Fearsome dinosaur stalks two continents
The first ever find of a dinosaur species on two continents is causing a rethink on how the North Atlantic Ocean formed.
Confirmation of a fossil from Portugal as being the remains of the fearsome predatory dinosaur Allosaurus fragilis has been reported in the Journal of the Geological Society.
Allosaurus fragilis, which grew to sizes in excess of 10 metres, was first described from the Upper Jurassic rocks (around 145 million year old) of Colorado, USA in 1877. Subsequently similar fossils from Africa, Europe and Australia have been referred to the same genus, but all are scrappy specimens and identifications could not be confirmed.
In 1988 a new specimen was found in Upper Jurassic rocks in Leiria (West Central Portugal), 135km north-north east of Lisbon. This specimen is a partial skeleton but complete enough to confirm that is belongs to A. fragilis. Several other types of dinosaur have been found to have a global distribution but this is the first time that an individual species has been confirmed to have been present on two separate continents.
Prior to this find, it was known that the ancient northern continent Laurasia had began to split apart in the late Jurassic but the size and depth of the forming North Atlantic Ocean had remained a matter of speculation. This find of a land-dwelling dinosaur on either side of the North Atlantic Ocean suggests that there was still significant land connections between Europe and North America at this time.