Mesozoic World

A report released in 2007 showed that a set of ancient footprints had provided compelling evidence that some dinosaurs were able to swim.

A fifteen metre-long trackway revealed one animal's underwater odyssey. It was discovered in the Cameros Basin in Spain, which was once a vast lake. The s-shaped prints suggested the beast clawed at sediment on the lake floor as it swam in something like three metres of water.

The marks were about 125 million years old, dating to the Early Cretaceous, according to the team of scientists who detailed the exploration and examination in the journal 'Geology'. They were left by a large, bipedal, carnivorous dinosaur.

Dr Loic Costeur, a palaeontologist at the University of Nantes, France, and a co-author of the paper explained that they had come across them about three or four years before the report was published. The Cameros Basin has thousands of walking footprints from diverse dinosaur fauna, but when the team saw these particular prints it was obvious straight away that this was a swimming dinosaur.

Immediately obvious

The underwater trackway, which is well-preserved in sandstone, is made up of twelve consecutive prints each consisting of two to three scratch marks. The footprints are quite peculiar in their shape and morphology - they are not at all like walking footprints. In walking footprints, the shape of the foot can be recognised; but here it is not at all the case: the marks are sets of grooves on the sediment surface.

They easily support the idea that the animal's body was supported by water as it was scratching the sediment. Ripple marks around the track suggested that the dinosaur was swimming against a current, attempting to keep a straight path.

Further investigation of the well-preserved track revealed more about the beast's swimming style. The dinosaur swam with alternating movements of the two hind limbs: a pelvic paddle swimming motion. It is a swimming style of amplified walking with movements which are similar to those used by modern bipeds, including aquatic birds.

For many years, the question of whether dinosaurs were able to swim remained unanswered. Investigations into dinosaur anatomy and ecology suggested it was possible, but very little hard evidence existed to document this behaviour. But Dr Costeur described the find as 'extremely exciting' and said it provided the first compelling evidence that dinosaurs were able to swim.

The trackway at La Virgen del Campo would serve to open the door onto several new areas of research. New biomechanical modelling would now be able to increase scientific understanding of dinosaur physiology and physical capabilities, as well as our view of the ecological niches in which they lived.

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