Compsognathus Growth Series

Back in the mid-1800's, fossils dug from the Solnhofen Limestone deposits near Eichstätt in Germany's Bavarian region produced wide acclaim for the preservation of pterosaurs, insects, crocs, snakes, lizards, and so forth. One specimen, a reptilian dinosaur, was found with a lizard coiled in its belly. Germany's Andreas Wagner, given the responsibility of describing the specimen, named it Compsognathus longipes, or "long-footed delicate jaw". A decade later another specimen was referred to the species, but it later turned out to be an Archaeopteryx specimen, and a new specimen wouldn't be found until the 1950's, when French researchers at the Solnhofen-aged site of Canjuers would recover a new specimen, much larger than the original, but would name it Compsognathus corallestris, or "delicate-jaw, dweller among corals," as the authors beleived the arms to be adapted into flippers and it swam in the warm, shallow seas of the Late Jurassic in Europe. But speculation has always considered the specimens to be the same species, with ontogenetic reasons accounting for the differences. The top specimen above is this French specimen, while the original German specimen is just below and to the right of it. At this point in history, the most substantial debate in regards to this odd, generic creature would be the number of fingers. Both specimens are preserved with only enough phalanges and claws to account for two fingers on each hand, as shown, and this argues the hands only had two fingers each. However others have argued that the third metacarpal, which is preserved, should preclude the presence of a third digit (shown here as a stub), but also fully developed with a claw. This evidence is lacking. At least until about 10 years ago, when two important discoveries were made.

The first was Sinosauropteryx prima, a "bird" found in China's Liaoning Province and from a formation just about 15 million years after the Solnhofen. This animal, with it's fantastically long tail and coating of fine, clumped-strands of "dinofuzz" (but similar to natal down in birds), also possessed three distinct, robust fingers on each hand, and more so, the hands were extremely large and heavy-clawed. This seems in direct contrast to the slender construction in Compsognathus. The second discovery was a small, peculiar skull from Germany's Solnhofen. Only recently, it was fully prepared and found to preserve a nearly complete and articulated skeleton missing only elements of the tail. Moreover, like Compsognathus longipes, the vertebrae were not fused together, and the head is extremely large compared to the rest of the animal. This results in a heavy-headed animal, and it is shown on the bottom of the picture in scale. It was named Juravenator starki, or "the Stark family's Jura [region] hunter". The skull is slightly smaller, 20% less, than the holotype of Compsognathus, while the remainder of the skeleton is clearly much smaller than that, showing features relating to the juvenile growth of this group of animals.

However, most peculiarly, Juravenator is likely a juvenile specimen of Compsognathus, and there is a revival of the idea that C. corallestris is an adult C. longipes, showing us that what you see above, rather than three different species, might be the same species in various stages of life.