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Researchers: Why crocodiles have not changed since the dinosaur age


They say, punctuated equilibrium (punk eek):

In the new research, published today in the journal Nature Communications Biology, the scientists explain how crocodiles follow a pattern of evolution known as ‘punctuated equilibrium’.

The rate of their evolution is generally slow, but occasionally they evolve more quickly because the environment has changed. In particular, this new research suggests that their evolution speeds up when the climate is warmer, and that their body size increases.

Lead author Dr Max Stockdale from the University of Bristol’s School of Geographical Sciences, said: “Our analysis used a machine learning algorithm to estimate rates of evolution. Evolutionary rate is the amount of change that has taken place over a given amount of time, which we can work out by comparing measurements from fossils and taking into account how old they are.

“For our study we measured body size, which is important because it interacts with how fast animals grow, how much food they need, how big their populations are and how likely they are to become extinct.”

The findings show that the limited diversity of crocodiles and their apparent lack of evolution is a result of a slow evolutionary rate. It seems the crocodiles arrived at a body plan that was very efficient and versatile enough that they didn’t need to change it in order to survive.

This versatility could be one explanation why crocodiles survived the meteor impact at the end of the Cretaceous period, in which the dinosaurs perished. Crocodiles generally thrive better in warm conditions because they cannot control their body temperature and require warmth from the environment.

University of Bristol, “Why crocodiles have changed so little since the age of the dinosaurs” at ScienceDaily

The paper is open access.

One way of looking at it: After you are a crocodile, there is no place for you to go.

In response to the question of what might count as sudden appearance, I would suggest three in reverse chronological order: 3. The Cambrian Explosion of species so radically disparate in their body plans that they are classified in different phyla. Even Richard Dawkins admits that they appear to be just planted there without any evolutionary history. Given the low species diversity within each phyla at their sudden appearance, he's right. The sudden appearance of new species with minor variations on pre-existing designs, however, I personally wouldn't count as sudden appearance. Technically, when two populations of the same species lose the ability to interbreed, they form two species out of one which could happen virtually instantaneously. Speciation is so trivial I wouldn't count it among the greatest hits of sudden appearance. 2. The origin of life on Earth could certainly be considered to be sudden. Try to get to even the simplest irreducibly complex organism gradually and natural chemical reactions will instantly begin the decay process even if you are 99% of the way to the first life form. It's sudden or nothing. 1. Finally, the origin of the entire universe would certainly count as sudden. If it wasn't sudden, we wouldn't call it the Big Bang. So who is responsible for all of this sudden appearance from the beginning of time? Reason tells us that either the Cosmos or its Creator has always existed and it's not the Cosmos. Battman
Body plans are irrelevant as there isn't any evidence that blind and mindless processes can produce developmental biology. Darwinian evolution and all of it's bastard offspring, are total nonsense, only for the weak of mind. ET
Battman: but there are real doubts about the sudden appearance of new body plans being natural as well. Depends on what you mean by 'sudden'. Do you have an example? JVL
If I have this right, their microevolution led to their macro-stasis. I'm good with that. Stasis is natural (observable in the fossil record as predictable and repeatable events, hence subject to the natural sciences) but there are real doubts about the sudden appearance of new body plans being natural as well. Assuming that unique unrepeatable and unpredictable events are natural tells a lot more about one's faith and philosophy than it does anything about science. Battman
An evolutionist's explanation of driving: "When I drive, I go slow, except when I go fast. I find that I get to places quicker if I go fast and not slow. And mostly I go straight, except when I make turns. And I find that the fewer turns I make, the faster I get there. Also, when I drive, I don't worry about how much gas I have, until I run out." PaV
All of a sudden I'm hungry for a steak mike1962
Body plan? Wow! Evos generally deny there is such a thing even though our classification systems are based on them. Alan Fox thinks that most animals are just deuterostomes. That's it. Basically Alan is unable to tell a fish from a human. ET
@ 2 That is Exactly why I laughed AaronS1978
OK, so except for a liking for warm weather (which ALL cold blooded animals share), there is NOTHING special about crocodiles (as compared to, oh, badgers). And the experts don't attempt to say ANYTHING about why there are also alligators (i.e., did alligators EVOLVE from crocodiles). And they don't say anything about Salt Water Crocodiles. So all in all, the experts say NOTHING. mahuna
Lol AaronS1978

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