Archaeopteryx

Archaeopteryx London specimen with well-preserved feathers

• Solnhofen, Eichstätt, Langenaltheim and Jachenhausen Franconian Alb, Bavaria, Germany, ( Solnhofen Formation)
• Coal Mine Guimarota in Leiria, Portugal

• Archaeopteryx lithographica ( type species )
• Archaeopteryx siemensii

Archaeopteryx ( from Ancient Greek ἀρχαῖος archaios " ancient " and πτέρυξ pteryx "wing, feather, wing "; corresponding translation: " old spring " or " ancient wing " ) is a genus of archosaurs, whose fossils in the Franconian Alb in the Solnhofen limestones the Upper Jurassic were discovered. Archaeopteryx is regarded as a transitional form (mosaic form) that mediates between theropod dinosaurs and birds. Since the deaf about great Archaeopteryx is attributed generally to the group of birds as close to original form, refers to the members of the genus as " ancient birds ."

Archaeopteryx was first described by Hermann von Meyer on the basis of an isolated spring impression in 1861. The first skeleton copy (called the London specimen ) was discovered in the same year and is mentioned in the first publication. To date, followed by at least nine other, different complete skeletons.

Features

The genus Archaeopteryx is a mosaic of primitive ( for birds ), that is reptilian features, the later of the modern birds ( Neornithes ) were stored, and derived, that is bird typical features ( but only in part as a characteristic only current knowledge of apply to birds).

Primeval include the presence of teeth and belly ribs ( Gastralia ), a long tail spine, a relatively small number of unfused sacral vertebra ( Sakralia ), unfused metacarpal, metatarsal and tarsal bones and pelvic bones, the three finger claws and the absence of a bony sternum.

The bird typical features can be the modern-looking asymmetrical flight feathers count also been melted to form a wishbone clavicles and the backward or sideways - backward oriented first toe ( hallux ) of the foot ( anisodactyler Birdfoot ).

Interpretation

The characteristics of the bird archeopteryx are occupied for some feathered dinosaurs, or, as in the case of the reverted first toe of Archaeopteryx, not unchallenged. Therefore, some paleontologists do not see the first bird as much as some birdlike theropod dinosaurs, which are not attributed to the birds (eg Microraptor ).

Within the last 20 years a large number of fossils of primitive birds and birdlike dinosaurs have been discovered, particularly in sedimentary rocks of the Lower Cretaceous of Northeast China ( the Jehol Group). Thus, Archaeopteryx is a mosaic form alone, but can be classified that the birds are successively in a similar (morphological, not temporal ) sequence of dinosaurs.

Representatives of the hypothesis, the flapping flight of birds was created out of the glide of an elevated point down, interpret the claws of Archaeopteryx than that of a tree climber, who slid down from the branches. In palaeoecological studies of the Fund horizons, however, some researchers came to the conclusion that the education center of the Solnhofen limestones there must have been a hot and dry climate and probably occurred no trees. In return, however, they pointed to high cliffs on the coast of the Jurassic sea, which are used as starting point for initial flight tests in question. Burgers and Chiappe showed that Archaeopteryx could possibly also start from the ground.

Important for enforcing the theory of evolution

Archaeopteryx fossils were and are considered the most valuable and most famous in the world. Charles Darwin had predicted in his development of the theory of evolution in 1859, that there should be transitional forms in the development of new species, which would have still features the old, but already features the new group. When Darwin published his theory, no such fossils were known, they were therefore termed missing links ( missing links ). Only two years later, the first skeletal specimen of Archaeopteryx was found.

The Archaeopteryx finds were the geologically earliest evidence of feathers of a vertebrate. The fact that they already had significant characteristics of birds, but also those of reptiles and dinosaurs, Archaeopteryx made ​​an important indicator of the accuracy of the Darwinian theory of evolution. The dispute over the theory of evolution was thus also a debate about Archaeopteryx.

Richard Owen wrote the first description of the London specimen ( see figure above). He refused because of his religious conviction from the theory of evolution and scrupulously avoided any reference to the possible interpretation as a mediating link between reptiles and birds. His description contained gross errors. Only Thomas Henry Huxley gave a systematic description of the London specimen and interpreted it as evidence for the theory of evolution. Owens bought at the fossil, contrary to the express instructions of the Supervisory Board of the London Museum of Natural History. This also weakened his hitherto undisputed position in the British science. Thus the way was paved for the theory of evolution and its supporters - in one of the most important scientific institutions in the world.

