Kesha -- Natural History Museum Grouses ... You Glittered Our Dino!

Kesha was stopped by security over the weekend at L.A.'s Natural History Museum for unwittingly making off with a dinosaur.

Our dino-sources tell us ... Kesha was at the museum Saturday for a wedding. On her way out she went to the gift store with her assistant and admired a faux T-Rex. She held the 3-ft tall critter in her hand and walked out of the store.

On her way to the car security stopped them and asked them what was up with the prehistoric beast. Each said they thought the other paid and apologized for the misunderstanding. Kesha forked over the dinosaur and left.

Problem is ... it was covered in glitter, so it had to endure a dino-wash ... not sure you can resell that.

And that wasn't Kesha's only problem. She posed on top of a Triceratops which was on display in the museum and got heat from archaeologists and others who felt it showed a lack of respect.

And that's a Raptor.