How the ‘terror crocodile’ grew so big

Deinosuchus is a giant crocodylian from the Late Cretaceous period of North America. It was 8 to 10 metres long and weighed between 2,500 and 5,000 kg, three to five times more than the largest crocodiles alive today. How Deinosuchus attained sizes to rival its dinosaurian contemporaries, on which it undoubtedly preyed, has remained a mystery. Did it exhibit accelerated growth rates, like its dinosaurian cousins1, or did it simply maintain primitive reptilian rates for decades (as was once proposed to explain gigantism in dinosaurs2)? We find that growth indices from Deinosuchus skeletons reveal rates comparable to those of smaller crocodylian taxa, indicating that the gigantic proportions were attained by prolonging development.