I have a question about dinosaurs?

Question

Why are they all called dinosaurs? I mean it looks to me like there is no moare a relationship between a triceritops and a dynoninchus then thate is between a hippo and a chicken. And how do we know they were all reptiles? Couldn't triceritops be a mammal. He looks like a rhino.

SO how do they know they didn't nurse? Is this just assumed because of the egg laying?

Answer 1

You are probably right to question why all of those animals are lumped together. In fact the word dinosaur does not figure into the formal scientific classification system. The name was applied to some of the first fossils discovered and came to be used for all of them.

It isn't unusual for two different animals with very different pedigrees to look and behave alike. Take for instance two types of kangaroo mouse. One lives in Australia and is actually a marsupial while the other lives in the Americas and is a true mammal (rodent). This is known as convergent evolution. In the same way the triceratops and rhino each evolved in its own time to fill the same sort of niche in the environment but there are enough differences to rule out that they are closely related.

Dinosaurs were first thought to be reptilian because of their bone structure, which of course is all scientists had to go on. Early representations had them being scaly and cold blooded.

Now there is a lot of support for the idea that many dinosaurs were quite different from today's reptiles. Some may have been warm blooded. Some certainly had feathers. Some probably grazed in herds or hunted in packs. What separates them from mammals is that so far their is no evidence that any of them gave birth like mammals. There are remains of eggs but no fossils have been found showing a developing fetus inside a mother dinosaur.

Perhaps they should be classified into a group or groups all by themselves. It is pretty certain that modern birds evolved from some dinosaurs. It is also known that small mammals were around before and during the main age of the dinos.

There is only one group of animals that lays eggs and nurses. They are very rare. The playpus is one member of this group. Their way of giving milk is different from mammals. The line of dinos that gave rise to birds didn't nurse or we would expect to fine some modern birds that do also.

Why this is true I am not sure but all babies that come hatch from eggs are ready for solid food (or partially digested food) and all that are born "live" (mammals) are not ready and must be fed on milk for a period after birth.

Answer 2

Dinosaurs aren't mentioned in the Old Testament simply because the writers didn't know about prehistoric matters. The Bible, though called the "Word of God," was nonetheless written by human beings. The only thing that can really be considered some sort of direct quote from God is the Ten Commandments. Everything else is just stories and parables, designed to try to explain the power of God. As such, the writers were limited in their knowledge of science. Even the Creation story was simply a way to try to explain what happened -- good grief, why would God be in a rush to get everything done in six days? It's not like there was an audience of observers that He was trying to impress. :-) Though I follow Judeo-Christian tenets, I don't take the Bible's stories literally. There are a lot of Bible-thumpers here, and a lot of rather rude atheists -- both sides mocking and deriding each other senselessly. For me, God is not only an omnipotent intelligent force but also the very essence of nature and the laws of physics -- far more impressive than just some robe-clad grandfatherly figure perched on a throne.

Answer 3

> Why are they all called dinosaurs?
It's historical. Some of the ones that were dug up early on had similarities to lizard bones, so they were called "terrible lizards." The name stuck.
Oddly, a name that didn't stick was "Noah's Ravens." People saw the tracks made by big predator dinosaurs, and thought they must have been made by a bird too big to fit on Noah's ark.

> how do we know they were all reptiles
They were dinosaurs. Neither bird, nor reptile.

> Couldn't triceritops be a mammal
My guess is that the skeletal remains appear to be more like dinosaur remains than like mammalian remains. If you're looking for giant rhino-like mammals, google things like baluchitherium.

Answer 4

In answer to your first question the term dinosaur simply means terrible lizard (from deino - terrible, and saurus - lizard).

Obviously though, that wasn't quite what you meant.

The basic root of your question relates to taxonomy, the classification of animals. Animals are grouped together in terms not of external physical characteristics but in terms of their basic body plan - and this is reflected in their skeletal structure.

For example, a whale looks much more like a big fish than it looks like a human, but it is much more closely related to humans than to fish. This was first realised because of the skeletal similarities. The most fundamental feature that all mammals have in common is actually their ear bones - all mammals have three ear bones - the malleus, the incus and the stapes. No other group of animals has this.

Similarly taxonomists and also paleontologists studying fossils look at common features in the skeletal structure of animals.

In that regard there is far more in common between a triceratops and a deinonychus than there is between a hippo and a chicken or a triceratops and a hippo. Similarly, as I suspect you know from the way you asked the question, the skeletal structure of a chicken is actually quite similar to that of a deinonychus, and this is because chickens, and all birds, evolved from theropod dinosaurs (of which deinonychus is one).

The answer above is nonsense - we have no DNA from fossil dinosaurs. However, zoologists have confirmed a great deal of the classification work that they have performed on morphological (shape) characteristics by genetic work on still living species, confirming the validity of the technique of classifying animals by bone structure.

These techniques are now very advanced. Very subtle features in jaws and teeth for example can tell you a great deal about the class of animal which it came from.

As for nursing animals, dinosaurs (e.g. protoceratops - related closely to triceratops) have been found with eggs and baby dinosaurs - so there is little doubt that dinosaurs were egg-laying. In terms of whether they nursed as well (as present day monotremes do) I'm afraid that I don't know the particular evidence for that but I suspect it is assumed on the basis of evolutionary relationships betweeen similar groups of creatures.

Long answer, but I hope that clarifies for you.

Answer 5

They are called dinosaurs because the people that named thought they looked like terrible lizards.

They are definitely not mammals because they do not have the same traits that mammals do, e.g. they are egg-laying, do not nurse, no fur, not warm blooded (though this is currently debated). They are closest to reptiles and birds. Modern birds are of course descended from dinosaurs. And a few think of birds as little feathered dinos.

Answer 6

dinosaur means giant lizards. just by comparing dinosaurs to modern day lizards tells us what they were. some later evolved into birds. mammals did live during the later days of dinosaurs but were small powerless animals. they outlasted the big animals during who-knows-what-happened, and took the land with full force.

Answer 7

They are united by a unique hip structure and some other features.

Answer 8

noo they know becaue they have studys dna and they are called dynsours becasue they lookkinda like lizzards thats what dyno -sour mean