Compsognathus

*Compsognathus longipes*

* Jurassic Park Institute Artwork
* Timothy Bradley Artwork (version 1)
* Timothy Bradley Artwork (version 2)
* Stan Winston Artwork
* Joe Tucciarone Artwork
* Robert F Walters Artwork

***Compsognathus*** ("elegant jaw") is a genus of small, bipedal, carnivorous theropod dinosaurs. Members of its single species *Compsognathus longipes* could grow to the size of a turkey. They lived around 150 million years ago, the latest Kimmeridgian age of the late Jurassic period, in what is now Europe. Paleontologists have found two well-preserved fossils, one in Germany in the 1850s and the second in France more than a century later.

Today, *C. longipes* is the only recognized species, although the larger specimen discovered in France in the 1970s was once thought to belong to a separate species and named *C. corallestris*.

Many presentations still describe *Compsognathus* as "chicken-sized" dinosaurs because of the small size of the German specimen, which is now believed to be a juvenile. *Compsognathus longipes* is one of the few dinosaur species for which diet is known with certainty: the remains of small, agile lizards are preserved in the bellies of both specimens. Teeth discovered in Portugal may be further fossil remains of the genus.

Although not recognized as such at the time of its discovery, *Compsognathus* is the first theropod dinosaur known from a reasonably complete fossil skeleton. Until the 1990s, it was the smallest known non-avialan dinosaur; earlier it was incorrectly believed that it was the closest relative of the early bird *Archaeopteryx*.

## Description

For decades, *Compsognathus* were famed as the smallest dinosaurs known; the first specimen collected was around 1 m (3.3 ft) in length. However, dinosaurs discovered later, such as *Caenagnathasia*, *Microraptor* and *Parvicursor*, were even smaller. The largest *Compsognathus* specimen is estimated to have weighed somewhere between 0.83 and 3.5 kg (between 1.8 and 7.7 lb).

*Compsognathus* were small, bipedal animals with long hind legs and longer tails, which they used for balance during locomotion. The forelimbs were smaller than the hindlimbs and featured three digits equipped with solid claws suited for grasping prey. Their delicate skulls were narrow and long, with tapered snouts. The skull had five pairs of fenestrae (skull openings), the largest of which was for the orbit (eye socket). The eyes were large in proportion to the rest of the skull.

The lower jaw was slender and had no mandibular fenestra, a hole in the side of the lower jawbone commonly seen in archosaurs. The teeth were small but sharp, suited for its diet of small vertebrates and possibly other small animals, such as insects. Its frontmost teeth (those on the premaxilla) were unserrated, unlike those further back in the jaw which were flattened and more strongly recurved. Scientists have used these dental characteristics to identify *Compsognathus* and its closest relatives. Reisdorf and Wuttke (2012) described the taphonomical phenomena of the German specimen of *Compsognathus*.

### Integument

Some relatives of *Compsognathus*, namely *Sinosauropteryx* and *Sinocalliopteryx*, have been preserved with the remains of simple feathers covering the body like fur, promoting some scientists to suggest that *Compsognathus* might have been feathered in a similar way. Consequently, many depictions of *Compsognathus* show them with coverings of downy proto-feathers. However, no feathers or feather-like covering have been preserved with *Compsognathus* fossils, in contrast to *Archaeopteryx*, which are found in the same sediments. Karin Peyer, in 2006, reported skin impressions preserved on the side of the tail starting at the 13th tail vertebra. The impressions showed small bumpy tubercles, similar to the scales found on the tail and hind legs of *Juravenator*. Additional scales had in 1901 been reported by Von Huene, in the abdominal region of the German *Compsognathus*, but Ostrom subsequently disproved this interpretation; in 2012 they were by Achim Reisdorf seen as plaques of adipocere, corpse wax.

Like *Compsognathus*, and unlike *Sinosauropteryx*, a patch of fossilized skin from the tail and hindlimb of the possible relative *Juravenator starki* shows mainly scales, though there is some indication that simple feathers were also present in the preserved areas. This may mean that a feather covering was not ubiquitous in this group of dinosaurs.

