Archaeopteryx

Archaeopteryx

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Archaeopteryx sometimes referred to by its German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....

 name Urvogel ("original bird" or "first bird"), is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

 that is closely related to bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s. The name derives from the Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

  (archaīos) meaning "ancient", and (ptéryx), meaning "feather" or "wing". Since the late 19th century, it has been generally accepted by palaeontologists, and celebrated in lay reference works, as being the oldest known bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

, though some more recent studies have cast doubt on this assessment, finding that it is instead a non-avialan dinosaur closely related to the origin of birds.

Archaeopteryx lived in the Late Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...

 Period around 150 million years ago, in what is now southern Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 during a time when Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 was an archipelago of islands in a shallow warm tropical sea, much closer to the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....

 than it is now. Similar in shape to a European Magpie
European Magpie
The European Magpie, Eurasian Magpie, or Common Magpie, , is a resident breeding bird throughout Europe, much of Asia and northwest Africa. It is one of several birds in the crow family named as magpies, and belongs to the Holarctic radiation of "monochrome" magpies...

, with the largest individuals possibly attaining the size of a raven
Raven
Raven is the common name given to several larger-bodied members of the genus Corvus—but in Europe and North America the Common Raven is normally implied...

, Archaeopteryx could grow to about 0.5 metres (1.6 ft) in length. Despite its small size, broad wings, and inferred ability to fly or glide, Archaeopteryx has more in common with other small Mesozoic dinosaurs than it does with modern birds. In particular, it shares the following features with the deinonychosaurs (dromaeosaurs and troodontids): jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes ("killing claw"), feathers (which also suggest homeothermy), and various skeletal features.

The features above make Archaeopteryx a clear candidate for a transitional fossil
Transitional fossil
A transitional fossil is any fossilized remains of a lifeform that exhibits characteristics of two distinct taxonomic groups. A transitional fossil is the fossil of an organism near the branching point where major individual lineages diverge...

 between dinosaurs and birds. 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 feather
Feather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...

 in 1861. That same year, the first complete specimen of Archaeopteryx was announced. Over the years, ten 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, though this is still debated.

Most of these eleven fossils include impressions of feathers—among the oldest direct evidence of such structures. Moreover, because these feathers are of an advanced form (flight feather
Flight feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...

s), these fossils are evidence that the evolution of feathers began before the Late Jurassic. The type specimen of Archaeopteryx was discovered just two years after Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

 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
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

.

Description



Archaeopteryx lived during the early Tithonian
Tithonian
In the geologic timescale the Tithonian is the latest age of the Late Jurassic epoch or the uppermost stage of the Upper Jurassic series. It spans the time between 150.8 ± 4 Ma and 145.5 ± 4 Ma...

 stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...

 of the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 Period, around 150.8–148.5 million years ago. Most of the specimens of Archaeopteryx that have been discovered come from the Solnhofen limestone
Solnhofen limestone
The Solnhofen Plattenkalk is a Jurassic Konservat-Lagerstätte that preserves a rare assemblage of fossilized organisms, including highly detailed imprints of soft bodied organisms such as sea jellies...

 in Bavaria
Bavaria
Bavaria, formally the Free State of Bavaria is a state of Germany, located in the southeast of Germany. With an area of , it is the largest state by area, forming almost 20% of the total land area of Germany...

, southern Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, which is a lagerstätte
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....

, a rare and remarkable geological formation known for its superbly detailed fossils.

Archaeopteryx was roughly the size of a raven
Raven
Raven is the common name given to several larger-bodied members of the genus Corvus—but in Europe and North America the Common Raven is normally implied...

, with broad wings that were rounded at the ends and a long tail compared to its body length. It could reach up to 500 millimetres (19.7 in) in body length, with an estimated weight of 0.8 to 1 kg (1.8 to 2.2 lb). Archaeopteryx feathers, although less documented than its other features, were very similar in structure and design to modern-day bird feathers. However, despite the presence of numerous avian features, Archaeopteryx had many theropod dinosaur
Theropoda
Theropoda is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants . Dinosaurs belonging to the suborder theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory...

 characteristics. Unlike modern birds, Archaeopteryx had small teeth as well as a long bony tail, features which Archaeopteryx shared with other dinosaurs of the time.

Because it displays a number of features common to both birds and dinosaurs, Archaeopteryx has often been considered a link between them. In the 1970s, John Ostrom
John Ostrom
John H. Ostrom was an American paleontologist who revolutionized modern understanding of dinosaurs in the 1960s, when he demonstrated that dinosaurs are more like big non-flying birds than they are like lizards , an idea first proposed by Thomas Henry Huxley in the 1860s, but which had garnered...

, following T. H. Huxley's lead in 1868, argued that birds evolved within theropod dinosaurs and Archaeopteryx was a critical piece of evidence for this argument; it had a number of avian features, such as a wishbone, flight feathers, wings and a partially reversed first toe, and a number of dinosaur and theropod features. For instance, it has a long ascending process of the ankle bone
Talus bone
-External links:* *...

, interdental plate
Interdental plate
The interdental plate refers to the bone-filled mesial-distal region between the teeth. The word "interdental" is a combination of "inter" + "dental" which originated in approximately 1870...

s, an obturator
Obturator foramen
The obturator foramen is the hole created by the ischium and pubis bones of the pelvis through which nerves and muscles pass.- General structure :...

 process of the ischium, and long chevrons in the tail. In particular, Ostrom found that Archaeopteryx was remarkably similar to the theropod family Dromaeosauridae
Dromaeosauridae
Dromaeosauridae is a family of bird-like theropod dinosaurs. They were small- to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek dromeus meaning 'runner' and sauros meaning 'lizard'...

.

The first remains of Archaeopteryx were discovered in 1861; just two years after Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

 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 fossil
Transitional fossil
A transitional fossil is any fossilized remains of a lifeform that exhibits characteristics of two distinct taxonomic groups. A transitional fossil is the fossil of an organism near the branching point where major individual lineages diverge...

s debate, and confirmation of evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

. Indeed, further research on dinosaurs from the Gobi Desert
Gobi Desert
The Gobi is a large desert region in Asia. It covers parts of northern and northwestern China, and of southern Mongolia. The desert basins of the Gobi are bounded by the Altai Mountains and the grasslands and steppes of Mongolia on the north, by the Hexi Corridor and Tibetan Plateau to the...

 and China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

 has since provided more evidence of a link between Archaeopteryx and the dinosaurs, such as the Chinese feathered dinosaurs
Feathered dinosaurs
The realization that dinosaurs are closely related to birds raised the obvious possibility of feathered dinosaurs. Fossils of Archaeopteryx include well-preserved feathers, but it was not until the early 1990s that clearly non-avialan dinosaur fossils were discovered with preserved feathers...

. Archaeopteryx is close to the ancestry of modern birds, and it shows most of the features one would expect in an ancestral bird. However, it may not be the direct ancestor of living birds, and it is uncertain how much evolutionary divergence was already present among other birds at the time.

Plumage



Specimens of Archaeopteryx were most notable for their well-developed flight feather
Flight feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...

s. They were markedly asymmetrical and showed the structure of flight feathers in modern birds, with vanes given stability by a barb-barbule-barbicel arrangement. The tail feathers were less asymmetrical, again in line with the situation in modern birds and also had firm vanes. The thumb
Thumb
The thumb is the first digit of the hand. When a person is standing in the medical anatomical position , the thumb is the lateral-most digit...

