Why have land mammals never evolved any species as gigantic as the sauropod dinosars?

Question

In particular, why are today's land mammals so relatively puny? Eg:
Bruhathkayosaurus 175-220 tons / Seismosaurus 45 m long / Sauroposeidon 18 m high cf.
African Bush Elephant 12 tons 7.3 m long 3.5 m high / Masai giraffe 5.8 m high

Answer 1

We believe that the large dinosaurs were thermo-regulators. This means that they overcame the inefficiencies of a large body in order to have a sort of pseudo warm blooded system. There is evidence in the bones of some creatures for both warm and cold blooded characteristic vasculation.

Basically what happens is that with such a large girth it would take the beast a very long time to cool. Compared with smaller reptiles that constantly need sun in order to have energy. Also moving a body around like that would generate alot of heat.

There is no need for mammals to grow this large for heat because they are warm blooded. A large body size for a warm blooded animal would be a liability. For the sauropods it may have been a failed trial at warm blood. This is something that appears to be common in evolution.

Answer 2

How about the Baluchitherium? A giant relative of the rhino.

I don't know why people are getting annoyed about creationists when the question is as reasonable as this. It's a good question, although the animal I mentioned is impressively huge its not in the same class as the big sauropod dinos and the truth is I don't know. It could be that mammals hadn't had time to evolve in to larger forms (than that) though human predation has been a cause for many large mammals to become extinct over the last few tens of thousands of years. The blue whale is larger than any dinosaur though.

I wonder if there was just so much more vegetation in prehistoric times that herbivores and the predators that fed on them could grow huge though I don't know what advantages it might offer necessarily.

Good question. I would seek out some academic books on palaeontology to see if anyone has attempted to answer this question.

Just ran a quick search - now called the Indricotherium apparently http://www.abdn.ac.uk/mammal/land.shtml

Answer 3

Creationism is bullsh*t. Every single one of the major celebrities of that movement are proven liars about everything from their supposed "credentials" to their supposed "facts." There's not a single one of them who knows what science is, for all their pretending to be "experts."

Evolution happened and anyone who is willing to read the evidence (instead of listening to creationists lie about the evidence) will quickly realize that we have overwhelming evidence of massive change in form and variation into new species over billions of years. Read "Blueprints: Solving the Mystery of Evolution" by Maitland A Edey for a synopsis of what we know and how we know it.

Now for the issue at hand. I hadn't thought of the body size in relation to warm blooded vs. cold blooded issue, but I should point out that there are many paleontologists who now suspect that many species of dinosaurs may have been warm blooded.

There was an age of massive mammals, with some far larger than elephants are today, though they never approached dinosaur size. It is very possible that warm bloodedness had something to do with that, I do not know. That time occurred during the Eocene and the Miocene. See "The Book of Life" edited by Steven J Gould for an illustrated guide including images of what we think they may have looked like.

PS, Creationists and their followers are ignorant LOSERS who want to drag this country back into the Dark Ages. I have NO respect for them at all, and I hope lots of them read this so they know it.

Answer 4

The Imperial Mammoth weighed in at around 8 tons.
The age of mega fauna eneded with the evolution of Homo sapiens, who were efficient hunters of these animals driving virtually all nonafrican mega fauna to extinction.
The list includes the Mammoths, Woolly Rhinos, Irish Elk, Moa etc. as well as the animals that relied on them as prey such as the Cave Bear and Sabre Tooth Cats.

Answer 5

Its just not biologically efficient to be that big. The species would die out from lack of food. They couldn't reproduce at any kind of level and still have enough food supplies. On Gallapagous Islands the birds' beak size changed depending upon the rain fall and corresponding seed size. Extrapolating from that, mammalian body size will change depending upon the size of the food.

Answer 6

For the same reason monkeys will never lose their tales and engineer bridges.


Evolution beyond mild adaptation is a myth.

Answer 7

Simple...there is no such thing as evolution.