Are Crocodiles Flawless? The Reptiles Haven't Changed in 200 Million Years
By: Elizabeth Gamillo (Smithsonian Magazine)
Crocodiles are fascinating critters. Especially Dundee.
The guy down below seems to be looking at the photographer.
I wonder what he has in mind...
S E E D E D C O N T E N T
Crocodiles are large reptiles with scaly complexions and menacing marble-like eyes. If we were to go back in time 200 million years, we would find that the crocodile's appearance would be unchanged. Today, there are only 25 different crocodile species, a stark difference in diversity compared to birds, which appeared on the fossil record millions of years after crocodiles did but have since evolved into 10,000 other species.
In a study published this month in Communications Biology , researchers of the University of Bristol found crocodiles have kept their distinct features over millions of years and lack diversity because of punctuated equilibrium, or long periods where species are stable. During these eras, the need to evolve only arises when the animal's environment forces them to adapt to new conditions, writes Max T. Stockdale, an expert in vertebrae macroevolution and paleontology and who was involved in the study, in the Conversation .
Fossil remains of crocodiles from as early as the Jurassic period show identifying characteristics in modern crocodiles. They both have lengthy snouts, husky tails, and rough, scaly hides. Stockdale and his team used an evolutionary mathematical model to analyze and compare modern crocodiles' body sizes with fossils of prehistoric crocodiles, he explains in the Conversation. The data collected revealed that most prehistoric crocodiles were evolving at a slower rate over time, with a few outliers evolving faster.
It turns out, slow and steady wins the race. The crocodiles that evolved slower were more likely to survive normal Earth-like conditions if there are no pressures to change, reports Caroline Delbert for Popular Mechanics . The other crocodiles that evolved faster went extinct.
Surviving crocodiles did not change throughout millions of years because they arrived at an equilibrium where they were efficient and versatile enough that they did not need to evolve to exist, reports the Conversation . Punctuated equilibrium is seen in species that evolve based on external factors like climate change or mass extinctions rather than evolving through sexual selection or predator versus prey situations. The crocodile may have reached this equilibrium through their abilities to survive without eating for long periods, and their sensitivity to temperature changes.
The researchers hope to use these findings to piece together Earth's evolutionary history and continue to look for other environmental factors that could have been a factor in the crocodile's consistent appearance.
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This croc story just in from CNN....
In evolution, good enough is success. The fact that a species has not changed in a long time simply means that there have not been sufficient mutations that have given the species a discernible survival / reproductive advantage in its current environment.
So I suppose we could say 'perfect' if that means 'continuing to successfully survive as a species'.
True... but too simple.
While these brutes have remained, unchanging, other species have appeared... and disappeared. Perhaps they've continually killed off any species that got close to their apex position, so they never had to encounter any species really at their level.
What is too simple about my comment? I identified the fundamental reason why evolution does not continue to perfection.
It seems to me that the seed doesn't just asks why crocs have remained unchanged. It underscores this lack of change, while other species did change... and a lot.
That's the question: why did crocs not change, while all the others did?
I understand your notion of "reaching 'good enough' and staying there". But why only the crocs?
The introduction of Pythons in the Everglades, by humans, is taking a noticeable toll on alligators and crocodiles.
That will be interesting. Two apex hunters!
Of course... we humans will probably stick our fat thumbs in before the beasties can settle it among themselves.
They already have. First, by introducing a population of Pythons that were never meant to be there and second, by sending in Python hunters [see Swamp People on History Channel].
Those things sure as hell made themselves right at home in the everglades.
I bet the snakes eat a lot of their young.
Have the crocs eaten any python hunters?
All sorts of species have hit periods where they made no changes. For example :
Species change in response to their environments. If a species has adapted suitably to its environment and this environment has not changed significantly, evolution can simply stall out. That does not mean the species is perfect, but it is good enough to continue. Most species continue to undergo change because their environments are forcing the issue. In most cases, the species goes extinct because it did not mutate fast enough to keep pace with environmental changes.
No.
They sure did and the pythons are eating mostly, the croc eggs I believe... don't quote me on that.
It's odd that many of the unchanged creatures come from the depths of the ocean. Crocs don't fall under that category, but I suppose their physical bodies are robust enough that what has occurred hasn't required them to evolve like other creatures.
I find reptiles fascinating. Thanks for the article!
From what I have read, they have not changed in appearance, but they have in size.
I thought I saw on one of the nature shows (or something) that there was a snubnose croc that had gone extinct.
I am not sure about crocks, but aligators are more closely related to fowl than they are to amphibians.
Crocs evolved from smaller lizards to the point where they were walking and hunting on dry land.
Somewhere in time between the Jurassic and Cretaceous periods
either super long hot or cold spells or high ocean levels drove the current versions back to 4 legged swimmers
although they still stand on their back legs in deep water.
Unlike Alligators, Crocs really do have salt glands and crocodile tears are real if they are living in salt water.
They tear when they eat for some reason, which is not readily apparent except on croc farms where they are trained to eat on dry land.
Visiting SC beaches involves being aware of the crocs much more than any sharks.
We warily watched a floating log one day for hours before we saw the tail slap and it reversed coarse up the coast.
The introduction of the Burmese python in the Florida Everglades has had a devastating effect on all wildlife including gators. The decline of some species in the Glades is over 80%, bobcat, opossum, deer, etc. It is a very serious problem and the pythons not only eat the gator eggs but will attack and kill gators.
The largest phyton captured or killed in the Glades was 18' 9'' and weighed over 100 lbs.
Florida is gator heaven in the US.
This is Chubbs he lives around a golf course in Naples, FL. Chubbs is around 13 feet long and weighs around 1,000 lbs.
When we lived in Australia we saw a lot of probably the largest and most dangerous of the lot, the Australian Saltwater Crocodile. Reaching 18 ft and weighing up to 2,000 lbs.
Very interesting critters, powerful and deadly as well.
Great article.
Morning. Actually a guy up Qld just fought off a 2 metre croc that grabbed him around the head and shoulders y'day.
He prised it's jaws apart and got himself out but it snapped shut on his fingers. Got puncture wounds head neck shoulder and hand...very lucky.
He is in hospital and expected to make a full recovery. They are now relocating the croc...
That's one lucky guy.
We breed them tough here..
Is Paul Hogan from your neighborhood?
Evening. No he lived in Sydney up in NSW...I live in Victoria..
He sounds like a real life Mick Dundee. I hope he recovers quickly.
We have plenty of these little guys running around our area.
The Brown Anoles
Are they called Watermelon Anoles due to the neck flap resembling a slice of watermelon?