Aresearcher is creating pedigrees for a trait he suspects to be dominant in humans. what are some of the likely features of his pedigrees for families with this trait?

A feature of a pedigree that indicate that a certain trait is a dominant trait is that one of the parents always have to have the trait.

There are, however, autosomal dominance and X-linked dominance.

For an autosomal dominant trait: 
- Appears equally frequent in both sexes.
- Both sexes transmit the trait.
- Present in all generations.
- When one parent has the trait and the other doesn't, approximately half of the offspring will present the trait.

For a X-linked dominant trait: 
- Both male and females can present the trait, but more females usually present it.
- Sons with the trait always have a mother that presents the trait as well.
- Daughters with the trait always have either a mother or father that presents the trait, or both.
- Fathers with the trait always have daughters with the same trait.

This post might have the info you need: