  We have used the moving cluster method to identify three L dwarfs and one T
dwarf in the Ursa Major/Sirius moving group (age 400 Myr). Five L dwarfs and
two T dwarfs are found to belong to the Hyades moving group (age 625 Myr).
These L and T dwarfs define 400- and 625- Myr empirical isochrones, assuming
that they have the same age. Moving group membership does not guarantee
coevality.
