Thursday, 15 July 2010

Falling Behind - Mega News Round-up

Whenever I stop posting often I start feeling guilty. I have had enough time to update the blog regularly but just haven't. I have planned a fair few lengthy posts which just don't seem to want to write themselves. So, in order to feel like I am making effort, I am going to do what I usually do when I fall behind. I am going to round up the best stories from ScienceDaily and say a little about them.

Triceratops and Torosaurus Were the Same Animal
Torosaurus  was a beast of a ceratopsian, stomping around in the late Cretaceous, showing off its three horns and enormous, impressive neck frill. In popular depictions of dinosaurs it is Triceratops  which reigns supreme amongst the ceratopsians, yet it turns out that these two dinosaurs may actually have been the same species, only at different stages of development.

A recent extensive study has shown that Triceratops  may be a younger version of Torosaurus  and that the adults are not simply scaled up juveniles. This is an important lesson for palaeontologists faced with the possibility of naming new species. As we cannot go out and watch our subjects growing and maturing, we cannot know exactly how they grow. If fossils are rare we are left largely in the dark. A young form and an old form can often appear like two different species, though closely related (imagine how wrong we could be with species which metamorphose!).

Another insight from this study is that it means diversity may have been a lot lower than previously thought towards the end of the Mesozoic. This will enable us to better understand what was going on to result in the demise of the non-avian dinosaurs and will also give insight into current extinction. For more, here is the obligatory SD link.

Sabre-Toothed Cats Were Strong Gits
I'm not normally very interested in what was going on in the Cenozoic, it is all too familiar looking. I mostly mention this story about Smilodon fatalis  because I just wish I could find a huge fossilised cat and call it Brontofelis or "thunder cat". It turns out that the Smilodon had very strong arms and used its formidable fangs after subduing its prey manually. See here for more.

Baby Brains and Evolution
A recent study, intended to shed light on abnormal brain development, has inadvertently given insight into human evolution. The study found that the regions which grow the most during infancy are the ones which seem to set us apart from our closest relatives such as language and reasoning. This is a testament both to the fact that changes in developmental timing can have massive effects, and to the fact that our evolutionary past has left its indelible stamp on our bodies. See here.

 More Insights into Multicellularity
Multicellularity has evolved several times. It has evolved in plants, animals, fungi and in green and red algae (and more times if you accept some of the hypotheses concerning the Ediacaran forms). It has also been observed evolving in some unicellular protists in response to predation. That said, it is still not fully understood. A recent study comparing the genomes of Volvox carteri  a multicellular algae, and Chlamydomonas reinhardtii a protist which is its closest unicellular relative, has shown that very few changes are needed for multicellularity to evolve.

Like many other aspects of evolution, the transition simply required using the same proteins for new jobs. The article uses the helpful analogy of a lego set in order to explain this, which I may steal (or perhaps I could say K'nex...). The organisms in question were used because Volvox  evolved multicellularity only 200 million years ago, whereas the other groups achieved it over 500 million years ago, so it is difficult to trace their genetic changes. Personally this is one of the more exciting bit of news, for more see here.

Borrowing Genes
Good old Drosophila, the fruit fly, has given yet more insight into evolution. A species of fruit fly has been observed being infected by a bacteria which conveyed an advantage. The flies then passed this bacteria on to their offspring and it spread through the population, much like genes do. Symbiosis as a source of new defence is a very intriguing strategy. It fits well for those who believe symbiosis and cooperation are major driving forces in evolution, though how prevalent it is remains to be seen. It is also a very rapid and efficient way of improving defences, as it happens a lot quicker than making a new gene, you just borrow the genes of another species. This if fascinating stuff, see here, perhaps more so than the previous mention of multicellularity. Dawkins will probably be drooling over this, as it lends credence to his selfish gene and extended phenotype views. Normally I don't like when scientists, or rather science journalists, claim that a new find will revolutionise our views of evolution, but this one should certainly not be ignored.

Island Evolution Challenged

It is commonly believed that evolution acts differently on islands. Big animals often evolve to be smaller, such as elephants, and smaller animals evolve unusually large sizes. A recent study challenges this view, suggesting that it is merely our perception that sees a pattern, when really none exists. See here.

Ostrich Movement Gives Insight into Dinosaur Movement

I must apologise, I am attempting to speed up here as I intended to go to bed an hour ago. This article is worth reading though.

Two-billion Year Old Multicellular Life
I unwittingly saved the best for last. Current wisdom holds that complex multicellular life appeared around 600 million years ago. Not any more. The earliest origin of multicellular life has now been set back a whopping 1.5 billion years to 2.1 billion years. More than 250 fossils have been found in Gabon and investigated through non-invasive methods. They have been carefully analysed and the conclusion is that they are indeed biological in origin. The image on the left shows both the internal and external morphology.

They vary in shape and size, reaching up to around 12cm, making them too big and complex to be single celled organisms. They have clearly defined, regular shapes and appear to have lived in colonies in often calm, shallow marine environments (20 to 30 centimetres). They potentially correlate with a rise in oxygen levels between 2.45 and 2 billion years ago. There was then a drop in oxygen levels around 1.9 billion years ago. This has some interesting implications. It is possible that these were another multicellular 'experiment' by life, much like how many see the Ediacaran forms. All of these Gabon forms may have gone extinct 1.9 billion years ago, leaving the Earth back in the....errrm....hands of the single celled organisms until mutlicellularity evolved again around 600 million years ago (though potential evidence for porifera is a lot older than the Ediacaran fossils).

This is one I am going to have to look more into, but for now I have to go to bed as I need to be up early to go fossil collecting in Runswick Bay, which I will talk about when I get back. Here is the article, hopefully the site where the fossils were found will be protected for years to come.

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