Compsognathus longipes is one of the few dinosaur species whose diet is known with certainty: the remains of small, agile lizards are preserved in the bellies of both specimens.

[10] In two publications in 1868 and 1870, Thomas Huxley, a major proponent of Charles Darwin's theory of evolution, compared Compsognathus with Archaeopteryx, which was considered the earliest known bird.

Following earlier suggestions by Carl Gegenbaur[11] and Edward Drinker Cope,[12] Huxley found that Archaeopteryx was closely similar to Compsognathus, and referred to the latter as a "bird-like reptile".

[5][15] Although Baur published a detailed study of the ankle in 1882, which is now the only available source of information of this part of the skeleton, his reconstruction was later found to be inconsistent with corresponding impressions on the slab.

[20][19] Collector Heinrich Fischer had originally labeled a partial foot consisting of three metatarsals and a phalanx, from the Solnhofen area, as belonging to Compsognathus longipes.

[34] Additional scales had in 1901 been reported by Von Huene, in the abdominal region of the German Compsognathus, but Ostrom subsequently disproved this interpretation;[5][35] in 2012 they were by Achim Reisdorf seen as plaques of adipocere, corpse wax.

[8] 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.

[43][16] 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.

[44][16] The Compsognathidae are a group of mostly small dinosaurs from the late Jurassic and early Cretaceous periods of China, Europe and South America.

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,[52] while others as part of the Maniraptora.

[55] 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.

Siamraptor Siamotyrannus Streptospondylus Xuanhanosaurus Poekilopleuron Piveteausaurus Piatnitzkysaurus Marshosaurus Leshansaurus Eustreptospondylus Condorraptor Asfaltovenator Sciurumimus Nedcolbertia Magnosaurus Duriavenator Afrovenator Compsognathus longipes Compsognathus corallestris Torvosaurus tanneri Torvosaurus gurneyi Megalosaurus Scipionyx Wiehenvenator Iberospinus Baryonychinae Spinosaurinae Allosauroidea (Incl.

Tanycolagreus Stokesosaurus Juratyrant Eutyrannosauria In a 2001 study conducted by Bruce Rothschild and other paleontologists, nine foot bones referred to Compsognathus were examined for signs of stress fracture, but none were found.

This interpretation was based on a supposed impression of the flipper that consists of several undulating wrinkles running parallel to the forelimb on the surface of the slab.

[18] In a 1975 popular book, L. Beverly Halstead depicts the animal as an amphibious dinosaur capable of feeding on aquatic prey and swimming out of reach of larger predators.

[59] Ostrom debunked this hypothesis, noting that the forelimb of the French specimen is poorly preserved, and that the wrinkles extend well beyond the skeleton and thus are likely sedimentary structures unrelated to the fossil.

[51] Marsh, who examined the specimen in 1881, thought that this small skeleton in the Compsognathus belly was an embryo, but in 1903, Franz Nopcsa concluded that it was a lizard.

[60] Ostrom identified the remains as belonging to a lizard of the genus Bavarisaurus,[61] which he concluded was a fast and agile runner owing to its long tail and limb proportions.

[5] Conrad made the lizard found in the thoracic cavity of the German specimen of Compsognathus the holotype of a new species Schoenesmahl dyspepsia.

[62] The lizard is in several pieces, indicating that the Compsognathus must have dismembered it while restraining it with its hands and teeth, and then swallowed the remains whole; a similar strategy is used by modern predatory birds.

[51] In 1964 German geologist Karl Werner Barthel had explained the discs as gas bubbles formed in the sediment because of the putrefaction of the carcass.

[64] In 2007, William Sellers and Phillip Manning estimated a maximum speed of 17.8 metres per second (40 mph) based on a computer model of the skeleton and muscles.

Both the German and French areas where Compsognathus specimens have been preserved were lagoons situated between the beaches and coral reefs of the Jurassic European islands in the Tethys Sea.

[67] Contemporaries of Compsognathus longipes include the early avialan Archaeopteryx lithographica and the pterosaurs Rhamphorhynchus muensteri and Pterodactylus antiquus.

In any case, the specimen would have arrived on the sea floor within a few hours after its death, as otherwise gases forming in its body cavity would have prevented it from sinking in one piece.

[68] This posture, known as the death pose, is found in many vertebrate fossils, and the German Compsognathus specimen was central in several studies that sought to explain this phenomenon.

[8] The veterinarian Cynthia Faux and the paleontologist Kevin Padian, in a 2007 study that gained much attention, supported the original opisthotonus hypothesis of Moodie.

This contradicts previous interpretations on the environment and taphonomy of Compsognathus and other fossils from the Solnhofen limestones, which assumed very slow burial at the bottom of lagoons into which the carcasses were transported from nearby islands.

[68][8] Reisdorf and Wuttke concluded that the death posture indeed resulted from the release of ligaments, more specifically the Ligamentum elasticum interlaminare, which spans the spine from the neck to tail in modern birds.

The release of this ligament would have occurred gradually while the surrounding muscle tissue decayed, and only after the carcass was transported to its final site of deposition.