Rats ‘could grow to be bigger than sheep’

Rats could grow to the size of sheep or even bigger as they evolve to fill vacant ecological niches, it is claimed. The terrifying scenario could become a reality as super-adaptable rats take advantage of larger mammals becoming extinct, an expert predicts.

“Animals will evolve, over time, into whatever designs will enable them to survive and to produce offspring,” said geologist Dr Jan Zalasiewicz, from the University of Leicester.

“For instance, in the Cretaceous Period, when the dinosaurs lived, there were mammals, but these were very small, rat and mouse-sized, because dinosaurs occupied the larger ecological niches.