Compsognathidae

Compsognathidae is a family of coelurosaurian theropod dinosaurs. They were small carnivores, generally conservative in form, hailing from the Jurassic and Cretaceous Periods. The bird-like features of these species, along with other dinosaurs such as Archaeopteryx inspired the idea for the connection between dinosaur reptiles and modern-day avian species.[4] Compsognathid fossils preserve diverse integument — skin impressions are known from four genera commonly placed in the group, Compsognathus, Sinosauropteryx, Sinocalliopteryx, and Juravenator.[5] While the latter three show evidence of a covering of some of the earliest primitive feathers over much of the body, Juravenator and Compsognathus also show evidence of scales on the tail or hind legs.

The first member of the group, Compsognathus, was discovered in 1861, after Johann A. Wagner published his description of the taxon.[6][7][8] The family it was created by Edward Drinker Cope in 1875.[9] 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.[6] With further discoveries, fossils have been uncovered across three different continents, in the countries of China,[10] France,[6] Germany,[6][7][8][5] Italy,[11] and Brazil.[7][9] Assignment to Compsognathidae is usually determined through examination of the metacarpal, which is used to separate Compsognathidae from other dinosaurs.[12] 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.[9][13]

Compsognathidae
Temporal range: Late JurassicEarly Cretaceous, 151.5–108 Ma
Possible Late Cretaceous record
Compsognathidae
Compsognathid skeletons to scale
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Clade: Tyrannoraptora
Family: Compsognathidae
Cope, 1871
Type species
Compsognathus longipes
Wagner, 1861
Genera[3]
Synonyms
  • Sinosauropterygidae Ji & Ji, 1996

History of Discovery

Compsognathus longipes cast 3
The holotype of C. longiceps

The first significant fossil specimen of Compsognathidae was found in the Bavaria region of Germany (BSP AS I 563) and given to collector Joseph Oberndorfer in 1859.[14] The finding was initially significant because of the small size of the specimen. 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").[15] In 1868, Thomas Henry Huxley, an explorer known for his travels with Charles Darwin and an early supporter of the theory of evolution, used Compsognathus in a comparison to similar feathered dinosaur Archaeopteryx in order to propose the origin of birds. While Huxley noticed that these dinosaurs shared a similar layout to birds and proposed an exploration of the similarities. He is credited as being the first person to do so.[16] This initial comparison sparked the interest into the origin of birds and feathers. In 1882, Othniel Charles Marsh named a new family of dinosaurs for this species Compsognathidae and officially recognized the species as part of Dinosauria.[17]

Notable Specimens

Juravenator Scale
Size comparison of the Juravenator specimen to human.

In 1971, a second nearly complete specimen of Composgnathus longipes was found in the area of Canjuers, which is located in the southeast of France near Nice.[6] This specimen was much larger than the original German specimen, but similarities led to experts categorizing the fossil as an adult Compsognathus longipes and leading to the further classification of the German specimen as a juvenile.[18] This specimen also contained a lizard in the digestive region, further solidifying the theory that compsognothids consumed small vertebrate species.

The holotype of Juravenator is the only known specimen of the species. Though Juravenator has previously been accepted as a member of Compsognathidae, recent research has led some experts to believe that Juravenator does not belong in this group. This is due to the fact that Juravenator could also be classified into a similar group within Coelurosauria, Maniraptoriformes. Maniraptorformes share many similarities with compsognathids and due to the fact that there has been only one verified specimen of Juravenator, experts have disagreed on exactly where to place this genus. Since 2013, Juravenator is still commonly classified as a coelurosaur, but near the family Maniraptorformes instead of Compsognathidae.[19]

A compsognathid specimen consisting of a single finger bone has been described from Late Jurassic sediments at Port Waikato, New Zealand. It is the first and so far, only dinosaur specimen known from Jurassic New Zealand. Possible coprolites have been referred to this specimen, however it is still not an official classified species.

Timeline

Description

Compsognathids share a variety of characteristics. The genera in this family demonstrate traits that are characteristic of theropods, such as smaller forelimbs than hind legs. Size, feathers, and metacarpal size are among the most important classifying common characteristics.

Size

Compysizes1
Comparison of German (green) and French (orange) Compsognathus longipes specimen

Compsognathids are considered to be among the smallest dinosaurs ever discovered. Compsognathus longipes was formerly the smallest known dinosaur. It was around the size of a chicken when fully grown: around 1 m (3 ft 3 in) long and weighing 2.5 kg (5.5 lb).[20] 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.[21] However, most of these specimens are incomplete, so these sizes remain estimates.

