On another forum, MIBRO did a lot of research on the skull fracure which is, actually, new to the forums. I want to share that with all of you.

MIBRO, if you are upset by this, please email me and I will change the post...

http://www.bartleby.com/107/18.html

THE STRENGTH OF BONE COMPARED WITH OTHER MATERIALS

The measurements are for:
Weight (Pounds per square foot)
Tension (per square foot)
Compression (per square foot)
Shear (per square foot)

Substance Medium steel
Weight 490
Tension 65,000
Compression 60,000
Shear 40,000

Substance Granite
Weight 170
Tension 1,500
Compression 15,000
Shear 2,000

Substance White Oak
Weight 46
Tension 12,500
Compression 7,000
Shear 4,000

Substance Compact bone (varies)
Weight from 119 to ?
Tension 13,200-17,700
Compression 18,000-24,000
Shear 11,800-7,150

MIBRO explains it this way:

I hope the table that shows the strength of bone compared to other materials posts. The table shows that it takes 18,000 pounds (yes, gls, that’s 9 tons) per square inch to cause bone compression. A conservative estimation of 100 Mpa’s per square meter was what I posted (that’s 14,503 pounds per square inch).

JonBenet’s weight (mass) at 45 lbs., together with the distance she would fall (height of 47 inches), and the power of her pulling away from someone (velocity)and falling (distance) is not great enough to create the force required to cause this injury. There is not enough mass, velocity or distance to mathematically meet the requirements of 14-18,000 pounds of pressure required to compress the skull.

Slamming JonBenet into a surface would require considerable power (velocity) to cause this injury. The physics to be considered do not add up mathematically.

A fall from a greater height (which would help solve the mathematical problem) would probably have caused other injuries (like a broken neck).

It is much more likely that a weapon was used with great force and that the weapon’s description would match the measurements of the fracture. Its edge should “match” (be less than) the width of the displaced skull fragment (1.75 x 0.5 inches).

MIBRO notes hir is not an expert - but the research sure makes one wonder!