Scientists have found new information on how prehistoric dogs hunted 40 million years ago - by analysing the skulls of lions, wolves and hyenas.
Experts in Scotland and Austria found that the first species of dog, known as Hesperocyon gregarius, pounced on its prey in the same way that species such as foxes and coyotes do today.
They also discovered that the largest dog species hunted in a similar way.
The Epicyon haydeni could grow to the size of a grizzly bear.
It lived from 16 million to seven million years ago.
The study focused on the hunting methods used by prehistoric members of a group of mammals known as carnivorans, which includes modern-day foxes, wolves, cougars and leopards.
Scientists at the universities of Edinburgh and Vienna used computerised scans of fossils and modern animals to create digital models of the inner ears of 36 types of carnivoran, including six extinct species.
Experts found that the size of three bony canals in the inner ear, the organ that controls balance and hearing, changed over millions of years as animals adopted different hunting styles.
Faster predators, such as cheetahs, lions and wolves, developed large ear canals that enabled them to keep their head and vision stable while chasing prey at speed, the team said.
According to the research, the inner ear structure indicates whether a species descended from dog-like animals or animals resembling cats.
A distinctive angle between two parts of the inner ear is much larger in dog-like animals, the team found.
The study is based on research carried out by Edinburgh PhD student Julia Schwab during studies in Vienna.
Ms Schwab, of the University of Edinburgh's School of GeoSciences, said: "For me, the inner ear is the most interesting organ in the body, as it offers amazing insights into ancient animals and how they lived.
"The first dog and the largest-ever dog are such fascinating specimens to study, as nothing like them exists in the world today."
The study has been published in the journal Scientific Reports.