Um, Zadok, correct me if I'm wrong, but I believe 187 was derived for CITPA creatures because Nekrataal was the most popular and it killed creatures, and 187 is the police code for murder, so any creature, like Nekrataal, with a CITPA was dubbed 187. Originally, only 4 creatures were known as 187, all from Visions: Man-o-war, Nekrataal, Uktabi Orangutan, and I think they were called Knights of the Mists(or something like that, they really sucked though).
And, that our lesson for today, kids. Until next time, when I will be Cheese Boy, I'm Mr. Wizard.
Ransac, Prince of Cheese