, however, did not yet bear a separately movable tuft of stiff feathers
Alula
The alula, or bastard wing, is a small projection on the anterior edge of the wing of modern birds. The alula is the freely moving first digit, a bird's "thumb," and is typically covered with three to five small feathers, with the exact number depending on the species...

.

The body plumage of Archaeopteryx is less well documented and has only been properly researched in the well-preserved Berlin specimen. Thus, as more than one species seems to be involved, the research into the Berlin specimen's feathers does not necessarily hold true for the rest of the species of Archaeopteryx. In the Berlin specimen, there are "trousers" of well-developed feathers on the legs; some of these feathers seem to have a basic contour feather structure but are somewhat decomposed (they lack barbicels as in ratite
Ratite
A ratite is any of a diverse group of large, flightless birds of Gondwanan origin, most of them now extinct. Unlike other flightless birds, the ratites have no keel on their sternum—hence the name from the Latin ratis...

s). However, in part they are firm and thus capable of supporting flight.

There was a patch of pennaceous feather
Pennaceous feather
Pennaceous feathers are also known as contour feathers. This type of feather is present in most modern birds, and has been shown in some species of maniraptoran dinosaurs....

s running along the back which was quite similar to the contour feathers of the body plumage of modern birds in being symmetrical and firm, though not as stiff as the flight-related feathers. Apart from that, the feather traces in the Berlin specimen are limited to a sort of "proto-down
Down feather
The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator and padding, used in goods such as jackets, bedding,...

" not dissimilar to that found in the dinosaur Sinosauropteryx
Sinosauropteryx
Sinosauropteryx was the first genus of dinosaur outside of Avialae to be found with evidence of feathers. They were covered with "furry" coats of very simple filament-like feathers...

, being decomposed and fluffy, and possibly even appeared more like fur than like feathers in life (though not in their microscopic structure). These occur on the remainder of the body, as far as such structures are both preserved and not obliterated by preparation, and the lower neck.

However, there is no indication of feathering on the upper neck and head. While these may conceivably have been nude, this may still be an artifact of preservation. It appears that most Archaeopteryx specimens became embedded in anoxic
Oxygen saturation
Oxygen saturation or dissolved oxygen is a relative measure of the amount of oxygen that is dissolved or carried in a given medium. It can be measured with a dissolved oxygen probe such as an oxygen sensor or an optode in liquid media, usually water.It has particular significance in medicine and...

 sediment after drifting some time on their back in the sea—the head and neck and the tail are generally bent downwards, which suggests that the specimens had just started to rot when they were embedded, with tendons and muscle relaxing so that the characteristic shape of the fossil specimens was achieved. This would mean that the skin was already softened and loose, which is bolstered by the fact that in some specimens the flight feathers were starting to detach at the point of embedding in the sediment. So it is hypothesized that the pertinent specimens moved along the sea bed in shallow water for some time before burial, the head and upper neck feathers sloughing off, while the more firmly attached tail feathers remained.

Flight


As in the wings of modern birds, the flight feathers of Archaeopteryx were somewhat asymmetrical and the tail feathers were rather broad. This implies that the wings and tail were used for lift generation. However, it is unclear whether Archaeopteryx was simply a glider or capable of flapping flight. The lack of a bony breastbone
Sternum
The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...

 suggests that Archaeopteryx was not a very strong flier, but flight muscles might have attached to the thick, boomerang-shaped wishbone, the platelike coracoids, or perhaps to a cartilaginous
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

 sternum
Sternum
The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...

. The sideways orientation of the glenoid (shoulder) joint between scapula
Scapula
In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....

, coracoid and humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....

—instead of the dorsally angled arrangement found in modern birds—might indicate that Archaeopteryx was unable to lift its wings above its back, a requirement for the upstroke found in modern flapping flight. According to a study by Philip Senter in 2006 Archaeopteryx was indeed unable to use flapping flight as modern birds do, but it may well have utilized a downstroke-only flap-assisted gliding technique.

Archaeopteryx wings were relatively large, which would have resulted in a low stall speed and reduced turning radius
Turning radius
The turning radius or turning circle of a vehicle is the size of the smallest circular turn that the vehicle is capable of making. The term turning radius is actually a misnomer, since the size of a circle is actually its diameter, not its radius. The less ambiguous term turning circle is preferred...

. The short and rounded shape of the wings would have increased drag, but could also have improved Archaeopteryx ability to fly through cluttered environments such as trees and brush (similar wing shapes are seen in birds which fly through trees and brush, such as crows and pheasants). The presence of "hind wings", asymmetrical flight feathers stemming from the legs similar to those seen in dromaeosaurids such as Microraptor
Microraptor
Microraptor is a genus of small, four-winged dromaeosaurid dinosaurs. Numerous well-preserved fossil specimens have been recovered from Liaoning, China...

, would also have added to the aerial mobility of Archaeopteryx. The first detailed study of the hind wings by Longrich in 2006 suggested that the structures formed up to 12% of the total airfoil
Airfoil
An airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....

. This would have reduced stall speed by up to 6% and turning radius by up to 12%.

The feathers of Archaeopteryx were asymmetrical. This has been interpreted as evidence that it was a flyer, as flightless birds tend to have symmetrical feathers. However, some scientists, including Thomson and Speakman, have questioned this. They studied more than 70 families of living birds, and found that some flightless types do have a range of asymmetry in their feathers, and that the feathers of Archaeopteryx fall into this range. However, the degree of asymmetry with Archaeopteryx is more typical for slow flyers than for flightless birds.

In 2010, Robert L. Nudds and Gareth J. Dyke in the journal Science published a paper in which they analysed the rachises of the primary feathers of Confuciusornis
Confuciusornis
Confuciusornis is a genus of primitive crow-sized birds from the Early Cretaceous Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago...

 and Archaeopteryx. The analysis suggested that the rachises on these two genera were thinner and weaker than those compared to modern birds relative to body weight. The authors determined that Archaeopteryx, along with Confuciusornis, were unable to use flapping flight. This study, however, was criticized by Currie
Philip Currie
Philip Henry Wodehouse Currie, 1st Baron Currie GCB , known as Sir Philip Currie between 1885 and 1899, was a British diplomat. He was Ambassador to the Ottoman Empire from 1893 to 1898 and Ambassador to Italy from 1898 to 1902.-Background and education:Currie was the son of Raikes Currie, Member...

 and Luis Chiappe. Chiappe suggested that it is difficult to measure the rachises of fossilized feathers, and Currie speculated that Archaeopteryx and Confuciusornis
Confuciusornis
Confuciusornis is a genus of primitive crow-sized birds from the Early Cretaceous Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago...

 must have been able to fly to some degree, as their fossils are preserved in what is believed to have been in marine or lake sediments, suggesting that they must have been able to fly over deep water. Gregory Paul also disagreed with the study, arguing in a 2010 response that Nudds and Dyke had overestimated the weights of these early birds, and that more accurate weight estimates allowed powered flight even with relatively narrow rachises. Nudds and Dyke had assumed a weight of 250 grams for the Munich specimen Archaeopteryx, a young juvenile, based on published weight estimates of larger specimens. Paul argued that a more reasonable body weight estimate for the Munich specimen is about 140 grams. Paul also criticized the measurements of the rachises themselves, noting that the feathers in the Munich specimen are poorly preserved. Nudds and Dyke reported a diameter of 0.75 millimetre (0.0295275590551181 in) for the longest primary feather, which Paul could not confirm using photographs. Paul measured some of the inner primary feathers, finding rachises 1.25-1.4 mm across. Despite these criticisms, Nudds and Dyke stood by their original conclusions. They claimed that Paul's statement that an adult Archaeopteryx would have been a better flyer than the juvenile Munich specimen was dubious. This, they reasoned, would require even thicker ranchis, evidence for which has not yet been presented.