## Discovery and species

*Compsognathus* is known from two almost complete skeletons, one from Germany that is 89 cm long (35 in) and another from France that is 125 cm (49 in). The physician and fossil collector Joseph Oberndorfer acquired the German specimen (BSP AS I 563) in 1859, discovered about the same year in the Solnhofen lithographic limestone deposits in the Riedenburg-Kelheim region of Bavaria. The limestone of the Solnhofen area has also yielded such well-preserved fossils as *Archaeopteryx* with feather impressions and some pterosaurs with imprints of their wing membranes. The German *Compsognathus* fossil itself most likely came from the Painten Formation of the Kapfelberg locality, specifically dated to the uppermost Kimmeridgian stage (150.8 million years ago); however, alternative possibilities include quarries near Jachenhausen or Goldberg, both from the Tithonian, to which stage *Compsognathus* has traditionally been dated. Johann A. Wagner discussed the specimen briefly in 1859, when he coined the name *Compsognathus longipes*, and described it in detail in 1861. In early 1868, Thomas Huxley compared the two species and, following earlier suggestions by Karl Gegenbaur and Edward Drinker Cope, concluded that, apart from its arms and feathers, the *Archaeopteryx* skeleton was closely similar to *Compsognathus*, and that the proto-bird was related to the dinosaurs. In 1896, Othniel Marsh recognized the fossil as a true member of the Dinosauria. John Ostrom thoroughly redescribed the species in 1978, making it one of the best-known small theropods at that time. The German specimen is on display at the Bayerische Staatsammlung für Paläontologie und historische Geologie (Bavarian State Institute for Paleontology and Historical Geology) in Munich, Germany, which bought the fossil from Oberndorfer in 1865.

The larger French specimen (MNHN CNJ 79) was discovered by quarry owner Louis Ghirardi around 1971 in the Portlandian lithographic limestone of Canjuers near Nice in southeastern France. It dates to the lower Tithonian. Although Alain Bidar originally described the specimen as a separate species called *Compsognathus corallestris*, Ostrom, Jean-Guy Michard and others have since relabeled it as another example of *Compsognathus longipes*. Quimby identified the smaller German specimen as a juvenile of the same species. In 1983, the Muséum national d'histoire naturelle in Paris acquired the French *Compsognathus* fossil; Michard thoroughly studied it there.

Collector Heinrich Fischer had originally labelled a partial foot, also from Solnhofen, as belonging to *Compsognathus longipes*. Though this identification was rejected by Wilhelm Barnim Dames in 1884,[30] Friedrich von Huene nevertheless in 1925 provisionally referred the specimen to *Compsognathus*. However, Ostrom's study of 1978 has disproven this. Jens Zinke has in 1998 assigned forty-nine teeth from the Kimmeridgian Guimarota formation of Portugal to the genus. These were not identical to those of *C. longipes*, having serrations on the front edge, but were because of general similarities in form referred to a *Compsognathus* sp.

In 1997 Virginia Morell renamed a related Chinese form, *Sinosauropteryx prima*, into a *Compsognathus prima*; this has found no general acceptance.

## Classification

Originally classified as a lizard, the dinosaurian affinities of *Compsognathus* were first noted by Gegenbaur, Cope, and Huxley between 1863 and 1868. Cope, in 1870, classified *Compsognathus* within a new clade of dinosaurs, the Symphypoda, which also contained *Ornithotarsus* (today classified as *Hadrosaurus*). Later, both genera were found to belong to other groups of Cope's classification of dinosaurs: *Compsognathus* to the Gonipoda (equivalent to Theropoda, in which it is now classified), and *Ornithotarsus* to the Orthopoda (equivalent to Ornithischia). Huxley, in 1870, rejected Cope's dinosaur classification scheme, and instead proposed the new clade Ornithoscelida, in which he included the Dinosauria (comprising several forms now considered as ornithischians) and another new clade, the Compsognatha, which contained *Compsognathus* as the only member. Later, these groups fell into disuse, although a resurrection of the Ornithoscelida was proposed in 2017. The group Compsognatha was used for the last time by Marsh in a 1896 publication, where it was treated as a suborder of Theropoda. In the same publication, Marsh erected the new family Compsognathidae. Friedrich von Huene, in 1914, erected the new infraorder Coelurosauria, which includes the Compsognathidae amongst other families of small theropods; this classification remained in use since.

The Compsognathidae are a group of mostly small dinosaurs from the late Jurassic and early Cretaceous periods of China, Europe and South America. For many years, *Compsognathus* was the only member known, but in recent decades paleontologists have discovered several related genera. The clade includes *Aristosuchus*, *Huaxiagnathus*, *Mirischia*, *Sinosauropteryx*, and perhaps *Juravenator* and *Scipionyx*. At one time, *Mononykus* was proposed as a member of the family, but this was rejected by Chen and coauthors in a 1998 paper; they considered the similarities between *Mononykus* and the compsognathids to be an example of convergent evolution. The position of *Compsognathus* and its relatives within the coelurosaur group is uncertain. Some, such as theropod expert Thomas Holtz Jr. and co-authors Ralph Molnar and Phil Currie in the landmark 2004 text *Dinosauria*, hold the family as the most basal of the coelurosaurs, while others as part of the Maniraptora.

