Seymour is a fossilised dog in the Fallout: New Vegas add-on Lonesome Road It is only obtainable with the Wild Wasteland trait.
Gameplay
'Seymour' has the appearance of a normal dog but with a reduced size, and is easy to carry being weightless.
Location
In the Cave of the Abaddon to the right of the entrance, standing on an overturned cabinet, close to a skeleton.
Behind the scenes
Seymour is a reference to the Futurama episode "Jurassic Bark" in which Fry finds his dog, Seymour, fossilized.
Gallery
Seymour, placed on an overturned filing cabinet near Sunflower Summers' skeleton