By the statements presented, we have the situation where the trilobites are the oldest of the species, thus they will be on the bottom layer. The corals are second ones that emerged, so they will be found in the second bottom layer, and after them come the amphibians that will be found in the third layer. The dinosaurs evolved after the amphibians, so since they are younger than them, they will be located in the second layer from the top, with the birds evolving from the later dinosaurs and being the youngest, they will be found in the top layer.
The central idea of this passage is that the cat is lazy and manipulative. She doesn't work, but her cunningness and cuteness allow her consistent privileges.
Both are normal distributions but standard normal distribution is a particular case of Normal distribution when the mean is 0 and standard deviation or variance is 1. This makes Y a “Standard” distribution. So basically X is Normally distributed and Y is “Standard” normally distributed.
