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c-allan

What Features of this Rock Rule out Fossil?

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c-allan

The rock in the image was actually found on Mars. I know it's probably not a fossil as NASA has addressed this saying it was likely formed by water and wind erosion. Please don't take this post the wrong way. I am not interested in perpetuating anything unscientific. I am just curious about the topic; how we can analyze rocks like these found on another planet. If one were on the team, and we spot something like this, to the untrained eye it would look like an astonishing find. But we have to be objective, and we have no idea what fossils on Mars might look like, in the unlikely case they actually exist. So I am just wondering how an expert would look at them? Aside from the low probability that such a fossil would exist, are there tell tale features that it is not a fossil.

 

Thanks!

 

 

image.png.c94dad595fbb17a4a72cec7c27911848.png

 

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jpc

It looks like it is some rock material that is different from the surrounding rock.  The surface also looks disturbed, like the rover is looking into its own tracks, so the rock could be part of whatever layer is below this surface.  I would say that without a hand sample, there is no reason to call this a fossil.  If we were in an Earthbound area of red rocks with proven white fossils, I would say... "Look a fossil", pick it up and have a look.  But here we are on a planet where no fossils have been found, and honestly, none are truly expected, so it defaults to A Rock.  But also, since we are on Mars, I would tell the rover to pick it up and have a look.  just in case. Ah, but you asked Why is this NOT a fossil?  In the US, we like to say (I wish we would practice it more) that a person is "Innocent until proven guilty".  I think on Mars we can say a rock is "A Rock until proven a fossil".   

 

Why is that gray rock on top of the photo not a fossil?  Yeah, the one just above the red femur-looking thing.

 

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c-allan
Posted (edited)
41 minutes ago, jpc said:

It looks like it is some rock material that is different form the surrounding rock.  The surface also looks disturbed, like the rover is looking into its own tracks, so the rock could be part of whatever layer is below this surface.  I would say that without a hand sample, there is no reason to call this a fossil.  If we were in an Earthbound area of red rocks with proven white fossils, I would say... "Look a fossil", pick it up and have a look.  But here we are on a planet where no fossils have been found, and honestly, none are truly expected, so it defaults to A Rock.  But also, since we are on Mars, I would tell the rover to pick it up and have a look.  just in case. Ah, but you asked Why is this NOT a fossil?  In the US, we like to say (I wish we would practice it more) that a person is "Innocent until proven guilty".  I think on Mars we can say a rock is "A Rock until proven a fossil".   

 

Why is that gray rock on top of the photo not a fossil?  Yeah, the one just above the red femur-looking thing.

 

Thanks. For me, if it is even a maybe that's pretty exciting. NASA didn't explicitly claim it is not a fossil with absolute certainty, but strongly implied it; however, the justification was only that fossils aren't expected. So I just felt unsure how to feel about it. Does it actually look like a fossil? Or is it obviously not a fossil for some reason? Is this something to be a little excited about?

 

I guess we may have to wait for a decade or so for the possibility to see verified fossils on Mars.

Edited by c-allan

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Randyw

The curiosity has a drill and 2 onboard laboratories to do rock analysis... Is was out of action for a bit but they’ve kinda got it working again.

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c-allan
c-allan
PaleoNoel

I agree with @jpc in that we should consider the images we see from Mars to be "rock until proven fossil". As for the rocks that vaguely look like a shark's head and the one I thought looked like a hadrosaur ungual, they are examples of pareidolia. Recognizing certain patterns and assuming their identity is an instinctual reaction that would have given us a reasonable paranoia when we were prey. Better to run from something that looks vaguely like a dinofelis than to run the risk of being eaten. This behavior can be seen when we see faces in clouds, middle fingers in deep space nebulas, elephants in eroded coastal rocks and the icon from my home state "the Old Man of the Mountain" (RIP).

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Missourian

If searching for fossils on Mars -- and a BIG if -- I would start with looking for microfossils, stromatolites and bioturbation/trace fossils. That is, look for what would be most likely to be found, assuming any are present at all. If you have that eureka moment of confirming life on Mars, then you could be more confident as you 'move up' to the more complex fossils we would all like to see.

