Other scientists think the extensive volcanic activity in India known as the Deccan Traps may have been responsible for, or contributed to, the extinction. However, paleontologists remained skeptical, as their reading of the fossil record suggested that the mass extinctions did not take place over a period as short as a few years, but instead occurred gradually over about ten million years, a time frame more consistent with massive volcanism. There was also a certain general distrust of a group of physicists intruding into their domain of expertise.
A very large impact crater has been recently reported in the sea floor off the west coast of India.The researchers suggest that the impact may have been the triggering event for the Deccan Traps. However, this feature has not yet been accepted by the geologic community as an impact crater.
Extreme volcanic activity and the additional acid rain may perhaps have altered the Earth's climate sufficient to generate mass extinction. The delayed Cretaceous was a time of high tectonic action and additional volcanic action. The super continent Pangaea was splitting up and the continents were taking on their modern-day forms. Extreme volcanic activity would discharge dust and acidic chemicals (like sulphuric acid) into the atmosphere, which causes global cooling, and possibly, mass extinctions.
Changes in the Earth's orbit that might have caused climactic cooling might have caused the extinction. In this circumstance, the dinosaurs couldn't acclimatize to the cold, but the hairy mammals could. This is steady with the type of weather in the late Cretaceous; toward the ending of the Cretaceous, there was a drop in sea level, causing land exposure on all continents, more seasonality, and greater extremes between equatorial and polar temperatures.
Mammals eating dinosaurs' eggs have been suggested as a cause of the K-T extinction. This doesn't explain why so many other species went extinct, or why there are chemical anomalies in the K-T layer.
Large amounts of methane changing the Earth's atmosphere (causing a greenhouse effect). The methane source would be from deep-sea algae deposits and/or from plant-eating dinosaur’s digestion by-products.
The herbivorous dinosaurs' over-foraging and the carnivorous dinosaurs over-culling of the herbivorous dinosaurs could have triggered mass starvation.
A nearby supernova (an exploding star) could have bathed the Earth in deadly radiation.