In 2004, scientists analyzing a detailed CT scan
Computed tomography
X-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...

 of the braincase of Archaeopteryx concluded that its brain was significantly larger than that of most dinosaurs, indicating that it possessed the brain size necessary for flying. The overall brain anatomy was reconstructed using the scan. The reconstruction showed that the regions associated with vision took up nearly one-third of the brain. Other well-developed areas involved hearing and muscle coordination. The skull scan also revealed the structure of the inner ear. The structure more closely resembles that of modern birds than the inner ear of non-avian reptiles. These characteristics taken together suggest that Archaeopteryx had the keen sense of hearing, balance, spatial perception and coordination needed to fly. Archaeopteryx had a cerebrum-to-brain-volume ratio 78% of the way to modern birds from the condition of non-coelurosaurian dinosaurs like Carcharodontosaurus
Carcharodontosaurus
Carcharodontosaurus was a gigantic carnivorous carcharodontosaurid dinosaur that lived around 100 to 93 million years ago, during the late Albian to early Cenomanian stages of the mid-Cretaceous Period...

 or Allosaurus
Allosaurus
Allosaurus is a genus of large theropod dinosaur that lived 155 to 150 million years ago during the late Jurassic period . The name Allosaurus means "different lizard". It is derived from the Greek /allos and /sauros...

. Those dinosaurs had a crocodile-like anatomy of the brain and inner ear.

Archaeopteryx continues to play an important part in scientific debates about the origin and evolution of birds. Some scientists see it as a semi-arboreal climbing animal, following the idea that birds evolved from tree-dwelling gliders (the "trees down" hypothesis for the evolution of flight proposed by O.C. Marsh
Othniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...

). Other scientists see Archaeopteryx as running quickly along the ground, supporting the idea that birds evolved flight by running (the "ground up" hypothesis proposed by Samuel Wendell Williston
Samuel Wendell Williston
Samuel Wendell Williston was an American educator and paleontologist who was the first to propose that birds developed flight cursorially , rather than arboreally . He was also an entomologist, specialising in Diptera.-Early life:Williston was born in Boston, Massachusetts to Samuel Williston and...

). Still others suggest that Archaeopteryx might have been at home both in the trees and on the ground, like modern crows, and this latter view is what today is considered best-supported by morphological characters. Altogether, it appears that the species was not particularly specialized for running on the ground or for perching. A scenario outlined by Elżanowski in 2002 suggested that Archaeopteryx used its wings mainly to escape predators
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...

 by glides punctuated with shallow downstrokes to reach successively higher perches, and alternatively to cover longer distances by (mainly) gliding down from cliffs or treetops.

Growth



A histological study by Erickson, Norell, Zhongue and others in 2009 showed that Archaeopteryx grew relatively slowly compared to modern birds, based on growth lines found in slices of Archaeopteryx bones. According to their study, all known skeletons of Archaeopteryx came from juvenile specimens. They estimated that Archaeopteryx reached adult size in about 970 days (about 2 years and 8 months), and weighed between 0.8 - 1 kilogram. The study also found that the birds Jeholornis and Sapeornis
Sapeornis
Sapeornis is a genus of primitive bird which lived during the Early Cretaceous . The genus contains only the species Sapeornis chaoyangensis which is known from fossils found in Jiufotang Formation rocks near Chaoyang, PRC...

 grew slowly, as did the dromaeosaurid Mahakala
Mahakala (dinosaur)
Mahakala is a genus of basal dromaeosaurid dinosaur from the Campanian-age Upper Cretaceous Djadokhta Formation of Ömnögov, Mongolia. It is based on a partial skeleton found in the Gobi Desert...

. The birds Confuciusornis
Confuciusornis
Confuciusornis is a genus of primitive crow-sized birds from the Early Cretaceous Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago...

 and Ichthyornis
Ichthyornis
Ichthyornis is a genus of toothed seabirds from the Late Cretaceous of North America. Its fossil remains are known from the chalks of Alberta, Alabama, Kansas, New Mexico, Saskatchewan, and Texas, in strata that were laid down in the Western Interior Seaway during the Turonian-Campanian ages,...

, however, grew very quickly, following a growth trend similar to that of modern birds. One of the few modern birds which exhibit slow growth is the flightless kiwi
Kiwi
Kiwi are flightless birds endemic to New Zealand, in the genus Apteryx and family Apterygidae.At around the size of a domestic chicken, kiwi are by far the smallest living ratites and lay the largest egg in relation to their body size of any species of bird in the world...

, and the authors speculated that Archaeopteryx and the kiwi had similar metabolism
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

s.

Daily activity patterns


Comparisons between the scleral ring
Sclerotic ring
Sclerotic rings are rings of bone found in the eyes of several groups of vertebrate animals, except for mammals and crocodilians. They can be made up of single bones or small bones together. They are believed to have a role in supporting the eye, especially in animals whose eyes are not spherical,...

s of Archaeopteryx and modern birds and reptiles indicate that it may have been diurnal, similar to most modern birds.

Paleoecology


The richness and diversity of the Solnhofen limestone
Solnhofen limestone
The Solnhofen Plattenkalk is a Jurassic Konservat-Lagerstätte that preserves a rare assemblage of fossilized organisms, including highly detailed imprints of soft bodied organisms such as sea jellies...

s in which all specimens of Archaeopteryx have been found have shed light on an ancient Jurassic Bavaria strikingly different from the present day. The latitude was similar to Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

, though the climate was likely to have been drier, as evidenced by fossils of plants with adaptations for arid conditions and lack of terrestrial sediments characteristic of rivers. Evidence of plants, though scarce, include cycad
Cycad
Cycads are seed plants typically characterized by a stout and woody trunk with a crown of large, hard and stiff, evergreen leaves. They usually have pinnate leaves. The individual plants are either all male or all female . Cycads vary in size from having a trunk that is only a few centimeters...

s and conifers while animals found include a large number of insects, small lizards, pterosaur
Pterosaur
Pterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight...

s and Compsognathus
Compsognathus
Compsognathus was a small, bipedal, carnivorous theropod dinosaur. The animal was the size of a turkey and lived around 150 million years ago, the early Tithonian stage of the late Jurassic Period, in what is now Europe. Paleontologists have found two well-preserved fossils, one in Germany...

.

The excellent preservation of Archaeopteryx fossils and other terrestrial fossils found at Solnhofen
Solnhofen
Solnhofen is a municipality in the district of Weißenburg-Gunzenhausen in the region of Franconia in the Land of Bavaria in Germany. It lies within the Altmühl valley....

 indicates that they did not travel far before becoming preserved. The Archaeopteryx specimens found are likely therefore to have lived on the low islands surrounding the Solnhofen lagoon rather than been corpses that drifted in from farther away. Archaeopteryx skeletons are considerably less numerous in the deposits of Solnhofen than those of pterosaurs, of which seven genera have been found. The pterosaurs included species such as Rhamphorhynchus belonging to the Rhamphorhynchidae
Rhamphorhynchidae
Rhamphorhynchidae is a group of early "rhamphorhynchoid" pterosaurs named after Rhamphorhynchus, that lived in the Late Jurassic. The family Rhamphorhynchidae was named in 1870 by Harry Govier Seeley.-Classification:...

