Evolution of Mammals Re-evaluated

AaxelB writes "A study described in the New York Times rethinks mammalian evolution. Specifically, that the mass extinction of the dinosaurs had relatively little impact on mammals and that the steps in mammals' evolution happened well before and long after the dinosaurs' death."

Comments

What About the Other Dinosaurs?

[Anonymous Coward]

Most paleontologists now think that birds descended from dinosaurs. So in a sense, even dinosaurs in one form escaped the calamity.

Don't forget varanus komodoensis ... and Strom Thurman, he died out only four years ago and was the most prominent organism to escape the icy grasp of natural selection!

Re:What About the Other Dinosaurs?

[Anonymous Coward]

"...Dinosaurs were created on day 6 of the creation week approximately 6,000 years ago, along with other land animals, and therefore co-existed with humans."

"...Dinosaurs lived in harmony with other animals, (probably including in the Garden of Eden) eating only plants;" and "pairs of each dinosaur kind were taken onto Noah's Ark during the Great Flood and were preserved from drowning."

"Dinosaur bones originated during the mass killing of the Flood;" and "some descendants of those dinosaurs taken aboard the Ark still roam the earth today."

And you can look that up!

Re:What About the Other Dinosaurs?

[Monokeros]

Easy. Elephants, hippos, alligators, lions, polar bears, and kitty cats were the food for the dinosaurs. The dinosaurs made their way through the dragons, unicorns, hobbits and fairies by the time the flood ended and the rest were spared. They're living on a ranch in Montana now.

Alternate theory

[Average_Joe_Sixpack]

Most sensible explanation

Re:Alternate theory

[franksands]

Sorry for the comment abuse, but I just had to post this comment from youtube:

evilc27 (2 hours ago)
The fact that we are born babies and evolve into people is evidence enough to dispel the myth of evolution. If we were born monkeys, then there would be billions of monkeys in the world as there are billions of people. This does not equate. People have called me stupid for expressing my facts, but I am far from stupid. I took an IQ test at my church school, and I scored 95. You cannot get more than 100% and so I am in the top 5% of the smartest people in the world. chew on that disbelievers.

This just made my day.

Re:From a friend

[Cro Magnon]

So in a sense, even dinosaurs in one form escaped the calamity. I found it pretty cool.

It's not so "cool" having to clean dinosaur droppings off my car, though.

Hrmm...

[grub]

But can they shoehorn it into the framework of a 6000 year old Earth?

Re:This is Great

[Coryoth]

Until the next "re-thinking." Will we ever have hard evidence, or just thought experiments? But we do have hard evidence - indeed it was hard evidence that helped lead to this rethinking. Recently there have been a number of finds of surprisingly large mammals that are much older than had previously been expected. They include a beaver like (pre)-mammal from the Jurassic that was almost half a metre long, discovered in 2004, and two species large carnivorous mammal from the cretaceous (dated to about 130 million years ago - or 65 million years prior to the dinosaur extenction) which were discovered in 2000 and 2005. Such large mammals (relatively speaking) during the time of the dinosaurs draws into question the previous belief that mammals were restricted to small rat/mouse like scavengers at that time. Instead we see evidence of large, active, meat eating mammals. This implies that mammals were rather less marginalised during the dinosaurs "reign" than previously thought, and imples that mammal evolutionary history needs to be rethought accordingly.

Many mammalian lineages predate the K-T extinction

[saforrest]

If you read The Ancestor's Tale by Richard Dawkins, you'll find that recent genetic evidence suggests that many of the distinct branches of modern mammals predate the K-T extinction.

In particular, by the time of the K-T extinction, I believe that the primate lineage had already separated from rodents, as well as the laurasiatheres (all hoofed mammals, lions, tigers, bears, etc.), xenarthrans (armadillos, sloths, etc.), and afrotheres (elephants, manatees, anteaters, etc.).

So, while most mammals in the Cretaceous may still have been tiny shrew-like creatures scurrying around in the underbrush, many of the modern lineages had already come into separate existence.

It is also interesting to read, in the book, that our nearest non-primate relatives aside from the tree shrews are rodents. I can sort of see it: give a mouse a little more finger dexterity and it wouldn't not that different from a lemur. It also might explain why rodents are such good laboratory specimens.

Re:Science rethinking.

[flitty]

Science is often championed as being very sure... especially evolution,

I'm calling you on this rediculous statement. Science is only as sure as they can prove. You'll hardly find a scientist who, under new evidence or studies, will say "nope, the way we used to believe is more correct, and i'll be damned if i take your new evidence into consideration!"
Sounds more like religion to me.

Re:Shamelessly off-topic, but must be done...

[Daniel Dvorkin]

There is obviously no evidence that the mutations which gave rise to speciations were "random" and not in some way directed, naturally or supernaturally, or otherwise forced in some particular direction.

"Obvious" if you ignore pretty much all work in molecular genetics at least since Watson and Crick.

Once we arrive at a better understanding of how DNA works, perhaps it will be possible to form mathematical models to determine whether or not the "random mutation" theory is feasible.

You mean, the way bioinformaticists and statistical geneticists do all the time, right now, and have been for years?

Maybe it's only feasible during intermittant radiation events that decimate populations by causing widespread mutations, leaving a few individuals with improvements, who go on to reproduce and build up populations again. Maybe it's not possible at all.

Do you have any data, at all, that would support either one of these hypotheses? Or are you just cut'n'pasting from some ID site somewhere?