Archaeopteryx

Archaeopteryx Temporal range: Late Jurassic (Tithonian), 150.8–148.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
The Berlin Archaeopteryx specimen (A. siemensii)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Clade:	Paraves
Family:	†Archaeopterygidae
Genus:	†Archaeopteryx Meyer, 1861 (conserved name)
Type species
†Archaeopteryx lithographica Meyer, 1861 (conserved name)
Referred species
†A. siemensii Dames, 1897 †A. albersdoerferi Kundrat et al., 2018
Synonyms[1]
Genus synonymy Griphosaurus Wagner, 1862 (rejected name) Griphornis Woodward, 1862 (rejected name) Archaeornis Petronievics, 1917 Jurapteryx Howgate, 1984 Wellnhoferia? Elżanowski, 2001 Species synonymy Griphosaurus problematicus Wagner, 1862 vide Woodward 1862 nomen rejectum Griphornis longicaudatus Owen 1862 vide Woodward 1862 nomen rejectum Griphosaurus longicaudatus (Owen 1862 vide Woodward 1862) Owen 1862 vide Brodkorb 1863 nomen rejectum Archaeopteryx macrura Owen, 1862 (rejected name) Archaeopteryx siemensii? (Dames, 1897) Archaeornis siemensii (Dames, 1897) Peteronievics vide Petroneivics & Woodward 1917 Archaeopteryx owenii Petronievics, 1917 (rejected name) Archaeopteryx recurva Howgate, 1984 Jurapteryx recurva (Howgate, 1984) Howgate 1985 Archaeopteryx bavarica Wellnhofer, 1993 ?Wellnhoferia grandis Elżanowski, 2001

Archaeopteryx (/ˌɑːrkiːˈɒptərɪks/; lit. 'old-wing'), sometimes referred to by its German name, "Urvogel" (lit. Primeval Bird) is a genus of bird-like dinosaurs. The name derives from the ancient Greek ἀρχαῖος (archaīos), meaning "ancient", and πτέρυξ (ptéryx), meaning "feather" or "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).^[2] Older potential avialans have since been identified, including Anchiornis, Xiaotingia, and Aurornis.^[3]

Archaeopteryx lived in the Late Jurassic around 150 million years ago, in what is now southern Germany, during a time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now. Similar in size to a Eurasian magpie, with the largest individuals possibly attaining the size of a raven,^[4] the largest species of Archaeopteryx could grow to about 0.5 m (1 ft 8 in) in length. Despite their small size, broad wings, and inferred ability to fly or glide, Archaeopteryx had more in common with other small Mesozoic dinosaurs than with modern birds. In particular, they shared the following features with the dromaeosaurids and troodontids: jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes ("killing claw"), feathers (which also suggest warm-bloodedness), and various features of the skeleton.^[5][6]

These features make Archaeopteryx a clear candidate for a transitional fossil between non-avian dinosaurs and birds.^[7][8] Thus, Archaeopteryx plays an important role, not only in the study of the origin of birds, but in the study of dinosaurs. It was named from a single feather in 1861,^[9] the identity of which has been controversial.^[10][11] That same year, the first complete specimen of Archaeopteryx was announced. Over the years, eleven more fossils of Archaeopteryx have surfaced. Despite variation among these fossils, most experts regard all the remains that have been discovered as belonging to a single species, although this is still debated.

Archaeopteryx was long considered to be the beginning of the evolutionary tree of birds. However, in recent years, the discovery of several small, feathered dinosaurs has created a mystery for palaeontologists, raising questions about which animals are the ancestors of modern birds and which are their relatives.^[12] Most of these twelve fossils include impressions of feathers. Because these feathers are of an advanced form (flight feathers), these fossils are evidence that the evolution of feathers began before the Late Jurassic.^[13] The type specimen of Archaeopteryx was discovered just two years after Charles Darwin published On the Origin of Species. Archaeopteryx seemed to confirm Darwin's theories and has since become a key piece of evidence for the origin of birds, the transitional fossils debate, and confirmation of evolution.