>for you bio-types, does the dog
>have the best nose in creaturedom
Of land mammals, it's one of the best. Dogs can perceive odors at concentrations way below most animals. The olfactory epithelium is highly innervated and a considerable fraction of the brain is devoted to processing the signals. I'm not at all surprised to hear that a dog bred for hunting by scent would pick up a whiff at 400 yards, if the source were fresh and the wind right.
Elephants are reputed to have excellent scent capabilities, too. How they compare with dogs or deer I don't know. Among domestic dogs the Bloodhound is the scenting champion, and in some states their tracking by scent is admissible in court as evidence. A well-trained Bloodhound is almost infallible. Other breeds are nearly as good: the DEA uses all kinds of dogs for drug searches and they can pick out explosives or drugs packed in luggage, warpped in plastci, and even with "decoy" scents added. Mostly Labs and various Spaniels, chosen mainly for docility, are used in this sort of work.
Scent "sense" is determined in part by the amount of nose area devoted to olfactory epithelium. All dogs are good, but the best ones have very long noses, like Bassetts and Bloodhounds, to maximize the functional area.
>what species have
>better snoze's?
Insects can pick up fantastically low concentrations of odorants--parts per trillion, certainly--but among mammals I don't know of anything that's much better than a dog. Woody may disagree but I think a dog is every bit as good as any whitetail in using his nose. Even sighthounds and non-sniffing dogs are much, much better than any humans and probably as good as a deer. Compared to my Lab, my Border Collie hasn't got a nose worth a damn, but she can still find the frisbee on half an acre of lawn in the dark within 30 seconds. My old mutt, who is blind and deaf, still knows from 50 feet away when I walk into the room with dog biscuits in my pocket and will sit up out of a sound sleep if I do.
If you're interested in the way the olfactory epithelium works, see:
http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab25/Lab25.htm