The other genera in this family are slightly larger than Compsognathus longipes, but generally similar in size. The largest compsognathid is Huaxiagnathus, which is estimated from its holotype to be around 1.8 m (5 ft 11 in) long,[22] while Sinocalliopteryx measures around 2.4 m (7 ft 10 in) long.[23] Sinosauropteryx is the most similar to Compsognathus, measuring at most 1.07 m (3 ft 6 in) long.[24]

Feathers

Sinosauropteryx color
Artistic recreation of Sinosauropteryx with feathers

Compsognathids had feathers. The phylogeny of Compsognathidae organizes this family near the development of feathers in dinosaurs. 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.[25] After this, more evidence of feather structure was found in other genera of Compsognathidae. Evidence of protofeathers bearing resemblance to Sinosauropteryx was found on Sinocalliopteryx specimens, including on the foot of the specimen.[26] There have been signs of basic feather structures on Juravenator, but evidence of this is still not definite. Samples of Juravenator skin show scales instead of feathers, leading into debates about Juravenator’s place within the family Compsognathidae.[27] However, a 2010 examination of Juravenator under UV light showed filaments similar to those seen on other compsognathid specimens, indicating that it is likely that these dinosaurs had some sort of feathering.[28]

Metacarpals

Another way of classification of Compsognathidae is shared metacarpal morphology. A 2007 study found similarities between compsognathid genera in certain metacarpal I morphologies. The conclusion of this study found that Composgnathidae had a distinct manual morphology where, like theropods, the first digit of the manus is larger than the other digits, but with a distinct metacarpal I morphology where the metacarpal is stocky and short. Compsognathidae also has a projection from the manus that is on this metacarpal.[12]

Palaeobiology

Diet

Compsognathidae were carnivores and certain specimen have contained the remains of their diet. The German specimen of Compsognathus included remains in the digestive region, which was initially thought to be an unborn embryo.[29] However, further analysis found that the remains belong to a lizard with an elongated tail and stretched legs.[17][30] Other compsognathids, such as Sinosauropteryx, have been shown to eat lizards.[24]

