Darwinius masillae, what do you expect?

[MatheusAgostin]

Have you heard about the Darwinius masillae? It must be our greatest ancestor. You can read more on wikipedia: http://en.wikipedia.org/wiki/Darwinius_masillae

 

So, what do you think? Is it a big deal or just another monkey? It's 95% conserved, so I think we can get a lot of cool information from it.

[Ophiolite]

Outstanding preservation. Interesting point in the evolution of primates. It is and will remain important. The media hype is probably part of an orchestrated attack on creationist thinking. So, yes - it is a big deal. And no, it is not any kind of monkey.

[SH3RL0CK]

I'd really like to get a good DNA sample from the fossil and compare to modern day primates, lemurs, etc. This could shed light on the potential for this to be a "missing link." I suppose that is asking too much though after 47 million years.

[CDarwin]

Outstanding preservation. Interesting point in the evolution of primates. It is and will remain important. The media hype is probably part of an orchestrated attack on creationist thinking. So, yes - it is a big deal. And no, it is not any kind of monkey.

 

The media hype is part of an orchestrated promotion of Phillip Gingrich and his adapoid theory of anthropoid origins. Darwinius masillae is an adapoid, and it supposedly has anthropoid features. Gingrich now has a huge soap box to scream from and I have a feeling he's going to try to shout down all the other scientists he's been arguing with for years about which Eocene primate group anthropoids evolved from. So, I'm skeptical of the missing link bit until we get some more objective analyses. But, still, beautiful skeleton.

 

I'd really like to get a good DNA sample from the fossil and compare to modern day primates, lemurs, etc. This could shed light on the potential for this to be a "missing link." I suppose that is asking too much though after 47 million years.

 

Or you could just look at the features of the skeleton and dentition using the same comparative techniques that have informed most of what we know about the relationships of modern and fossil forms since Cuvier. There really is an enormous amount of potential for analysis here. The teeth alone could be all we need to determine where it fits with respect to adapoids and anthropoids.

Edited May 22, 2009 by CDarwin
Consecutive posts merged.

[SH3RL0CK]

Originally Posted by SH3RL0CK

I'd really like to get a good DNA sample from the fossil and compare to modern day primates, lemurs, etc. This could shed light on the potential for this to be a "missing link." I suppose that is asking too much though after 47 million years.

 

Or you could just look at the features of the skeleton and dentition using the same comparative techniques that have informed most of what we know about the relationships of modern and fossil forms since Cuvier. There really is a whole lot of potential for analysis here. The teeth alone could be all we need to determine where it fits with respect to adapoids and anthropoids.

 

Ideally, you should do both. Unfortunately, there is probably no DNA remaining. And we will only be able to look at comparative techniques. Still, what a great discovery.

[CDarwin]

Ideally, you should do both. Unfortunately, there is probably no DNA remaining. And we will only be able to look at comparative techniques. Still, what a great discovery.

 

Well, of course it would be nice.

 

Actually, a molecular clock calculating the time of divergence between modern anthropoids and lemurs (assuming adapoids to be ancestral to lemurs) or distantly related species within the two groups, might be relevant to determining if this fossil is from the right time to be a transitional form. I believe a number of those have been done. I'm not sure which is the best respected.

 

This seems to be the most recent: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WNH-4K2252T-3&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a56d57416735b41d0c7d9acc2de860ec

 

According to that, the two major anthropoid groups diverged 40 mya and the two most distantly related strepsirrhines (the group of lemurs and bushbabies) 57.1 mya. If we are to suppose that modern strepsirrhines evolved from adapoids, then this fossil couldn't be a transtional form to anthropoids since the divergence between lemurs and anthropoids is 77.5 mya.

 

I'm not making a point; I just find that interesting. I'd never seen those numbers before.

Edited May 22, 2009 by CDarwin

[Mokele]

Actually, the molecular clock for mammals isn't accurate - it places divergences prior to the KT boundary for many, many lineages, and would require vast and diverse lineages to remain "hidden" for over 50 million years. We actually have a very good fossil record for this time period, including for small animals that fossilize poorly (such as snakes, lizards, frogs, birds, etc.), so the idea that these lineages have simply been 'missed' in fossil collection requires an implausible level of special pleading. It's also worth noting that the fossil-based divergence times haven't changed in over 50 years, in spite of massive increases in specimens and numerous new deposits.

 

The problem is the adherence to an underlying assumption, that of constant mutation rates, which is extremely unlikely to hold true in such extreme circumstances as the death of every terrestrial animal larger than a few dozen kg in mass.

 

It's also worth noting that it's unlikely any fossil is the *actual* organism that another evolved from. It's very possible that the "transitional fossil" may be a late-surviving descendant of the *actual* transitional form. As such, forms that look "transitional" or "primitive"

Edited May 23, 2009 by Mokele

[CDarwin]

Actually, the molecular clock for mammals isn't accurate - it places divergences prior to the KT boundary for many, many lineages, and would require vast and diverse lineages to remain "hidden" for over 50 million years. We actually have a very good fossil record for this time period, including for small animals that fossilize poorly (such as snakes, lizards, frogs, birds, etc.), so the idea that these lineages have simply been 'missed' in fossil collection requires an implausible level of special pleading. It's also worth noting that the fossil-based divergence times haven't changed in over 50 years, in spite of massive increases in specimens and numerous new deposits.

 

I haven't read much paleontology outside of primate stuff, so I wasn't aware of that. That's interesting. I think there are a lot of primate paleontologists who are still working on the assumption that primates diverged in the Cretaceous.

 

It's also worth noting that it's unlikely any fossil is the *actual* organism that another evolved from. It's very possible that the "transitional fossil" may be a late-surviving descendant of the *actual* transitional form. As such, forms that look "transitional" or "primitive"

 

Apparently that wasn't the discovers' point anyway. In the paper they just argued that some of D. masillae traits suggests that adapoids should be realigned with the Haplorhini, with anthropoids and tarsiers, instead of the Strepsirhini. And all the traits they used were already described in other adapoids. Not quite up to the "missing link" hype.

[Mokele]

I haven't read much paleontology outside of primate stuff, so I wasn't aware of that. That's interesting. I think there are a lot of primate paleontologists who are still working on the assumption that primates diverged in the Cretaceous.

 

Apparently the mammal divergence and phylogeny has been a big source of contention between molecular folks and paleo folks. Oddly enough, this sort of issue doesn't seem to come up in other vertebrates. PM me your email and I can send you Benton's paper on the subject.