Scientists have many theories about what caused the extinction of dinosaurs. Below are thoughts on some of the most common theories:

• Since about 90% of dinosaurs were herbivores (plant eaters), it was thought that when an asteroid hit earth and many tons of dust was thrown into the atmosphere that the result was a "long night" due to the lack of sunlight that was able to reach earth, the plants died out and without a food source, so did the dinosaurs.

• It could also have been the combination of the Chicxulub asteroid impact event (causing worldwide fires and environmental catastrophe) in association with the Deccan Traps volcanic event, which occurred at around the same time, or possibly as a result of, the asteroid impact event.

• There are many theories that are written throughout history of why the dinosaurs exactly were driven into extinction. Most are meteor impact related. By looking at craters all over the world, scientists can estimate the meteors size, speed and its impacts effect on the local environment. See the related link for more information.

• Though the large meteorite impact (Chicxulub) figures prominently in a lot of the theories of how the dinosaurs became extinct, the idea of a gamma ray burst has also come up now that we are aware of them and the threat they pose. Additionally, there was an "outburst" of volcanic activity during this period. This extinction event is at the Cretaceous-Tertiary (K-T) boundary.

• It should also be added that several other large impact events occurred right about the time of Chicxulub, including Silverpit and Boltysh craters, among others. It seems the deck was "stacked against" the dinosaurs, regardless of how you look at it. It is possible that things are "found" to "corroborate" extinction by space rock, but the facts are pretty convincing, even for the skeptic.

• It was noted but is worth repeating: many of the ideas that represent credible ways that could have triggered the dinosaurs' extinction could have arisen separately and acted in concert to kill off all these creatures. One thing is certain - they're gone. And the demise of the terrible lizards was caused by something dramatic given the relatively narrow window in which they disappeared.

• The hypothesis that states an asteroid-impact was the sole cause of the extinction is just that - an hypothesis, not a fact. Most paleontologists feel that the asteroid impact was just one of a series of catastrophic events that ultimately wiped out the dinosaurs. There is evidence of a huge meteor strike just off the Yucatan Peninsula, true. And a meteor may well have put a final period to the extinction pulse. But there is also evidence that other factors may have been involved. For one thing, the dinosaurs didn't become extinct all at once. The pulse seems to have taken more than 10-thousand years to complete which makes the asteroid theory implausible as a complete explanation. There is evidence that there was massive volcanic activity also, and a drastic climatic change. The dinosaurs were in decline in number of species long before the K/T extinction was over. Furthermore, some dinosaurs did survive into Laramide time - the birds are still around (admittedly that's begging the issue, but it's not unreasonable to ask how they managed to survive when so many their brethren were killed).

• Dinosaurs were already fast becoming endangered species before the Chicxulub impact. Increased volcanic activity such as the Deccan Traps in modern day India was slowly killing many species. Between 68 to 60 million years ago 150,000 km2 of igneous rock was deposited in places more than 2 km thick. The bulk of the eruptions occurred about 66 million years ago near modern day Mumbai. These eruptions lasted as little as 33,000 years but the effect on the environment would have been staggering. Dust and debris thrown into the atmosphere along with sulphur dioxide would have cooled the earth. Also many poisonous gases would also have been released. Studies on modern day birds suggest that these poisonous gases not only directly killed dinosaurs but also caused thinning of the shells of their eggs which meant that many would fail to hatch.

• It has also been suggested that disease killed off the dinosaurs. A very deadly and contagious disease may have circulated among the dinosaurs forcing them to become extinct. Still yet another theory is that the Earth just gradually changed in climate over a long time period and the dinosaurs were not able to adapt to the cooler, dryer climate.
• When the continents broke up, they couldn't get to new feeding grounds when theirs were exhausted

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It mst also be pointed out that the avian type dinosaurs (the birds), did not become extinct and are living today.