, the group which dominated the niche
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...

 currently occupied by seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...

s, and which became extinct at the end of the Jurassic. The pterosaurs, which also included Pterodactylus
Pterodactylus
Pterodactylus is a genus of pterosaurs, whose members are popularly known as pterodactyls. It was the first to be named and identified as a flying reptile...

, were common enough that it is unlikely that the specimens found are vagrants
Vagrancy (biology)
Vagrancy is a phenomenon in biology whereby individual animals appear well outside their normal range; individual animals which exhibit vagrancy are known as vagrants. The term accidental is sometimes also used...

 from the larger islands 50 km (31.1 mi) to the north.

The islands that surrounded the Solnhofen lagoon were low lying, semi-arid
Semi-arid
A semi-arid climate or steppe climate describes climatic regions that receive precipitation below potential evapotranspiration, but not extremely...

 and sub-tropical with a long dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...

 and little rain. The closest modern analogue for the Solnhofen conditions is said to be Orca Basin
Orca Basin
The Orca Basin is a mid-slope, silled, mini-basin in the northern Gulf of Mexico some 300 km southwest of the Mississippi River mouth on the Louisiana continental slope. It is unique amongst the mini-basins in this area, in containing a large brine pool of anoxic salt brine...

 in the northern Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

, though that is much deeper than the Solnhofen lagoons. The flora
Flora
Flora is the plant life occurring in a particular region or time, generally the naturally occurring or indigenous—native plant life. The corresponding term for animals is fauna.-Etymology:...

 of these islands was adapted to these dry conditions and consisted mostly of low (3 m [10 ft]) shrubs. Contrary to reconstructions of Archaeopteryx climbing large trees, these seem to have been mostly absent from the islands; few trunks have been found in the sediments and fossilized tree pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...

 is also absent.

The lifestyle of Archaeopteryx is difficult to reconstruct and there are several theories regarding it. Some researchers suggest that it was primarily adapted to life on the ground, while other researchers suggest that it was principally arboreal. The absence of trees does not preclude Archaeopteryx from an arboreal lifestyle as several species of extant bird live exclusively in low shrubs. Various aspects of the morphology of Archaeopteryx point to either an arboreal or ground existence, including the length of its legs and the elongation in its feet; some authorities consider it likely to have been a generalist capable of feeding in both shrubs and open ground, as well as alongside the shores of the lagoon. It most likely hunted small prey, seizing it with its jaws if it was small enough, or with its claws if it was larger.

History of discovery



Over the years, eleven body fossil specimens of Archaeopteryx and a feather that may belong to it have been found. All of the fossils come from the limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 deposits, quarried for centuries, near Solnhofen
Solnhofen
Solnhofen is a municipality in the district of Weißenburg-Gunzenhausen in the region of Franconia in the Land of Bavaria in Germany. It lies within the Altmühl valley....

, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

.

The initial discovery, a single feather, was unearthed in 1860 or 1861 and described in 1861 by Christian Erich Hermann von Meyer
Christian Erich Hermann von Meyer
Christian Erich Hermann von Meyer was a German palaeontologist.He was born at Frankfurt am Main.In 1832 von Meyer issued a work entitled Palaeologica, and in course of time he published a series of memoirs on various fossil organic remains: molluscs, crustaceans, fishes and higher vertebrata,...

. It is currently located at the Humboldt Museum für Naturkunde in Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

. This is generally assigned to Archaeopteryx and was the initial holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

, but whether it actually is a feather of this species or another, as yet undiscovered, proto-bird is unknown. There are some indications it is indeed not from the same animal as most of the skeletons (the "typical" A. lithographica).

The first skeleton, known as the London Specimen (BMNH 37001), was unearthed in 1861 near Langenaltheim
Langenaltheim
Langenaltheim is a municipality in the Middle Franconian district of Weißenburg-Gunzenhausen in Germany....

, Germany and perhaps given to a local physician Karl Häberlein in return for medical services. He then sold it for £700 to the Natural History Museum
Natural History Museum
The Natural History Museum is one of three large museums on Exhibition Road, South Kensington, London, England . Its main frontage is on Cromwell Road...

 in London, where it remains. Missing most of its head and neck, it was described in 1863 by Richard Owen
Richard Owen
Sir Richard Owen, FRS KCB was an English biologist, comparative anatomist and palaeontologist.Owen is probably best remembered today for coining the word Dinosauria and for his outspoken opposition to Charles Darwin's theory of evolution by natural selection...

 as Archaeopteryx macrura, allowing for the possibility it did not belong to the same species as the feather. In the subsequent 4th edition of his On the Origin of Species, Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

 described how some authors had maintained "that the whole class of birds came suddenly into existence during the eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

 period; but now we know, on the authority of Professor Owen, that a bird certainly lived during the deposition of the upper greensand; and still more recently, that strange bird, the Archeopteryx, with a long lizard-like tail, bearing a pair of feathers on each joint, and with its wings furnished with two free claws, has been discovered in the oolitic
Oolite
Oolite is a sedimentary rock formed from ooids, spherical grains composed of concentric layers. The name derives from the Hellenic word òoion for egg. Strictly, oolites consist of ooids of diameter 0.25–2 mm; rocks composed of ooids larger than 2 mm are called pisolites...

 slate
Slate
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering...

s of Solnhofen
Solnhofen
Solnhofen is a municipality in the district of Weißenburg-Gunzenhausen in the region of Franconia in the Land of Bavaria in Germany. It lies within the Altmühl valley....

. Hardly any recent discovery shows more forcibly than this how little we as yet know of the former inhabitants of the world."

The Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

 term "pteryx" (πτέρυξ) primarily means "wing", but can also designate merely "feather". Von Meyer suggested this in his description. At first he referred to a single feather which appeared like a modern bird's remex
Flight feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...

 (wing feather), but he had heard of and been shown a rough sketch of the London specimen, to which he referred as a "Skelet eines mit ähnlichen Federn bedeckten " ("skeleton of an animal covered in similar feathers"). In German, this ambiguity is resolved by the term Schwinge which does not necessarily mean a wing used for flying. Urschwinge was the favored translation of Archaeopteryx among German scholars in the late 19th century. In English, "ancient pinion" offers a rough approximation.

Since then nine specimens have been recovered:

The Berlin Specimen (HMN 1880) was discovered in 1874 or 1875 on the Blumenberg near Eichstätt
Eichstätt
Eichstätt is a town in the federal state of Bavaria, Germany, and capital of the District of Eichstätt. It is located along the Altmühl River, at , and had a population of 13,078 in 2002. It is home to the Katholische Universität Eichstätt-Ingolstadt, the lone Catholic university in Germany. The...

, Germany, by farmer Jakob Niemeyer. He sold this precious fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 for the money to buy a cow in 1876, to inn-keeper Johann Dörr, who again sold it to Ernst Otto Häberlein, the son of K. Häberlein. Placed on sale between 1877 and 1881, with potential buyers including O.C. Marsh
Othniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...

 of Yale University's Peabody Museum, it was eventually bought by the Humboldt Museum für Naturkunde, where it is now displayed, for 20,000 Goldmark
Goldmark
Goldmark can refer to:*German Goldmark, coinage of the German Empire*Karl Goldmark , composer*Rubin Goldmark, composer*Peter Carl Goldmark, scientist and inventor*Peter J. Goldmark, rancher, geneticist and politician...

