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Israeli scientist identifies ‘missing link’ in elephant history
Posted By Nicky Blackburn On December 6, 2006 @ 10:15 am In | No Comments
According to fossil evidence, the animal named Eritreum melakeghebrekristosi by Shoshani, or Eritreum for short, had a long snout and small tasks. It fed mostly on vegetation.
A 27-million-year-old fossil unearthed in Eritrea could be the ‘missing link’ between modern elephants and their ancestors, according to new research by a team of scientists led by Israeli-born scholar Jeheskel Shoshani.
The research, which was published in the online version of Proceedings of the National Academy of Sciences in the US, describes an animal which weighed about half a ton and stood at 1.5 meters tall, about the size of a cow rather than today’s modern elephants.
According to fossil evidence, the animal named Eritreum melakeghebrekristosi by Shoshani, or Eritreum for short, had a long snout and small tusks. It fed mostly on vegetation.
Shoshani, a professor of biology at the University of Asmara in Eritrea and the lead author of the study, acquired the fossil, the lower part of a mandible, in the late 1990s. The fragments of jawbone had originally been discovered by an Eritrean farmer called Melake Ghebrekristos after they had been washed up in floods in the Dogali fossile site in the eastern part of the African country. The farmer gave the bones to a primate expert from Germany who later passed them on to Shoshani.
“When I saw the bones, I noticed right away that they were too small and I felt like I was holding a diamond,” Shoshani said in an interview with Israeli paper Ha’aretz,.
Examination of the bones revealed that they were dated between 27 to 28 million years old. This is highly significant. Elephants date back some 55 million years, but modern elephants only assumed their present appearance and size about one million years ago. Until now, however, scientists had never discovered any elephant remains from between 34 million to 24 million years ago. “These specimens data from exactly the time where there is a gap,” Shoshani told National Geographic magazine.
The jawbone pieces were discovered with teeth in place, allowing Shoshani’s team to note that they feature the horizontal tooth displacement found in modern elephants. Unlike most other mammals, which develop baby teeth and then replace them with a permanent set of teeth, modern elephants have five sets of teeth which rotate during their lifetime. New teeth grow at the back of the elephant’s mouth, then push toward the front. They wear down, fall out, and are replaced by new ones, like a conveyer belt.
If the scientists’ theory is correct, Eritreum would be the earliest known proboscidean, a group of mammals that includes elephants and their extinct relatives, to exhibit this characteristic.
The size of the teeth also indicates the species’ intermediate evolutionary stage. The teeth are the same size as the teeth of paleomastodons, a related family that lived some 35 million years ago, but are smaller than another family of proboscideans that lived between 12 and 2 million years ago, preceding today’s large elephants.
According to Ha’aretz, 63-year-old Shoshani grew up on Kibbutz Misgav Am, where he worked as a shepherd. After his army service he tended animals at the Tel Aviv zoo.
He moved to the US to study veterinary medicine, but later moved into the field of evolutionary biology. In 1986 he completed his doctorate at Wayne State University in Michigan, where he specialized in elephant physiology.
In 1998, Shoshani moved to Eritrea, a poor country in the north east of Africa which received its independence from Ethiopia only seven years earlier, to study a unique population of elephants who had been isolated from other members of the species, leading to inbreeding and genetic mutations.
Researching the elephants proved extremely difficult, however, as the herd roamed an area on the Ethiopian-Eritrean border, where thousands of people have been killed in a brutal war that has been raging for the last eight years. Shoshani, who was often the only Israeli in Eritrea apart from Israeli embassy staff, now researches the elephants from Ethiopian territory.
While it is customary to name new species after the scientist who discovers them, Shoshani told Ha’aretz that he chose to name his ancient elephant after the farmer who found it, and the country in which it was unearthed. He said he hoped this would help encourage the people of Eritrea to assist scientific research.
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