Here is some additional information, including a link
– Mikko
Not strictly dino-related, but may be of interest:
Marc E.H. Jones, Paul O’higgins, Michael J. Fagan, Susan E. Evans & Neil
Curtis (2012) Shearing Mechanics and the Influence of a Flexible Symphysis
During Oral Food Processing in Sphenodon (Lepidosauria: Rhynchocephalia).
Anatomical Record (advance online publication)
doi: 10.1002/ar.22487 http://onlinelibrary.wiley.com/doi/10.1002/ar.22487/abstract
The New Zealand tuatara, Sphenodon, has a specialized feeding system in
which the teeth of the lower jaw close between two upper tooth rows before
sliding forward to slice food apart like a draw cut saw. This shearing
action is unique amongst living amniotes but has been compared with the
chewing power stroke of mammals. We investigated details of the jaw movement
using multibody dynamics analysis of an anatomically accurate
three-dimensional computer model constructed from computed tomography scans.
The model predicts that a flexible symphysis is necessary for changes in the
intermandibular angle that permits prooral movement. Models with the
greatest symphysial flexibility allow the articulation surface of the
articular to follow the quadrate cotyle with the least restriction, and
suggest that shearing is accompanied by a long axis rotation of the lower
jaws.
This promotes precise point loading between the cutting edges of particular
teeth, enhancing the effectiveness of the shearing action.
Given that Sphenodon is a relatively inactive reptile, we suggest that the
link between oral food processing and endothermy has been overstated. Food
processing improves feeding efficiency, a consideration of particular
importance when food availability is unpredictable. Although this feeding
mechanism is today limited to Sphenodon, a survey of fossil
rhynchocephalians suggests that it was once more widespread.
Here is some additional information, including a link
– Mikko
Not strictly dino-related, but may be of interest:
Marc E.H. Jones, Paul O’higgins, Michael J. Fagan, Susan E. Evans & Neil
Curtis (2012) Shearing Mechanics and the Influence of a Flexible Symphysis
During Oral Food Processing in Sphenodon (Lepidosauria: Rhynchocephalia).
Anatomical Record (advance online publication)
doi: 10.1002/ar.22487
http://onlinelibrary.wiley.com/doi/10.1002/ar.22487/abstract
The New Zealand tuatara, Sphenodon, has a specialized feeding system in
which the teeth of the lower jaw close between two upper tooth rows before
sliding forward to slice food apart like a draw cut saw. This shearing
action is unique amongst living amniotes but has been compared with the
chewing power stroke of mammals. We investigated details of the jaw movement
using multibody dynamics analysis of an anatomically accurate
three-dimensional computer model constructed from computed tomography scans.
The model predicts that a flexible symphysis is necessary for changes in the
intermandibular angle that permits prooral movement. Models with the
greatest symphysial flexibility allow the articulation surface of the
articular to follow the quadrate cotyle with the least restriction, and
suggest that shearing is accompanied by a long axis rotation of the lower
jaws.
This promotes precise point loading between the cutting edges of particular
teeth, enhancing the effectiveness of the shearing action.
Given that Sphenodon is a relatively inactive reptile, we suggest that the
link between oral food processing and endothermy has been overstated. Food
processing improves feeding efficiency, a consideration of particular
importance when food availability is unpredictable. Although this feeding
mechanism is today limited to Sphenodon, a survey of fossil
rhynchocephalians suggests that it was once more widespread.
Press Release with video:
http://www.ucl.ac.uk/news/news-articles/May2012/120530-new-zealand-reptile-shows-chewing-not-just-for-mammals