University of Portsmouth palaeontologists have discovered a tiny dinosaur that could be the worlds smallest.

 

AM

The bird-like dinosaur that lived in the Mesozoic era as early as 250 million years ago, and believed to be the size of a magpie, was found by fossil hunter Dave Brockhurst at Ashdown Brickworks in East Sussex.   Dr Darren Naish and Dr Steve Sweetman who have analysed the fossil have concluded that the mini-dinosaur is a meat eating dinosaur which estimate measured just 33 and 40cm in length making it the smallest dinosaurs discovered from the Mesozoic era.

Dr Steve Sweetman said: "This is such an exciting find as it represents the smallest dinosaur we have yet discovered in the European fossil record. Originally it was identified as the vertebra of a snake but once I saw it I knew straight away it was far more likely to be the vertebra of a tiny theropod. My colleague Darren is a theropod expert so I borrowed the specimen, showed it to him, and we concluded that it was in fact a tiny adult theropod dinosaur."

The dinosaur, which has been named Ashdown maniraptoran after the brickworks, has been identified from only a single neck vertebra, which nevertheless contains enough information to show it was part of the large group that included all of the two-legged, meat-eating dinosaurs called theropods.

Dr Naish said: "Determining the total length of the specimen from just a single bone is highly speculative, but we used two techniques to provide a rough estimate of size."

The palaeontologists were able to confirm that the remains came from a fully grown dinosaur because the main body of the neck vertebra is fully fused to the arch-shaped part of the vertebra that sits on top which indicates the mini-dinosaur was skeletally mature.

The methods used were complex, the first involving duplicating digital versions of the vertebra to make a complete neck.  This 'digital' neck was then positioned within the silhouette of a maniraptoran. This technique suggested a total length for the Ashdown maniraptoran of just 45 cm.

Dr Naish said: "This method is more art than science because it relies on the assumption that the silhouette is correct to begin with but it gives us a reasonable idea of roughly what length the specimen could have been."

The second method to estimate the size of the Ashdown maniraptoran also involved using the reconstructed digital neck, but this time with data from neck length of other maniraptorans.  This technique suggested a total length for the Ashdown maniraptoran of somewhere between 33 and 50 cm, with the lower being most likely.

The dinosaur-bearing rocks at the Ashdown Brickworks in East Sussex have yielded lots of other fossils including the remains of salamanders, frogs, lizards, turtles, crocodiles, and various kinds of large dinosaur.