#3042: T. Rex Evolution

[A graph is shown. The Y-axis is labelled and has two labeled ticks at the top and halfway up from the X-axis:]

Limbs

4

2

[The X-axis is not labelled but represents time and it has ticks every 10 million years, from 180 million years ago until present time. Every fifth tick is a bit larger and has a label beneath it. Except the one at the present time. Below the last tick is an arrow pointing to that tick with a label. There is another arrow that points to about 65 million years ago and this also has a label:]

150 million years ago

100 MYA

50 MYA

Now

Extinction

[The graph shows three animals positioned from the top left, to the middle to the bottom right of the graph.]

[The first animal is a regular dinosaur walking on its hind legs, with fairly long front legs. It is positioned at 4 limbs and 150 million years ago. A label is written above and right of it:]

4 normal limbs

[An arrow goes along the diagonal of the chart down and right and points to the second animal, a Tyrannosaur Rex, which is located in the middle of the chart next to 2 limbs and, just left of the "extinction" arrow. Larger than the first and with almost no front legs. A label is written above and right of it:]

Barely more than 2

[A dashed arrow with a label in the middle continues along the diagonal of the chart to the last animal: A leg-less "dinosaur" with a big open mouth. The animal lies on its belly but with the head part and the tail lifted from the ground. A label is written above it.]

?

???

[Caption below the panel:]

If T. rex hadn't gone extinct

(Linear extrapolation)