. The transaction was financed by Ernst Werner von Siemens
Ernst Werner von Siemens
Ernst Werner Siemens, von Siemens since 1888, was a German inventor and industrialist. Siemens' name has been adopted as the SI unit of electrical conductance, the siemens...

, founder of the famous company
Siemens AG
Siemens AG is a German multinational conglomerate company headquartered in Munich, Germany. It is the largest Europe-based electronics and electrical engineering company....

 that bears his name. Described in 1884 by Wilhelm Dames
Wilhelm Dames
Wilhelm Dames was a German paleontologist of the Berlin University, who described the first complete specimen of the early bird Archaeopteryx in 1994. This specimen is currently in the Humbolt Museum für Naturkunde.-References:...

, it is the most complete specimen, and the first with a complete head. It was in 1897 named by Dames as a new species, A. siemensii; a recent evaluation supports the A. siemensii species identification.

Composed of a torso, the Maxberg Specimen
Maxberg specimen
The Maxberg specimen is a fossil of the prehistoric bird Archaeopteryx, discovered in 1956 in Germany. It takes its name from the Maxberg Museum, where it was exhibited for a number of years....

 (S5) was discovered in 1956 near Langenaltheim; it was brought to the attention of professor Florian Heller
Florian Heller
Florian Heller is a German footballer playing for 1. FSV Mainz 05. He made his debut on the professional league level in the 2. Bundesliga for SpVgg Greuther Fürth on 3 August 2003 when he came on as a substitute in the 72nd minute in the game against SpVgg Unterhaching.-External links:* at...

 in 1958 and described by him in 1959. It is currently missing, though it was once exhibited at the Maxberg Museum
Maxberg Museum
The Maxberg Museum is a German museum situated in Mörnsheim in the natural park of Altmuhtal, near Solnhofen. It was founded by Alphons L. Zehntner in 1929....

 in Solnhofen. It belonged to Eduard Opitsch
Eduard Opitsch
Eduard Opitsch was a German quarry owner whose name is associated to a specimen of the prehistoric bird Archaeopteryx, the Maxberg specimen....

, who loaned it to the museum until 1974. After his death in 1991, the specimen was discovered to be missing and may have been stolen or sold. The specimen is missing its head and tail, although the rest of the skeleton is mostly intact.

The Haarlem Specimen (TM 6428, also known as the Teyler Specimen) was discovered in 1855 near Riedenburg
Riedenburg
Riedenburg is a town in the district of Kelheim, in Bavaria, Germany. It is situated on the river Altmühl, northwest of Kelheim and northeast of Ingolstadt.-References:...

, Germany and described as a Pterodactylus
Pterodactylus
Pterodactylus is a genus of pterosaurs, whose members are popularly known as pterodactyls. It was the first to be named and identified as a flying reptile...

 crassipes in 1877 by von Meyer. It was reclassified in 1970 by John Ostrom
John Ostrom
John H. Ostrom was an American paleontologist who revolutionized modern understanding of dinosaurs in the 1960s, when he demonstrated that dinosaurs are more like big non-flying birds than they are like lizards , an idea first proposed by Thomas Henry Huxley in the 1860s, but which had garnered...

 and is currently located at the Teylers Museum
Teylers Museum
Teyler's Museum , located in Haarlem, is the oldest museum in the Netherlands. The museum is in the former home of Pieter Teyler van der Hulst . He was a wealthy cloth merchant and Amsterdam banker of Scottish descent, who bequeathed his fortune for the advancement of religion, art and science...

 in Haarlem
Haarlem
Haarlem is a municipality and a city in the Netherlands. It is the capital of the province of North Holland, the northern half of Holland, which at one time was the most powerful of the seven provinces of the Dutch Republic...

, the Netherlands. It was the very first specimen, despite the classification error. It is also one of the least complete specimens, consisting mostly of limb bones and isolated cervical vertebrae and ribs.

The Eichstätt Specimen (JM 2257) was discovered in 1951 near Workerszell, Germany and described by Peter Wellnhofer
Peter Wellnhofer
Peter Wellnhofer is a German paleontologist at the "Bayerische Staatssammlung fur Paläontologie" in Munich. He is best known for his work on the various fossil specimens of Archaeopteryx or "Urvogel", the first known bird...

 in 1974. Currently located at the Jura Museum
Jura Museum
The Jura Museum situated in Eichstätt, Germany is a Natural History Museum that has an extensive exhibit of Jurassic fossils from the quarry of Solnhofen, including marine reptiles, pterosaurs, and one specimen of the early bird Archaeopteryx...

 in Eichstätt
Eichstätt
Eichstätt is a town in the federal state of Bavaria, Germany, and capital of the District of Eichstätt. It is located along the Altmühl River, at , and had a population of 13,078 in 2002. It is home to the Katholische Universität Eichstätt-Ingolstadt, the lone Catholic university in Germany. The...

, Germany, it is the smallest specimen and has the second best head. It is possibly a separate genus (Jurapteryx recurva) or species (A. recurva).

The Solnhofen Specimen (BSP 1999) was discovered in the 1970s near Eichstätt
Eichstätt
Eichstätt is a town in the federal state of Bavaria, Germany, and capital of the District of Eichstätt. It is located along the Altmühl River, at , and had a population of 13,078 in 2002. It is home to the Katholische Universität Eichstätt-Ingolstadt, the lone Catholic university in Germany. The...

, Germany and described in 1988 by Wellnhofer. Currently located at the Bürgermeister-Müller-Museum
Bürgermeister-Müller-Museum
The Bürgermeister-Müller-Museum is a natural history museum in Solnhofen, Germany. It was founded in 1954, when the mayor Friedrich Mueller brought his private collection to the public...

 in Solnhofen, it was originally classified as Compsognathus
Compsognathus
Compsognathus was a small, bipedal, carnivorous theropod dinosaur. The animal was the size of a turkey and lived around 150 million years ago, the early Tithonian stage of the late Jurassic Period, in what is now Europe. Paleontologists have found two well-preserved fossils, one in Germany...

 by an amateur collector, the same burgomaster Friedrich Müller after which the museum is named. It is the largest specimen known and may belong to a separate genus and species, Wellnhoferia
Wellnhoferia
Wellnhoferia is a genus of early prehistoric bird closely related to Archaeopteryx. It 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 in Archaeopteryx...

 grandis. It is missing only portions of the neck, tail, backbone, and head.

The Munich Specimen (S6, formerly known as the Solnhofen-Aktien-Verein Specimen) was discovered on 3 August 1992 near Langenaltheim and described in 1993 by Wellnhofer. It is currently located at the Paläontologisches Museum München
Paläontologisches Museum München
The Paläontologische Museum München is a German national natural history museum situated in Munich, Bavaria. It is associated with the Ludwig-Maximilians-Universität...

 in Munich
Munich
Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...

, to which it was sold in 1999 for 1.9 million Deutschmark. What was initially believed to be a bony sternum
Sternum
The sternum or breastbone is a long flat bony plate shaped like a capital "T" located anteriorly to the heart in the center of the thorax...

 turned out to be part of the coracoid, but a cartilaginous sternum may have been present. Only the front of its face is missing. It may be a new species, A. bavarica.

