Hypnomys

Hypnomys, otherwise known as Balearic giant dormice, is an extinct genus of dormouse (Gliridae) in the subfamily Leithiinae. Its species are considered examples of insular gigantism. They were endemic to the Balearic Islands in the western Mediterranean from the Early Pliocene until their extinction around the 3rd millennium BC. They first appeared in the fossil record on Mallorca during the Early Pliocene (around 5 million years ago), presumably as a result to the evaporation of the Mediterranean sea during the Messinian salinity crisis (5.96-5.33 million years ago) connecting the Balearic Islands with mainland Europe. They later spread to Menorca, and a possible molar is also known from Ibiza. Hypnomys became extinct during the late Holocene (around 4500-4000 years ago) likely shortly after human arrival on the Balearics. They were one of only three native land mammals to the islands at the time of human arrival, alongside the shrew Nesiotites and goat-antelope Myotragus. Their closest living relatives are of the genus Eliomys, including the European garden dormouse (Eliomys quercinus).

== History of discovery == The first remains of Hypnomys were discovered in 1910 on the island of Mallorca in the Balearic Islands by British palaeontologist Dorothea Bate, with remains also found by Bate on Menorca a year later. Upon first examination, Bate considered the fossils to represent those of Eliomys or Leithia, but in 1918 described the remains into the new genus Hypnomys, describing two species, H. morpheus on Mallorca, and H. mahonensis on Menorca.