THE OLD SHIELDS ACTUALLY USED WHEN SPEARING LIONS WERE NOT FLAT BUT HAD SOME EDGES AND WERE CURVED SORT OF LIKE A SHALLOW BOAT SHAPE. THEY HAD SOME WEIGHT AND WERE THICK AND REINFORCED BY THE WOODEN FRAMEWORK AND WERE LARGE ENOUGH TO COVER THE WARRIOR WHEN HE CROUCHED DOWN.
THE ONES I HAVE HANDLED MADE TODAY ARE MUCH MORE FLIMSY AND FLAT AND ARE MOSTLY FOR CEREMONIES OR DANCES. THEY ARE ALSO CARRIED BY YOUNG BOYS DURING THEIR INITIATION CEREMONIES TO BECOME WARRIORS. I DON'T KNOW TOO MUCH ABOUT THE INITIATION BUT HAVE SEEN THE BOYS CARRING THEIR SHIELDS AND STICKS AND WEARING A DIFFERENT COSTUME AND WITH WHITE PAINT OR ASHES ON THEIR FACES IN TANZANIA. YOUR EXAMPLE WOULD FALL INTO THESE LAST TWO CATAGORIES AND LIKELY IS FOR INITIATION AS I BELIEVE THOSE ARE DISCARDED WHEN THE BOY BECOMES A MAN AND WARRIOR.
THE INITIATION SHIELD I HAVE IS 31.5 X 22 INCHES AND BASICALLY FLAT