 

If examining rocks on the surface that might have a chance of being/containing fossils, I would look for unmistakable, complex structure and/or symmetry. Otherwise, chasing down every rock that has a suggestive shape will be a wild goose chase. Finding fossils on Earth is hard enough. :)

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c-allan
1 hour ago, PaleoNoel said:

I agree with @jpc in that we should consider the images we see from Mars to be "rock until proven fossil". As for the rocks that vaguely look like a shark's head and the one I thought looked like a hadrosaur ungual, they are examples of pareidolia. Recognizing certain patterns and assuming their identity is an instinctual reaction that would have given us a reasonable paranoia when we were prey. Better to run from something that looks vaguely like a dinofelis than to run the risk of being eaten. This behavior can be seen when we see faces in clouds, middle fingers in deep space nebulas, elephants in eroded coastal rocks and the icon from my home state "the Old Man of the Mountain" (RIP).

I guess this must be true. I didn't see anything that looked like a shark head to me. For the one that looks like an ungual, it is hard for me to imagine what kind of geologic process could produce it, but then again I'm not a geologist.

Edited by c-allan

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c-allan
46 minutes ago, Missourian said:

If examining rocks on the surface that might have a chance of being/containing fossils, I would look for unmistakable, complex structure and/or symmetry. Otherwise, chasing down every rock that has a suggestive shape will be a wild goose chase. Finding fossils on Earth is hard enough. :)

Yeah, I didn't expect to see anything. I started looking at them because someone posted one image that looks interesting. Then as I started looking through a lot of images, I found lots of symmetric, organic looking objects. I know that large complex life on ancient Mars would be unexpected, but it doesn't seem so unlikely to me that it's not even worth looking for signs of it. There is a lot of uncertainty about what is habitable, and how long it takes for complex life to evolve in different settings. All we have is Earth as a reference, and we've been constantly surprised. Most of Earth's complex life emerged only about 500 million years ago during the Cambrian explosion, and we still don't know for sure what cause that to happen. We even have theories about life transferring between planets. Ancient Venus was also likely habitable for quite a while. There are a lot of possibilities for all we know. 

 

In any case, I think it wont be too long until we find out if any of these things could be fossils, because the search for life on Mars seems to be intensifying, with both the US and China expected to land their new rovers next February. Eventually, if there are fossils of large complex life there, we'll be able to verify it. But you're right, I think finding microbial life first is more likely.

 

But hey, maybe you are now one of the first people to see Mars fossils. ;) How cool is that.

Edited by c-allan

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digit
13 hours ago, c-allan said:

For the one that looks like an ungual, it is hard for me to imagine what kind of geologic process could produce it, but then again I'm not a geologist.

Erosion is the process. Go to some place that normal geology combined with erosion has produced wonderfully original landscapes and it is not difficult to see that a wide variety of shapes and forms can be produced without requiring any need for a biological basis. The following for erosional features can be found in a single western state-Utah.

 

DSC_3066.jpg     DSC_3716.jpg

 

DSC_4237.jpg     DSC_4719.jpg

 

As for objects smaller than a breadbox (does anybody use those anymore?) which are interesting enough in shape and form to cause somebody to pick it up and ask if it is a fossil, we have a steady stream of them from new members to this forum. We see a diversity of interesting forms and more than our share of backyard "dinosaur eggs". To get an idea how easy it is for a rock to appear to be an interesting fossil you can search this forum for the term "pseudofossil" or "pareidolia" and you'll see a wealth of posts involving non-extraterrestrial rocks that have caused folks to be convinced of their fossil origin (even when they are most decidedly merely geologic oddities). In fact, fossil hunters come across all sorts of novelties that urge us to bend over and pick them up when we are hunting in known fossil rich areas that we've created a topic dedicated to showing off our pseudofossils (as many hunters enjoy collecting these "fakers").

