Dinosaur Growth and Brain Size: The Truth Behind Their Evolution

  • Thread starter Tyger
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In summary, dinosaurs had big size and small brains because they had gizzards like chickens have. Mammals live shorter lives because their teeth wear out quickly, but Dinosaur teeth would last much longer. Small brains were because eggs only provide a limited amount of nutrients and oxygen. Mammals are the largest land animals, but dinosaurs hold the record for largest land mammals.
  • #1
Tyger
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This is sort of an unofficial poll on two questions. How was it that Dinosaurs could grow so big, and why did they have such small brains.

I'll give my ideas of why, please add yours.

So big? Because they had gizzards like chickens have. That means they didn't have to use their teeth to chew their food, which mammals spend a lot of time doing. They could just eat and eat and let the gizzard break down the food. Also mammmals have fairly short lives becasue their teeth tend to wear out quickly, but Dinosaur teeth would last much longer. That gave them more time to grow larger. Although some plant eating Dinosaurs had formidable rows of teeth in the skulls.

Small brains? Because they were hatched from eggs. Brains use a lot of nutrients and oxygen but eggs only provide a limited supply of both.
 
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  • #2
What I think...

Big size? Some theories propose that this was due to relatively large oxygen concentrations at the time. Not all dinos are so big, and it could be just luck of the draw that a few did, and lived in surroundings that encouraged it.

Small brains? Because they didn't need big brains. Brains are expensive when it comes to energy consumption, and it may be that having a big brain just wasn't advantageous for dinosaurs. Who needs a big brain when your size is your primary defense? However, some of the smaller dinos have very well developed brains for their small size. Hence the theory that they used them for advanced tactics like pack hunting. And remember, evolution is based on random chance. You can't gaurantee what would happen...
 
  • #3
Originally posted by Tyger
Also mammmals have fairly short lives becasue their teeth tend to wear out quickly, but Dinosaur teeth would last much longer. That gave them more time to grow larger. Although some plant eating Dinosaurs had formidable rows of teeth in the skulls.

Some mammals live quite a while...primates, dolphins, elephants. And being large isn't that directly related to how long you live (for animals, as opposed to plants). We have growth periods and decay periods. As you may have noticed, most people stop growing by the time that they reach 20.
 
  • #4
Actually mammals trump dinosaurs for largest species by a lot (blue whales) -- but for land animals you're right. :) I've heard the theory that dinosaurs, being egg-layers, had to commit to defending their nest from predators, which forced them into a size "arms race", despite the fact that gigantism is generally a poor evolutionary strategy. Mammals who were able carry their children with them could adopt strategies of fleeing or scattering and did not have to resort to large size.
 
  • #5
There is* a niche for large animals and a niche for small animals. With such a possibility available, it's likely that some creature will fill it. Size has some benefits such as safety from predators, less heat loss, etc. So as long as there is ample food supply to support such an anatomy, there is the possibility for such growth. Many time periods since the dinos have had giant-sized animals (but it seems that the dinos hold the record for largest land mammals in history).

* Or, "used to be" at least. Nowadays (geologically speaking), humans have a way of eliminating large animals through direct predation and/or habitat destruction, etc.
 
  • #6
Originally posted by Phobos
Many time periods since the dinos have had giant-sized animals (but it seems that the dinos hold the record for largest land mammals in history).

Except of course, dinosaurs weren't mammals! ;)
 
  • #7
d'oh! There goes all my credibility!
...um, Phobos, what credibility?

Of course, I meant "animals". Such typos happen now and then when you draw your posts from an infinite number of monkeys typing on an infinite number of typewriters. :wink:
 
  • #8
I've pretty much agree with Phobos (about that niche thing, not about his credibility been gone). Gigantism is an evolutionary strategy that works. The dinosaurs ran this planet for a very long time, time enough to develop this strategy to grade extremes. Unlike other strategies, gigantism leaves an excellent fossil record.

There were probably dinosaurs faster than anything we have today, but the only way we have of directly gauging the speed of dinosaurs is by their footprints. Since becoming fast means becoming light weight, the real speedsters probably didn't leave much evidence. I would imagine dinosaurs developed extreme proficiency in venoms, toxicity, camouflage, maybe even electrocution. None of it would show up in a fossil.
 

1. How did dinosaurs grow and evolve over time?

Dinosaurs evolved and grew over millions of years through a process called natural selection. This means that individuals with advantageous traits were more likely to survive and reproduce, passing on these traits to their offspring.

2. How did dinosaur brain size change during their evolution?

Dinosaur brain size varied greatly among different species and did not necessarily increase over time. Some dinosaurs, like the Tyrannosaurus rex, had relatively large brains compared to their body size, while others had smaller brains. However, research suggests that some dinosaurs may have had more advanced cognitive abilities than previously thought.

3. Did dinosaurs experience a growth spurt during their adolescent years?

It is not clear whether dinosaurs experienced a growth spurt during their adolescent years, as there is limited evidence to support this. However, some evidence suggests that certain species of dinosaurs grew at a rapid rate during their juvenile years, while others had a slower growth rate throughout their lifespan.

4. Did dinosaurs have a similar growth pattern to modern-day animals?

Dinosaurs likely had a growth pattern similar to modern-day animals, with a period of rapid growth during their juvenile years followed by a slower growth rate in adulthood. However, there is still much debate and research being conducted on this topic.

5. How did dinosaur growth and brain size contribute to their survival and extinction?

Dinosaur growth and brain size likely played a significant role in their survival and extinction. Larger body size and advanced cognitive abilities may have allowed some species to adapt to changing environments and outcompete others for resources. However, it is also possible that these factors may have contributed to their downfall during mass extinction events.

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