References

  1. ^ J. N. Choiniere, J. M. Clark, C. A. Forster and X. Xu. 2010. A basal coelurosaur (Dinosauria: Theropoda) from the Late Jurassic (Oxfordian) of the Shishugou Formation in Wucaiwan, People's Republic of China. Journal of Vertebrate Paleontology 30(6):1773-1796
  2. ^ a b Holtz, Thomas R. Jr. (2012) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2011 Appendix.
  3. ^ Hendrickx, C., Hartman, S.A., & Mateus, O. (2015). An Overview of Non- Avian Theropod Discoveries and Classification. PalArch’s Journal of Vertebrate Palaeontology, 12(1): 1-73.
  4. ^ Etnier, Michael A. "Neptune's Ark: From Ichthyosaurs to Orcas." (2008): 25.
  5. ^ a b Xu, Xing. "Palaeontology: Scales, feathers and dinosaurs." Nature 440.7082 (2006): 287-288.
  6. ^ a b c d e Peyer, Karin. "A reconsideration of Compsognathus from the Upper Tithonian of Canjuers, southeastern France." Journal of vertebrate Paleontology 26.4 (2006): 879-896.
  7. ^ a b c Sales, Marcos AF, Paulo Cascon, and Cesar L. Schultz. "Note on the paleobiogeography of Compsognathidae (Dinosauria: Theropoda) and its paleoecological implications." Anais da Academia Brasileira de Ciências 86.1 (2014): 127-134.
  8. ^ a b Wagner, A. "Neue Beiträge zur Kenntnis der urweltlichen Fauna des lithographischen Schiefers; V. Compsognathus longipes Wagner." Abhandlungen der Bayerischen Akademie der Wissenschaften 9 (1861): 30-38.
  9. ^ a b c Naish, Darren, David M. Martill, and Eberhard Frey. "Ecology, systematics and biogeographical relationships of dinosaurs, including a new theropod, from the Santana Formation (? Albian, Early Cretaceous) of Brazil." Historical Biology 16.2-4 (2004): 57-70.
  10. ^ Shu'an, Ji, et al. "New material of Sinosauropteryx (Theropoda: Compsognathidae) from western Liaoning, China." Acta Geologica Sinica (English Edition) 81.2 (2007): 177-182.
  11. ^ Dal Sasso C., Maganuco S. "Scipionyx samniticus (Theropoda: Compsognathidae) from the Lower Cretaceous of Italy: osteology, ontogenetic assessment, phylogeny, soft tissue anatomy, taphonomy and palaeobiology." Memorie, XXXVI-I (2011): 1-283.
  12. ^ a b Gishlick, Alan D., and Jacques A. Gauthier. "On the manual morphology of Compsognathus longipes and its bearing on the diagnosis of Compsognathidae." Zoological Journal of the Linnean Society 149.4 (2007): 569-581.
  13. ^ Brett-Surman, Michael K., Thomas R. Holtz, and James O. Farlow, eds. The complete dinosaur. Indiana University Press, 2012 pp 360.
  14. ^ Wellnhofer, P. (2008). "Dinosaurier". Archaeopteryx — der Urvogel von Solnhofen. Munich: Verlag Dr. Friedrich Pfeil. p. 256. ISBN 978-3-89937-076-8.
  15. ^ Wagner, Johann Andreas (1861). "Neue Beiträge zur Kenntnis der urweltlichen Fauna des lithographischen Schiefers; V. Compsognathus longipes Wagner". Abhandlungen der Bayerischen Akademie der Wissenschaften. 9: 30–38.
  16. ^ Switek, B. (2010). Thomas Henry Huxley and the reptile to bird transition. Geological Society, London, Special Publications, 343(1), 251-263.
  17. ^ a b Ostrom, J. H. (1978). The osteology of Compsognathus longipes Wagner. Zitteliana.
  18. ^ Callison, G.; H. M. Quimby (1984). "Tiny dinosaurs: Are they fully grown?". Journal of Vertebrate Paleontology. 3 (4): 200–209. doi:10.1080/02724634.1984.10011975.
  19. ^ Godefroit, Pascal; Cau, Andrea; Hu, Dong-Yu; Escuillié, François; Wu, Wenhao; Dyke, Gareth (2013). "A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds". Nature. 498 (7454): 359–362. Bibcode2013Natur.498..359G. doi:10.1038/nature12168. PMID 23719374
  20. ^ "What was the biggest dinosaur? What was the smallest?" (May 17, 2001)
  21. ^ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 152
  22. ^ Hwang SH, Norell MA, Ji Q, Gao K-Q (2004) A large compsognathid from the Early Cretaceous Yixian Formation of China. J Syst Pal 2: 13–30. doi:10.1017/S1477201903001081.
  23. ^ Therrien, F., & Henderson, D. M. (2007). My theropod is bigger than yours… or not: estimating body size from skull length in theropods. Journal of Vertebrate Paleontology, 27(1), 108-115.
  24. ^ a b Switek, Brian (August 31, 2012). "Stomach Contents Preserve Sinocalliopteryx Snacks"
  25. ^ Chen, P.; Dong, Z.; Zhen, S. (1998). "An exceptionally well-preserved theropod dinosaur from the Yixian Formation of China". Nature. 391 (8): 147–152. doi:10.1038/34356.
  26. ^ Ji, S., Ji, Q., Lu J., and Yuan, C. (2007). "A new giant compsognathid dinosaur with long filamentous integuments from Lower Cretaceous of Northeastern China." Acta Geologica Sinica, 81(1): 8-15
  27. ^ Goehlich, U.B.; Tischlinger, H.; Chiappe, L.M. (2006). "Juravenator starki (Reptilia, Theropoda) ein neuer Raubdinosaurier aus dem Oberjura der Suedlichen Frankenalb (Sueddeutschland): Skelettanatomie und Weichteilbefunde". Archaeopteryx. 24: 1–26.
  28. ^ Chiappe, L.M.; Göhlich, U.B. (2010). "Anatomy of Juravenator starki (Theropoda: Coelurosauria) from the Late Jurassic of Germany". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 258 (3): 257–296. doi:10.1127/0077-7749/2010/0125.
  29. ^ Report of the 65th Meeting of the British Association for the Advancement of Science, Ipswich, 1895, London, 1895, 743
  30. ^ Nopcsa, Baron F. (1903). "Neues ueber Compsognathus". Neues Jahrbuch fur Mineralogie, Geologie und Palaeontologie (Stuttgart). 16: 476–494.
Aniksosaurus

