No worries! It can take up to 24 hours for an egg to be fertilized. From there the embryo needs about a week to work from the ovary through the fallopian tube and get to the uterus.
The term thagomizer was coined by Gary Larson in humor, in a 1982 Far Side comic, in which a group of cavemen in a faux-modern lecture hall are taught by their caveman professor that the spikes on a stegosaur's tail are so named after the late Thag Simmons.
thagomizer (plural thagomizers) An arrangement of spikes found on the tails of various stegosaurs. 2001, Holtz, Thomas R.; Riley, Terry, The Little Giant Book of Dinosaurs, page 54: Like the thagomizer of the stegosaur, the ankylosaurid tail club was probably used to smash into attackers.