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Evolution of Mammals Re-evaluated

Posted by ScuttleMonkey on from the shaking-the-tree-to-see-what-falls-out dept.

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."

5 of 249 comments (clear)

  1. Alternate theory by Average_Joe_Sixpack · · Score: 5, Funny

    Most sensible explanation

    1. Re:Alternate theory by franksands · · Score: 5, Funny

      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.

  2. Hrmm... by grub · · Score: 5, Funny


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

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  3. Re:This is Great by Coryoth · · Score: 5, Informative

    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.
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  4. Many mammalian lineages predate the K-T extinction by saforrest · · Score: 5, Informative

    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.