For almost a century, *Compsognathus longipes* was the only well-known small theropod species. This led to comparisons with *Archaeopteryx* and to suggestions of an especially close relationship with birds. In fact, *Compsognathus*, rather than *Archaeopteryx*, piqued Huxley's interest in the origin of birds. The two animals share similarities in shape and proportions, so many in fact that two specimens of *Archaeopteryx*, the "Eichstätt" and the "Solnhofen", were for a time misidentified as those of *Compsognathus*. Many other types of theropod dinosaurs, such as maniraptorans, are now known to have been more closely related to birds.

Below is a simplified cladogram placing *Compsognathus* in Compsognathidae by Senter *et al.* in 2012.

## Paleobiology

### Paleopathologies

In 2001 nine elements attributed to *Compsognathus* feet were examined for signs of stress fracture. The results showed none.

### Diet

The remains of a small lizard have been found in the German specimens thoracic cavity. This shows that *Compsognathus* hunted small animals and maybe insects. Marsh, examining the specimen in 1881, thought the remains were an embryo, but was confirmed a lizard by Nopsca in 1903. Ostrom identified the remains as *Brevarisaurus*, a fast-running lizard. This lizard is thought to have been a fast runner, meaning *Compsognathus* would have needed sharp vision and agility to catch the small animal. Later Conrad announced in the press that the lizard was the only holotype of *Schoenesmahl*. The remains are in a single piece, probably swallowed whole. The French specimen has unidentified Sphenodontids and lizards in its gastric contents.

### Eggs

The slate preserving the German remains show several circular shapes, 10 millimeters (0.39 inches) in diameter near the carcass. Griffiths interprets them as eggs in 1993. However, several authors have doubted that these shapes belong to the genus, as they are found outside the actual corpse, belonging to another animal. The closely-related *Sinosauropteryx* bears two oviducts that contain two unlaid eggs. These were larger and there were less of them. Instead of being eggs, Werner in 1964 states that they are spherical gas bubbles, formed and fossilized due to carcass putrefaction.

### Speed

Sellers and Manning placed an estimate of *Compsognathus* speed in 2007 by using a computer model to reconstruct the skeleton and muscles. They placed its speed at 17.8 m/a (40 miles/hour).

## Paleoecology

Late Jurassic of Europe is characteristically dry, and the German archipelago *Compsognathus* lived on edged the Tethys. The fine limestone *Compsognathus* are found in originate from calcite, which further originates from marine animal shells. Both France and German sediments where *Compsognathus* are found were deposited around lagoons, which are surrounded by islands and reefs. *Compsognathus* lived with *Archaeopteryx*, the pterosaur *Rhamphorynchus* and *Pterodactylus*, horseshoe crabs and marine and terrestrial Crocodylomorphs. The reefs were inhabited by echinoderms, fish, crustaceans and molluscs. *Compsognathus* may have been one of the top land predators at this time and place.

Discussion about the taphonomy of the German specimen is complicated. How and when it died are unclear as the exact locality, position and orientation has been lost. The orientation of the specimen can not be truly reconstructed, and, as a compression fossil, it would have been preserved on both upper and lower surfaces of the slabs. One theory states that it was fossilized on its side, and that the left limbs are better articulated than the right. This may mean that the individual was laying on its left side, embedded on the bottom of the upper slab.

The German specimen is very articulated, only the skull, hands, cervical ribs and gastralia being disarticulated. The braincase is displaced, positioned behind the skull. The first tail vertebrae is articulated 90°, breaking between the 7 and 8 vertebrae. The neck curves strongly, the head placed above the pelvis. The spine of the trunk and tail are also curved. It sports the iconic death pose. It is thought that this position is caused by cerebral spasms while the animal is dying. Another theory places this as the Ligamentum elasticum releasing, which curls the animal. The latter would have occurred slowly as muscle tissues were in the process of decay.

## History

Although not recognized as such at the time of its discovery, *Compsognathus* is the first dinosaur known from a reasonably complete skeleton. Until the 1980s and 1990s, *Compsognathus* was the smallest known dinosaur and the closest supposed relative of the early bird *Archaeopteryx*. For nearly a century, *Compsognathus* was the only well-known small theropod. This led to comparisons with *Archaeopteryx* and to suggestions of a relationship with birds. The two theropods share many similarities in shape, size and proportions, so many in fact that a featherless skeleton of an *Archaeopteryx* was for many years misidentified as a *Compsognathus*.

