Sinocalliopteryx

Extinct as can be!

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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).

Discovery[]

The type species Sinocalliopteryx gigas was named and described in 2007 by Ji Shu'an, Ji Qiang, Lü Junchang and Yuan Chongxi. The generic name is derived from Sinae, Latin for the Chinese and Greek καλός, kalos, "beautiful", and πτέρυξ, pteryx, "feather". The large size of this "giant compsognathid" lent Sinocalliopteryx its specific name, gigas, meaning 'giant'. 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.

The holotype, JMP-V-05-8-01, was discovered at Hengdaozi, in Sihetun, in Liaoning Province, from the Jianshangou Beds of the Yixian Formation dating from the Barremian-Aptian, about 125 million years old. It consists of a nearly complete skeleton with skull, compressed on a single plate, of an adult individual. Extensive remains of protofeathers have been preserved. In 2012 a second specimen was described, CAGS-IG-T1, of an individual larger than the holotype. The skull was about 10% longer, the feet about a third, a difference explained by positive allometry. The specimen consists of a partial skull, tail, hands, feet and ribcage. It shows filaments on the tail.

Description[]

Sinocalliopteryx is known from a complete skeleton with preserved filamentous integumentary structures (hair-like 'protofeathers'). Part of the leg of a dromaeosaurid (a small, fast-moving dinosaur that walked on 2 legs) and also some gastroliths (stomach stones) were found in its abdomen. Sinocalliopteryx had an elongated head with a pointed snout, showing a convex upper profile. There were four teeth in the premaxilla which were small but exceptionally had denticles on their front edges. Only six, larger, teeth were present in the maxilla of the holotype specimen but the number of its tooth positions could not be adequately determined.

Sinocalliopteryx standing over its Sinornithosaurus prey, as a breeding pair of Confuciusornis take flight behind. Both latter genera have been found as prey of different Sinocalliopteryx individuals. The scene is set on the shores of the lake in which they will ultimately be preserved in ash. Image source: Julius T. Csotonyi

The carnivores in question are a pair of Sinocalliopteryx. These dinosaurs were close cousins of the much earlier Compsognathus, albeit quite a bit larger. While Compsognathus was turkey-size, about three feet long, Sinocalliopteryx grew to be about eight feet long.

Additionally Sinocalliopteryx was covered in primitive feathers. The original description of the dinosaur mentioned the vestiges of simplified feathers around the body of Sinocalliopteryx, and this makes sense given the dinosaur’s relationships. While considerably bigger than its close relatives, Sinocalliopteryx was a compsognathid–a group of theropod dinosaurs that also includes feathered forms such as Sinosauropteryx and Juravenator. The stomach of Sinocalliopteryx contains the remains of dromaeosaurid dinosaur in its gut contents. Since the original discovery, paleontologists have identified a second Sinocalliopteryx specimen containing the remains of two Confuciusornis, an archaic bird, and bones from an unidentified ornithischian dinosaur. However it remains unknown if the Sinocalliopteryx truly killed these animals, or simply scavenged them after they died.

Sinocalliopteryx eating. Credit: Matthew P. Martyniuk

Sinocallioptery may have been skilled at catching live birds. The fact that one Sinocalliopteryx fed on two Confuciusornis in quick succession could mean that the large dinosaur was adapted to catching flying prey. “The evidence of bird predation in Sinocalliopteryx,” Xing and colleagues conclude, “suggests that it was a highly capable stealth hunter.” However the researchers noted that this behavior “is speculative.” While it may seem improbable, the Sinocalliopteryx in question could have scavenged one or both of those birds, as well as the non-avian dinosaur remains in its stomach. Like many predators, Sinocalliopteryx most likely hunted live prey and took advantage of carrion.

The bone of the ornithischian dinosaur that the Sinocalliopteryx had eaten was corroded by stomach acid. The more delicate bird bones, by contrast, had not been so damaged. This means that the Sinocalliopteryx ate the ornithischian first, followed by one bird and, later, another. More than that, the acid damage indicates that at least some dinosaurs had highly-acidic foreguts where bone was broken down–comparable, but not exactly like, the stomachs of crocodilians and perhaps some bone-eating birds like the bearded vulture.

The stomach contents of Sinocalliopteryx show that it was a generalist, and fed upon a wide variety of animals. Said prey items could have included primitive mammals, birds, and small dromaeosaurids.

Sinocalliopteryx

Contents

Discovery[]

Description[]

References[]

Gallery[]