Aniksosaurus (meaning "spring lizard", from Modern Greek Άνοιξη, "Spring", referring to the fact it was found on 21 September 1995, the onset of Spring on the Southern Hemisphere) is a genus of dinosaur from what is now Chubut Province, Argentina. It was a theropod, specifically a coelurosaur, which lived in the Cenomanian to Turonian of the Cretaceous period, between 96-91 million years ago. The type species, Aniksosaurus darwini, was formally described from the Bajo Barreal Formation of the Golfo San Jorge Basin by Rubén Dario Martínez and Fernando Emilio Novas in 2006; the name was first coined in 1995 and reported in the literature in 1997. The specific epithet honors Charles Darwin who visited Patagonia in 1832/1833 during the Voyage of the Beagle.

Aristosuchus

Aristosuchus was a small coelurosaurian dinosaur whose name was derived from the Greek ἄριστος (meaning bravest, best, noblest) and σουχος (the Ancient Greek corruption of the name of the Egyptian crocodile-headed god Sobek). It shared many characteristics with birds.

Beipiaognathus

Beipiaognathus (meaning Beipiao jaw) is a dubious genus of coelurosaurian theropod from the Early Cretaceous Yixian Formation of Liaoning, China.The genus was initially assigned to the Compsognathidae based on the presence of two traits: fan-shaped dorsal neural spines and a robust I-1 phalanx on the hand. However, it also differs from other compsognathids in several ways: the teeth are unserrated and conical; the ulna is proportionally longer; the II-1 phalanx on the hand is longer and more robust; and the tail is much shorter.However, Andrea Cau has informally noted a number of points in the fossil that are indicative of it having been artificially assembled, thus rendering the specimen a phylogenetically uninformative chimaera.

Calamosaurus

Calamosaurus (meaning "reed lizard") was a genus of small theropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation of the Isle of Wight, England. It is based on two cervical vertebrae (BMNH R901), collected by Reverend William Fox.

Coeluridae

Coeluridae is a historically unnatural group of generally small, carnivorous dinosaurs from the late Jurassic Period. For many years, any small Jurassic or Cretaceous theropod that did not belong to one of the more specialized families recognized at the time was classified with the coelurids, creating a confusing array of 'coelurid' theropods that were not closely related. Although they have been traditionally included in this family, there is no evidence that any of these primitive coelurosaurs form a natural group with Coelurus, the namesake of Coeluridae, to the exclusion of other traditional coelurosaur groups.

Coelurosauria

Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs.

Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyrannosaurs, ornithomimosaurs, and maniraptorans; Maniraptora includes birds, the only dinosaur group alive today.Most feathered dinosaurs discovered so far have been coelurosaurs. Philip J. Currie considers it likely and probable that all coelurosaurs were feathered. In the past, Coelurosauria was used to refer to all small theropods, but this classification has since been abolished.

Compsognathus

Compsognathus (; Greek kompsos/κομψός; "elegant", "refined" or "dainty", and gnathos/γνάθος; "jaw") is a genus of small, bipedal, carnivorous theropod dinosaur. Members of its single species Compsognathus longipes could grow to around the size of a turkey. They lived about 150 million years ago, during the Tithonian 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 size of the German specimen, which is now believed to be a juvenile. 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. 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, with the preceding centuries incorrectly labelling them as the closest relative of Archaeopteryx.

Compsognathus was the first dinosaur genus to be portrayed with feathers, by Thomas Henry Huxley in 1876.

Dilong paradoxus

Dilong (帝龍, which means 'emperor dragon') is a genus of basal tyrannosauroid dinosaur. The only species is Dilong paradoxus. It is from the Lower Cretaceous Yixian Formation near Lujiatun, Beipiao, in the western Liaoning province of China. It lived about 126 million years ago.

Herbstosaurus

Herbstosaurus is the name given to a genus of pterosaurs that lived during the Late Jurassic period, in what is now Argentina. In 1969 Argentine paleobotanist Rafael Herbst in the province Neuquén at Picun Leufú dug up a piece of sandstone holding a number of disarticulated bones of a small reptile. At the time it was assumed the rock dated to the Middle Jurassic (Callovian), about 163 million years ago.

