The koala is one of the few mammals, other than primates, to have fingerprints.  Their fingerprints are very similar to human fingerprints.  According to an infamously dubious, free, online encyclopedia, human and koala fingerprints are so similar that “even with an electron microscope it can be quite difficult to distinguish between the two.”

Crime Scene Investigator: Here’s the gun from the murder scene.

Forensic Scientist: Thanks.  Once I just take a look at this gun with my trusty electron microscope, I will be able to pinpoint the killer immediately.

Looks in electron microscope.

Forensic Scientist: I see the prints.  It looks like I’ve narrowed it down to two suspects.  But it’s quite difficult to distinguish between the two, even with my electron microscope.

LATER:

Behind one-way glass, a witness looks at the two suspects in a police line-up.  A 46 year-old man with a history of violence and drug addiction …and…  a 25-pound koala with a pouch full of revenge.

“The nose print of a dog is like the fingerprint of a person – no two are alike. Get a good relief and you can identify your dog by the mark it leaves behind!” 

I’m guessing your dog’s face will help you distinguish your dog too. Or maybe its general appearance or its collar…  Maybe this fact is supposed to help me track my dog…or help the police if my dog committed a crime or something.  But I would have to rely on the fact that he used his nose to shoot a gun.  Wow!  I can identify my dog by “the mark it leaves behind!”  I don’t know about you, but my dog doesn’t walk around with ink on its nose pressing it up against things.  Or shooting people.