Animation Description
This animation begins with a line drawing of a caiman skeleton with the right rear foot highlighted in yellow. When the foot is clicked, we zoom in on the foot and the rest of the skeleton disappears. The bone at the back of the heel has a bony knob that points upwards, and this bone is labeled "heel bone." When the word "more" in the right panel is clicked, a line drawing of a parrot skeleton with the right foot hightlighted appears. When the foot is clicked, we zoom in on the foot and the rest of the skeleton disappears. The bone that leads to the toes is smooth, and this bone is labeled "heel bone lacks knob." When the word "more" in the right panel is clicked, a line drawing of a T. rex skeleton with the right foot hightlighted appears. When the foot is clicked, we zoom in on the foot and the rest of the skeleton disappears. The bone that leads to the toes is smooth, and this bone is labeled "heel bone." A multiple choice question appears in the right panel. When "b) no" is clicked, a succcess message appears. When any other option is clicked, the user is instructed to "Try again." This tells us that T. rex does not have a bony knob on its heel bone.
Animation Text
Panel 1:
Let's study the heel in the caiman, the parrot, and T. rex. First, click on the caiman's heel to take a close look at its shape.
Panel 2:
Notice that the caiman has a distinct knob on its heel bone (calcaneum). But what about the parrot?
Panel 3: Click on the parrot's heel to zoom in.
Panel 4:
Notice that the parrot does not have a knob on its heel. Caimans inherited a heel bone that is different from that of birds.
Panel 5:
Now let's examine T. rex. Click on its heel to see whether the knob is present.
Panel 6:
Does T. rex have a knob on its heel bone?
a)Yes
b) No
c) We can't tell
Answers:
a) Yes: Oops. Look closer at the heel-bone of T. rex. Does it really have a bump?
b) No: Good job! This heel shape is a unique feature in caimans and crocodiles.
c) We can't tell: Oops. Look closer at the heel-bone of T. rex.