Archaeopteryx

• 1. Introduction

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  Archaeopteryx lived about 150 million years ago in what is now southern Germany, when Europe was a scatter of islands in a shallow, warm sea close to the equator. Its name means ancient wing, and German speakers call it the Urvogel, the primeval bird. It had sharp teeth, three clawed fingers and a long bony tail, yet it also carried true flight feathers. The first skeleton came out of the ground in 1861, only two years after Charles Darwin published On the Origin of Species. Fourteen body fossils are now known, and every one of them comes from limestone quarries near Solnhofen. For well over a century, palaeontologists and popular reference books called Archaeopteryx the oldest known bird. That title is now in doubt, and so are many other things about the animal. How did a handful of fossils travel from Bavarian quarries to museums on three continents? Why did an astronomer accuse them of being fakes? Could this creature really fly, and what was it actually related to?

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• 2. A Feather in the Quarry

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  The story starts with a single feather, unearthed in 1860 or 1861 and described in 1861 by Hermann von Meyer. It now sits in the Natural History Museum of Berlin. Meyer coined the genus name from two Ancient Greek words, one meaning ancient and one meaning feather or wing. He had also heard of a skeleton found in the same limestone, and had been shown a rough sketch of it. He described that animal in German as a skeleton of a creature covered in similar feathers.

  That skeleton is known as the London Specimen. It was found in 1861 near Langenaltheim and perhaps handed to a local physician, Karl Häberlein, as payment for medical services. Häberlein sold it for 700 pounds, roughly 83,000 pounds in 2020 money, to the Natural History Museum in London. Most of the head and neck are missing. Richard Owen described it in 1863 as Archaeopteryx macrura, leaving open the possibility that it was a different species from the feather.

  Darwin took notice. In the fourth edition of his book he wrote of the strange bird with a lizard-like tail and two free claws on each wing, and added: "Hardly any recent discovery shows more forcibly than this how little we as yet know of the former inhabitants of the world."

  The founding feather itself later became a puzzle. In 2019 a report said laser imaging had revealed the structure of its quill, which had been hidden for a long time. The authors concluded that the feather did not match any other Archaeopteryx feather and came from another dinosaur. A 2020 challenge called that unlikely and identified it, from its shape, as most probably an upper major primary covert.

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• 3. Fossils With Price Tags

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  A farmer named Jakob Niemeyer found the Berlin Specimen on the Blumenberg near Eichstätt in 1874 or 1875. In 1876 he sold it to an innkeeper, Johann Dörr, to raise money for a cow. Dörr passed it to Ernst Otto Häberlein, the son of the physician who had sold the London fossil. Between 1877 and 1881 it was offered around, and one possible buyer was O. C. Marsh of Yale University's Peabody Museum. Berlin's natural history museum finally paid 20,000 Goldmark, with the money coming from Ernst Werner von Siemens, founder of the company that carries his name. Wilhelm Dames described it in 1884. It remains the most complete specimen and the first with a complete head.

  Not every fossil ended up so safely. The Maxberg Specimen, a torso found in 1956 near Langenaltheim, belonged to Eduard Opitsch, who loaned it to the Maxberg Museum in Solnhofen until 1974. After Opitsch died in 1991, people discovered it was gone. It may have been stolen or sold, and its whereabouts are still unknown.

  The Munich Specimen was found on the 3rd of August 1992 near Langenaltheim. A museum in Munich bought it in 1999 for 1.9 million. The Haarlem Specimen is older still. It was found in 1855 and described in 1857 by Meyer as a pterosaur, Pterodactylus crassipes. Only in 1970 did John Ostrom reclassify it, which makes it the first Archaeopteryx ever collected, long unrecognised. A fragment found in 2000, just one wing, is nicknamed the chicken wing.

  Private collections hid others. The Daiting Specimen, found in 1990, was known for years only from a cast. Palaeontologist Raimund Albertsdörfer bought the original in 2009, and it appeared with six other originals at the Munich Mineral Show that October. In 2022 it moved to the Museum of Evolution at Knuthenborg Safaripark in Denmark. The Thermopolis Specimen sat in a Swiss private collection before going to the Wyoming Dinosaur Center. The Field Museum in Chicago acquired the fourteenth fossil in 2022, from a Swiss private collection that had bought it in 1990, before Germany banned exports of the fossils in 2015. A thirteenth, fragmentary specimen was published in January 2025. That same year, Jingmai O'Connor and colleagues formally described the Chicago fossil and reported the first known tertials, specialised inner flight feathers.

