More than two decades ago, a team from the University of Jammu discovered the gigantic skull of an extinct elephant in the Kashmir Valley in India. A new analysis of this mysterious fossil to discover the age and evolutionary context of this megaherbivore led to the conclusion that it was a Palaeoloxodon. More importantly, this impressive skull sheds light on a little-known episode in the evolutionary history of elephants.
An extinct elephant
« From the general shape of the skull, it is quite obvious that the elephant belonged to the Palaeoloxodon, or straight-tusked elephants, among the largest land mammals that ever livedsaid Steven Zhang, study co-author and paleontologist from the University of Helsinki in Finland. “ What has intrigued experts for some time, however, is that the Kashmir fossil does not have a thick, forward-projecting crest at the top of the skulla characteristic yet typical of other Palaeoloxodon skulls found in India. »
Fully grown adult Palaeoloxodon measured almost four meters high and weighed more than 900 kgmaking them slightly smaller than the elephant species living today. They first evolved in Africa about a million years ago, an early African form that had a narrow, convex forehead and underdevelopment of the cranial crest. The more recent Palaeoloxodon, known mainly from fossils discovered in Europe and India, have a very broad and flattened forehead often associated with a thick crest which projects forward from the roof of the skull.
Perplexed scientists
Since the discovery of the Kashmir skull, determining Palaeoloxodon’s position in the elephant evolutionary tree and whether the development of the crest on their skull could differentiate them have sparked controversy among paleontologists. Some recent research has shown that the skull crest of Palaeoloxodon became more prominent with developmental and sexual maturity. If scientists could examine their teeth to determine the age of the animal when it died, then it would be possible to compare skulls of individuals at similar stages of maturity.
« From the size, wisdom teeth, and a few other telltale features of the skull, it is evident that the animal was a majestic male elephant in the prime of life, but the lack of a well-developed cranial crest, especially compared to other mature male skulls from Europe and India, tells us that we have a different species here“, believes Zhang.
The international team of scientists behind the new study noted how features of the Kashmir skull actually looked more like another found this time in Turkmenistan and studied in the 1950s which represents a distinct species: Palaeoloxodon turkmenicus . The Turkmen skull also lacks a crest on the roof of the skull and has similar characteristics to a well-known European species called Palaeoloxodon ancient (see below). According to the team, this has led a number of experts to suggest that the Turkmen specimen is an individual divergent from the European species Palaeoloxodon ancient.
« However, with the Kashmir skull added to the equation, it now becomes apparent that both specimens can be theorized as representing a distinct species about which we knew very little before with a wide distribution from Central Asia to the northern Indian subcontinentsaid Advait Jukar, study co-author and paleontologist at the Florida Museum of Natural History, in a statement.
Unraveling the mystery of this intriguing skull
To examine the problem more closely, the team measured protein breakdown in tooth enamel from the skull of the Kashmiri Palaeoloxodon. These remains were discovered along with 87 basalt stone tools used by prehistoric humans who are believed to have used the elephant in some way without there being any hard evidence of hunting or cutting. However, the study of these tools also played a key role here in helping paleontologists identify the species.
By measuring the breakdown of proteins in the tooth enamel of the Kashmir skull and examining the stone tools buried alongside it, the researchers concluded that the Kashmir skull dates from the Middle Pleistocene period, approximately 300,000 to 400,000 years ago. This age similar to that of the Turkmen skull supports the idea that both represent a species distinct from other Eurasian Palaeoloxodon. According to the team, with its broad, flat forehead and only the faintest trace of a cranial crest,P. turkmenicuscould finally represent a little-known missing link which fills an evolutionary gap in our understanding of the evolution of these prehistoric megaherbivores.
The article appears in the Journal of Vertebrate Paleontology (see here).
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