Brain of giant prehistoric rabbit reconstructed to understand evolutionary development of mammals
Scientists have created a virtual “cast” of the brain of a prehistoric rabbit that lived millions of years ago, providing insights into the evolutionary development of mammals’ brains.
An ancient relative of today’s rabbit called the Megagalus, which lived 34 million years ago and may have weighed around 2kg, its skull was found by a researcher from the University of Chicago Walker Museum during paleontological excavations in 1941 on the site of a ranch in Nebraska, in the American Midwest.
The skull underwent X-ray microtomography, which allowed a 3D image to be created. After that, scientists virtually filled it, creating a digital brain cast.
Now scientists in Poland and Canada have used this rare find to create a “cast” of the animal’s brain.
First, the skull underwent X-ray microtomography, which allowed a 3D image to be created. After that, they virtually filled it, creating a digital brain cast.
The ancient relative of today’s rabbit called the Megagalus, which lived 34 million years ago, may have weighed around 2kg.
Prof. Łucja Fostowicz-Frelik of the Institute of Paleobiology at the Polish Academy of Sciences, which initiated and led the research, said: “Our pioneering early ‘rabbit’ brain research is very important for the evolutionary biology of the entire Euarchontoglires group, including lagomorphs, rodents, squirrels, lotocots and primates, including humans.”
The reconstructed brain provides information on the size of its basic parts, but also on the blood vessels on the brain’s surface and cranial nerves.
Prof. Łucja Fostowicz-Frelik said: “Our pioneering early ‘rabbit’ brain research is very important for the evolutionary biology of the entire Euarchontoglires group, including lagomorphs, rodents, squirrels, lotocots and primates, including humans.”
One of the scientists’ findings is that the ancient rabbit whose skull was found in America had slightly less developed cerebral hemispheres than rabbits today.
"However, it is difficult to say whether this means that these modern rabbits are ‘smarter’,” said Fostowicz-Frelik, pointing to a trend at the time in which there was a gradual increase in cerebral hemispheres visible in all groups of animals.
Diagram showing relationship between the skull volume and body weight in selected groups of Euarchontoglires. Scientists estimate the brain of the Megalagus rabbit (marked with an asterisk) is proportionally smaller in relation to the weight of the animal than in modern lagomorphs, and closer in this respect to the early primates.
Similar animals did not spread in Europe for good until several million years later – around 20 million years – ago, from Asia, she added.
Working with Prof. Mary Silcox from the University of Toronto Scarborough and her team, and Dr Sergi Sergim López-Torres, who is also at the Institute in Warsaw, their findings were published in an article entitled “Cranial endocast of the stem lagomorph Megalagus and brain structure of basal Euarchontoglires” published in the Proceedings of the Royal Society B.
