[5] Compsognathid fossils preserve diverse integument — skin impressions are known from four genera commonly placed in the group, Compsognathus, Sinosauropteryx, Sinocalliopteryx and Juravenator.

"Ubirajara jubatus", informally described in 2020, had elaborate integumentary structures on its back and shoulders superficially similar to the display feathers of a standardwing bird-of-paradise, and unlike any other non-avian dinosaur currently described.

[10] This classification was accepted by Othniel Charles Marsh in 1882, and added to the Coelurosauria clade by Friedrich von Huene in 1914 after additional fossils had been found.

[13] However, classification is still complicated due to similarities to the body of several other theropod dinosaurs, as well as the lack of unifying, diagnostic features that are shared by all compsognathids.

[10][14] Some authors have proposed that Compsognathidae is not a monophyletic group, and at least some compsognathids represent juvenile specimens of larger tetanuran theropods, such as carnosaurs and tyrannosaurs.

In 1861, after an initial period of review, Johann A. Wagner presented his analysis of the specimen to the public and named the fossil Compsognathus longipes ("elegant jaw").

[19] In 1868, Thomas Henry Huxley, an early supporter of Charles Darwin and his theory of evolution, used Compsognathus in a comparison to similar feathered dinosaur Archaeopteryx in order to propose the origin of birds.

[23] A compsognathid specimen consisting of a single finger bone has been described from Late Jurassic (Tithonian Age, about 150 million years ago) sediments at Port Waikato, New Zealand.

[24] However, recently discovered adult specimens of other dinosaurs are smaller than Compsognathus, including Caenagnathasia, Microraptor and Parvicursor, all of which are estimated to be less than 1 m long.

In 1998, evidence of filamentous protofeathers was presented in a study on Sinosauropteryx, marking the first time that any sort of feather structure was found outside of birds and their related species.

[13] 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,[43] while others as part of the Maniraptora.

[46] Tyrannosauroidea Sinocalliopteryx Huaxiagnathus Sinosauropteryx Compsognathus Juravenator Scipionyx Maniraptoriformes A number of authors have suggested that Compsognathidae is not a monophyletic group as currently defined, and that at least some "compsognathids" represent the juveniles of other tetanurans, including carnosaurs and tyrannosaurs.

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.