Scientists have many theories about what caused the extinction of dinosaurs. Below are thoughts on some of the most common theories:

• Since about 90% of dinosaurs were herbivores (plant eaters), it was thought that when an asteroid hit earth and many tons of dust was thrown into the atmosphere that the result was a "long night" due to the lack of sunlight that was able to reach earth, the plants died out and without a food source, so did the dinosaurs.

• It could also have been the combination of the Chicxulub asteroid impact event (causing worldwide fires and environmental catastrophe in association with the Deccan Traps volcanic event, which occurred at around the same time, or possibly as a result of, the asteroid impact event.

• There are many theories that are written throughout history of why the dinosaurs exactly were driven into extinction. Most are meteor impact related. By looking at craters all over the world, scientists can estimate the meteors size, speed and its impacts effect on the local environment. See the related link for more information.

• Though the large meteorite impact (Chicxulub) figures prominently in a lot of the theories of how the dinosaurs became extinct, the idea of a gamma ray burst has also come up now that we are aware of them and the threat they pose. Additionally, there was an "outburst" of volcanic activity during this period. This extinction event is at the Cretaceous-Tertiary (K-T) boundary.

• It should also be added that several other large impact events occurred right about the time of Chicxulub, including Silverpit and Boltysh craters, among others. It seems the deck was "stacked against" the dinosaurs, regardless of how you look at it. It is possible that things are "found" to "corroborate" extinction by space rock, but the facts are pretty convincing, even for the skeptic.

• It was noted but is worth repeating: many of the ideas that represent credible ways that could have triggered the dinosaurs' extinction could have arisen separately and acted in concert to kill off all these creatures. One thing is certain - they're gone. And the demise of the terrible lizards was caused by something dramatic given the relatively narrow window in which they disappeared.

• The hypothesis that states an asteroid-impact was the sole cause of the extinction is just that - an hypothesis, not a fact. Most paleontologists feel that the asteroid impact was just one of a series of catastrophic events that ultimately wiped out the dinosaurs. There is evidence of a huge meteor strike just off the Yucatan Peninsula, true. And a meteor may well have put a final period to the extinction pulse. But there is also evidence that other factors may have been involved. For one thing, the dinosaurs didn't become extinct all at once. The pulse seems to have taken more than 10-thousand years to complete which makes the asteroid theory implausible as a complete explanation. There is evidence that there was massive volcanic activity also, and a drastic climatic change. The dinosaurs were in decline in number of species long before the K/T extinction was over. Furthermore, some dinosaurs did survive into Laramide time - the birds are still around (admittedly that's begging the issue, but it's not unreasonable to ask how they managed to survive when so many their brethren were killed).

• Dinosaurs were already fast becoming endangered species before the Chicxulub impact. Increased volcanic activity such as the Deccan Traps in modern day India was slowly killing many species. Between 68 to 60 million years ago 150,000 km2 of igneous rock was deposited in places more than 2 km thick. The bulk of the eruptions occurred about 66 million years ago near modern day Mumbai. These eruptions lasted as little as 33,000 years but the effect on the environment would have been staggering. Dust and debris thrown into the atmosphere along with sulphur dioxide would have cooled the earth. Also many poisonous gases would also have been released. Studies on modern day birds suggest that these poisonous gases not only directly killed dinosaurs but also caused thinning of the shells of their eggs which meant that many would fail to hatch.

• It has also been suggested that disease killed off the dinosaurs. A very deadly and contagious disease may have circulated among the dinosaurs forcing them to become extinct. Still yet another theory is that the Earth just gradually changed in climate over a long time period and the dinosaurs were not able to adapt to the cooler, dryer climate.

