Giant Rabbit Skeleton (Nuralagus rex) found on the Spanish island of Minorca

Unfrotunately, Nuralagus rex, also known as the Menorcan King of the Rabbits was too big to hop.

Due to his short stiff spine he would have been forced to clumsily haul himself along like a beaver getting out of water, researchers have said.

A creature initially mistaken for an extinct tortoise has turned out to be a giant bunny that had tiny ears and couldn't hop.

The 5-million-year-old remains of Nuralagus rex were found on the Spanish island of Minorca by independent researcher Josep Quintana. 

At an estimated 12 kilograms, it was around 10 times the weight of wild Spanish rabbits today.

Quintana came across the first fossil in the early 1990s when he was 19. He initially thought it was part of an extinct Minorcan tortoise. Later, Meike Köhler and Salvador Moya-Sola of the Autonomous University of Barcelona's Catalan Institute of Paleontology identified it as a giant rabbit.

Now the three have uncovered enough fossils to reconstruct the entire animal and name it. They say its closest relative was Alilepus, a now-extinct genus whose members were about a tenth the size of N. rex and lived in Eurasia and North America at the time.

Land bridge

Quintana says the ancestors of N. rex colonised Minorca 5.3 million years ago when sea levels in the Mediterranean dropped by about 1.5 kilometres, connecting the Balearic Islands to the mainland.

As sea levels rose again and cut Minorca off, N. rex evolved separately from Alilepus. It shared the island with tortoises, bats and a large dormouse species, and in the absence of predators chose life in the slow lane. 

"If you don't have natural enemies, why run?" asks Quintana. Gradually, its legs grew shorter, its ears shrank and its spine lost the curvature that helps rabbits hop.

Journal reference: Journal of Vertebrate Paleontology, vol 31, p 231