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• 4. The Forgery Charge

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  In 1985 an amateur group that included the astronomer Fred Hoyle and the physicist Lee Spetner began publishing papers claiming that the feathers on the Berlin and London fossils were forged. They argued that feather impressions had been pressed into a thin layer of cement. They said the tail had been faked as one large feather. They also claimed that the other known specimens had no feathers, and they doubted that slabs could split so cleanly.

  Alan J. Charig and colleagues at the Natural History Museum in London took the claims apart. The Maxberg and Eichstätt fossils, they pointed out, plainly show feathers. Smooth splitting is normal at Solnhofen, because dead animals settled onto hardened surfaces that became natural break planes, leaving most of a fossil on one half of a slab. A difference in texture around the feathers is also what real feathers would cause.

  The suggested motives contradicted each other. One was that Richard Owen forged the evidence to back Darwin's theory. The other was that Owen set a trap, hoping Darwin would endorse the fossils so Owen could expose them. Owen's known views of Darwin made the first unlikely. The second would have backfired, because Owen himself wrote a detailed paper on the London fossil.

  The physical evidence also pointed to authenticity. Hairline cracks run through both rock and feather impressions, and old mineral growth covers the slabs. Spetner's group argued that the cracks would have spread through a hidden cement layer. They overlooked that the cracks were old and filled with calcite, so they could no longer spread. X-ray spectroscopy on the London fossil did find a foreign substance. It was not cement and was most probably a fragment of silicone rubber left over from making moulds. Charig and his colleagues added that the rock slabs contain no air bubbles at all, which they took as further proof of authenticity.

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• 5. Feathers and Claws

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  A full-grown Archaeopteryx reached about 50 centimetres in body length, with a wingspan near 70 centimetres and a mass of 500 to 1000 grams. Its wings were broad and rounded, and its tail was long for its body. Its jaws held small teeth, and each hand ended in three separate clawed digits. That mix of features made it, for a long time, the textbook link between dinosaurs and birds. In the 1970s John Ostrom, following an argument that Thomas Henry Huxley made in 1868, used it to support the idea that birds evolved within theropod dinosaurs. Ostrom found it strikingly similar to the family Dromaeosauridae.

  The Thermopolis Specimen sharpened that picture. A paper in Science on the 2nd of December 2005 described its well-preserved feet. Archaeopteryx lacked the reversed toe that every modern bird has, which would have limited its ability to perch on branches. It did have the hyperextensible second toe, the so-called killing claw, that was once thought to belong only to deinonychosaurs. Gregory S. Paul had claimed to see this toe in 1988, but other scientists accepted it only after Thermopolis.

  The flight feathers were strongly asymmetrical and built like those of modern birds, with vanes held together by a barb, barbule and barbicel arrangement. The Berlin Specimen shows well-developed feather trousers on the legs and a patch of firm feathers along the back. The rest of the body carried a fluffy proto-down like that of the dinosaur Sinosauropteryx, which may have looked more like fur than feathers. The eleventh specimen revealed feathers on both the upper and lower legs. The twelfth, from the Painten Formation, is the only one with no preserved feathers.

  In 2011 the graduate student Ryan Carney and colleagues carried out the first colour study. They used scanning electron microscopy to find melanosomes in the isolated feather of 1861, then compared them with those of 87 modern bird species. The feather was black with a 95% likelihood, most probably a covert on the wing. A 2013 study suggested a more complex mix of light and dark plumage. In 2020 Carney and colleagues showed in Scientific Reports that the feather was entirely matte black, and that the rest of the plumage pattern remains unknown.

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• 6. Could It Fly

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  A thick, boomerang-shaped wishbone may have anchored the flight muscles of Archaeopteryx, which had no bony breastbone. Its shoulder joint also faced sideways rather than upward, which may have kept it from raising its wings above its back. In 2006 Philip Senter concluded that it could not flap like a modern bird, but may have glided with downstroke-only flaps. Large wings would have given a low stall speed and a tight turning radius. The short, rounded shape resembles that of crows and pheasants, birds that weave through brush. In 2006 Longrich found that hind wings, asymmetrical feathers on the legs, formed up to 12% of the airfoil. That could have cut stall speed by up to 6% and turning radius by up to 12%.

  Feather shape fed the argument. Flightless birds tend to have symmetrical feathers, but Thomson and Speakman studied more than 70 families of living birds and found that some flightless types show a range of asymmetry. The feathers of Archaeopteryx fell inside that range, closer to slow flyers than to flightless birds.

