 Scientists have produced a wide range of maximum speed estimates , mostly around 11 metres per second ( 25 mph ) , but a few as low as 5 – 11 metres per second ( 11 – 25 mph ) , and a few as high as 20 metres per second ( 45 mph ) . Researchers have to rely on various estimating techniques because , while there are many tracks of very large theropods walking , so far none have been found of very large theropods running — and this absence may indicate that they did not run . 