 

http://www.thefossilforum.com/index.php?/topic/90731-pseudofossils-pareidolia-and-other-rorschachery/

 

13 hours ago, c-allan said:

In any case, I think it wont be too long until we find out if any of these things could be fossils, because the search for life on Mars seems to be intensifying, with both the US and China expected to land their new rovers next February. Eventually, if there are fossils of large complex life there, we'll be able to verify it. But you're right, I think finding microbial life first is more likely.

Live has existed on our planet for approximately 3.6 billion years and for the majority of that time (~3 billion years) it has been unicellular. If there is any evidence of life on Mars you can bet any additional rovers looking for evidence will be looking for microscopic signs or chemical signatures and they won't be wasting valuable time on the surface by taking photos of rocks with a passing resemblance to femurs or unguals.

 

In the cosmic lottery of planet formation Mars was shortchanged enough mass to keep the core at a sufficient temperature to keep it molten. Without the molten iron convection action at the core its magnetic field dissipated some 4.2 billion years ago. Without the protection of this important envelope against the solar wind, the atmosphere and (virtually all) surface water was stripped away. Unless, any putative life on Mars was a real anomaly and went from singular cell form to beasties capable of making use of femurs and unguals in a very short amount of time, the odds are that any life on Mars would not have progressed beyond the single cell stage.

 

We are indeed privileged to be able to see high-resolution imagery from a distant planet (decades ago only scientists involved with the missions would have had access). While it may be fascinating to peruse these images and wonder at how different (and in some cases similar) the environments appear to earthy landscapes, searching them for rocks that may contain (macro) fossils would be a highly quixotic waste of effort. Time would be better spent searching for fossils here on earth. ;)

 

 

Cheers.

 

-Ken

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c-allan
2 hours ago, digit said:

Without the molten iron convection action at the core its magnetic field dissipated some 4.2 billion years ago. Without the protection of this important envelope against the solar wind, the atmosphere and (virtually all) surface water was stripped away. Unless, any putative life on Mars was a real anomaly and went from singular cell form to beasties capable of making use of femurs and unguals in a very short amount of time, the odds are that any life on Mars would not have progressed beyond the single cell stage.

 

We are indeed privileged to be able to see high-resolution imagery from a distant planet (decades ago only scientists involved with the missions would have had access). While it may be fascinating to peruse these images and wonder at how different (and in some cases similar) the environments appear to earthy landscapes, searching them for rocks that may contain (macro) fossils would be a highly quixotic waste of effort. Time would be better spent searching for fossils here on earth. ;)

 

 

Cheers.

 

-Ken

I think just recently we've found that Mars had a magnetic field longer than we had previously thought. Currently we have evidence that the magnetic field was active at 4.5 billion years ago and 3.7 billion years ago. Previously it was known to be active 4.2 billion years ago, and it was though to have stopped at least 3.9 billion years ago (since some 3.9 billion year old rocks were found that lacked evidence of magnetism). They seem to offer two main explanations for why the 3.9 billion year old rocks aren't magnetized (1) the magnetized rock in the crater they were found in were displaced by the impact. (2) The dynamo briefly paused (e.g. during a reversal). 

 

Quote

Reinterpretation of weak basin magnetizations on Mars

Our results demonstrate that the martian dynamo was active 4.5 and 3.7 Ga ago. The existence of a dynamo field before and after the large basins Hellas, Utopia, Isidis, and Argyre requires an explanation for the general absence of magnetic fields over those basins. The impact demagnetization hypothesis is based on the argument that magnetization is absent within, but present around, the basin. Although this is true, unexplained observations worth noting are as follows: (i) Large tracts of Noachian crust surrounding the basins Hellas and Argyre are also unmagnetized or very weakly magnetized (fig. S7). Shock demagnetization can affect the basin exterior (27) but fails to explain the heterogeneity of magnetization around the basin or the extensive Noachian aged areas in the southern hemisphere with similarly weak or no magnetization. (ii) Short-wavelength signatures may be present in the interior of the basins (fig. S7) (16, 17), although lower-altitude tracks or surface measurements are necessary to confirm this.

