Allosaurus Shepherd

The affected creatures don't lose any abilities when they become Dinosaurs.

Effects that modify an affected creature's power or toughness without setting it will apply no matter when they started to take effect. The same is true for counters that change the creature's power or toughness.

A spell or ability that counters spells can still target spells that can't be countered. When that spell or ability resolves, the uncounterable spell won't be countered, but any additional effects of the countering spell or ability will still happen.