Acrater in mexico's yucatan peninsula may be the result of an impact that brought about the extinction of numerous species at the end of the period.

Cretaceous

Explanation:

From what has been examined so far, there are evidence that at the end of the Cretaceous period a very large asteroid or comet stuck the Earth. The impact was where modern day Yucatan is located, and it released such an enormous energy that it managed to change the face of the Earth. The explosion itself managed to kill off pretty much everything nearby, but there was also a very hot wave that circled the whole planet. Enormous amounts of dust and ashes were released into the atmosphere that blocked the Sun, and the volcanoes all over the globe were triggered. This caused major climate and environmental changes, leading to a mass extinction, with the most noticeable victims being the dinosaurs.

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.