Compsognathus

Skeletal reconstruction of Compsognathus in the North American Museum of Ancient Life

• Germany
• France

• Compsognathus longipes

Compsognathus ( " Delicate pine ", from Greek κομψός kompsos, petite ' and γνάθος gnathos, pine ' ) is a genus of small theropod dinosaurs from the family of Compsognathidae who lived in the Upper Jurassic ( Tithonian early ) in Europe. Compsognathus reached the size of a Truthuhns and like most theropods, a bipedal carnivore. So far, two well-preserved skeletons were discovered, one at the time of the 1850s in Germany and the second over a century later in France.

Compsognathus is one of the few dinosaurs whose diet is known based on fossil finds - as found in the bellies of both individuals the remains of small, agile lizards. The specimen found in Germany is the first fully-preserved fossil of a dinosaur that was discovered, although it was initially attributed to a lizard. The only known type ( type species ) is Compsognathus longipes, although earlier, was performed in France discovered the specimen as a separate species, Compsognathus corallestris.

Until the 1980 and 1990s, Compsognathus was considered the smallest known dinosaurs and as the closest relative of Archaeopteryx. Therefore Compsognathus has also become known outside the scientific community.

• 5.1 Manual
• 5.2 Nutrition and locomotion
• 5.3 Possible eggs finds and integument
• 5.4 springs and the connection of birds

Features

Compsognathus is known from two skeletons almost perfectly preserved. The skeleton found in Germany belonged to an animal about 89 centimeters long, while the skeleton discovered in France suggests an approximately 125 centimeters long animal. For decades, Compsognathus as the smallest known dinosaur - but later smaller dinosaurs were discovered, such as Caenagnathasia, Microraptor or Parvicursor. Weight estimates ranging from 0.26 to 0.58 kg for the smaller and 0.83 to 3.5 kg for the larger specimen.

Like other Compsognathiden Compsognathus had short arms, each with three strong fingers and a relatively long but thin skull. The tail has remained incomplete in both fossils. The related Sinosauropteryx had more than 60 caudal vertebrae that Compsognathus has had a long tail similar to the proportional longest tail of all known theropods, which is suspected. As with related genera of the skull had five paired cranial window, the eye socket ( orbital window) was the largest. The lower jaw was thin, the Mandibularfenster lacked - an opening in the lower jaw, which is found usually in archosaurs. The teeth were small but sharp, which they were adapted to the prey, which consisted of small vertebrates and possibly other small animals such as insects. The front teeth in the premaxillary bone ( premaxilla ) were not sawn in contrast to the remaining teeth. Differences Sinosauropteryx show up in a shorter skull, longer neck ribs and relatively longer arms that reached 40 % of the leg length.

History of discovery and finds

The German Fund ( holotype, specimen number BSP AS I 563 ) from the Solnhofen limestones in the Riedenburg - Kelheim region of Bavaria was acquired by the physicist and fossil collector Joseph Oberdorfer in 1859. The exact location was kept secret by seemingly Oberdorfer and is still unknown. The find is dated to the late Kimmeridgian or early Tithonian. Johann Andreas Wagner studied the fossil and published in 1859 a brief description; followed in 1861, a more extensive description. Wagner coined the name Compsognathus longipes ( " Leggy petite pine "), but the Fund held for a kind of lizard. John Ostrom in 1978 published an extensive description of what makes Compsognathus one of the best -known small theropods at that time was. The specimen was considered significant icon of the so-called opisthotonos hypothesis. The hunched posture, however, is not due to agony but on decomposition processes after death. The fossil discovered in Germany is now exhibited in the Bavarian State Collection for Palaeontology and Geology in Munich historical.

The larger French skeleton ( copy number MNHN CNJ 79) was probably discovered in 1971 and dates from the limestone at Canjuers near Nice in southeastern France. The find is dated to the lower Tithonian and consists of two blocks of rock - on the first block to the skull and Postkranium are (residual skeleton ) to the seventh caudal vertebrae, on the second the caudal vertebrae are preserved 9-31. It lacks only the rear ( distal ) end of the tail and a few hand bones. Initially, the fossil was privately owned by the Ghirardi family, the owners of the limestone quarries in Canjuers. In 1983, the Muséum national d' histoire naturelle in Paris buy the collection of the family, including the French Compsognathus instance. This fossil was first described in 1972 by Alain Bidar and colleagues; after the acquisition by the Paris museum, the fossil of JG Michard was prepared and examined in detail. The latest study of the fossil comes from Karin Peyer (2006).