The fossil record

So far, eleven more or less well -preserved skeletons of the genus Archaeopteryx, as well as a single feather were found. All these fossils came from the upper layers of white Jura in the quarries near Solnhofen, Langenaltheim and Jachenhausen at Ried castle. The footprint of each spring was discovered in 1860, the first skeleton in 1855 ( " the Haarlem specimen" ) and the date last copy in 2011. It concerns the following items (in order of the date on which the relevant Fund was first recognized as Archaeopteryx ):

1 " Spring ", discovered in 1860 in the municipality of Solnhofen quarry in 1861 and described by the Frankfurt vertebrate paleontologist Hermann von Meyer ( 1801-1869 ), who coined the still valid generic name Archaeopteryx was the first known discovery. The one part of the replica is in the Museum of Natural History in Berlin, the other side in the Paleontological Museum in Munich. Whether the isolated spring actually comes from Archaeopteryx, is not known. For a long time, however, this specimen was problematically the holotype.

2 The " London specimen ", found in 1861 on the Long Altheimer Haardt in Solnhofen, one of the three most important pieces. It was the first complete discovery of a skeleton and is the type - specimen of Archaeopteryx lithographica. It was a few months after the discovery of the London Natural History Museum (then belonging to the British Museum ) by its owner, the Pappenheimer district physician Carl Friedrich Häberlein ( 1787-1871 ) was acquired. The driving force here was the British naturalist Richard Owen, then director of the natural history collection of the British Museum and outspoken opponent of Darwin's theories, who wanted to prevent the purchase, that Darwin's theory of evolution is supported by the first bird. The fossil long remained under lock and key findings were published only gradually in small portions.

3 The " Berlin specimen " (found 1874-1876 on the Blumenberg near Eichstätt ), applies with its distinct spring prints and a well-preserved skull as the probably most beautiful and complete piece. The Finder Jakob Niemeyer swapped the Fund for a cow to the value of 150 to 180 marks. The new owner John Doerr, a quarry owner, it sold for 2,000 marks to Ernst Otto Häberlein ( 1819-1886 ) from Pappenheim, the son of the seller of the London specimen, who also prepared the Fund. Initially interested in the Bavarian State Collection and Yale University for the lost piece, but both could not afford the high price. Even a German zoologist Please to Emperor Wilhelm I was not successful. Finally, Werner von Siemens acquired the specimen in 1879 for 20,000 marks and passed it on permanent loan to the Mineralogical Museum of the Humboldt University of Berlin, which two years later, the purchase price refunded to him. It is since the Museum of Natural History in Berlin and is also on permanent display since 2007.

4 The " Maxberger copy " (1956 on the Long Altheimer Haardt at Solnhofen ), a torso with some spring prints, 1991 was to the death of its discoverer Edward Opitsch in his private possession. Since then, it is considered lost.

5 The " Haarlem specimen" ( 1855 Jachenhausen at Ried castle ) has been to 1855 found five years before the spring, but only in 1970 assigned by John Ostrom Archaeopteryx. This specimen was classified by Hermann von Meyer 1860 as Pterodactylus crassipes, hence its species name crassipes should have according to the priority rules of the naming of fossils litographica replace the name. This was prevented by vigorous use of Ostrom. The fragment is in possession of the Teylers Museum, Haarlem.

6 The " Eichstätt specimen " ( 1951 Workerszell in Eichstätt ) was initially as a small predatory dinosaur Compsognathus, was rediscovered in 1973 and described in 1974 by Peter Wellhofer. The piece is in the possession of the Jura Museum in Eichstätt.

7 The " Solnhofen specimen" was discovered in the 1960s by a Turkish guest workers in the vicinity of Eichstätt and also initially misidentified as a Compsognathus, 1988 but described by Peter Wellhofer. It hangs in the mayor -Müller Museum Solnhofen (2001 decided by the Higher Regional Court of Nuremberg, that the fossil must not be issued to a quarry owner, who had claimed that it had been in 1985 were removed from his possession, the dismissal of the action has become final;. Yet is the actual origin is still not completely resolved ).

8 The " copy of the Solnhofen stock association" ( found in the summer of 1992 in a quarry of " Solnhofer shares -Verein AG " on the Long Altheimer Haardt at Solnhofen ) can be seen in the Paleontological Museum in Munich. In 1993, the discovery of Peter Wellhofer as a new species Archaeopteryx bavarica was introduced into science. The beautiful feather impressions and the skeleton very well preserved enabled many new insights. The structure described by Wellhofer than sternum has, however, proved by recent studies as part of the Raven leg. The potentially quite good flying skills remain, however obtained, since the sternum was probably present as verknorpelte structure. Numerous details of the skull, jaws and the tail of the magpie large prehistoric bird opened new perspectives on the evolution of birds. Through these peculiarities of this last great discovery is undoubtedly one of the three most important, some consider him even more beautiful than the Berlin specimen.