Can the absence of magnetic field signatures over the basins be explained if a dynamo was operating during basin formation? At least two possibilities exist: (i) The giant impacts excavated large fractions of the crust, possibly removing material capable of carrying strong magnetizations. For crater diameters, D, up to ~500 km, the excavation depth, d, is ~0.1D, i.e., up to 50 km (37). Transient crater diameter estimates for Argyre, Isidis, and Hellas range from 750 to 1400 km (38). Although the d/D ratio for such large basins is uncertain, the depths would exceed 50 km, effectively penetrating and removing magnetized crust. The observations of very weak fields over the BB, cf. the surrounding southern highlands, suggest that this is plausible. Weak, small-scale signals may exist within the Argyre, Isidis, Hellas, and Utopia basins but require more lower-altitude observations for definitive identification. Material excavation, with only weak or small-scale subsequent magnetization, would produce a magnetic field signature at MGS and MAVEN altitudes barely distinguishable from basin-localized demagnetization. (ii) We also cannot exclude a fortuitous scenario in which a dynamo field at the time of basin formation was substantially weakened or intermittent, as a result of a reversing dynamo field (39). (iii) Alternatively, the dynamo was inactive during the time of basin formation, for example, because of inherently changing dynamo processes (i.e., from a thermally to a compositionally driven dynamo).

Implications of a dynamo 4.5 and 3.7 Ga ago

Evidence for a dynamo both ~4.5 and ~3.7 Ga ago has major implications for Mars’ evolution. Assuming a thermo-chemically driven magnetic dynamo, Mars must have sustained sufficiently vigorous core convection at its very earliest times and at the time of LP flow emplacement. Furthermore, the observations at LP suggest that a substantial fraction of the magnetization is carried in a thin, shallow magnetized unit. The resulting magnetizations are consistent with magnetization of pyroclastic flows in a 3.7-Ga old surface field with a strength similar to that of Earth’s present field. Excavation during large impacts may have played a key role in establishing a heterogeneous distribution of magnetic carriers in the martian crust, particularly removing magnetic minerals from the interior of major basins. This scenario allows a dynamo to plausibly persist from 4.5 to 3.7 Ga ago, thereby opening the possibility for a range of new magnetization processes to affect the martian surface, including depositional and crystallization remanence. For example, morphological evidence for water in the form of valley networks at the surface of Mars is dated between the Noachian and the Early Hesperian (3), before and overlapping with the timing of formation of LP and hence the dynamo. Water circulating in the martian crust in the presence of a field could have resulted in hydrothermal alteration facilitating magnetization or remagnetization of magnetic minerals (40).

Furthermore, the results link to current and planned missions’ e.g., the interior structure is a primary goal of the InSight mission currently operating on the martian surface (41). The dynamo timing results presented here provide a major step forward in understanding Mars’ thermal evolution, especially when combined with existing constraints on heat flow, mantle temperature, interior composition, and physical models of structure of the martian core. Also, if a global magnetic field protects the atmosphere from solar wind energetic particles, a prolonged dynamo would delay the effects of some of the atmospheric removal processes and hence have implications for martian atmospheric loss rates (42). This is important for addressing one of the main MAVEN goals of atmospheric escape rates through time (42). The collection of martian samples and their return to the Earth will finally be underway with sample collection by the Mars 2020 rover to be launched next year. An extended dynamo, consistent with the new results here, is of key importance for the Jezero landing site selected for Mars 2020, because units that could be sampled might have formed at a time of an active dynamo field (43). Future laboratory investigation of return samples will be the next major step in Mars exploration and, if magnetized, for planetary paleomagnetism.

