Sinocalliopteryx

Taxobox
name = "Sinocalliopteryx"
fossil_range = Early Cretaceous
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Saurischia
subordo = Theropoda
unranked_familia = Coelurosauria
familia = Compsognathidae
genus = "Sinocalliopteryx"
genus_authority = Ji "et al.", 2007
subdivision_ranks = Species
subdivision =
*"S. gigas" Ji "et al.", 2007 (type)

"Sinocalliopteryx" (meaning 'Chinese beautiful feather') is a genus of compsognathid dinosaur from the Lower Cretaceous Yixian Formation of China. While similar to the related "Huaxiagnathus", "Sinocalliopteryx" is larger, and at 2.37 meters (7.78 ft) in length, it is the largest known compsognathid genus, and the large size of this "giant compsognathid" lent "Sinocalliopteryx" its specific name, "S. gigas", meaning 'giant.'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.] "Sinocalliopteryx" is also distinguished from "Huaxiagnathus", as well as other compsognathids, by its relatively long hands in relation to its arms, which were also longer overall than in most compsognathids, a feature possibly related to its size.

Paleobiology

Like many other theropods of the Yixian Formation, "Sinocalliopteryx" was preserved with "protofeathers," simple filamentous integument (structures covering the skin), very similar to that found in "Sinosauropteryx". The integument of "Sinocalliopteryx" differ in length across the body, with the longest protofeathers covering the hips, base of the tail, and back of the thighs. These longest protofeathers measured up to 10 centimeters (4 in) in length. Interestingly, protofeathers were also found on the metatarsus (upper part of the foot). While these were not nearly as long or modern as the corresponding feathers of "four-winged" dinosaurs such as "Microraptor" and "Pedopenna", they do indicate that foot-feathers or similar structures first arose in dinosaurs much more primitive than previously known.

The well-preserved skeleton of "Sinocalliopteryx" contained the partial leg of a dromaeosaurid within the abdominal cavity, comprised of a complete lower leg and foot with toes and claws in their natural, articulated position. While the leg is very large in relation to the abdominal cavity, it is clearly situated within it, lying between the ribs. Ji and colleagues, who described "Sinocalliopteryx" in 2007, suggested that this could indicate it preyed upon the smaller, bird-like dinosaur. This discovery indicated that "Sinocalliopteryx" may have been an agile, active, "fierce" predator, especially since other compsognathids have been found with (presumably fast-moving) lizards and small mammals in their abdominal cavities.

In addition to the dromaeosaurid leg, four irregularly-shaped stones were found in the abdomen, with no similar stones present in any other portions of the skeleton or embedded in the surrounding rock. The authors interpreted these as gastroliths (gizzard stones) similar to those found with "Nqwebasaurus" and "Baryonyx". Other theropods, such as "Caudipteryx" and a Mongolian ornithomimid, were also found with gastoliths, though in those cases the stones were much more numerous and smaller in size. Ji and colleagues speculated that, since the later two dinosaurs were probably primarily herbivores, the number and size of gastroliths may correspond with diet; that is, herbivores ingested many small stones, while carnivores ingested only a few larger stones to aid in digestion.

The large size of "Sinocalliopteryx" compared to its relatives is also notable, and may indicate a trend towards large size among compsognathids (a group well-known for their small size compared to other, giant theropod dinosaurs), similar to the trends towards larger sizes in other dinosaurian lineages.

References

External links

* [http://blog02.linkclub.jp/media/2885/20070319-Sinocalliopteryx_gigas.jpgPhoto of specimen] . Retrieved 2007-APR-02.