As humans mine more of the earth, new fossils are brought to light. Recently, amber from a lignite mine in Gajarat, India has produced a treasure trove of insect and other fossils. New fossil finds always help to fill in some of the missing details of the evolution of life on earth.
This particular site has produced a lot of fossils that are about 52 million years old. The site was formed around the time that India collided with Asia, or a few million years prior to that event. The plant fauna from the site includes broadleaf trees from the family, Dipterocarpaceae, that are prevalent in modern Asian rainforests. This suggests that tropical rain forests were present at Gajarat 52 million years ago (mya). This and evidence from other sites suggest that the tropical rainforest ecosystems date back to the dinosaur extinction 65 mya.
The second finding is that insect and other fauna at this site is remarkably similar to insect fauna at other sites in Asia. This suggests that India may have collided with Asia a few million years earlier than previously thought, or that there was some connection between Island India and mainland Asia prior to the collision. Perhaps, volcanic islands formed a chain along the plate boundary between Asia and India as the collision approached. Entomologist Alex Wild and author of the Myrmecos Blog, however, suggests that the fauna may be less well related to other Asian species based on possible misidentification of one of the ant species found in the amber. Further study will be useful for resolving the question he raises.
The Gajarat amber is soft. Unlike the harder Baltic amber, it cannot be made into jewelry. The soft amber is easier to dissolve and extract insect specimens.
One of the Authors of the study published in PNAS in October is David Grimaldi of the American Museum of Natural History. Readers interested in learning more about evolution and the evolution of insects should check out his book, Grimaldi and Engel, The Evolution of the Insects. It is a great reference for any entomologist and something to add to your Christmas wish list (only 47 shopping days left).