Monday, 28 January 2013

J is for Juravenator

Continuing on with our alphabet, we come to J. Unfortunately, there are no dinosaurs from Alberta that start with the letter 'J', so we bring you 'J is for Juravenator', which is a small theropod from Germany.

Juravenator is known from a single specimen found in southern Germany, and lived during the Late Jurassic, approximately 151 million years ago. Although it is only known from one specimen, this specimen is extremely well preserved and almost entirely complete. First discovered in 1998, it had an interesting past. It was very difficult to prepare, as the surrounding rocks are very tough and the bones are fragile, and at one point it was abandoned, thought to not be worth it. After gaining press from 1999-2001, it was finally looked at again in 2003 when they discovered a nearly complete dinosaur, which was named in 2006 [1]. The name means 'Jura-hunter', where Jura signifies that it was found in the Bavarian Jura mountains. The fossil was found in layered limestone from the Solnhofen region of Germany, typified by very fine-grained sediments. This area is known for the beautiful preservation of fossils due to the quiet lagoon-type setting these animals died in. 
Image of Juravenator from Goehlich and Chiappe [1]

The single specimen of Juravenator is a juvenile, known by the lack of fusion between bones and still-open sutures in the vertebrae [1]. Like other small theropods, it was a bipedal carnivore, and was less than a metre in length (but remember, it's just a juvenile!). The initial description found that Juravenator had no evidence of feathers or integumentary covering, which was interesting considering it was thought to be closely related and nested within many dinosaurs known to have filamentous coverings [1]. However, a re-examination of the fossil in 2010 revealed (through the use of ultra-violet light) that the animal actually had many small filaments covering various parts of the body, which is similar to other closely related coelurosaurs like Sinosauropteryx [2]. These filaments are thought to be 'primitive feathers' and can be found in many theropod dinosaurs. Another interesting thing about Juravenator is that it also shows evidence of scales, which is highly unusual as scales and filaments are rarely found together [2]. Of further interest, it happens to be one of the most complete non-avian (as in not a bird) theropod skeletons to be found in Europe!

Hopefully you enjoyed learning about the small theropod Juravenator. You can learn more about this little dino from Brian Switek's post, since we independently came up with the same guy for our features! Next week, we'll be back to dinosaurs from Alberta for our dinosaurian alphabet, with the letter 'K'!

1. Goehlich, U.B., and Chiappe, L.M. 2006. A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago. Nature 440: 329-332.
2. Chiappe, L.M., and Goehlich, U.B. 2010. Anatomy of Juravenator starki (Theropoda: Coelurosauria) from the Late Jurassic of Germany. Neues Jahrbuch fuer Geologie und Palaeontologie - Abhandlungen 258: 257-296.

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