| Juravenator Temporal range: Late Jurassic 151.5 Ma |
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| Holotype | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | Dinosauria |
| Order: | Saurischia |
| (unranked): | Coelurosauria |
| Family: | Compsognathidae |
| Genus: | Juravenator Göhlich & Chiappe, 2006 |
| Species | |
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J. starki Göhlich & Chiappe, 2006 |
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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, about 151 or 152 million years ago. It is known from a single, juvenile specimen. 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.
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Juravenator was originally classified as a member of the family Compsognathidae, making it a close relative of Compsognathus, which preserved evidence of scales on the tail of one specimen, but also of Sinosauropteryx and Sinocalliopteryx, for which there is fossil evidence of a downy, feather-like covering.[1] However, a patch of fossilized Juravenator skin (from the tail base and hind leg) shows primarily normal dinosaur scales, as well as traces of what may be simple feathers.[2] Paleontologist Xu Xing, in his comments on the find in the journal Nature, initially suggested that the presence of scales on the tail of Juravenator could mean that the feather coat of early feathered dinosaurs was more variable than seen in modern birds. Xu also questioned the interpretation of Juravenator as a compsognathid, suggesting the extensive scaly hide could be a primitive trait, though Compsognathus itself also preserves scales on its tail. Xu considered it most likely that Juravenator and other primitive feathered dinosaurs simply possessed more extensive scales on their bodies than modern birds, which retain scales only on the feet and lower legs.[3]
Xu's interpretation was supported by further study of the Juravenator fossil. The first follow-up study to the initial description reported that faint impressions of filamentous structures, possibly primitive feathers, were present along the top of the tail and hips.[2] A more in-depth study, published in 2010, examined the specimen under ultra-violet light. The examination under UV revealed a more extensive covering of filament-like structures, similar in anatomy to the primitive feathers of other compsognathids, including Sinosauropteryx.[4]
While first classified as a member of the family Compsognathidae, subsequent studies have found problems with the initial study that produced those findings. 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.[5] Studies conflict on whether or not compsognathids belong to this later group or are more primitive. Additional work published by Luis Chiappe and Ursula Göhlich in 2010 found that Juravenator was most similar in anatomy to Compsognathus, and that it probably did belong to Compsognathidae if that is actually a natural group. They also suggested that "compsognathids", including Juravenator, may form a grade of primitive coelurosaurs rather than a monophyletic clade.[4]
Comparisons between the scleral rings of Juravenator and modern birds and reptiles indicate that it may have been nocturnal.[6]