Re: really weird idea about Ichthyosaurs

[John Schneiderman <dino@revelation.unomaha.edu>]

Didn't Ichthyosaurs have a relatively small optic lobes, but with big
eyes.  My guess is large eyes to compensate poor vision.  Which makes
Ichthyosaurs close to surface hunters.  Can anyone report on the size of
the ofactory.  

---John Schneiderman (dino@revelation.unomaha.edu)


On Tue, 17 Mar 1998, Ralph Miller III wrote:

> Betty Cunningham <bettyc@flyinggoat.com> writes:
> > What if Ichthyosaurs used their eyes to recieve sound vibrations instead
> > of a melon? Perhaps not as true sound but as simple vibration info
> > 
> > -The eye is full of fluid (like a melon)
> > -The eye is huge in nearly all cases-larger than Mosasaurs, Plesiosaurs,
> > or Cetaceans.  Perhaps larger than needed for sight alone.
> > -The eye is surrounded by very tiny bones that could transmit sound into
> > vibration (like ear bones do)
> 
> As I understand it, a cetacean's sonar sound-emitting process begins within
> the cranium, possibly in the air sac system of the head, and the sound
> waves radiate forth in a narrow cone, from a concave bone surface at the
> front of the skull, and through the lens we call the melon.  I am under the
> impression that the sonar echo is then received through the mandible, which
> transmits the vibrations to the inner ear.  To reconcile this data with
> your analogy, you might instead propose that the ichthyosaur is _sending_
> the sounds laterally out both eyeballs, but if such is the case, the
> initial sound emission might function less effectively in pinpointing prey
> than the forwardly-directed narrow beam of sound employed by extant
> cetaceans.  I trust that list members will correct my description of
> cetacean sonar technique if I am in error.
> 
> -- Ralph Miller III     gbabcock@best.com
> 
> Are we getting off-topic yet?
>    
>