Usually, it's because the sperm gets into the fallopian tube before the egg is released. Once there, the sperm wait for an egg to arrive. After fertilization, it can take 5-10 days for the fertilized egg to begin to attach itself to the lining of the uterus. Pregnancy begins when this happens.
The arrangement of spikes originally had no distinct name; the term Thagomizer was coined in 1982 by cartoonist Gary Larson in his comic The Far Side, and thereafter became gradually adopted as an informal term within scientific circles, research, and education.
The term Lebensraum was coined by the German geographer, Friedrich Ratzel (1844-1904). During the last two decades of the 19th century, Ratzel developed a theory according to which the development of all species, including humans, is primarily determined by their adaptation to geographic circumstances.