9 A very fragmentary ninth Fund ( copy 8 ) was documented since 1997 only by a cast long were owners and depository unknown. 2009 presented the fossil dealers Raimund villages Albers 's acquired a copy in the Munich Mineral Show for the first time to the public.

10 In 2004, it was reported on a further, likewise fragmentary Fund, which is now in the mayor -Müller Museum Solnhofen.

11 The " Thermopolis specimen " in 2005 was bought by the owner of the Wyoming Dinosaur Center in Thermopolis and examined, among others, by Gerald Mayr, the results were published in Science, issue of December 2005. Other highlights of the new instance is next to his extremely good state of preservation, the fact that the first time the head is seen from above and the metatarsal has an upward extension.

12 The so far last copy was discovered in 2011 by a finder, whose name is being kept secret, in a quarry experience in Schamhaupten in the district of Eichstätt. Still in possession of the finder, the fossil is claimed by the owners of the quarry to supply it to museum purposes.

Most of the Archaeopteryx specimens show a crooked spine. This typical reverse curvature formed only after the death of the animals out in the water grave.

Outer systematics

Archaeopteryx is usually defined as the most primitive bird, that is, all the styles with the modern birds ( Neornithes ) distant related than Archaeopteryx, regarded as the birds do not belong. Among the Mesozoic birds there are some that are related only little closer to the modern birds than Archaeopteryx: Rahonavis and Jeholornis have with Archaeopteryx, among others, the long bony tail in common, the more advanced birds ( Pygostylia ) passed.

Within the theropod dinosaurs Deinonychosaurier are considered close relatives of birds - both groups are summarized in the parent group Paraves ( Eumaniraptora ). One feature that connects the Deinonychosaurier with Archaeopteryx and Rahonavis is the hyperextensible ( " hyperextensible " ) second claw of the foot. Springs with a closed feather banner were probably pronounced already in the ancestors of Paraves.

According to Benton (2005 ) are within the Paraves following relationships before:

Troodontidae

Dromaeosauridae

Archaeopteryx

Rahonavis

Jeholornis

Pygostylia.

There are a number of phylogenetic analyzes that arrive at different conclusions regarding the relationships birdlike Deinonychosaurier and primitive birds. According to the hypothesis of Mayr et al some feathered Dromaeosauriden as Microraptor were closer related to the Pygostylia than Archaeopteryx; in the group of birds in the bird's flight would therefore probably evolved independently several times.

Critics of the dinosaur origin of birds believe that the similarity of the ancient birds to theropod dinosaurs was due to massive convergent evolution. After Feduccia et al (2005 ) the birds had evolved from a yet to be determined group of primitive archosaurs while Microraptor dinosaurs and other feathered dinosaurs but were in fact no early forms of flightless birds.

Archaeopteryx and Xiaotingia

The inclusion of a listed 2011 because of new fossil finds Archaeopteryx -like dinosaur of the late jurassic time Tiaojishan lineup (Liaoning, China) in a phylogenetic analysis led to the relationships of Archaeopteryx adopted so far have been doubted. The analysis showed that Archaeopteryx might have been used together with the new genus Xiaotingia that resembles Deinonychosauriern in some features closer to the Deinonychosauriern than with later birds:

Troodontidae

Dromaeosauridae

Archaeopteryx

Xiaotingia

Rahonavis

Jeholornis

Pygostylia.

According to this hypothesis would Archaeopteryx, depending on the definition of the group of birds that either do not belong to the birds, or the birds castles also with a Deinonychosaurier.

Inside systematics

Whether belong to Archaeopteryx finds one or more species has been debated since the first description of the Berlin specimen, resulting in the accumulation of synonymous genus and species names that have been awarded for the same specimens and revised again reflects.

Elzanowski arranged in his revisions of the then known specimens of four different species, which he for the Solnhofen specimen, which is significantly different anatomically particularly his view of the other, suggesting belonging to a separate class:

• Archaeopteryx lithographica, holotype: London specimen;
• Archaeopteryx siemensii, holotype: Berlin specimen;
• Archaeopteryx bavarica, holotype: Munich copy;
• Wellnhoferia grandis, holotype: Solnhofen specimen.

The finding that the known Archaeopteryx specimens do not belong to a single species, is confirmed by Mayr et al (2007). In their description of the Thermopolis instance they compare the Fund with far last formerly known fossil material of Archaeopteryx. Contrary to the analysis of Elzanowski they come to the conclusion that the differences of the ten skeletal remains justified no longer than two kinds:

• Archaeopteryx lithographica, holotype: London specimen, also belonging: Solnhofen specimen;
• Archaeopteryx siemensii, holotype: Berlin specimen, also associated with: Munich copy, Thermopolis specimen.