Photo by Drees. Photo by Jackman. They have the club of the antennae with the segments separated rather than compact like scarab beetles. Males have elongated mandibles that are used to joust with rival males.
Females have more normal jaws.
Larvae are similar in shape to white grubs of Scarabeidae but larger. There are relatively few species of stag beetles in Texas. Some tropical forms have very elongated mandibles in the males. Larvae take a year or multiple years to develop. Larvae develop in damp, decaying wood.