A new expedition of palaeontologists from the University of Pisa to the Ica desert in Peru aims to extend the excavation that in 2023 uncovered part of the skeleton of Perucetus colossus, the cetacean that lived around 40 million years ago and is considered to have been the heaviest animal that ever existed on Earth. Thanks to the use of a large excavator/digger, the researchers were able to significantly expand the search area: starting from the top, several cubic metres of rock were removed from the hillside, up to about one metre above the fossiliferous layer. This has created a large terrace on which the Peruvian palaeontologists can work more easily, using pneumatic hammers to remove the layers of rock that still hide the rest of the skeleton, including – hopefully – the skull.
In the context of the ProArcheo project, co-funded by the University of Pisa, Professor Giovanni Bianucci, the project coordinator, and other palaeontologists from the Department of Earth Sciences of the University of Pisa (Professor Alberto Collareta, Dr Giulia Bosio and PhD student Francesco Nobile), together with geologists and micropalaeontologists from the Universities of Camerino and Milano Bicocca, took part in the expedition. Part of the research was carried out as part of a PRIN project coordinated by Alberto Collareta.
Last year, the discovery of the giant mammal’s remains stirred up a worldwide media hype, to the extent of being regarded as one of the three most extraordinary scientific discoveries of 2023. Perucetus had attracted attention not only because of its massive size – up to 20 metres long – but mainly because it may have been the heaviest animal ever to walk the Earth. In fact, its mass was estimated to reach 340 tonnes, almost twice that of the largest blue whale. The results of the fossil study have been published in the magazine Nature.
“The previous excavations, which lasted more than ten years – Bianucci explains – were severely hampered by the prohibitive conditions of the site. In fact, the fossil was partially buried in a hill located in one of the most inaccessible and inhospitable areas of the Ica Desert, and the rock containing the fossil was extremely hard. The use of the excavator – Bianucci continues – was therefore an extreme solution dictated by the huge importance of the find and the impossibility of continuing the excavation by traditional means. In fact, when recovering fossil finds, great care is taken to limit as much as possible the impact on these desert areas, still untouched by man”.
The discovery of the remains of Perucetus in 2023.
“The fragmented nature of the skeleton found (consisting of 13 vertebrae, 4 ribs and part of the pelvis) – Collareta explains – has left many questions unanswered about various aspects of Perucetus’ morphology and ecology. In particular, the absence of a skull and teeth allows only speculative assumptions about its diet: was it a herbivore, like modern manatees, or a scavenger feeding on the carcasses of marine vertebrates?”
“The next step will therefore be crucial in order to get new clues about what the only known specimen of this extraordinary giant sea creature from almost 40 million years ago looked like and what it fed on”, Bianucci concludes.