Guwahati: An international team which explored the caves in the Tolegre area, South Garo Hills has come up with interesting findings which can throw new light on the age of limestones in the area.
Between March 5 and 22, Core Geo Expeditions, a non-profit research organisation consisting of local and international cavers and speleologists, explored the caves in the Tolegre area, South Garo Hills.
The international team, led by Ayush Singh (Mumbai, Maharashtra, India), Thomas Arbenz (Switzerland) and Eric Momin (Tura, Meghalaya, India) consisted of cavers from Meghalaya (India), Switzerland, the United Kingdom and Romania, and also included biologists from India and Switzerland, documenting the species of bats living in the area. The results of the expedition will be documented in a detailed report later this year.
Researchers say that if closer analyses of the “Tolegre Fossil” prove the assumed genus, it will be the first of its kind in India.
On March 14, a team consisting of Dr Tudor L. Tămaș (Babeș-Bolyai University, Cluj-Napoca, Romania), Milton M. Sangma and Salban M. Sangma (both from Baghmara, South Garo Hills, Meghalaya, India) was surveying Gongdap Kol, a temporary sinkhole with a large entrance on a bedding plane, situated close to a dry meander of the Chibe river.
The limestones in which the cave is developed belong to the Siju formation, consisting of banded alternations of arenaceous, foraminiferal limestones with pyrite, carbonaceous shales, and marls.
The age of the limestones in the Siju Formation is considered Middle Eocene (late Lutetian – early Bartonian, approximately 38 to 43 million years ago).
After a serious amount of crawling through low passages, the survey was concluded at 251 m for Gongdap Kol, the second cave of the day, and the team was returning from the end of a lateral passage. When sliding sideways to reach the passage junction, they noticed a large fossil jaw (22 cm visible) with three large black fangs (between 3.7 – 8 cm) exposed in the limestones at the base of the passage wall.
A fourth tooth was loose and had its root exposed; it measures 4.8 cm with the root. In a transversal view of the section exposed through erosion/dissolution by the cave water, the two exposed jawbones measure 7 x 3.9 cm (the one containing the teeth) and 5.6 x 4.2 cm (the one situated behind). Since they had just the survey kit with them, they crawled back to the entrance to pick up their cameras and phones, then back to the fossil site and documented the discovery with scaled photos and 3D-Scans.
Later on (in the expedition), based on the pictures they took, the fossil, located just under a nummulitic level in the limestone, was suggested to be a whale ancestor – Archaeoceti – possibly Ambulocetus? or Rodhocetus? by Dr. Lionel Cavin from the Museum of Natural History in Geneva (Switzerland).
Based on the age of the limestones, it may also belong to a more recent (ca. 40 million years), Bartonian genus.
“Archaeoceti fossils have been studied from other parts of India and Pakistan, notably Remingtonocetus and Babiacetus from Gujarat or Himalayacetus from Himachal Pradesh, but if closer analyses of the “Tolegre Fossil” proves the assumed genus, it will be the first of its kind in India,” the researchers said.
Two other visits to the site occurred in the last days of the expedition (March 20th/21) for additional measurements and to get high-resolution video footage and photos.
Once the importance of the discovery was established, the authorities were duly informed.
“South Garo Hills, as we discovered, is a treasure trove of knowledge and such an exploration initiative would not have been possible without the support of the District Administration, the Nokma, our lovely hosts, the Tolegre U.P. School, the guides, all the lovely people of Tolegre, Nokatgre and the neighbouring regions and our friends at MAA,” the team said.
Also Read: Rare orchid recorded in Sikkim, but its future looks uncertain