 

https://advances.sciencemag.org/content/6/18/eaba0513?utm_source=miragenews&utm_medium=miragenews&utm_campaign=news

 

Edited by c-allan

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digit

Granted that we have a rather limited dataset for what is necessary for life (as we know it) to emerge and prosper. We know that the organic molecules that our form of life is based on are rather easily assembled through natural processes. Assembling these essential components into self-replicating structures to bootstrap the evolution of unicellular and ultimately more complex lifeforms is significantly more difficult than assembling flat-pack furniture from IKEA without the instruction manual. ;) The leap from unicellular life to multicellular is still a topic of great debate and we are able to pick up bits and pieces of clues that help to lend or detract support for various theories and ideas. Protection from predation (unicellular organisms had been ingesting each other in a very simplistic trophic structure for an enormous amount of time) may have been one motivation for life becoming more complex.

 

A few years I read through a fascinating book that I'd refer you to if you truly have an interest in how multicellular animals evolved and diversified.

https://www.amazon.com/Rise-Animals-Evolution-Diversification-Animalia/dp/0801886791

 

Life does seem to have some conditions and a fair bit of time to evolve into something we can detect. If it were a simple step to get from organic molecules to complex life forms we'd not be having this conversation as our probes would be finding plenty of examples from every probe we sent to peek at other planets and moons. It has proven to be very elusive and Mars was further from the Goldilocks conditions that helped life prosper and rise on Earth so logic would imply (but never prove) that life might have possibly gotten a start on Mars but should not have been able to evolve incredibly faster than it did here on Earth.

 

Playing the Devil's Advocate has a long tradition of taking the opposing side to expose arguments to thorough examination. They can provide animated conversations between friends and colleagues (especially over an adult beverage or two). Back to your original question:

On 7/24/2020 at 5:22 PM, c-allan said:

image.png.c94dad595fbb17a4a72cec7c27911848.png

 

I am just curious about the topic; how we can analyze rocks like these found on another planet. If one were on the team, and we spot something like this, to the untrained eye it would look like an astonishing find. But we have to be objective, and we have no idea what fossils on Mars might look like, in the unlikely case they actually exist. So I am just wondering how an expert would look at them? Aside from the low probability that such a fossil would exist, are there tell tale features that it is not a fossil.

 

There is nothing in the scattering of rock shards above that screams out to me of something that could have functionally been part of a higher form of animal life. I've seen a lot of fossils (and non-fossil fakers) in my time (but not nearly as many as professionals). We may have no idea what Martian creatures would have looked like (supposing for the fact of argument that such a thing could exist) but all animals are subject to physical forces. If they moved they would have to have some means of doing so. If they had to support significant weight they would have to have load bearing elements. We know that symmetry and repetition tend to be fundamental to even the simplest life forms and so we would look for those basic signs. I'd say the folks who have the best chance of detecting extra-terrestrial life forms are those who study rocks for the earliest signs of life on this third rock from the sun. Being able to distinguish the signal that separates organic living organization from geological processes simply obeying physical laws is a real skill. You'd see many examples in the book referenced above.

 

In reference to your point explicitly, while an "untrained" eye might find something "astonishing" in the image above, those who have seen lots and lots of rocks fractured by natural processes would not see a single thing that would move the needle in the above image of broken rocks. How would an expert look at the rocks in the image? Skeptically. How do you know that the rocks in a gravel parking lot are not fragments of a new species of dinosaur--or for that matter pieces of meteorite? You don't know for sure. But unless you have some specific reason for initiating such a proposition you are simply wasting your limited time trying to falsify such arguments. Rather than asking what the telltale features are that indicate a rock is not a fossil you should be asking what features might indicate that it is. Scientists would clearly never spot signs of life on Mars if they had to "disqualify" every single rock they encountered as a potential fossil. Instead, they search rover imagery for interesting rocks. They have found signs of past liquid water from looking at specific rocks on Mars but not (yet) signs of life.

 

On 9/14/2020 at 12:18 PM, c-allan said:

sn65-downsample.thumb.JPG.87ceaee64e2b8642fbbf289069bfc3b6.JPG

You have highlighted numerous rocks in rover images above but I am at a loss to explain why those particular rocks are of such interest to you. There is nothing that I can see to recommend those particular rocks from the rest scattered on the surface.

 

 

Cheers.

 

-Ken

 

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