I’ve been told that Evolution is the process by which populations of organisms acquire and pass on novel traits from generation to generation, affecting the overall makeup of the population leading to the emergence of new species.

Why then, didn't these things keep evolving...

!-Alligators and Crocodiles - The crocodile family is thought to have lived 230 million years ago and remains virtually unchanged since that time.

!- Army Ants - date back 100 million years to the time of the dinosaur.

Army ants defy evolution Cornell News 5/5/03 "army ants in essence have not changed a bit."

* Cockroaches - dates back 350 million years

300 million-year-old cockroach discovered Ananova
Mega cockroach News in Science - 08-11-2001

* Coelacanth - Dates back 400 million years. The Coelacanth pre-dates the dinosaurs by millions of years, and was once thought to have gone extinct with them 65 million years ago until it was discovered alive and well in 1938.

New 'living fossil' identified BBC News Sci-Tech 3/25/99
Coelacanth Surprise Sighting ABCNews 9/23/99
DINOFISH.com - coelacanth: The Fish Out of Time
'Living fossils' discovered off South Africa coast - December 1, 2000 CNN.com
Sulawesi Coelacanth - The Discovery

*Crinoid or Sea Lilly have been found in sedminents dating back 150 million years and yet the modern living variety is virtually identical.

Living fossils by Joachim Scheven. Creation 17(3):52 June 1995
Undersea mountains yield living 'fossils' - June 26, 2000 CNN.com

* Cycads date back 240 million years ago

* Dragonfly dates back 230 million years, but is unchanged in almost every detail

Emperor Dragonfly
The Energizer Bunnies of Evolution - Science Musings 1993-7-26

* Ginkgo tree belongs to the family Ginkgoaceae which dates back to 270 million years. They were thought to be extinct until they were discovered in 1691 in the Japan.

Ginkgo is living fossil Ancient plants mirror modern trees. Nature June 2003
GINKGO BILOBA -The Ginkgo Pages -Index

* Horseshoe Crab - Believed to have lived 300 million years ago, but remain almost identical today.

Horseshoe Crabs - A Living Fossil- by Maryland Dept of Natural Resources

* Nautilus - believed to have lived 500 million years ago, but remains almost completely unchanged

Ammonite Fossils & Ammonites Evolution by Discovering Fossils
Chambered Nautilus
The Chambered Nautilus- the John Templeton Foundation

* Neopilina molluscs - Discovered living in the early 1950s these mollusks share a close relationship with fossils that existed about 400 to 500 million years ago.

Neopilina A Living Fossil by Clausen, C. D. Origins 3(1):56-59 (1976).
Neopilina - a living fossil

* Salamanders

Salamander Origins Pegged To Asia- National Geographic News 3/28/2001. A recent fossil find in China was dated to 150 mya, and is virtually unchanged from what we find living today in the neighborhood swamp.

* Sturgeon is claimed to be 250 million years old, and living since the time of the dinosaurs.

Seven-foot living 'dinosaur' lurks in Oregon- Eurek Alert 12/19/02

* Tuatara is a lizard which is thought to have been around longer than any other living reptile, and unchanged in over 200 million years.

Tuatara - More ancient than the dinosaurs
Tuatara - World Wide Fund for Nature. "The tuatara is the sole survivor of a group of reptiles that have existed for 200 million years"
Tuatara Reptile, New Zealand

* Velvet Worm dates back 500 million years

Velvetworm a Living Fossil USDA ARS

* Wollemi Pine - "Dinosaur Tree" - Not discovered living until 1994, this genus of trees dates back to about 150 million years ago and coexisted with the dinosaurs.

Jurassic pot plants on sale soon - BBC NEWS Science-Nature 9/25/2003
'Living Fossil' From 50 Million Years Ago "The Wollemi Pine" 1995

Do things reach an optimum developmental stage and stop evolving?

What do you think?

I don't think it's a matter of them stopping evolving. It's just the adaptations they have are suitable for the environment they're in. Once that environment changes they'll gradually change as well.

Of course I could always be wrong.

evolution never stops...once in while it reaches optimal high(sharks) and the design is need no improvement unless the environment changes requires evolution.

yes, exactly, sometimes an animal is perfectly suited...sorry, im lost for words here

Aye... evolution isn't a fast proccess... and alot of creatures have adapted to their suited habbitats so well that they don't have to evolve drasticly to continue living there or die out.

