What is thought to have caused the mass extinction at the end of the cretaceous period?

the impact of a massive comet or asteroid 10 to 15 km (6 to 9 mi) wide, 66 million years ago

Explanation:

science-ocean floors and habitats study guide by volleyballqueen3817 a major advance in ocean-floor mapping. list four sections of the ocean floor. algae that use sunlight to produce their own food through photosynthesis. all of the feeding relationships that exist in a habitat. drying out, predators, find food.

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.