No there is no desert underpass in Ruby
To obtain a Ditto in Pokemon Ruby or Sapphire, you must trade with Pokemon Emerald, where you can find it in the Desert Underpass, or you can trade it with any games from either Generation I or Generation II. - Badminton
You can find it in the Desert Underpass.
You'll have to trade it from another version. It is available in Pokemon Emerald at the Desert Underpass (Near Fallarbor), and many places in versions Fire Red and Leaf Green.
The Desert Underpass contains the Fossil you did not pick up at the Mirage Tower on Route 111. The Desert Underpass is also the location to find wild Ditto.
Go to Fallabor Town after you have defeated the Elite Four. Just northwest of that town will be a house were the fossil maniac lives. Go there, and you'll find the Desert Underpass he dug behind/below his house.
Trapinch are found in the desert.
The desert.
go to the desert underpass in the fossil maniacs house his house is right next to the move tutor
in the desert on Pokemon emerald,sapphire,and ruby EASY
In Pokemon Emerald, both the Root and Claw fossils can be obtained. One may be selected at Mirage Tower and the other will be found at the end of the Desert Underpass.
it is right side
trapinch is located in the desert part of Pokemon sapphire or ruby; maybe in emerald.