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Re: Dilophosaurus??



>In the movie, there is a seen where
>the evil computer guy played by Wayne Knight is attacked by a
>creature that was identified in the movie as a Dilophosaurus. Some
>questions: is that the correct name?

Dilophosaurus is a real name, but the two known species of this dinosaur
(D. wetherilli and D. sinensis) are considerably larger than shown in the
movie.  Also, I've noticed that the head they use is just the Tyrannosaurus
head recolored, given new eyes, and topped with crests.  The true
Dilophosaurus skull (shown on the signs along the trail, for example) is
very distinctive, and has a "kink" in the front portion of the jaw, between
the premaxilla and maxilla bones.

>Is there any actual evidence
>that they spit to blind their victims, or is that pure movie magic?

Pure movie/novel magic, based on some mistaken scientific assumptions.
When Dilophosaurus was first well described, S. Welles thought that a) the
premaxilla/maxilla joint was mobile and weak and so b) Dilophosaurus must
have scavenged rotting flesh.  It has since been shown that the jaws of
Dilophosaurus are well supported by bones on the inside, that it has
proportionately some of the largest teeth of the theropods, and looks like
it could have easily dispatched living prey by jaws and claws.

Nevertheless, Michael Crichton picked up on the idea that its jaws were too
weak to kill, so in the novel he gave it poison.  In the movie, Spielberg
decided to combine the two poisonous ceratosaurs used in the novel
(Procompsognathus and Dilophosaurus), and wound up with the dog-sized
animal.

There is so far no evidence of poison glands nor poison grooves in any
dinosaur.  There is a tooth from (possibly) an archosaur of the Triassic of
Virginia with a potential poison groove, and the fossil varanoid
(monitor-Gila Monster group) Cretaceous lizard Estesia also seems to have
poison grooves.  However, neither of those forms are dinosaurs.

>Finally, in the movie. the animal flared out a neck crest that
>made it look like a giant version of a modern lizard (flying lizard
>or Jesus lizard??) I have seen on nature shows. I have seen picutres
>(I think) of a Dilophosaurus in several books, but I don't recall
>the crest. Was this fabricated also?
>Thanks, and sorry for repeating well-worn subject matter.

There is no evidence of a frilled lizard-type frill in Dilophosaurus,
although if the structure was supported with cartilage, it might not
preserve in the fossil record.

More significant is the fact that we already know what one major display
structure of this theropod is (the epynomous two crests [di- lophos] on its
skull).  I feel that it is unlikley that this particular genus had a lot of
other displays (what next - flashing lights!).  It seems more likely that a
theropod without big crests, horns, or spines would be a better candidate
for a soft tissue display structure.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.