Juravenator

Taxobox
name = "Juravenator"
fossil_range = Late Jurassic

---

image_width = 250px
image_caption = "Juravenator starki"
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Saurischia
unranked_familia = Coelurosauria
familia = Compsognathidae?
genus = "Juravenator"
genus_authority = Göhlich & Chiappe, 2006
subdivision_ranks = Species
subdivision = "J. starki" Göhlich & Chiappe, 2006

"Juravenator" is a genus of small (70 cm long) coelurosaurian dinosaur, which lived in the area which would someday become the Jura mountains of Germany, 150 million years ago. "Juravenator" was originally published as a member of the family Compsognathidae, making it a close relative of "Sinosauropteryx" and "Sinocalliopteryx", for which there is fossil evidence of a downy, feather-like covering, yet a patch of fossilized "Juravenator" skin shows only normal dinosaur scales, with no sign of feathers at all. While it may simply have never had feathers, paleontologist Mark Norell suggest that the presence of scales on the "Juravenator" tail could mean a number of things [http://www.chron.com/disp/story.mpl/nation/3724592.html] :

* "Juravenator" could have lost its feathers secondarily on at least some parts of its body, like some modern, partially featherless birds.
* Feathers could have evolved more than once in different types of dinosaur.
* Since the only known "Juravenator" skeleton is juvenile, it could be that this species only grew a significant covering of feathers as they aged, or lost feathers seasonally.
* The feathers might simply have not been preserved in this specimen. "Feathers are really just difficult things to preserve," Norell says, though Luis Chiappe, director of the Dinosaur Institute at the Natural History Museum of Los Angeles County points out that the fossil skin does not show the follicles normally associated with dinosaur skin that has lost its feathers. Xu, Xing. (2006) "Scales, feathers, and dinosaurs". "Nature", 440: 287-288. 16 March 2006]

Additionally, subsequent studies have found problems with the initial study that placed "Juravenator" among the compsognathids. Rather than grouping it with "Sinosauropteryx" and other compsognathids, Butler "et al." found that it was not a compsognathid, but rather a basal member of the group Maniraptora. Studies conflict on whether or not compsognathids belong to this later group or are more primitive, though all other maniraptoran skin impressions also show evidence of feathers.

The fossil, found in 1998 by amateur paleontologist Klaus-Dieter Weiß in a lime pit near Eichstätt, had been nicknamed "Borsti" in German, a name commonly given to bristle-haired dogs, on the assumption the creature was endowed with bristly protofeathers.

References

*Butler, R.J., and Upchurch, P. (2007). "Highly incomplete taxa and the phylogenetic relationships of the theropod dinosaur "Juravenator starki"." "Journal of Vertebrate Paleontology", 27(1): 253-256.
*Göhlich, U.B., and Chiappe, L.M. (2006). "A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago." "Nature", 440: 329-332.

External links

* [http://news.nationalgeographic.com/news/bigphotos/5733093.html An image of Juravenator from National Geographic]