In 1974/1975 paleontologist Rodolfo Magín Casamiquela named the find as a new genus. The type species is Herbstosaurus pigmaeus. The genus name honours Herbst and connects his name to Greek sauros, "lizard", a usual element in the name of dinosaurs — Casamiquela assumed the new genus was a theropod dinosaur. The specific name is derived from Greek pygmaios, "dwarf": it was thought the form presented a small Compsognathus-like coelurosaurian belonging to the Coeluridae and one of the smallest dinosaurs then known.

Huaxiagnathus

Huaxiagnathus is a genus of theropod dinosaur from the Lower Cretaceous of China. It was a compsognathid, large for that group at about half a meter longer than Compsognathus and larger specimens of Sinosauropteryx, with the largest specimen about 1.8 meters (5.9 feet) in length.

The name Huaxiagnathus is derived from the Chinese Hua Xia, 華夏, a traditional word for "China", and from the Greek gnathos, Latinised into gnathus, meaning "jaw."

Juravenator

Juravenator is a genus of small (75 cm long) coelurosaurian theropod dinosaur, which lived in the area which would someday become the top of the Franconian Jura of Germany, about 151 or 152 million years ago. It is known from a single, juvenile specimen.

Mirischia

Mirischia is a small (two meter-long) genus of compsognathid theropod dinosaur from the Albian stage (Early Cretaceous Period) of Brazil.

Nqwebasaurus

Nqwebasaurus (IPA: [ᵑǃʷɛbaˈsɔɹəs]; anglicized as or ) is a basal coelurosaur and is the basal-most member of the coelurosaurian clade Ornithomimosauria from the Early Cretaceous of South Africa. The name Nqwebasaurus is derived from the Xhosa word "Nqweba" which is the local name for the Kirkwood district, and "thwazi" is ancient Xhosa for lightning. Currently it is the only known coelurosaur discovered in Africa and shows that basal coelurosaurian dinosaurs inhabited Gondwana 50 million years earlier than previously thought. The type specimen of Nqwebasaurus was discovered by William J. de Klerk who is affiliated with the Albany Museum in Grahamstown. It is the only fossil of its species found to date and was found in the Kirkwood Formation of the Uitenhage Group. Nqwebasaurus has the unofficial nickname "Kirky", due to being found in the Kirkwood.

Ornitholestes

Ornitholestes (meaning "bird robber") is a small theropod dinosaur of the late Jurassic (Brushy Basin Member of the Morrison Formation, middle Kimmeridgian age, about 154 million years ago) of Western Laurasia (the area that was to become North America).

To date, Ornitholestes is known only from a single partial skeleton with a badly crushed skull found at the Bone Cabin Quarry near Medicine Bow, Wyoming, in 1900. It was described by Henry Fairfield Osborn in 1903. An incomplete hand was later attributed to Ornitholestes, although it now appears to belong to Tanycolagreus. The type (and only known) species is O. hermanni. The specific name honors the American Museum of Natural History preparator Adam Hermann.

Romualdo Formation

The Romualdo Formation is a geologic Konservat-Lagerstätte in northeastern Brazil's Araripe Basin where the states of Pernambuco, Piauí and Ceará come together. The geological formation, previously designated as the Romualdo Member of the Santana Formation, named after the village of Santana do Cariri, lies at the base of the Araripe Plateau. It was discovered by Johann Baptist von Spix in 1819. The strata were deposited during the Albian stage of the Early Cretaceous in a lacustrine rift basin with shallow marine incursions of the proto-Atlantic. At that time, the South Atlantic was opening up in a long narrow shallow sea.

The Romualdo Formation earns the designation of Lagerstätte due to an exceedingly well preserved and diverse fossil faunal assemblage. Some 25 species of fossil fishes are often found with stomach contents preserved, enabling paleontologists to study predator–prey relationships in this ecosystem. There are also fine examples of pterosaurs, reptiles and amphibians, invertebrates (particularly insects), crocodylomorphs, and plants. Even dinosaurs are represented (Spinosauridae, Tyrannosauroidea, Compsognathidae). The unusual taphonomy of the site resulted in limestone accretions that formed nodules around dead organisms, preserving even soft parts of their anatomy. In preservation, the nodules are etched away with acid, and the fossils often prepared by the transfer technique.Local mining activities for cement and construction damage the sites. Trade in illegally collected fossils has sprung up in the last decade, driven by the remarkable state of preservation and beauty of these fossils and amounting to a considerable local industry. An urgent preservation program is being called for by paleontologists.