Dames described in 1884, four foot bones from the Solnhofen limestones, which held von Huene (1925 ) for a further Compsognathus - Fund. Ostrom (1978 ) refuted this association, as these bones other proportions than the corresponding bones of Compsognathus. Zinke (1998 ) described 49 teeth from the Guimarota lineup of Portugal ( Kimmeridgian ) as another Compsognathus - Fund.

System

Outer systematics

As early as 1868, Thomas Huxley assumed that this animal was closely related to the dinosaurs. Huxley turned to a new order, the Ornithoscelida, which should contain the subordination Dinosauria and the new subordination Compsognatha. Compsognathus was the only representative of the Compsognatha. 1896 saw Othniel Charles Marsh this genus as a true member of the dinosaurs, the Compsognatha classified as subordination of theropods and put on a new family, the Compsognathidae. Friedrich von Huene (1914 ) rejected the name Compsognatha and ordered the Compsognathidae within the Coelurosauria one - this assignment is still considered valid.

Long Compsognathus was the only representative of the Compsognathidae; in recent decades paleontologists have discovered several related genera. Today, the Compsognathidae are the genera Aristosuchus, Huaxiagnathus, Mirischia, Sinosauropteryx, and sometimes also attributed Juravenator and Scipionyx. Although Mononykus was once also considered a member of this family, Chen and colleagues ( 1998), however, refuted this association - these authors see the similarities between Mononykus and Compsognathiden as an example of convergent evolution. The position of Compsognathus and its relatives within the Coelurosauria is controversial. Some researchers, such as Thomas Holtz, Ralph Molnar and Philip Currie (2004) hold the Compsognathidae for the most original Coelurosauria family, while others postulate a classification within the Maniraptora.

Inside systematics

Currently, it is recognized with Compsognathus longipes only a single species of this genus. Originally described Bidar (1972 ) the larger French specimen as a second type, Compsognathus corralestris. This should be distinguished by their size and by a supposed fin-like, probably equipped with webbed hands of Compsognathus longipes. Ostrom (1978 ) showed, however, that the French copy with the German copy down to the size is almost identical. Callison and Quimby (1984 ) identified the smaller specimen discovered in Germany as a young animal of the same species

Paleoecology

During the Upper Jurassic, Europe was a dry, tropical archipelago at the edge of the Tethys Sea. Both localities - the Solnhofen area and Canjuers - were at the time of deposits lagoons that lay between the beaches and coral reefs of the jurassic temporal islands of the Tethys Sea. Contemporaries of Compsognathus include the early birds or bird-like dinosaur Archaeopteryx and Wellnhoferia and pterosaurs ( Pterosauria ) Rhamphorhynchus and pterodactyl with a. The same deposits that also contained the remains of Compsognathus - harboring numerous fossils of marine organisms such as fish, echinoderms, crustaceans and molluscs, which confirms that Compsognathus lived on the coast. Apart from Archaeopteryx and Wellnhoferia no other dinosaur has been discovered in association with Compsognathus.

Paleobiology

Hand

The specimen discovered in Germany in the 19th century shows only two fingers on each arm, what enticed scientists to believe the animal had actually possessed only two fingers. The fossil discovered later in France, however, shows that the hand of Compsognathus - similar to other members of the Compsognathidae - was actually equipped with three fingers. The forelimbs of the German Fossils are, as we know today, is only incompletely. Bidar supposed that the French specimen had had during his lifetime webbed fingers. In the 1975 book The Evolution and Ecology of the Dinosaurs LB Halstead Compsognathus corallestris describes as a living amphibious dinosaur that hunted prey in the water and was able to bring to larger predators in safety by swam out of the water. This hypothesis was rejected by later authors.