An eighth, fragmentary specimen was discovered in 1990, not in Solnhofen limestone, but in somewhat younger sediments at Daiting
Daiting
Daiting is a municipality in the district of Donau-Ries in Bavaria in Germany.-Archaeopteryx - Daiting Specimen:An eighth, fragmentary specimen of Archaeopteryx was discovered in the late 1980s in the somewhat younger sediments at Daiting...

, Suevia. It is therefore known as the Daiting Specimen, and had been known since 1996 only from a cast, briefly shown at the Naturkundemuseum in Bamberg
Bamberg
Bamberg is a city in Bavaria, Germany. It is located in Upper Franconia on the river Regnitz, close to its confluence with the river Main. Bamberg is one of the few cities in Germany that was not destroyed by World War II bombings because of a nearby Artillery Factory that prevented planes from...

. Long remaining hidden and therefore dubbed the 'Phantom', the original was purchased by palaeontologist Raimund Albertsdörfer in 2009. It was on display for the first time with six other original fossils of Archaeopteryx at the Munich Mineral Show in October 2009. A first, quick look by scientists indicates that this specimen might represent a new species of Archaeopteryx. It was found in a limestone bed that was a few hundred thousand years younger than the other finds.

Another fragmentary fossil was found in 2000. It is in private possession and since 2004 on loan to the Bürgermeister-Müller Museum in Solenhofen, so it is called the Bürgermeister-Müller Specimen; the institute itself officially refers to it as the "Exemplar of the families Ottman & Steil, Solnhofen". As the fragment represents the remains of a single wing of Archaeopteryx, the popular name of this fossil is "chicken wing".

Long in a private collection in Switzerland, the Thermopolis Specimen (WDC CSG 100) was discovered in Bavaria and described in 2005 by Mayr, Pohl, and Peters. Donated to the Wyoming Dinosaur Center
Wyoming Dinosaur Center
right|290px|thumb|Wyoming Dinosaur CenterThe Wyoming Dinosaur Center is located in Thermopolis, Wyoming and is one of the few dinosaur museums in the world to have its own excavation within driving distance...

 in Thermopolis, Wyoming
Thermopolis, Wyoming
Thermopolis is the largest town in, and the county seat of Hot Springs County, Wyoming, United States. As of the 2000 census, the town population was 3,172....

, it has the best-preserved head and feet; most of the neck and the lower jaw have not been preserved. The "Thermopolis" specimen was described in the December 2, 2005 Science journal article as "A well-preserved Archaeopteryx specimen with theropod features"; it shows that the Archaeopteryx lacked a reversed toe — a universal feature of birds — limiting its ability to perch on branches and implying a terrestrial or trunk-climbing lifestyle. This has been interpreted as evidence of theropod
Theropoda
Theropoda is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants . Dinosaurs belonging to the suborder theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory...

 ancestry. In 1988, Gregory S. Paul
Gregory S. Paul
Gregory Scott Paul is a freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dinosaurs and his detailed illustrations, both live and skeletal...

 claimed to have found evidence of a hyperextensible second toe, but this was not verified and accepted by other scientists until the Thermopolis specimen was described. "Until now, the feature was thought to belong only to the species' close relatives, the deinonychosaurs
Deinonychosauria
The Deinonychosauria were a clade of coelurosaurian theropod dinosaurs from the Late Jurassic and Cretaceous periods. These omnivores and carnivores are known for their switchblade-like second toe claws and for displaying numerous bird-like characteristics. The clade has been divided into two...

."

The Thermopolis Specimen was assigned to Archaeopteryx siemensii in 2007. The specimen itself, currently on loan to the Royal Tyrrell Museum, Drumheller, Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...

, Canada, is considered the most complete and well preserved Archaeopteryx remains yet.

In 2011 the discovery of an eleventh specimen was announced. It is said to be one of the more complete specimens, but is missing the skull and one forelimb. It is privately owned and has yet to be given a name or described scientifically.

Taxonomy


Today, the fossils are usually assigned to a single species A. lithographica, but the taxonomic history is complicated. Dozens of names have been published for the handful of specimens, most of which are simply spelling errors (lapsus). As interpreted today, the name A. lithographica only referred to the single feather described by von Meyer
Christian Erich Hermann von Meyer
Christian Erich Hermann von Meyer was a German palaeontologist.He was born at Frankfurt am Main.In 1832 von Meyer issued a work entitled Palaeologica, and in course of time he published a series of memoirs on various fossil organic remains: molluscs, crustaceans, fishes and higher vertebrata,...

. In 1954 however, Gavin de Beer
Gavin de Beer
Sir Gavin Rylands de Beer FRS was a British evolutionary embryologist. He was Director of the British Museum , President of the Linnean Society, and received the Royal Society's Darwin Medal for his studies on evolution.-Biography:...

 concluded that the London specimen was the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

. In 1960, Swinton accordingly proposed that the name Archaeopteryx lithographica be placed on the official genera list making the alternative names Griphosaurus and Griphornis invalid. The ICZN, implicitly accepting de Beer's standpoint, did indeed suppress the plethora of alternative names initially proposed for the first skeleton specimens, which mainly resulted from the acrimonious dispute between von Meyer and his opponent Johann Andreas Wagner
Johann Andreas Wagner
Johann Andreas Wagner was a German palaeontologist, zoologist and archaeologist.Wagner was a professor at the University of Munich, and curator of the Zoologische Staatssammlung ....

 (whose Griphosaurus problematicus—"problematic riddle
Riddle
A riddle is a statement or question or phrase having a double or veiled meaning, put forth as a puzzle to be solved. Riddles are of two types: enigmas, which are problems generally expressed in metaphorical or allegorical language that require ingenuity and careful thinking for their solution, and...

-lizard"—was a vitriolic sneer at von Meyer's Archaeopteryx). In addition, in 1977 the first specific name of the Haarlem specimen, crassipes, described by von Meyer as a pterosaur
Pterosaur
Pterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight...

 before its true nature was realized, was also suppressed.

The relationships of the specimens are problematic. Most subsequent specimens have been given their own species at one point or another. The Berlin specimen has been designated as Archaeornis siemensii, the Eichstätt specimen as Jurapteryx recurva, the Munich specimen as Archaeopteryx bavarica and the Solnhofen specimen was designated as Wellnhoferia grandis.

Recently, it has been argued that all the specimens belong to the same species. However, significant differences exist among the specimens. In particular, the Munich, Eichstätt, Solnhofen and Thermopolis specimens differ from the London, Berlin, and Haarlem specimens in being smaller or much larger, having different finger proportions, having more slender snouts, lined with forward-pointing teeth and possible presence of a sternum. These differences are as large as or larger than the differences seen today between adults of different bird species. However, it is also possible that these differences could be explained by different ages of the living birds.

Finally, it has been noted that the feather, the first specimen of Archaeopteryx described, does not agree well with the flight-related feathers of Archaeopteryx. It certainly is a flight feather
Flight feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...

 of a contemporary species, but its size and proportions indicate that it may belong to another, smaller species of feathered theropod, of which only this feather is so far known. As the feather was in the early 21st century seen as the type specimen
Biological type
In biology, a type is one particular specimen of an organism to which the scientific name of that organism is formally attached...

, this would have created significant nomenclatorial
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...

 confusion because the name Archaeopteryx should then no longer be applied to the skeletons. In 2007, two sets of scientists therefore petitioned the ICZN
International Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 28 members from 20 countries, mainly practicing zoological taxonomists...

 requesting that the London specimen be explicitly made the type by designating it as the new holotype specimen, or neotype. This suggestion was upheld by the ICZN after four years of debate, and the London specimen was designated the neotype on October 3, 2011.

