Report Abuse. An egg lives for around 12 hours after ovulation. Sperm can live for about five days inside the uterus, so providing those two time frames collide, it can be pretty soon after sex.
The tail arrangement is believed to have been a defensive weapon against predators. The term thagomizer was coined by Gary Larson in a 1982 Far Side comic strip, in which a group of cavemen in a faux-modern lecture hall are taught by their caveman professor that the spikes were named for the late Thag Simmons.
Word History:  'O frabjous day! Callooh! Perhaps Lewis Carroll would chortle a bit himself to find that people are still using the word chortle, which he coined in Through the Looking-Glass, published in 1872. In any case, Carroll had constructed his word well, combining the words chuckle and snort.