Latin name: Leucrota
Other names: Leucrocuta
A composite beast with a mouth that stretches from ear to ear

General Attributes
The leucrota is a swift beast that lives in India. It is a composite animal, the result of a mating between a hyena and a lioness, the same size as an ass, but with a horse’s head, chest and legs like a lion, hind quarters like a stag, and cloven hoofs. It has an extremely wide mouth, that stretches from one ear to the other. It does not have individual teeth, but only a single bone where teeth should be. Like the hyena, the leucrota can make sounds that resemble human speech.

Sources (chronological order)
Pliny the Elder [1st century CE] (Natural History, Book 8, 30): The leucrocota is the size of an ass, and has the neck, tail and breast of a lion, the haunches of a stag, cloven hooves, a badger’s head, and a mouth that opens from ear to ear, with ridges of bone instead of teeth. It is the swiftest of wild animals, and is said to be able to imitate the human voice.

Source: Medieval Bestiary.

all the animals of Satan’s bestiary, assembled in a consistory and set as guard and crown of the throne that faced them, singing its glory in their defeat, fauns, beings of double sex, brutes with six-fingered hands, sirens, hippocentaurs, gorgons, harpies, incubi, dragopods, minotaurs, lynxes, pards, chimeras, cynophales who darted fire from their nostrils, crocodiles, polycaudate, hairy serpents, salamanders, horned vipers, tortoises, snakes, two-headed creatures whose backs were armed with teeth, hyenas, otters, crows, hydrophora with sawtooth horns, frogs, gryphons, monkeys, dog-heads, leucrota, manticores, vultures, paranders, weasels, dragons, hoopoes, owls, basilisks, hypnales, presters, spectafici, scorpions, saurians, whales, scitales, amphisbenae, iaculi, dipsases, green lizards, pilot fish, octopi, morays, and sea turtles.

Source: The Name of the Rose by Umberto Eco.