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Why it was possible for dinosaurs to exist ?

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I allready asked experts in conferences and they simple ignore me.

 

Any ideas?

 

forgive me , I think they are right or you had asked your question not as sufficient as you would it to be understood.

 

look what things I have understood ;

 

I am looking your topic sentence : and I think probably it is not so related with (medical ) science (or other parts of science), it seems more related with belief.

 

then ,of course you had given some instructions about morphology , this means yes this would be related with science (definitely!)

 

but I am looking your question and ...

 

I think this is very easy question to give answer. for instance

 

at first we can not refute the evolution

 

and secondly some types of animals already existed but now they are extinct ( we may give "dodo" as example to this)

 

if you were asking something relevant evolution (like asking what are the differences between mammooth and elephants) then yes that would be good question (and probably this also would be simple). but if you were asking the possibility whether the scientists will be able to create a new and real type of dinasours (just similar ones existed in the past) then

 

yes this would be very good question.

 

but of course all these are my own ideas.

 

please do not feel any negative sensation,I appreciate being curious at science.

Edited by blue89

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"Or to put the question differently, why are all current land animals smaller than dinosaurs were?"

It's a valid question.

A possible answer is "the mammals waited till they were asleep (and cold) then ate them."

(really big mammals have a different problem- they tend to overheat)

Another possible answer is " I haven't a blessed clue".

 

No answer to that question makes any difference to the other question i.e "why-it-was-possible-for-dinosaurs-to-exist".

The answer to that was evolutionarily (or divinely, if you insist) good engineering.

 

The answer was not " The laws of physics went up the Swanee and some 'magic' that I made up, but can't explain can't explain made gravity smaller"

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All dinosaurs with long necks ( and counterbalancing tails ) were herbivores which needed to get at the tops of giant trees ( the flora was different at the time also ).

You being an engineer, it should be simple enough to look up the strength of various type of bones, then armed with the fact that weight goes up with volume, or the cube of length, and get a ball-park figure for the max weight a bone can support for a given lenght.

But why are you even looking at present day elephants for a guideline to max size ?

Have you seen the length of a giraffe's slender neck ?

Its bones easily support its weight !

 

Edit:

The atmosphere may have had different composition, but its density would have been essentially the same.

Same for mass and size of the Earth. Even changes in spin are trivial.

Edited by MigL

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I asked because you second sentence is not another way of putting your first one.

Your first one included all animals.

 

However your question is a fair one and related to the OP.

 

A possible answer is the OP idea that the prevailing conditions constrain or force animal size is a good one.

Unfortunately he is focusing on the wrong conditions IMHO.

 

So the main condition determining size is thought to be the availability of food.

It is interesting to note that under suitable conditions species can shrink as well as grow.

For example the fossil pygmy elephants found in some Mediterranean islands, thought to have crossed from Africa when the med was dry and then shrunk to fit the food supply when stranded on islands.

 

https://en.wikipedia.org/wiki/Dwarf_elephant

 

Note the biggest dinosaurs were thought to be vegetarian, like the blue whale in the picture.

Plants in the time of the dinosaurs were larger than today, so perhaps obtaining and digesting enough to grow to the larger size was easier then.

Predators obviously had to become large enough to overcome the behemoths, would a modern lion be capable of taking one on?

Yes, plants were larger too. That cannot be a coincidence.

If, as you propose, the dinosaurs were larger because the plants were larger, then the question resumes to: why were the plants larger?

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Yes, plants were larger too. That cannot be a coincidence.

If, as you propose, the dinosaurs were larger because the plants were larger, then the question resumes to: why were the plants larger?

 

 

CO2 levels were higher back then. If plants were indeed bigger (any reference for this?), that would contribute.

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If, as you propose, the dinosaurs were larger because the plants were larger, then the question resumes to: why were the plants larger?

 

Perhaps because they had bigger predators? :)

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CO2 levels were higher back then. If plants were indeed bigger (any reference for this?), that would contribute.

Yes that make sense.

 

But I cannot find (quickly) any solid reference.

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The history of plant sizes is outlined in

 

The Emerald Planet, which I have referenced several times.

 

A word about geological timing is in order here.

 

The superlarge plants were a particular feature of the carboniferous period 300 - 350 MYA

At this time athe first large animals appeared and a flourishing ecosystem developed.

These animals were not dinosaurs.

They were entirely wiped out at the end of the Permian in the PT mass extinction 250 MYA

 

The dinosaurs developed subsequently in the lateter Jurassic and cretaceous and were themselves wiped out in the KT mass extinction 60 MYA

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The history of plant sizes is outlined in

 

The Emerald Planet, which I have referenced several times.

 

A word about geological timing is in order here.

 

The superlarge plants were a particular feature of the carboniferous period 300 - 350 MYA

At this time athe first large animals appeared and a flourishing ecosystem developed.

These animals were not dinosaurs.

They were entirely wiped out at the end of the Permian in the PT mass extinction 250 MYA

 

The dinosaurs developed subsequently in the lateter Jurassic and cretaceous and were themselves wiped out in the KT mass extinction 60 MYA

Yes.

I am looking for reference of plant gigantism at the time dinosaurs lived.

To speak frankly, I didn't even found anything at the carboniferous period. Some today's plants are about the same size. Other kind of plants though.

Edited by michel123456

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I'm wondering what is meant by "plants were bigger". Because they couldn't have been taller than our current tallest trees (~100m), whose height is limited by physics. In that light, being "bigger" is a moot point, since dinosaurs were nowhere near that tall. Plants would tend to grow tall in competition for sunlight. Nothing special would be needed to drive this.

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