''''" () is a genus of bird-like dinosaurs. The genus name derives from the Ancient Greek (), meaning 'ancient', and (), meaning 'feather, wing'. Between the late 19th century and the early 21st century, Archaeopteryx was generally accepted by palaeontologists and popular reference books as the oldest known bird (member of the group Avialae). Older potential avialans have since been identified, including Anchiornis, Xiaotingia, Aurornis, and Baminornis.

Archaeopterygidae is a group of paravian dinosaurs, known from the latest Jurassic and earliest Cretaceous of Europe. In most current classifications, it contains only the genera Archaeopteryx and Wellnhoferia. As its name suggests, Protarchaeopteryx was also once referred to this group, but most paleontologists now consider it an oviraptorosaur. Other referred genera, like Jurapteryx, Wellnhoferia, and "Proornis", are probably synonymous with Archaeopteryx (the former two) or do not belong into this group (the last). Jinfengopteryx was originally described as an archaeopterygid, though it was

Wellnhoferia (named after Peter Wellnhofer) is a genus of early prehistoric bird-like theropod dinosaur closely related to Archaeopteryx. It is known from a single species, W. grandis, that lived in what is now Germany, during the Late Jurassic. While Wellnhoferia was similar to Archaeopteryx, it had a shorter tail and its fourth toe was shorter than that of Archaeopteryx. Andrzej Elżanowski (2001) of the Institute of Zoology of the University of Wrocław, Poland, determined the differences resulted from a "phylogenetic reduction rather than individual variation."