An Ancient Descendant: The Straight-Tusked Elephant
Imagine. It is the end of the Late Pleistocene around 100,000 years ago. Ancient creatures that have long since been extinct roam throughout Europe. In the mix of biodiversity, something unexpected is found roaming the plains: an elephant. The Straight-Tusked Elephant, Elephas antiquus, is an ancient ancestor of the elephants that we know and love today.
The Straight-Tusked Elephant is one of the largest pachyderms to be discovered, standing 12 feet tall and weighing in at around 13 tons², about two times the weight of an average African Savannah elephant.¹ As inferred by its name, a key characteristic of straight-tusked elephants is their long and relatively straight tusks. They also have unusually long tongues, hypothesized to have measured over 80 inches long.⁴ Scientists believe that Straight-Tusked elephants used their tongue and trunk to graze on leaves from trees over 25 feet tall.⁴ It is estimated that these elephants roamed the plains of Western Europe in herds of about a dozen.⁵ They were eventually out-competed by the Woolly Mammoth.⁵
Upon skeletal reconstruction and anatomical analysis, it was assumed that the Straight-Tusked elephant was a descendant of the Asian elephant, Elephas maximus.³ However, it is very difficult to find evolutionary relationships between species of animals solely based on anatomy. An additional way to understand evolutionary relationships is by analyzing similarities in DNA sequences. It is easier to extract DNA from relatively younger fossils that have been preserved in colder temperatures. However, very few DNA sequences have been extracted from fossils over 100,000 years old. Paleontologist Matthias Meyer and his team of researchers have been capable of extracting the DNA of four Straight-Tusked elephants ranging from 120,000 to 240,000 years old.³ The DNA extracted from fossils of the ancient creatures was then used to analyze the true relationships between the Straight-Tusked elephant and the three live elephant species (the Asian elephant, African Savanna elephant, and the African Forest elephant). The analysis³ disproved previous hypotheses, proving that the Straight-Tusked elephants are most closely related to the African Forest elephant, Loxodonta cyclotis, not the Asian elephant, as it was previously thought to be. This is extremely important with the recreation of evolutionary trees. It proves that African elephant lineage was not only restricted within Africa, but it also stretched throughout Western Europe as well.
Results from the DNA sequencing demonstrates the added insight DNA analysis can provide for understanding evolutionary relationships of animals. Future research could include obtaining DNA sequences from other extinct elephant species in order to accurately piece together the evolutionary tree of elephants. Only through DNA sequencing can scientists be sure of the evolutionary relationships between different species of the past and the present.
References:
¹"African Elephant.” National Geographic. September 21, 2018. Accessed October 24, 2018. https://www.nationalgeographic.com/animals/mammals/a/african-elephant/
²Larramendi, Asier. “Shoulder height, body mass, and shape of proboscideans.” Acta Palaeontologica Polonica 61, no. 3 (2015): 537–574.
³Meyer, Matthias, Eleftheria Palkopoulou, Sina Baleka, Mathias Stiller, Kirsty EH Penkman, Kurt W. Alt, Yasuko Ishida et al. “Palaeogenomes of Eurasian straight-tusked elephants challenge the current view of elephant evolution.” eLife 6 (2017): e25413.
⁴Shoshani, J., N. Goren-Inbar, and R. Rabinovich. “A stylohyoideum of Palaeoloxodon antiquus from Gesher Benot Ya’aqov, Israel: morphology and functional inferences.” In Proceedings of the First International Congress of La Terra degli Elefanti, The World of Elephants. Consiglio Nazionale delle Ricerche, Roma, pp. 665–667. 2001.
⁵Strauss, Bob. “Straight-Tusked Elephant Facts.” ThoughtCo. March 17, 2017. Accessed October 24, 2018. https://www.thoughtco.com/straight-tusked-elephant-elephas-antiquus-1093149
