Visible crew/equipment: When the group is flying into the island, there's a shot of the plane flying in front of the cloud, and there's the obvious shadow of the helicopter that filmed that shot. (00:15:25)
Visible crew/equipment: Just after hearing the Spinosaurus roar, bright studio lights are reflected on the front of the plane when it is turning to take off from Isla Sorna. (00:19:45)
Visible crew/equipment: Once inside the abandoned building on the island they proceed to walk down some steps after the candy machines. The upper body of a lurking crew member can be seen in a lit doorway in the background of the shot as the group descend the metal staircase. (00:39:39)
Visible crew/equipment: When Paul Kirby is climbing onto the crane in the river sequence you can see a light to the left of the operator's cabin. There was no power on that side of the island to power the light. To the right you can even see a blue tent standing perfectly. Surely the wind would have blown it over by now. (01:15:30)
Answer: While the movie doesn't explain this, it most certainly wasn't a dinosaur (since a carnivorous dinosaur would eat him). However, in Jurassic Park Adventures: Survivor, he dies from internal injuries due to the rough "landing".
Bishop73
I have a theory that it was a dinosaur that spits acid.