The barn owls of South Africa, star witnesses of the e

The Wonderwerk Cave in South Africa is home to an exceptional collection of small mammal fossils dating from 2 million years ago to the Lower Palaeolithic. For the first time, the Complutense University of Madrid (UCM) and the National Museum of Natural Sciences of Spain (MNCN-CSIC) have, following an analysis of the processes that gave rise to these formations, demonstrated that the dominant predator throughout this long period remained constant: the barn owl (Tyto alba).

The information obtained and published in International Quaternary is of great importance. “Given the absence of predator changes during the sequence, we can confirm that any possible change in the composition of the micro-mammal assemblage does not result from a predator’s preferences, but from environmental changes” , explains Sara García Morato, researcher. at the Department of Geodynamics, Stratigraphy and Paleontology of UCM and MNCN.

Micro-mammals are considered good environmental and climatic indicators because they react quickly to changes in their environment. Prior to carrying out a paleo-environmental study, a taphonomic analysis is first required in order to confirm the origin and the agent or agents at the origin of the fossil assemblage.

According to García Morato, “In the case of the South African deposit, this long continuation of the same type of predator ensures that paleoecological interpretations of the site provide us with reliable paleoenvironmental results over nearly 2 million years. , which is quite exceptional.

To carry out the work, the researchers study the different skeletal elements of micro-mammals, the degree of breakage and the damage caused to bone tissue during the digestion process.

These results are compared to the patterns of different predators, in this case nocturnal and diurnal raptors and carnivorous mammals, which could give rise to assemblages of micro-mammals. “Each predator produces its distinctive signature on the prey it ingests,” says Yolanda Fernández Jalvo, researcher at MNCN.

“In this study, the fossils obtained revealed little modification, which is typically associated with the presence of barn owls”, continues Marin Monfort, lead author of the study and researcher at the museum.

Tendency to aridity

In addition to predator changes, taphonomic studies serve to confirm or rule out the presence of other processes such as transport, acid corrosion, or the formation of manganese deposits, all of which have implications for paleoenvironmental, paleoecological, and paleoclimatic interpretations. . .

In the case of Wonderwerk, manganese oxides can be found, usually deposited on the surface of bones when the atmosphere is humid. “The presence of manganese oxides decreases as the era to which the fossils correspond is more modern, which allows us to confirm a climatic trend towards greater aridity in the region”, adds Fernández Jalvo.

Besides UCM and MNCN, the study also involved the University of Valencia, the Natural History Museum in London, the University of Toronto, the University of the Witswatersrand in South Africa, and other institutions.

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