Dinocroc (2004)

Experiment gone wrong Dinocroc escapes from a lab into the Gereco land preserve.  The Gereco scientist says there's nothing to worry about because the preserve is locked up tight so it can't get out.  Yet a twelve year old boy has no problem getting into the area to look for his dog.  Yeah, that isn't good.

The croc knocks down a gate and is free to roam the public waterways.  Animal control screams that they must close the beaches, but no one listens.  Then the Dinocroc dines on the local population and people in power start to believe in the power of the croc.  Croc hunter Dick Sydney is called in to take out the beast, but the prehistoric growing menace is not impressed.

No one shall ask why twelve year old Michael thinks the thing moving through the water is his dog. Wouldn't it make more sense to look for your dog on land? Or why his older brother appears to get over his grief the same day tragedy strikes.