Actuallity, the fresh water crocs in austraila show evidence that they are still evolving into something suited to where they live in. They're smaller then the salt waters... and more nimble... they can actually gallop between water holes... lakes and ponds... something that was recently found out... (recently is in terms of a couple of decades)

This is just one example..

yes, evolution happens over the course of millions of years

evolution is a process by which all creatures adapt to a changing environment. Should any creature exist within an environment that does not require adaptation then that creature will not change. All of us that share this earth are shaped by our environment.

that doesn't prove anything, if anything that shows that creature has reached point where the changes are so minute as to not make the creature appear to have changed in our eyes. Evolution = changes in the genetics of a population over time, if that population is split or something happens that forces certain traits to be beneficial, then after a period of time speciation can occur. it has been said that given enough time humans would have speciated(i.e. without contact with one another).

And if you understood biology... you'd know that it takes millanias of "micro" evolutions to have one seemingly huge evolutionary jumps.

Although the typical amphibious version of crocodilians have been succesful and virtually unchanged for over 200 millions years, there are some spectacular examples of some species rapidly evolving to fill other ecological niches. One crocodile evolved into quite literally a theropod dinosaur in the age of mammals. Another in Australia, contemporary with humans, remained quadraped, but became a complete land dweller. Even the teeth of both of these crocs evolved from typical conical fish getters into narrow flesh cutters like the carnivorous dinosaurs.

If the large carnivorous mammals (and mankind) were to become extinct, crocodilians may again exploit the terrestial predator niche.

yes, Posthosuchus was a Triassic precursor of the archosaur DC said (name slips my mind)...obiously, the water reptiles were more adapted, while the land-dwellers died out

humans already have speciated.

very slightly...just as extreme as a color change in the crocs

not true, humans as we know ourselves would have changed further without contact with other groups, due to geographical differences, and if we had speciated, became seperated species of humans, then we would not have viable offspring between lets say Africans and Europeans or Asians and The Native peoples of the Western Hemisphere, in other words humans are mixing to the point where we are becoming one species with a variety of traits that allow for our survival.

So these disparate organisms, through countless generations, over hundreds of millions of years of volcanic eruptions, a couple super volcano eruptions, continents drifting and colliding, continents rising or sinking, floods, tsunamis, seas and oceans spreading and shrinking, at least one global killer asteroid impact, and several ice ages have maintained near perfect Homeostasis?...

never perfect homeostasis, only they haven't changed much in their structure, design and function will have remained relatively unchanged.

I didn't say perfect homeostasis...

meanwhile 99.99 to some impressive %, of every other organism changed?

Just not these examples...

good to know that if we heat the planet too much, raise sea levels, pollute the atmosphere, or make it too cold, bringing on a new glaciation they’ll be OK... after all they’ve survived it many times before.

Rrriight...

In nature these changes take place slowly over millennia. Human impact can be noticed within a little time as a year, big difference

Also animals never had to deal with pollution until we arrived on the scene.

what do you think spews out of volcano's, and super volcanoes, laughing gas?, and the KT asteroid was supposedly a very sudden geological event. But I guess nobody told these organisms the ride was over...

Volcanic gas has been spewing out since the earth was born, do you not think that any life than came along after would be naturally impervious to this at natural levels, and of course any localised event would kill out a local population.


I never mentioned the asteroid, you where talking in a future tense and didn't even mention it in the part I quoted.


BTW "laughing gas" or Nitrous oxide does not come from a volcanic source. I think your thinking of something else.

to say they are unchanged is false behavior is an adaption aswell so an animals aperance could be the same but behavior diffrent not to mention an adaption isnt always a plus sometimes its a bad thing people often make that mistake aswel for instance we and our early ancestors are similar to almost every detail in apercance but we are far more mentaly evolved then they are

The changes have to *last*. If something big happens, then a year or so it goes back to relatve normal, they won't change. They don't have the time.

the thing is maybe their current structure are perfect and need not to change. Evolution is a way of adapting to the changes around them.

once again an enviorment constantly changes the animals that were perfect for there enviorment all die easily becuase once a sm all change happens they die and an adaptation is NOT always a plus some times its harmful people for the love of god please understand the words of a zoologist evolution is a process of an species to better suit there sroundings and when that always changes the species must too an adaption may or may not be a trait carried on by the species if u were born with 6 fingers this is an adaption (unless some chemical force was acting on this) but it does not mean people are evolving into having six fingers

i'm just saying that their almost perfect structure are adaptable in most environment need only to change little or non.

behavior is a change dont just look at physical look at mental too

Agreed. Once a species has traits favorable to their niche, they don't need to evolve new ones. If something radical happened to change their environment, then they would either adapt, leave, or perish.