## Skin Texture

Some relatives of *Compsognathus* have been preserved with the remains of simple feathers covering the body like fur, promoting some scientists to suggest that *Compsognathus* might have been feathered in a similar way. Consequently, many depictions of *Compsognathus* show it with a covering of downy proto-feathers. However, no feathers or feather-like covering have been preserved with *Compsognathus* fossils, in contrast to *Archaeopteryx*, which was found in the same sediments. In 2006, reported skin impressions preserved on the side of the tail starting at the 13th tail vertebra were found. The impressions showed small bumpy tubercles. Additional scales had earlier been reported in the abdominal region of the German *Compsognathus*, but this interpretation was later disproved.

## JPInstitute.com Description

Compsognathus became well known from being featured in "The Lost World: Jurassic Park." It was one of the smallest dinosaurs we know about. This little hunter probably ate bugs and small lizards. In fact, the first fossil skeleton of this dinosaur had the remains of its last meal, a lizard, still in its stomach.

Compsognathus is one of those dinosaurs around which some controversy swirls. Some paleontologists feel that, like the much larger Tyrannosaurus, the little Compsognathus had only two fingers. Others feel strongly that it had three. Since there are only two known fossils, and the bones are not perfectly preserved in an articulated (as they were in life) manner, it may take more discoveries to solve this issue.

Compsognathus is considered an important link in the study of bird evolution. The original fossil of this dinosaur was found in the same place as Archeopteryx, the early feathered reptile. Compsognathus shares a number of characteristics with this creature, but Compsognathus did not appear to have feathers. This is one of those interesting dinosaurs where scientists hope to find more specimens to learn the answers to many questions.

## Dinosaur Field Guide Description

Compsognathus ("delicate jaw') was once considered the smallest known dinosaur. The first discovered fossil of Compsognathus was less than 28 inches (70 cm) long: however, this specimen was probably not fully grown. Even so, adult Compsognathus probably weighed only about 7.7 pounds (3.5 kg). Although scientists now regard birds as dinosaurs (and therefore, there are many living dinosaurs smaller than Compsognathus), this little meat-eater from the Jurassic Period of Europe is still one of the smallest dinosaurs known from the Mesozoic Era, the Age of Dinosaurs.
Inside the belly of the original Compsognathus specimen is the skeleton of a fast-running lizard. This shows that Compsognathus was a meat-eater like its bigger relatives (such as Tyrannosaurus and Giganotosaurus), but it hunted much smaller prey. It lived on the same tropical islands as Archaeopteryx, and perhaps it would even eat its smaller flying relative. Compsognathus had short arms that were probably not very useful in catching prey, but that were handy for holding on to victims it snatched up in its jaws. For many years, it was thought that Compsognathus had only two fingers on each hand (as in Tyrannosaurus and other tyrant dinosaurs). However, it now seems that Compsognathus had three fingers on each hand like most meat-eaters. Compsognathus seems to have been a close relative of the Chinese Sinosauropteryx, and like that Asian dinosaur it probably had a covering of "protofeathers." Unfortunately, neither protofeathers nor scales were preserved in the known
fossils of Compsognathus.

### Fun Facts

Compsognathus was the first dinosaur known from a nearly complete fossil.

## Trivia

Only two skeletons of Compsognathus are presently known: one from Germany and a slightly larger one from France. In Jurassic Park II: The Lost World, the genetically recreated Compsognathus ran around in packs, attacking much larger animals. While some smaller predators did hunt in packs, there is no evidence that the real Compsognathus did this.

## Links

http://web.archive.org/web/20031207231645fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_comps.html#

## References

1. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `gegenbaur1863`
2. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `cope1867`
3. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `huxley1868`
4. ↑ Template:Cite journal
5. ↑ 5.0 5.1 Template:Cite journal
6. ↑ Template:Cite wikisource
7. ↑ Template:Cite journal
8. ↑ Template:Cite journal
9. ↑ 9.0 9.1 Template:Cite journal
10. ↑ 10.0 10.1 10.2 10.3 Cite error: Invalid `<ref>` tag; no text was provided for refs named `peyer06`
11. ↑ Template:Cite journal
12. ↑ Template:Cite journal
13. ↑ Template:Cite journal
14. ↑ Template:Cite journal
15. ↑ Template:Cite journal
16. ↑ Template:Cite journal
17. ↑ Template:Cite journal
18. ↑ Template:Cite journal
19. ↑ Template:Cite journal
20. ↑ Template:Cite book
21. ↑ Template:Cite journal
22. ↑ Template:Cite journal
23. ↑ Template:Cite book
24. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Lambert`
25. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `weishampel04`
26. ↑ Template:Cite journal