baboon

“They were showing Ridley the baboon because it was an interesting anatomical structure,” Bakowski recalls.

“It sounds like a baboon getting his nose hairs ripped out.”

That would mean they had more neurons than baboons, with perhaps even enough intelligence to use tools — the T. rex's notoriously tiny arms notwithstanding.

"The possibility that T. rex might have been as intelligent as a baboon is fascinating and terrifying, with the potential to reinvent our view of the past," concluded Dr Darren Naish.

Giraffes have roughly the same number of neurons that crows and baboons have, Holtz pointed out, but they don’t use tools or display complex social behavior in the way those species do.