This news release is available in Spanish.
From the east of France all the way to Russia the hazel dormouse now inhabits practically the whole of Europe. However, on the Iberian Peninsula it is absent just where its first remains were found and which had come from the Miocene, an epoch in which it developed between 23 and 5 million years ago. After spreading to other parts of Europe, it was no longer found in the peninsular fossil register since the start of the Pliocene (at least 4.5 million years ago.) Yet on the Gipuzkoan site of Lezetxiki (Arrasate-Mondragon) UPV/EHU researchers have found remains of the Muscardinus avellanarius from the Upper Pleistocene (between 125,000 and 10,000 years ago). The discovery has been published in the prestigious journal Quaternary Science Reviews.
The discovery made by researchers in the Department of Stratigraphy and Palaeontology and the Department of Geography, Prehistory and Archaeology is a doubly significant one. Firstly, the teeth of the hazel dormouse found in Lezetxiki are the first remains of this species belonging to the Quarternary period to have been found on the Iberian Peninsula because, even though the oldest remains of this genus are from peninsular sites of the Miocene, the absence of more modern records indicates that it disappeared from these lands in the later period, the Lower Pliocene. Secondly, Lezetxiki is the southernmost point in Europe in which dormouse remains have been found, which expands the geographical distribution of this species.
Today, the presence of the hazel dormouse is routinely linked to the existence of hazelnuts (hence its name) although it can be found in different types of forest. Due to its small size and the fact that it rarely descends from the trees, it is a species that predatory birds find difficult to hunt so its presence in sites tends to be insignificant.
The palaeoecological information provided by the hazel dormouse remains found at Lezetxiki confirms the conclusions of the analysis of the microfaunal set identified on the same levels: in short, the climate at that time was similar to that of today so the area around the cave would have been dominated by a wooded landscape.
Lezetxiki is known internationally because it is one of the few sites on the Cantabrian Coast where human remains belonging to Neanderthals and Homo heidelbergensis have been found. What is more, it is not the first time that this cave has held palaeontological surprises. During the most recent digs led by the UPV/EHU lecturer Álvaro Arrizabalaga, his research team also recovered a fragment of a lower jaw of one of the last European exemplars of the macaque (Macaca sylvanus), as well as the first remains of the northern birch mouse (Sicista betulina) located on the Iberian Peninsula.
Garcia-Ibaibarriaga, N., Arrizabalaga, A., Iriarte-Chiapusso, M.J., Rofes, J. and Murelaga, X. 2015. The return to the Iberian Peninsula: first Quaternary record of Muscardinus and a palaeogeographical overview of the genus in Europe. Quaternary Science Reviews 119: 106-115.
Castaños, P., Murelaga, X., Arrizabalaga, A., Iriarte-Chiapusso, M.J., 2011. First evidence of Macaca sylvanus (Primates, Cercopithecidae) from the Late Pleistocene of Lezetxiki II cave (Basque Country, Spain). Journal of Human Evolution 60: 816-820
Rofes, J., Garcia-Ibaibarriaga, N., Murelaga, X., Arrizabalaga, A., Iriarte-Chiapusso, M.J., Cuenca-Bescós, G., Villaluenga, A., 2012. The southwesternmost record of Sicista (Mammalia; Dipodidae) in Eurasia, with a review of the palaeogeography and palaeoecology of the genus in Europe. Palaeogeography, Palaeoclimatology, Palaeoecology 348-349: 67-73