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Reconstructing the Skull of a Cat-Sized Mouse

Scans of skull fragments
Hennekam, J.J.

When University of York Ph.D. student Jesse Hennekam went to the Palermo Museum in Italy, he found himself staring extra hard at a chunk of rock that was excavated from a cave in northwest Sicily in the 1970s. That observation would lead him to be the first person to digitally reconstruct the skull of a giant dormouse that lived on the island about two million years ago. His findings have been reported in the journal Open Quaternary.

According to Hennekam:

“I noticed what I thought were fragments of skull from an extinct species embedded in one of the cave floor segments. We arranged for the segment to be sent to Basel, Switzerland for microCT scanning and the resulting scans revealed five fragmented skulls of giant dormice present within the rock.”

Hennekam then used the scans to digitally remove the bone fragments and, using a digital visualization software program known as Avizo, arranged them and filled in the blanks to recreate the skull, which measures 10 cm long. A head that big would have belonged to a rodent about the same size as a house cat. 

Giants and Dwarves

The discovery could help researchers understand more about a phenomenon known as island gigantism, which is the tendency for animals isolated on islands to grow to extraordinary sizes. While it’s not uncommon for species to shrink in size on islands due to competition for food sources, gigantism is a less understood phenomenon. In fact, Hennekam’s scans of the cave slab also indicated that the cave once contained a giant owl, which joins the other odd and ancient inhabitants of Sicily, including giant swans and dwarf elephants.

“Perhaps, with fewer terrestrial predators, larger animals are able to survive as there is less need for hiding in small spaces, or it could be a case of co-evolution with predatory birds where rodents get bigger to make them less vulnerable to being scooped up in talons,” said Hennekam. 

The skull reconstruction could also help inform future research into the dormouse’s eating habits and, therefore, the environment in Sicily millions of years ago.