DINOSAUR VERSUS MAMMAL SIZE EXPANSION

[GSP1954@aol.com]

Despite claims to the contrary, the size expansion of dinosaurs was over all
superior to that of land mammals. Mammals reached ~5 tonnes (titanotheres)
after about 30 Myr years after the K/T extinction, then 15-20 tonnes (

indricotheres) after 40 Myr, then decreased to the 5-15 tonnes seen in big
proboscideans. Sauropods reached the size of bull African elephants (~5
tonnes) ~30 Myr after the first dinosaurs appeared, the size of whales and
bigger than any land mammals (~30 tonnes) 60 Myr after their first
appearance, and the size of big whales (50-150 tonnes) ~80 Myr after the
first appearance. They then maintained that size for over 80 Myr. 

Growth is easier in the oceans because the cost of swimming is much lower
than walking, so juveniles can gather food more easily and at less cost. Even
so, it took whales 40 or more Myr to become truly massive, and 100 tonne blue
whales appeared only a few million years ago.

GSPaul