Fossils are not only the actual remains of organisms, such as teeth, bones, shell, and leaves (body fossils), but also the results of their activity, such as burrows and foot prints (trace fossils), and organic compounds they produce by biochemical processes (chemical fossils).
There are two types of dysmenorrhoea: primary dysmenorrhoea and secondary dysmenorrhoea. Primary dysmenorrhoea is another name for common menstrual cramps. Cramps usually begin one to two years after a woman starts getting her period. Pain usually is felt in the lower abdomen or back and can be mild to severe. Common menstrual cramps often start shortly before or at the onset of the period and last for one to three days. They usually become less painful as a woman ages and may stop entirely after the woman has a baby. Secondary dysmenorrhoea is pain caused by a disorder in the woman's reproductive organs.
Cramps typically start just before and are most severe during the first days of menstrual flow. Younger women and those who have never been pregnant or delivered a baby are more likely to have and to have worse cramps. Interestingly, cramps also seem to increase in perimenopause (the transition to menopause). The pain of cramps is due to increased release by the lining and muscle walls of the uterus of a fatty hormone called a prostaglandin.