Visiting Mio-Pleistocene fossil sites of Menorca

The last week of May-first of June, I travelled to Minorca (Balearic Islands, Spain) with some paleocollegues to visit the historic fossil sites described by Dorothea Bate, and we talked about new research projects.

Dorothea Bate (1878-1951) was a pioneering British paleontologist and ornithologist, best known for her work on the fossil fauna of the Mediterranean islands. She was one of the first women to establish a career in paleontology and made significant contributions to the field. She joined the Natural History Museum in London at the age of 19, starting in the Department of Geology. Bate's most significant work involved the study of fossil mammals and birds from Mediterranean islands such as Crete, Cyprus, or Balearic Islands (Majorca and Minorca). She discovered several extinct species, including the Cretan dwarf elephant (Elephas creticus), the Cypriot pygmy hippopotamus (Hippopotamus minor), and the dwarf goat (Myotragus balearicus), giant dormouse (Hypnomys morpheus) and the giant shrew (Nesiotites hidalgo) from Balearic Islands (Spain). Bate's work significantly advanced the understanding of island biogeography and the evolution of insular dwarfism and gigantism. In a male-dominated society, Dorothea was known for her determination, curiosity, and passion for natural history and demonstrated her exceptional dedication and resilience.

We visited the small coastal site Punta Esquitxador 17, which has a karstic origin. There, we could observe in situ material, such as long bones, teeth, and a complete mandible of Hypnomys mahonensis. Hypnomys is an extinct genus of dormice that lived on the Balearic Islands (Majorca and Minorca). The genus includes species like Hypnomys mahonensis, known for its larger size compared to modern dormice. These rodents evolved unique adaptations due to their isolated environment, developing robust skulls and strong teeth for processing a varied diet. The genus went extinct, likely due to a combination of climate change, human impact, and the introduction of new predators or competitors.

Figure 1. Historic fossil site described by Dorothea Bate at the start of XXth century. In it, reamins of turtle can be found. CC BY-NC-ND 4.0 DEED B. Moncunill-Solé.

Figure 2. Remains observed in situ in the fossil sites visited. On the left, a jaw of Hypnomys mahonensis (Punta Esquitxador 17), one of the giant species of the dormouse from the Balearic Islands (Spain); and on the right, a fragment of bone of Nuralagus rex (Punta Nati-2), the giant leporid from Menorca (Spain). CC BY-NC-ND 4.0 DEED B. Moncunill-Solé.

Figure 3. Skull of Myotragus balearicus, exposed in the Museu de Menorca (Maó, Minorca, Spain). CC BY-NC-ND 4.0 DEED B. Moncunill-Solé.

Around the same hole, in Punta Nati-2, there is sedimentary layers full of Gymnesicolagus aff. gelaberti (Middle Miocene). This species is very similar to Gymnesicolagus gelaberti described in Mallorca. G. aff. gelaberti had a very big size (ca. 5.4 kg), consequence of the insular evolution. It also shows a very short diastema, a primitive character shared with continental ochotonids and insular leporids. The fauna from Punta Nati-2 may represent an endemic association or a faunal group closely related to the fauna of Mallorca, but in an older context. The age of Gymnesicolagus and the presence of a similar species in Mallorca and Minorca suggest a connection between both islands and the existence of an emerged area in Minorca after the Tortonian transgression.

In addition, we can also visit Punta Nati-2, the type locality of Nuralagus rex, the giant leporid (rabbit) from Menorca. Punta Nati-2 is a fossil site of karstic origin located around a vertical hole that connects with the sea. Nuralagus rex, also known as the Menorcan giant rabbit, is an extinct species of rabbit that lived on the island of Menorca during the Pleistocene epoch. It is notable for its large size, much larger than any modern rabbit species, which is an example of insular gigantism. Unlike its modern relatives, N. rex had a robust and heavy body, short limbs, and a reduced ability to hop. Its adaptations likely included a slow-moving lifestyle and a diet of tough, fibrous vegetation. The species' extinction is thought to be due to environmental changes and possibly human activities. N. rex provides valuable insights into how isolation and unique island conditions can drive distinctive evolutionary paths.

We ended the fieldtrip visiting the Museu de Menorca, where in a cabinet (at the beginning of the exposition) you can view a skull of Myotragus balearicus from sa Cova Es Rovellar (125000-2200 aC). Check here a 3D reconstruction. I enjoyed a lot this experience!