Obscure Dinosaur of the Week: Juravenator starki

Name: Juravenator starki
Etymology: After the Bavarian Jura mountains, and the Latin 'venator' (hunter); and the Stark family, who own the quarry where the fossil was found
Distribution: Late Jurassic (Late Kimmeridgian) of Germany
Type Specimen: Near complete articulated skeleton, missing only the last third of its tail
Estimated size: 75-80 cm (juvenile)
First described by: Göhlich et al., 2006

Interesting fact: This little guy should be more famous...

Although the average person may not have heard of Juravenator starki, it's certainly well known to palaeontologists, due to its near perfect preservation. All the skeletal elements are present, except for the last third of the tail. There's even soft tissue preservation, along the tibiae (lower leg) and between the 8th and 22nd caudal vertebrae (part of the tail) (Göhlich et al., 2006). Because of this fantastic preservation it has been included in numerous papers, including those focusing on its anatomy (Chiappe et al., 2010), estimated body size (Therrien et al., 2007), eye function and possible nocturnality (Schmitz et al., 2011), phylogenetic relationships (Butler et al., 2007), and of course, taphonomy (Reisdorf et al., 2012).

A number of coelurosaurs  have been found possessing fossilised feathers or feather-like structures. J. starki is also a coelurosaur, however the authors found an, "...absence of feathers or feather-like structures..." in this specimen, including no evidence of structures that would support feathers in the preserved soft tissue. You might expect that in an almost perfectly preserved specimen such as this, if there were any feathers present then they would have been fossilised. But absence of evidence is not necessarily evidence of absence. And quite rightly, the authors point out that changes in season or growth stages may influence the presence or absence of feathers.

Look at this beautifully preserved holotype! Everything is in place, except for the tip of the tail. Soft tissue imprints around the tail are labelled 'st'.

Simplified cladogram of all non-avian dinosaurs. J. starki was a coelurosaur, within theropoda.

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References
Butler, R. J., Upchurch, P. 2007. Highly incomplete taxa and the phylogenetic relationships of the     theropod dinosaur Juravenator starki. Journal of Vertebrate Paleontology 27(1), 253-256.

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.

Göhlich, U. B., Chiappe, L. M. 2006. A new carnivorous dinosaur from the Late Jurassic Solnhofen     archipelago. Nature 440, 329-332.

Reisdorf, A. G., Wuttke, M. (2012). Re-evaluating Moodie’s Opisthotonic-Posture Hypothesis in         Fossil Vertebrates Part I : Reptiles — the taphonomy of the bipedal dinosaurs Compsognathus     longipes and Juravenator starki from the Solnhofen Archipelago (Jurassic, Germany).                 Palaeobiodiversity and Palaeoenvironments 92 (1), 119-168.

Schmitz, L., Motani, R. 2011. Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit             Morphology. Science 332 (6030), 705-708.

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.