A Pre-Extinction Apocalypse
In the rolling Mikir Hills of Karbi Anglong, a unique fossil record tells a story of an apocalypse before the apocalypse. Here, embedded within sedimentary rock, are the remains of ammonites—coiled-shell cephalopods related to modern squid and octopus—that perished in the final days of the Cretaceous Period, approximately 66 million years ago. These fossils are a record of life, but a account of its demise. They died out during a period of intense environmental stress caused by a large volcanic events in Earth's history: the Deccan Traps eruptions.
Long before the Chicxulub asteroid delivered its final blow to the dinosaurs, these massive volcanic floods in west-central India were already pumping climate-altering gases into the atmosphere. For hundreds of thousands of years, eruptions released staggering quantities of sulfur dioxide and carbon dioxide, triggering rapid climate shifts and ocean acidification. Marine life was hit hard. The acidic water made it difficult for organisms like ammonites and plankton to build their calcium carbonate shells. The Karbi Anglong ammonite beds capture this slow-motion extinction event. The fossils here show evidence of environmental stress; their final growth rings are often stunted or malformed, a record of their struggle to survive in poisoned waters.