Synonyms


If two names are given, the first denotes the original describer of the "species", the second the author on whom the given name combination is based. As always in zoological nomenclature, putting an author's name in parentheses denotes that the taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...

 was originally described in a different genus.
  • Pterodactylus crassipes Meyer, 1857 [suppressed in favor of A. lithographica 1977 per ICZN Opinion 1070]
  • Rhamphorhynchus crassipes (Meyer, 1857) (as Pterodactylus (Rhamphorhynchus) crassipes) [suppressed in favor of A. lithographica 1977 per ICZN Opinion 1070]
  • Archaeopteryx lithographica Meyer, 1861 [nomen conservandum]
  • Scaphognathus crassipes (Meyer, 1857) Wagner, 1861 [suppressed in favor of A. lithographica 1977 per ICZN Opinion 1070]
  • Archaeopterix lithographica Anon., 1861 [lapsus]
  • Griphosaurus problematicus Wagner, 1862 [nomen oblitum 1961 per ICZN Opinion 607]
  • Griphornis longicaudatus Woodward, 1862 [nomen oblitum 1961 per ICZN Opinion 607]
  • Griphosaurus longicaudatum (Woodward, 1862) [lapsus]
  • Griphosaurus longicaudatus (Owen, 1862) [nomen oblitum 1961 per ICZN Opinion 607]
  • Archaeopteryx macrura Owen, 1862 [nomen oblitum 1961 per ICZN Opinion 607]
  • Archaeopterix macrura Owen, 1862 [lapsus]
  • Archaeopterix macrurus Egerton, 1862 [lapsus]
  • Archeopteryx macrurus Owen, 1863 [unjustified emendation]
  • Archaeopteryx macroura Vogt, 1879 [lapsus]
  • Archaeopteryx siemensii Dames, 1897
  • Archaeopteryx siemensi Dames, 1897 [lapsus]
  • Archaeornis siemensii (Dames, 1897) Petronievics, 1917
  • Archaeopteryx oweni Petronievics, 1917 [nomen oblitum 1961 per ICZN Opinion 607]
  • Gryphornis longicaudatus Lambrecht, 1933 [lapsus]
  • Gryphosaurus problematicus Lambrecht, 1933 [lapsus]
  • Archaeopteryx macrourus Owen, 1862 fide Lambrecht, 1933 [lapsus]
  • Archaeornis siemensi (Dames, 1897) fide Lambrecht, 1933? [lapsus]
  • Archeopteryx macrura Ostrom, 1970 [lapsus]
  • Archaeopteryx crassipes (Meyer, 1857) Ostrom, 1972 [suppressed in favor of A. lithographica 1977 per ICZN Opinion 1070]
  • Archaeopterix lithographica di Gregorio, 1984 [lapsus]
  • Archaeopteryx recurva Howgate, 1984
  • Jurapteryx recurva (Howgate, 1984) Howgate, 1985
  • Archaeopteryx bavarica Wellnhofer, 1993
  • Wellnhoferia
    Wellnhoferia
    Wellnhoferia is a genus of early prehistoric bird closely related to Archaeopteryx. It 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 in Archaeopteryx...

     grandis Elżanowski, 2001


The last four taxa may be valid genera and species.

"Archaeopteryx" vicensensis (Anon. fide Lambrecht, 1933) is a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...

 for what appears to be an undescribed pterosaur.

Authenticity


Beginning in 1985, a group including astronomer
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

 Fred Hoyle
Fred Hoyle
Sir Fred Hoyle FRS was an English astronomer and mathematician noted primarily for his contribution to the theory of stellar nucleosynthesis and his often controversial stance on other cosmological and scientific matters—in particular his rejection of the "Big Bang" theory, a term originally...

 and physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

 Lee Spetner
Lee Spetner
Lee M. Spetner is an American physicist and author, known best for his critique of the modern evolutionary synthesis. In spite of his opposition to neo-Darwinism, Spetner accepts a form of non-random evolution outlined in his 1996 book "Not By Chance! Shattering the Modern Theory of...

 published a series of papers claiming that the feathers on the Berlin and London specimens of Archaeopteryx were forged. Their claims were repudiated by Alan J. Charig
Alan J. Charig
Alan Jack Charig was an English palaeontologist and writer who popularised his subject on television and in books at the start of the wave of interest in dinosaurs in the 1970s....

 and others at the British Museum (Natural History). Most of their evidence for a forgery was based on unfamiliarity with the processes of lithification; for example, they proposed that based on the difference in texture associated with the feathers, feather impressions were applied to a thin layer of cement
Cement
In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed...

, without realizing that feathers themselves would have caused a textural difference. They also expressed disbelief that slabs would split so smoothly, or that one half of a slab containing fossils would have good preservation, but not the counterslab. These, though, are common properties of Solnhofen fossils because the dead animals would fall onto hardened surfaces which would form a natural plane for the future slabs to split along, leaving the bulk of the fossil on one side and little on the other. They also misinterpreted the fossils, claiming that the tail was forged as one large feather, when this is visibly not the case. In addition, they claimed that the other specimens of Archaeopteryx known at the time did not have feathers, which is untrue; the Maxberg and Eichstätt specimens have obvious feathers. Finally, the motives they suggested for a forgery are not strong, and contradictory; one is that Richard Owen
Richard Owen
Sir Richard Owen, FRS KCB was an English biologist, comparative anatomist and palaeontologist.Owen is probably best remembered today for coining the word Dinosauria and for his outspoken opposition to Charles Darwin's theory of evolution by natural selection...

 wanted to forge evidence in support of Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

's theory of evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

, which is unlikely given Owen's views toward Darwin and his theory. The other is that Owen wanted to set a trap for Darwin, hoping the latter would support the fossils so Owen could discredit him with the forgery; this is unlikely because Owen himself wrote a detailed paper on the London specimen, so such an action would certainly backfire.

Charig et al. pointed to the presence of hairline cracks in the slabs running through both rock and fossil impressions, and mineral growth over the slabs that had occurred before discovery and preparation, as evidence that the feathers were original. Spetner et al. then attempted to show that the cracks would have naturally propagated through their postulated cement layer, but neglected to account for the fact that the cracks were old and had been filled with calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...

, and thus were not able to propagate. They also attempted to show the presence of cement on the London specimen through X-ray spectroscopy
X-ray spectroscopy
X-ray spectroscopy is a gathering name for several spectroscopic techniques for characterization of materials by using x-ray excitation.-Characteristic X-ray Spectroscopy:...

, and did find something that was not rock. However, it was not cement, either, and is most probably from a fragment of silicone rubber left behind when molds were made of the specimen. Their suggestions have not been taken seriously by palaeontologists, as their evidence was largely based on misunderstandings of geology, and they never discussed the other feather-bearing specimens, which have increased in number since then. Charig et al. reported a discolouration: a dark band between two layers of limestone – however, they say it is the product of sedimentation. It is natural for limestone to take on the colour of its surroundings and most limestones are coloured (if not colour banded) to some degree – the darkness was attributed to such impurities. They also mention that a complete absence of air bubbles in the rock slabs is further proof that the specimen is authentic.

