My wife insists that my 4-year old only speaks Mandarin with her ("妈妈听不懂.  说中国话！"). Recently, he tries to use German wherever he can.

But often he just cannot comply, because he lacks his core vocab: "Mama, what is Protoceratops in Chinese?"

I had to help out here. Thanks to Wikipedia I could answer my son's (and in turn my wife's) most pressing questions:

Protoceratops: 原角龙

Triceratops: 三角龙

Stegosaur: 剑龙

Ankylosaurus: 甲龙

Tyrannosaurus Rex: 霸王龙

Pterodactylus: 翼手龙

Diplodocus: 梁龙

These are the ones my son wanted to know. I guess he will ask more later (probably all the Chinese ones like the Huangfengosaurus - he will be in Beijing soon).

We definately need a lesson on Dinosaurs.