As they mention in passing at the end of the article, there are modern cockroaches of comparable size. We had a couple as pets when I was growing up, since my mother raised them for the biology lab at UIUC. The large ones they're referring to are probably madagascan hissing roaches (which I'm sure will turn up plenty of results on Google). They're generally around 3", don't look much like domestic cockroaches, and they hiss when you disturb them. They actually made pretty good pets, IIRC (it was a long time ago).