This Gigantic Rabbit Was 30lbs and Towered Over Today’s Versions

For most of their history, members of the rabbit family fitted perfectly into an image of small, floppy-eared critters that were relatively small in size. However, the recent discovery of a gigantic rabbit weighing over 25 pounds suggests that the size range exhibited by the members of this family that we are familiar with may not be entirely accurate. The discovery also confirms that, as far as evolution is concerned, strange things happen on islands. 

Nuralagus is a genus of rabbit from the family Leporidae. It is known from a single species, Nuralagus rex, described in 2011. Nuralagus rex lived during the Late Neogene era, which was about 2.5 million years ago. The name Nuralagus rex translates roughly as “Rabbit King of Minorca,” which refers to the Island where the rabbit was discovered and a sly reference to the giant dinosaur, the Tyrannosaurus rex. Of course, this rabbit is not anywhere near the dinosaur in size, but it was pretty gigantic for a rabbit.  

Discovery

The gigantic rabbit lived on Menorca, an island in the western Mediterranean, during the Pliocene epoch. The Island located south of Spain was once home to a unique assemblage of animals. Their isolation allowed them to evolve into fascinating specimens. 

The fossils of this giant rabbit are known from fissure-fill deposits on the Northwest part of the Island. The fossil was first described in 1981. However, it wasn’t until 2011 before the first complete description of the genus and species was eventually published. 

Paleontologists had to painstakingly dissolve the red limestone rocks around the bones with acetic acid before they were able to extract bone pieces that provided a clear picture of how this massive bunny might have looked. Bones recovered included the front half of its skull and numerous postcranial bones from other parts of its body. 

What Did This Gigantic Rabbit Look Like? 

From the bits and pieces of bones recovered from multiple individuals, paleontologists have been able to piece together how this giant rabbit might have looked. Of course, the massive size of this bunny was the most astounding discovery. 

According to estimates, it weighed an average of 12 kg (26 lb). However, paleontologists have uncovered gigantic rabbit fossils of individuals that might have weighed up to 23 kg (50 lb). By the average estimates, the Nuralagus would have been about six times the size of its living cousin, the Common European rabbit. The Flemish Giant Rabbit is the only living rabbit comparable in size to the giant Nuralagus. It has an average weight of 6.8 kilograms (15 lb) with a maximum weight of up to 10 kilograms (22 lb). 

The massive size of the Nuralagus meant some changes in its overall anatomy. It was a bulky animal that could not hop around like present-day rabbits. It had relatively short and stiff lumbar vertebrae, which would have made leaping difficult.  

Gigantic rabbits also had splayed forelimbs and hindlimbs. This arrangement was necessary to spread the rabbit’s bulky weight over a larger area and reduce pressure on its joints. The structure of the lower arm bones of this rabbit would have allowed the entire forefoot (instead of just the tips of the toes) to make contact with the ground. It had curved fingers that were spread out on its robust arms. This would have made it easier for this titano-bunny to dig up roots and other foods underground.  

Why Was the Nuralagus So Big? 

Scientists believe that the king rabbit’s massive size is one of the oldest examples of the “Island rule” in mammals. According to this theory, when restricted to living on an Island for several million years, big animals are likely to evolve into small sizes while smaller animals are likely to become bigger. 

This tendency to evolve into different sizes is due to two major factors: reduced availability of food and the lack of predators. In the case of this giant rabbit, the lack of predators allowed it to evolve differently. 

One major clue that this rabbit didn’t have to deal with predators was that it had a relatively small head with small eyes and ears. These traits suggest that the rabbit was not built to detect prey or escape from danger quickly. 

Living on an isolated island meant the Nuralagus did not have to deal with large predators. So far, the only large predators scientists have found in deposits from the same location are the barn owls. While these were large, they were not big enough to prey on the Nuralagus. Since the Island was virtually free from predators, it provided a setting that allowed the rabbit to evolve into the modified giant version. 

Interestingly, this rabbit species isn’t the only one that has evolved this way. Scientists have drawn similarities between the Nuralagus rex and Pentalagus furnessi (also known as the Amami rabbit). The Amami rabbit also lived on an island with no natural predators. This allowed it to develop similar physical characteristics such as small eyes and relatively smaller ears compared to other species of rabbits and hares. 

When Did This Gigantic Rabbit Go Extinct?

This gigantic rabbit lived and flourished for a long time on Menorca island. However, they probably became extinct towards the end of the Pliocene epoch, about 2.5 million years ago. At the time, their home island Menorca became united with Mallorca as a single island. Low sea levels as a result of glaciation connected these two islands. This allowed the migration of other mammals to the Island. The invading species, which comprised the goat-antelope Myotragus, the Nesiotites (a type of shrew), and the dormouse Hypnomys outcompeted the giant rabbit and eventually drove them to extinction. 

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The photo featured at the top of this post is © NobuTamura email:[email protected] palaeocritti / CC BY-SA 3.0 – License / Original