The landmark findings involving more than 350 fossils will become an important reference point for the origins of horses, rhinos and tapirs, following a 15-year study.
The study has just been published above Journal of Vertebral Paleontology describes a family of fossils that shed light on the origin of perissodactyls – a group of bizarre ungulates that include horses.
It provides insight into the controversial question of where these hoofed animals evolved, concluding that they appeared in or near present-day India.
The research spans years of field trials, bringing together an almost complete picture of the skeleton anatomy of Cambaytherium – an extinct relative of the perissodactyls that lived on the Indian subcontinent nearly 55 million years ago. .
The findings describe a sheep-sized animal with moderate running ability and intermediate traits between specific species of perissodactyls and their more general mammalian precursors.
Comparing its bones to many other living and extinct mammals, it was found that Cambaytherium represented a more primitive stage of evolution than any known perissodactyl species, supporting the group’s origin. at or near India before they dispersed to other continents as the land connection with Asia formed.
The selected article is published as part of the credibility The Memoirs of the Society of Vertebrates, a special annual publication that offers in-depth analysis of the most important vertebrate fossils.
Cambaytherium, first described in 2005, is the most primitive member of an extinct group that branched out just before perissodactyls evolution, providing scientists with unique clues about ancient origins. and group evolution.
Modern orders Artiodactyla (even ungulates), Perissodactyla and Primate appeared abruptly in the early Eocene about 56 million years ago across the Northern Hemisphere, but their geographical origin remains a mystery. hides, ”explained Ken Rose, professor emeritus at Johns Hopkins University and lead author of the study.
Rose is intrigued by a new theory that suggests that perissodactyls may have evolved in isolation in India. At the time, India was an island continent that drifted north, but then it collided with Asia to form a mainland.
He noted: “In 1990, Krause and Maas proposed that these orders may have developed in India, in the process it drifted north from Madagascar, scattered across the northern continents when India colliding with Asia.
With this new theory, Rose and her colleagues received funding from the National Geographic Association to explore India in search of rare fossils-bearing rocks at the exact age that could provide evidence. is important for the origin of perissodactyls and other mammal groups.
The first trip to Rajasthan in 2001 was unsuccessful, only finding a few fish bones.
“The following year, our Indian colleague, Rajendra Rana, continued to explore the lignite mines in the south and to the Vastan mine in Gujarat.”
This new mine shows much more promise.
“In 2004 our team was able to go back to the mine, where our Belgian collaborator, Thierry Smith, found the first mammal fossils, including Cambaytherium.”
Encouraged, the team returned to the mine and collected fossil bones of Cambaytherium and many other vertebrate animals, despite the challenging conditions.
“The heat, the constant noise and the coal dust in the lignite mines are very difficult – basically trying to work hundreds of feet down near the bottom of the open pit lignite mines being mined 24/7,” Rose said. “.
After years of difficult field research, the team can finally unravel a mammal mystery.
Despite the abundance of perissodactyls in the Northern Hemisphere, Cambaytherium suggests that this group may have evolved isolated in or near India during the Paleocene (66-56 million years ago), before dispersing into another continent when the land link with Asia takes shape.
Funds used to support field and laboratory research are provided by the National Geographic Association, the LSB Leakey Foundation, and the US National Science Foundation.