Learn more about the time period that took place 488 to 443 million years ago. 3 min read During the Ordovician period, part of the Paleozoic era, a rich variety of marine life flourished in the ...

Having cramps a week or more before your period is usually not a symptom of PMS. Implantation cramps feel very similar to menstrual cramps and happen after conception. Other reasons you may have ...