Dinosaur Tails

Compared to most modern land animals, dinosaur's had huge tails, which gave them two big advantages over animals with smaller tails.

1. They could use their powerful tail to fend off predators.
2. They could use their tail to quickly change direction when moving.

However, there is one big disadvantage with a bulky tail. It's heavy to carry around. Only if gravity was so weak that the weight of the tail was of no consequence would the two advantages weigh up for the disadvantage.

For modern land animals, the disadvantage of a bulky tail is clearly greater than the advantage, and hence we see animals that would have otherwise benefited from a bulky tail walk around with very small tails. Giraffes, unlike the long necked dinosaurs, have very short tails. They cannot rest on their tails as they reach for the upper branches of trees. The elephant has a very short tail too. It cannot use its tail to defend itself from a flock of lions.

Two legged animals such as the ostrich would have had a huge advantage in a bulky tail when running away from predators, as it would enable them to change direction very quickly, yet they have hardly any tail at all. Kangaroos are the only large two legged animals that still retain a bulky tail.

It seems that bulky tails have gone the way of the dinosaurs, and an explanation for this could be that this is because gravity has increased over time.

It should also be noted that there is no sign of dinosaurs having had any problem keeping their bulky tails off the ground. Fossilized dinosaur footprints do not show any sign of a heavy tail being dragged along. There is no line carved out for their tail between the footprints of dinosaurs.

African elephant

By Yathin S Krishnappa - Own work, CC BY-SA 3.0, Link