Nutrition and locomotion

Marsh discovered in 1881, a little skeleton in the abdominal region of the German copy and thought it was the remains of an embryo. In 1903, however, showed Franz Nopcsa that it is in fact the skeleton of a lizard that had eaten the animal. Ostrom she wrote in 1994 to the genus Bavarisaurus and concluded that this lizard was a fast, agile runner: she had a long tail, and the proportional long legs indicate a rapid locomotion. These conclusions suggest that Compsognathus must have possessed as predators of these animals good vision and the ability to rapidly accelerate in order to hunt these lizards can. The Bavarisaurus skeleton is preserved in one piece, which shows that Compsognathus swallowed its prey whole, without crushing them. In the belly of the French specimen fossils were found of indefinite lizards or Sphenodonten.

Othenio Abel expressed in 1922 based on a sequence track lithographicum known as Kouphichnium the conjecture, some small dinosaurs such as Compsognathus would have moved hopping. Also, the paleontologist Martin Wilfarth turned the track cause as little dinosaurs - in his opinion the animal for locomotion spread his arms had put forward in order to swing the hind legs forward through it. Only in 1940 proved Kenneth E. Caster, that it is the traces of a horseshoe crab of the genus Limulus in the Kouphichnium tracks. A recent study has estimated the speed of Compsognathus based on muscle models at 64 km / h.

Possible eggs finds and integument

On the rock record of the German Compsognathus instance are located below the rib cage 13/2 balls with a diameter of ± 10 mm. Although they are usually attributed to the frequent in the Solnhofen limestones crinoid Saccocoma she pointed Matthias Mäuser 1983 as count your eggs. However, later authors questioned this hypothesis, since the fossils were found outside the body. Nopcsa (1903), Barthel (1964 ) and Reisdorf & Wuttke (2012 ) attributed the genesis of the structures in question to gaseous products of putrefaction, which originated during the decomposition of the carcass on the seafloor. Further doubt made ​​after the discovery of a skeleton of Sinosauropteryx wide, containing two fossil eggs in the abdominal region. These eggs are also proportionately larger, less numerous than the supposed Compsognathus eggs.

Friedrich von Huene in 1901 described the German copy skin imprints in the abdominal region as well as a dermal armor of hexagonal horn plates, which should have at least covered the tail and the neck of the animal. Structures on the arms of the French specimen was considered the thick skin of webbed (see above). In his redescription of Compsognathus but could Ostrom (1978 ) refute all these interpretations. Reisdorf & Wuttke (2012 ) interpret the structures formed on the German Compsognathus specimen recently as Adipocire - pseudomorphs.

Springs and the connection of birds

A whole century Compsognathus was the only well -known small theropod - this also led to comparisons with Archaeopteryx and to speculation regarding a relationship with the birds. Actually woke Compsognathus, Archaeopteryx and less Huxley interest in the origin of birds. Compsognathus and Archaeopteryx show many similarities in shape, size and proportions - so many that at least a featherless skeleton of an Archaeopteryx was kept for many years mistaken for that of a Compsognathus. Many other theropods like Deinonychus, Oviraptor or Segnosaurus apply today but still as close relative of birds.

None of the Compsognathus fossils shows imprints of feathers or feather -like structures - in contrast to Archaeopteryx, which comes from the same sediments; thus show many pictures Compsognathus without springs. The only springs that are known of Archaeopteryx are the large tail and flight feathers; short springs which probably covered the body, are not preserved. The closely related genera with Compsognathus Sinosauropteryx and Sinocalliopteryx have been preserved along with the remains of simple feathers, which probably covered the body like a coat, indicating that Compsognathus might have been similar to pinnate. In another alleged Compsognathiden from Germany, Juravenator, found themselves in contrast, remains of a scaly skin, but without any signs of a possible fletching. This could mean that springs only in some Compsognathiden occurred, although a study carried out in 2007 by Butler and Upchurch concludes that Juravenator was no Compsognathide.

Compsognathus in popular culture

Compsognathus is one because of its small body size, its supposedly two -fingered hand and the completeness of the type specimen to the popular dinosaurs. A long time he was due to its small body size as unique as most other small dinosaurs were discovered much later.

In the recent past these dinosaurs appeared in the movies " The Lost World: Jurassic Park" ( The Lost World: Jurassic Park ) and "Jurassic Park III " on. In " The Lost World: Jurassic Park" one of the characters is incorrectly referred to as " Compsognathus triassicus " what the name Compsognathus combined with the style name of Procompsognathus. The " Compys " are displayed in Jurassic Park as a social, hunting animals in groups - in fact there is no evidence of such a life.