Some adjectives that begin with the letter F are:

• fabled
• fabulous
• factual
• fad
• faded
• failed
• failing (as in a failing grade)
• faint
• fair, fairer, fairest
• faithful
• faithless
• fake
• fallacious
• fallow
• false
• faltering
• familiar
• famished
• famous
• fanatical
• fanciful
• fancy, fancier, fanciest
• fantabulous
• fantastic
• fantastical
• far, farther, farthest
• far-fetched
• far-off
• fascinated
• fascinating
• fashionable
• fast, faster, fastest
• fastidious
• fasting
• fat, fatter, fattest
• fatal
• fated
• fatherly
• fatigued
• fatty
• faulty
• favorable
• favorite
• feared
• fearful
• fearing
• fearless
• fearsome
• feathered
• feathery
• feeble
• feigned
• feisty, feistier, feistiest
• feline
• felonious
• female
• feminine
• feral
• ferocious
• fertile
• fervent
• festering
• festive
• festooned
• few
• fey
• fibrous
• fickle
• fictional
• fictitious
• fidgety
• fierce, fiercer, fiercest
• fiery
• fifth
• fifty
• Filipino
• filled
• filling
• filthy, filthier, filthiest
• final
• financial
• fine, finer, finest
• finicky
• finished
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• Finnish
• fireproof
• firm, firmer, firmest
• first
• firsthand
• fishy, fishier, fishiest
• fit, fitter, fittest
• fitful
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• fitting
• five
• fixated
• fixed
• fizzy, fizzier, fizziest
• flabby, flabbier, flabbiest
• flagrant
• flaky, flakier, flakiest
• flamboyant
• flammable
• flared
• flashy, flashier, flashiest
• flat, flatter, flattest
• flattering
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• flawed
• flawless
• flecked
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• fleshy
• flexible
• flighty, flightier, flightiest
• flimsy
• flippant
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• flitting
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• floppy, floppier, floppiest
• floury
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• fluctuating
• fluent
• fluffy
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• fluky
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• flustered
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• fluttering
• flying
• foamy, foamier, foamiest
• focused (as in He's a very focused individual)
• foggy
• folksy
• foolhardy
• foolish
• forceful
• foregoing
• foreign
• forgetful
• forked
• formal
• formative
• former
• formidable
• forsaken
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• fortuitous
• fortunate
• forward
• foul, fouler, foulest
• fouled
• found
• four
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• foxy
• fractured
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• fragrant
• frail
• frank
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• frantic
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• freaked-out
• freaky, freakier, freakiest
• free
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• freezing
• French
• frenetic
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• fresh
• fretful
• friendly, friendlier, friendliest
• frightened
• frightening
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• frigid
• frilly
• frisky
• frivolous
• frizzy, frizzier, frizziest
• frontal
• frosted
• frosty, frostier, frostiest
• frothy
• frozen
• frugal
• fruitful
• fruity
• frumpy
• frustrating
• fudgy
• full
• full-figured
• fumbling
• fun
• functional
• fundamental
• funky
• funny, funnier, funniest
• furrowed
• furry, furrier, furriest
• furtive
• fussy, fussier, fussiest
• futile
• future
• futuristic
• fuzzy, fuzzier, fuzziest

· fanatical

· fearless

· feisty

· fickle

· finicky

· flaky

· flawless

· forgetful

· funny

In a word, no, but scientists can make educated guesses. The closest living relatives of the dinosaurs are crocodilians and birds, and we can look to the ways they vocalize to give us a hint.

Alligators and crocodiles use their larynxes to communicate—they’ll hiss, groan, and yes, roar (here’s a compilation of their sounds). Dinosaurs might have had larynxes, but since those don’t fossilize, it’s impossible to know for sure. Birds, meanwhile, use an organ called a syrinx, which seems to have evolved after dinosaurs. That might indicate that dinos couldn’t vocalize at all, which would be a bummer.

However, there’s also a possibility that they evolved a unique way to vocalize. For example, based on studying their skulls and inner ears, some have theorized that hadrosaurs used their crests to bellow at each other.

So, they probably didn’t roar, but bellowing can be pretty cool too, right?

Answer 1

if you mean strongest, then probably one of the sauropods, such as seismosaurus or amphicoelias if it existed. However, they aren't neccessarily the most effective at battle, since t-rex was tall enough to reach their neck and simply crush it (which in turn would be smashed to bits by Ankylosaurus which in turn would be crushed by the large sauropods...)

Answer 2

Amphicoelias probably it could just crush everything in its way.