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Five-million-year-old whale fossil found in Mallorca quarry
A FOSSIL of a whale’s head dating back approximately 5.7 million years has been found in a limestone quarry in Santanyí on the island of Mallorca.
The first of its type ever to be found in the so-called ‘chalk strip’ across the Mediterranean, the skull was discovered inside a chunk of stone weighing three-quarters of a metric tonne in a mine near s’Horta, part of the town of Felanitx.
Members of the archaeological team, from the University of the Balearic Islands’ (UIB’s) Earth Sciences Research Group – part of the Faculty of Biology – say there is absolutely no doubt the fossil is that of a skull of a sea creature of the Mysticeti sub-order, which refers to baleen whales, so-named because of the series of baleen plates along their upper jaws which act as a filter system.
This sub-order is also known as ‘whalebone whales’ or ‘great whales’ and, in the case of the head found, shares features typical of the Balaenopteridae family – referred to as ‘rorquals’ and covering the fine whale, humpback whale and the blue whale, which is the largest species on earth and grows to 25 metres (82 feet) in length.
Sightings of fin whales, which grow to 21 metres (just under 69 feet), are fairly common in around September in the western Mediterranean, especially near the Cabo de la Nao cove between Dénia and Jávea (northern Alicante province), mainland Spain’s easternmost point, since the area is directly on their migration path south from the Ligurian Sea.
The quarry in Santanyí corresponds with a Mediterranean-wide stratum known as the Terminal Carbonatic Complex, or ‘chalk strip’, which formed during the so-called ‘Salt Crisis’ at the end of the Miocene era between 5.9 and 5.3 million years ago.
Natural barriers, including Spain’s ‘bridge to Africa’ through the Alborán Sea, prevented the Atlantic and Mediterranean mixing and cut off the salt supply from the former to the latter, meaning the Mediterranean almost became a giant freshwater lake until the waves began to reclaim the land and the salt balance was restored in the Pliocene era, between 5.3 and 2.6 million years ago.
It is thought the giant whales which would have been native to the area became temporarily extinct during the Salt Crisis, but started to reappear there once normal sea conditions began to return.
The whale found in Santanyí is thought to be one of those which died out during the Salt Crisis, especially given its location in the limestone strip which formed around the same time.
But as yet, it is the first fossil of a great whale to be found there, and the first from so long ago, the UIB team reports.
The dimensions of the fossil, compared with others of the Balaenopteridae family and to skeletons of much more recent examples, have led the researchers to believe the creature whose skull they have found would have been about eight metres (26 feet) long and around seven or eight metric tonnes in weight.
These features are similar to the modern-day species known as the Common Minke – a type which lives in any kind of ocean, from tropical to polar, and which is the smallest of the rorqual family: up to 5.5 metres (18 feet) long and 5.6 tonnes in weight when fully grown.
The above photograph of a rorqual whale skeleton is similar to the type which would have been found in Santanyí.
Picture: JISA39/Wikimedia Commons
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