Archaeopteryx and Protoavis


In 1984, Sankar Chatterjee
Sankar Chatterjee
Sankar Chatterjee is a paleontologist, and is the Paul W. Horn Professor of Geosciences at Texas Tech University and Curator of Paleontology at the Museum of Texas Tech University. He earned his Ph. D. from the University of Calcutta in 1970 and was a Post-doctoral Fellow at the Smithsonian...

 discovered fossils which he claimed in 1991 belonged to a fossil bird far older than Archaeopteryx. These fossils, believed to be around 210 to 225 million years old, have been assigned the name Protoavis
Protoavis
Protoavis is a problematic taxon of archosaurian known from fragmentary remains from Late Triassic Norian stage deposits near Post, Texas. Much controversy remains over the animal, and there are many different interpretations of what Protoavis actually is...

. The fossils are too badly preserved to allow an estimate of flying ability; although Chatterjee's reconstructions usually show feathers, many paleontologists, including Paul (2002) and Witmer (2002) have rejected the claims that Protoavis was an earlier bird (or, alternatively, that it existed at all). The fossils were found disarticulated, and were collected from different locations. Because the fossils are in poor condition, Archaeopteryx remains the earliest universally recognized bird.

Phylogenetic position



Modern paleontology has consistently placed Archaeopteryx as the most primitive bird. It is not thought to be a true ancestor of modern birds but, rather, a close relative of that ancestor (see Avialae
Avialae
Avialae is a clade of dinosaurs containing their only living representatives, birds , and the most immediate extinct relatives of birds.-Competing definitions:...

 and Aves). Nonetheless, Archaeopteryx was often used as a model of the true ancestral bird . Several authors have done so. Lowe (1935) and Thulborn (1984) questioned whether Archaeopteryx truly was the first bird. They suggested that Archaeopteryx was a dinosaur that was no more closely related to birds than were other dinosaur groups. Kurzanov (1987) suggested that Avimimus
Avimimus
Avimimus , meaning "bird mimic" , was a genus of bird-like maniraptoran dinosaur that lived in the late Cretaceous in what is now Mongolia, around 70 million years ago.-Description:...

 was more likely to be the ancestor of all birds than Archaeopteryx. Barsbold (1983) and Zweers and Van den Berge (1997) noted that many maniraptora
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea...

n lineages are extremely birdlike, and suggested that different groups of birds may have descended from different dinosaur ancestors. The discovery of the closely related Xiaotingia
Xiaotingia
Xiaotingia is a genus of bird-like theropod dinosaur from early Late Jurassic deposits of western Liaoning, China, containing a single species, Xiaotingia zhengi.-Discovery:...

 in 2011 led to new phylogenetic analyses which suggested that Archaeopteryx is a deinonychosaur rather than an avialan, and therefore not actually a "bird" under most common uses of that term. A more thorough analysis was published soon after to test this hypothesis, and failed to arrive at the same result; it found Archaeopteryx to be a bird in its traditional position at the base of Avialae, while Xiaotingia was recovered as a basal deinonychosaur, or troodontid. The authors of the follow-up study noted that uncertainties still exist, however, and that it may not be possible to confidently state whether or not Archaeopteryx is a member of Avialae or not barring new and better specimens of relevant species.

Modern analogs


The Hoatzin
Hoatzin
The Hoatzin , also known as the Hoactzin, Stinkbird, or Canje Pheasant, is a species of tropical bird found in swamps, riverine forest and mangrove of the Amazon and the Orinoco delta in South America...

 (Ophisthocomus hoazin), Guyana
Guyana
Guyana , officially the Co-operative Republic of Guyana, previously the colony of British Guiana, is a sovereign state on the northern coast of South America that is culturally part of the Anglophone Caribbean. Guyana was a former colony of the Dutch and of the British...

's national bird, has been often called a modern analog to Archaeopteryx. Since Archaeopteryx had three functional claws on each wing, some earlier systematists speculated that the Hoatzin was descended from it, because nestling Hoatzins have two functional claws on each wing. However, modern workers believe that the young Hoatzin's claws are of more recent origin, and may be a secondary adaptation resulting from its frequent need to leave the nest and climb about in dense vines and trees well before it is capable of flight.

In popular culture



Since Archaeopteryx has been long considered the earliest known bird, it has thus received widespread attention. Its easily recognizable appearance and the intense public interest in dinosaurs have caused Archaeopteryx to become a feature of worldwide popular culture.

A main belt asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

 discovered in 1991, 9860 Archaeopteryx
9860 Archaeopteryx
9860 Archaeopteryx is a main-belt asteroid discovered on August 6, 1991 by Eric Walter Elst at the European Southern Observatory. It is named after the earliest known bird Archaeopteryx, which dates from the Jurassic Period.- External links :*...

, was named in honour of the genus.

In one of the "strangest" appearances of Archaeopteryx in popular culture, Alfred Jarry's
Alfred Jarry
Alfred Jarry was a French writer born in Laval, Mayenne, France, not far from the border of Brittany; he was of Breton descent on his mother's side....

 1897 play ('Ubu cuckolded, or the Archaeopteryx') includes an Archaeopteryx as an important character.

See also


  • Dinosaur
    Dinosaur
    Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

  • Origin of birds
  • Feathered dinosaurs
    Feathered dinosaurs
    The realization that dinosaurs are closely related to birds raised the obvious possibility of feathered dinosaurs. Fossils of Archaeopteryx include well-preserved feathers, but it was not until the early 1990s that clearly non-avialan dinosaur fossils were discovered with preserved feathers...

  • Temporal paradox (paleontology)
    Temporal paradox (paleontology)
    The temporal paradox, or time problem is a controversial issue in the evolutionary relationships of birds. It was described by paleornithologist Alan Feduccia.-Objection to consensus:The concept of a "temporal paradox" is based on the following facts...


Further reading

  • de Beer, G.R. (1954). Archaeopteryx lithographica: a study based upon the British Museum specimen. Trustees of the British Museum, London.
  • Chambers, P. (2002). Bones of Contention: The Fossil that Shook Science. John Murray, London. ISBN 0-7195-6059-4.
  • Feduccia, A. (1996). The Origin and Evolution of Birds. Yale University Press, New Haven. ISBN 0-300-06460-8.
  • Heilmann, G.
    Gerhard Heilmann
    Gerhard Heilmann was a Danish artist and paleontologist who created artistic depictions of Archeopteryx, Proavis and other early bird relatives apart from writing The Origin of Birds, a pioneering and influential account of bird evolution...

     (1926). The Origin of Birds
    The Origin of Birds (book)
    The Origin of Birds is an early synopsis of bird evolution written in 1926 by Gerhard Heilmann, a Danish artist and amateur zoologist. The book was born from a series of articles published between 1913 and 1916 in Danish, and although republished as a book it received mainly criticism from...

    . Witherby, London.
  • Huxley T.H. (1871). Manual of the anatomy of vertebrate animals. London.
  • von Meyer, H. (1861). Archaeopteryx litographica (Vogel-Feder) und Pterodactylus von Solenhofen. Neues Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefakten-Kunde. 1861: 678–679, plate V [Article in German] Fulltext at Google Books.
  • Shipman, P. (1998). Taking Wing: Archaeopteryx and the Evolution of Bird Flight. Weidenfeld & Nicolson, London. ISBN 0-297-84156-4.
  • Wellnhofer, P. (2008). Archaeopteryx. Der Urvogel von Solnhofen (in German). Verlag Friedrich Pfeil, Munich. ISBN 978-3-89937-076-8

External links