In addition, the weathering of Romualdo Formation rocks has contributed soil conditions unlike elsewhere in the region. The Araripe manakin (Antilophia bokermanni) is a very rare bird that was discovered only in the late 20th century; it is not known from anywhere outside the characteristic forest that grows on the Chapada do Araripe soils formed ultimately from Romualdo Formation rocks.

Scipionyx

Scipionyx (pronounced "SHIH-pee-oh-nicks" or "ship-ee-OH-nicks") is a genus of compsognathid theropod dinosaur from the Early Cretaceous of Italy, around 113 million years ago.

There is only one fossil known of Scipionyx, discovered in 1981 by an amateur paleontologist and brought to the attention of science in 1993. In 1998 the type species Scipionyx samniticus was named, the generic name meaning "Scipio's claw". The find generated much publicity because of the unique preservation of large areas of petrified soft tissue and internal organs such as muscles and intestines. The fossil shows many details of these, even the internal structure of some muscle and bone cells. It was also the first dinosaur found in Italy. Because of the importance of the specimen, it has been intensely studied.

The fossil is that of a juvenile only half a metre (twenty inches) long and perhaps just three days old. The adult size is estimated to have been about two metres (6.5 feet). Scipionyx was a bipedal predator, its horizontal rump balanced by a long tail. Its body was probably covered by primitive feathers but these have not been found in the fossil, that is without any skin remains.

In the guts of the fossil some half-digested meals are still present, indicating Scipionyx ate lizards and fish. Perhaps these had been fed to the young animal by its parents. Several scientists have tried to learn from the position of the internal organs how Scipionyx breathed, but their conclusions often disagree.

Sinocalliopteryx

Sinocalliopteryx (meaning 'Chinese beautiful feather') is a genus of carnivorous compsognathid theropod dinosaurs from the Lower Cretaceous Yixian Formation of China (Jianshangou Beds, dating to 124.6 Ma).

While similar to the related Huaxiagnathus, Sinocalliopteryx were larger. The type specimen, at 2.37 meters (7.78 ft) in length, in 2007 was the largest known compsognathid exemplar. In 2012 an even larger specimen was reported.

Sinosauropteryx

Sinosauropteryx (meaning "Chinese reptilian wing", simplified Chinese: 中华龙鸟; traditional Chinese: 中華龍鳥; pinyin: Zhōnghuá lóng niǎo; literally: 'Chinese dragon bird') is a compsognathid dinosaur. Described in 1996, it was the first dinosaur taxon outside of Avialae (birds and their immediate relatives) to be found with evidence of feathers. It was covered with a coat of very simple filament-like feathers. Structures that indicate colouration have also been preserved in some of its feathers, which makes Sinosauropteryx the first non-avialian dinosaurs where colouration has been determined. The colouration includes a reddish and light banded tail. Some contention has arisen with an alternative interpretation of the filamentous impression as remains of collagen fibres, but this has not been widely accepted.

Sinosauropteryx was a small theropod with an unusually long tail and short arms. The longest known specimen reaches up to 1.07 metres (3.51 feet) in length, with an estimated weight of 0.55 kilograms (1.21 pounds) It was a close relative of the similar but older genus Compsognathus, both genera belonging to the family Compsognathidae. Only one species of Sinosauropteryx has been named: S. prima, meaning "first" in reference to its status as the first feathered non-avialian dinosaur species discovered. Three specimens have been described. The third specimen previously assigned to this genus represents either a second, as-yet unnamed species or a distinct, related genus.

Sinosauropteryx lived in what is now northeastern China during the early Cretaceous period. It was among the first dinosaurs discovered from the Yixian Formation in Liaoning Province, and was a member of the Jehol Biota. Well-preserved fossils of this species illustrate many aspects of its biology, such as its diet and reproduction.

Theropoda

Theropoda ( or , from Greek θηρίον "wild beast" and πούς, ποδός "foot") or theropods () are a dinosaur suborder that is characterized by hollow bones and three-toed limbs. They are generally classed as a group of saurischian dinosaurs, although a 2017 paper has instead placed them in the proposed clade Ornithoscelida as the closest relatives of the Ornithischia. Theropods were ancestrally carnivorous, although a number of theropod groups evolved to become herbivores, omnivores, piscivores, and insectivores. Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago (Ma) and included the sole large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 66 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by about 10,500 living species.

Coelurosauria

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