  In 2010 Robert Nudds and Gareth Dyke published a paper in Science arguing that the feather shafts of Archaeopteryx and Confuciusornis were too thin and weak for flapping flight. Philip Currie noted that the fossils lie in marine or lake sediments, which suggests that they could cross deep water. Gregory Paul replied that Nudds and Dyke had assumed 250 grams for the juvenile Munich Specimen when about 140 grams was more reasonable. He also said the poorly preserved feathers there could not be measured reliably. Nudds and Dyke stood by their conclusions.

  The brain tells another story. A 2004 CT scan of the London Specimen showed that vision took up nearly one-third of the brain. The inner ear resembled that of modern birds, suggesting good balance and coordination. Newer work cautions that the brain was no larger than in several other non-avian dinosaurs. A study published in March 2018 argued for a flight stroke closer to the grabbing motion of maniraptoran dinosaurs, with bone features like those of pheasants, which fly in intermittent bursts.

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• 7. Names and Family Tree

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  Johann Andreas Wagner answered Meyer's Archaeopteryx with Griphosaurus problematicus, meaning problematic riddle-lizard, and it was meant as a vitriolic sneer. That quarrel between Wagner and Meyer helped produce ten published names for a handful of specimens. The international naming commission, the ICZN, later suppressed the rival names for the early skeletons. In 1954 Gavin de Beer concluded that the London fossil was the proper reference specimen.

  That created a real difficulty, because the name was officially tied to the lone feather. If the feather came from another animal, the name Archaeopteryx could no longer apply to the skeletons. In 2007 two sets of scientists petitioned the ICZN to name the London fossil as a new reference specimen. After four years of debate the commission agreed, and on the 3rd of October 2011 the London Specimen became the neotype.

  Today most fossils are assigned to one or two species, A. lithographica and A. siemensii. A 2007 review separated them mainly by large flexor tubercles on the foot claws of A. lithographica. A. siemensii, named by Dames in 1897, covers at least the Berlin, Munich and Thermopolis specimens. The supposed species Wellnhoferia grandis seems indistinguishable from A. lithographica except for its larger size.

  The bigger question is where Archaeopteryx sits among dinosaurs. It is not thought to be a true ancestor of modern birds, but a close relative of that ancestor. Lowe in 1935 and Thulborn in 1984 suggested it was simply a dinosaur no closer to birds than others. The discovery of Xiaotingia in 2011 led to analyses placing Archaeopteryx among the deinonychosaurs, and a follow-up study could not repeat that result. Studies by Hu and colleagues in 2018, Wang and colleagues in 2018 and Hartman and colleagues in 2019 again found a deinonychosaur. Hartman's group thought flight probably evolved separately in it. Older potential avialans, including Anchiornis, Xiaotingia, Aurornis and Baminornis, have since been identified. The authors of the follow-up study said the question may stay open without new and better specimens.

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• 8. Life on the Lagoon

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  The Solnhofen region sat at a latitude similar to Florida today, although the climate was probably drier. The islands around the lagoon were low, semi-arid and sub-tropical, with a long dry season and little rain. Fossils show cycads and conifers, and plenty of insects, small lizards, pterosaurs and Compsognathus. The closest modern analogue for the conditions is said to be Orca Basin in the northern Gulf of Mexico, although the basin is much deeper. Plants were mostly low shrubs, and large trees seem to have been mostly absent, since few trunks and no fossil tree pollen turn up. Pterosaurs outnumber Archaeopteryx in the deposits, with seven genera found, including Rhamphorhynchus and Pterodactylus.

  That landscape makes the lifestyle hard to pin down. Marsh proposed that flight began with tree-dwelling gliders. Samuel Wendell Williston favoured running along the ground. The currently best-supported view is that Archaeopteryx was at home in both places, like modern crows. In 2002 Elżanowski sketched an animal that used glides with shallow downstrokes to reach higher perches. It most likely hunted small prey, seizing it with its jaws or claws. A 2026 CT study of the Chicago fossil reported structures interpreted as oral papillae and a mobile tongue, features seen in modern birds.

  In 2009 Erickson, Norell and colleagues estimated growth from bone porosity, since the bones could not be cut into growth rings. They calculated that reaching adult size may have taken at least 970 days, with 375 days in a Late Jurassic year. The slow pace resembles that of the flightless kiwi. Comparisons of the eye's scleral rings suggest it was active by day.

  Most specimens share a stiff death pose, with the head, neck and tail bent downward. The pose suggests the carcasses drifted on their backs in the sea and had just begun to rot when anoxic sediment buried them. In some fossils the flight feathers were already detaching.

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