The original "sawtooth" shirt was developed by Jack A. Weil. Jack was actually the inventor of the Western shirt design.
He wanted cowboys to wear more striking and handsome style shirts, but keep some normality to the design.
For those who aren't familiar with who Jack A. Weil is, you may know his brand Rockmount Ranch Wear. Jack patented the sawtooth design pocket flaps and diamond snap buttons, the name "sawtooth" from what the cult historians have said was actually from the jagged stitching on the pockets and yoke, which resembled "sawteeth".
Rockmount Sawtooth
Nowadays, the name is recognised by the pocket design and even Jack himself called them sawtooth pockets.
In the 1950s, with Jack's patent expiring, Levi's brought out their own sawtooth denim shirt design. It featured similarly shaped chest pockets, round "Gripper" or "Dot" snaps and a different yoke.
Levi's sold this style of the shirt, first under their "Short Horn", "Denim Family" and "Long Horn" labels.
Today, LVC bring out different shade variations, with a few other brands selling their own versions.
Levi's Short Horn Sawtooth
Levi's LongHorn Sawtooth