Movement Based Visual Acuity (S/F) / (C/N)

Visual acuity deals with how sharp or acute an organism’s
vision is. Different variables such as light, shape, color, and movement can
affect the vision of different types of animals and even humans. In Jurassic
Park Dr. Alan Grant states that the Tyrannosaurus’ visual acuity is based on
movement, which in 1993 (and earlier) was a theory in the paleontological
community. He states this at the dig site at the beginning of the film and
later on, during the “main road attack” he tells Lex to stay still because
“[the tyrannosaur’s] vision’s based on movement.”

During the main road attack, Lex Murphy and Dr. Grant stay
still, looking the mighty rex in the face. The tyrannosaur smells them but
seemingly cannot see them, which seemed to validate Dr. Grant’s theory (this
also takes place in Michael Crichton’s novel.) But later on, in Jurassic Park
3, this trick doesn’t seem to work. When the group has a run in with a lone
tyrannosaur Grant says “Nobody move a muscle.” Nobody moves, but the
tyrannosaur roars at them anyway- apparently able to see them now. So what
happened in between the two films? The Lost World: Jurassic Park provides
little to no answer. The vision of the tyrannosaurs is mentioned once in the
film when the rexes find the human camp Dr. Ian Malcolm tries to tell everyone
in the camp to not move. None of them listen and subsequently the rexes give
chase. Whether or not staying still would have worked anyways is unknown.

In the novel The Lost World by Michael Crichton, Lewis
Dodgson tries to use the “don’t move” tactic and Malcolm, watching over a
monitor, states that the rival are stupid and “misinformed.”  Dodgson’s team member George Baselton ended
up then being attacked and killed by the tyrannosaurs.

So is the visual acuity of the InGen tyrannosaurs based on
movement or is it not? After the release of Jurassic Park in 1993 sometime the
theory was discredited, meaning it was widely accepted as untrue. Scans of
tyrannosaur brain cases support the theory that this animal actually may have
had fairly good eye sight. When Crichton was writing the novel though, and
during the production of the film this was a proposed theory so it was added
in. Since the theory has been discredited there have been several theories as
to why the tyrannosaur in the first film possibly could not see Grant or Lex.
One of the widely common theories on this is the fact that frogs were used to
help fill in the gaps of the DNA of the InGen dinosaurs, and frogs have a
movement based visual acuity. But then why would this trait be passed on to
this single tyrannosaur and not the others? Perhaps it’s just a serendipitous
defect in the individual on Isla Nublar. The truth is there is no definitive
answer as to why the tyrannosaur seen in Jurassic Park couldn’t see Grant or
Lex.