Mammal Rise and the Dinos

SezMe

post-pre-born
SezMe
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As a lay reader of evolution, I have bought into the conventional wisdom that the extinction event 65 million years ago basically wiped out the dinos. This, in turn, allowed mammals to "bloom". At least I thought that was (is?) the conventional wisdom.

But this article suggests otherwise. I found it to be an interesting read but I'd like to see some commentary from those of you whole have more knowledge than I. Thanks.
 
It's the annoying thing about relying on a fossil record to deduce what happened in the past. It's a scatter of snapshots from throughout history, which of course has numerous gaps where we have no information. Thus as we accumulate fossils and learn to see where they fit in the record, our ideas on how certain species dominated and how various groups fluctuated will also improve.

Mammals were always thought to be small, shrew like things until niches opened up to allow them to diversify. We now feel that this is a touch simplistic, as evidence has arisen which suggests that mammal-like organisms were more diverse than we thought much earlier than we realized. There are examples of large mammals which dominated various environments throughout the periods when dinosaur species were so plentiful.

The niches opened by the decimation of the dinosaur biodiversity were taken advantage of by numerous mammalian species, however the speciation 'boom' as such is now recognized to have happened far earlier over a larger stretch of time, where (as the article said) their diversity shrank until the Eocene.

Ah, life. An amazing spectrum, no?

Athon
 
It's interesting stuff. The problem is, we can never know what would have happened if an asteroid hadn't landed. Maybe mammals would have taken over anyway, maybe they wouldn't, we really can't tell. In the end, all we know for sure is that an asteroid did land and the dinosaurs did die out. There can be no doubt that the former must have had some kind of effect on the latter, but we might never know just how big the effect was since we can't go back and see what would have happened if things were different.
 
This is an excellent example of self-correcting science at work. In this case, we have a slightly different theory of the rise of mammals. We may never know which is more correct, but we can consider both when more evidence becomes available.
 
This makes sense when you consider that dinosaurs were preceded by large, mammal-like reptiles (such as the Dimetrodon), which suggests that mammallian evolution was pretty far along by the time dinosaurs appeared.

Of course, there's nothing to keep the large mammal-like reptiles from evolving into tiny mammals.
 
Oh, I'm perfectly willing to let my thread die, I've just been having some fun with my apparently short-lived "X Proves God's Existence" theme. :(

Anyhoo, carry on with this thread folks, nothin' to see here.

:cool:
 
I've seen some evidence, which I'll need to dig up, that between the extinction of the dinosaurs and the true "age of mammals" we currently live in* there was an age of birds where flightless raptors were the dominant terrestrial tetrapod.

* yes, yes, time since the Cambrian has been the age of nematodes and since the Ordovician has been the age of insects, but work with me here...
 
Thanks for the link, Level. What I could read from that paper was interesting. I find it fascinating that we could be discussing details of what happened to various biota tens of millions of years ago.
 
I am by no means an authority, but the things I have read in the relevant fields seem to point to mammals as being small, shrew-like things 60 million years ago, but tiny differences in groups of "shrew-like" mammals could be much more important genetically than they seemed phenotypically. I have read the same argument against the Cambrian explosion, that different groups had emerged and diversified, but they happened to all share a superficial resemblance.
I could very well be wrong in this.
 
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