An Assortment Of Martian Fossils
This is a fantastic collection of fossils that includes starfish, crinoids, trilobites, and leaves. I will overlay the best specimens with hot links you can click on to get a better and more in depth view.
This is like shooting fish in a barrel. The original image is on the NASA site here.
Unhappy note: You will discover that in order to see what was inside the spheres in this image (which I call blueberry urchins), the RAT (rock abrasion tool) was used to completely destroy this fossil bed. Clearly NASA did not know what this was, as it is really a terrible thing to see these fantastic specimens destroyed. To see what the result of the abrasion was, click here.
Fortunately, I was able to rescue something from this. I have now been able to identify the undersides of some of the organisms, including the tiny split feet of the flat, armored crawling organism just above the lower right blueberry urchin. I am constructing anaglyphs that will show the lower interior layer with the associated upper layer.
For the interior views of the ground down spherules, click here. See the questions and answers below the fossils.
Questions and answers:
1. Why don't these look more like fossils I have seen before?
Because they are covered in a thin layer of dried mud.
2. Why are there so many fossils in this one area?
Because something killed them all at once, and nothing ate them before they were fossilized.
3. Why does the "mud" look so rounded and smooth?
Because Mars had almost no atmosphere when these were made- the mud was "vacuum boiling" in the very low atmospheric pressure. Look at the broken off areas and you can see very fine bubbles all over in the mud.
4. If there was so little air, how could all these things live?
Because they got their oxygen from the water- and in the water, they are protected from the near vacuum and also the ultraviolet from the sun. A brine solution (stronger than our seawater) can still hold lots of dissolved gases and also be pretty resistant to boiling away in low atmospheric pressures.
5. So what killed all these animals like this?
Probably the same meteor impact that made Eagle Crater, the crater that Opportunity landed in. It is an impact crater in the middle of Meridiani Planum.
6. How can you be so sure it is an impact crater?
Because not only does it have the proper shape, but the bedrock itself is split in radial cracks running from the center outward, in precisely the same way that glass windows "spiderweb" when a rock goes through them. There is also the fact that all these organisms are "thrown" against the outcrops and covered in the layer of mud.
7. Well, then- what are all those "worm tracks" in some of the outcrops?
They were probably made by smaller organisms that survived the blast, trying to crawl back to lower levels in an attempt to reach the water. I would think that organisms on Mars would have such an instinct if they were expected to survive, in the same way that terrestrial organisms have some common "hard-wired" instincts that help them survive.
8. Some of those organisms look too primitive or too modern to exist at the same times. How do you explain that?
Surely there would be some differences in the way things evolved on Mars as compared to Earth. Also, it would be silly to think that we have a complete fossil record for our planet- we are making new findings all the time that change our views of evolution and life's development. So as long as the organisms can get along with each other and their environment, they did.
9. If these are alien organisms, why don't they look more "alien"?
The best explanation is that we recognize what we are most familiar with- perhaps there are more "alien" looking things in those fossils, but we simply do not know what to look for. On the other hand, why assume that alien organisms must be very strange? Biology and evolution, like chemistry and physics, work the same everywhere, as far as we can tell. So we would actually expect that alien organisms would follow the same rules as terrestrial ones.