# Tag Info

## Hot answers tagged fossils

19

Bones don't last very long in jungles. Or in forests. Or almost anywhere. Fossils are the consequence of one highly unlikely fluke after another. Darwin himself commented on this. It takes just-right circumstances to have the bones of a recently deceased animal not be eaten by scavengers or turned into rot by bacteria. It takes yet another set of just-right ...

15

You don't say which lake, but these are almost certainly crinoid stem fossils. Crinoids, or sea lilies, are echinoderms (relatives of starfish and sea urchins) that anchor themselves to the sea floor and feed on plankton. In some crinoids, the animal's sea urchin-like calyx is connected to the anchor by a long stem to a holdfast which anchors it. The stem ...

15

Because you find fossils by looking at exposed bedrock, deserts by their nature often have huge expanses of exposed bedrock. The lack of plants is also a big benefit, plant roots tend to destroy fossils Fossils are everywhere you have sedimentary rock* deserts are actually rather poor at forming fossils compared to many other environments. They are FOUND ...

14

The biggest temporal gap would be (IMO) the Precambrian, specifically pre-Ediacarian. Accordingly the biggest gap in the evolutionary history is the origin of eukaryots, both because of the paucity of pre-Ediacarian formations but also because few of the early protists were likely to be fossilizable. From the probable apparition of life ca. 3.8-3.5 Ga (e. ...

13

OK, so you've found yourself an interesting rock and you want to know how to identify it. I am going to go ahead and assume that you haven't studied Geology before (apologies if that's an assumption too far). The first thing you can do is to head to your local public library and find a basic "rocks, minerals and fossils" identification book, and try to ...

12

I don't think there is a really conclusive absolute test one can carry out without further preparations. In the case of a permineralised fossil, this would probably require thin sectioning and close examination to see if any cellular structure diagnostic of wood remains. Overall I'd think though that if it looks like wood and has been replaced by minerals, ...

10

I would contend that the fact that the location is a desert has little to nothing to do in most cases to the existence of fossils at the location. Most of the fossils in the location, at least the ones that make most headlines like major dinosaur deposits, were left there millions of years ago. The fact that a location today is a desert has no indication ...

9

The oldest undisputed fossil are Stromatolites, bacterial mats, the oldest of which are dated ay 3.7 billion years ago. The key term here is undisputed, there are other possible fossils but it is very hard to have certainty with chemical or cellular fossils. The oldest uncertain fossils trace back to 4.28 billion years and are possible bacteria trapped in ...

8

There are definitely many examples of overlying Mesozoic strata that contain characteristic dinosaur fossils (and ichnofossils – i.e. trace fossils). One of the best examples is the Mesozoic stratigraphy of Utah and Colorado. However, most geologic intervals are characterised by less ‘famous’ fossil material (e.g. molluscs, trilobites or pollen grains). This ...

8

Your analogy with burying a box is not as accurate as you think. It needs specific sedimentary conditions for the remains of an organism to fossilize: being buried in soil is far from enough. Fossilization is such that, eventually, the fossil will be embedded in its stratum, meaning that tectonic events (as you suggest) that would displace the fossil will ...

8

You need to be very wary of anything written in the non-scientific media about science. The media loves woo and controversy because those are the things that garners readers, and that in turn garners advertising revenue. By way of analogy, suppose as near-adult in gym class someone said "My gym shoes smell bad. Bad! Awfully bad!" Someone else would ...

8

The ‘Oligo-Miocene’ part The Oligocene and the Miocene are epochs of geological time. The Oligocene lasted from ~33.9 million years ago to ~23 million years ago; the Miocene followed immediately after the Oligocene, and lasted until ~5 million years ago. Oligo-Miocene refers to events that happened around the boundary between the two epochs at ~23 million ...

7

Biostratigraphy - observing which fossils were present in which stratigraphic units, and using minimally-deformed sequences to determine age order - gives us relative ages of fossils. Absolute ages, however, rely on geochemical chronometers: just like dating the reversals in the Earth's magnetic polarity by establishing how old the oceanic crust that ...

7

Trace fossils are marks or things left behind by living things do their thing, they are indirect remains of organisms, coprolites (poop), footprints, egg shells, ect. If we found a fossilized beehive or beaver dam those would also be trace fossils. Bioturbation is a specific type of traces fossil, marks of disturbances of the sediment itself animals leave ...

7

These are most likely manganese dendrites. It is not a fossil, and not organic. These usually form in cracks in rocks, and most likely this slab was broken along an existing crack. You can read more about it now: https://www.mindat.org/min-26645.html One comment: this is not basalt. Basalt is black. Most likely some form of limestone.

7

The short answer is no. Most metals do not fossilize well, they are too reactive/water soluble. Metals are usually what is doing the fossilizing, dissolved metal in groundwater is being attracted to the electrical properties of organic material and filling in or swapping places with a porous material. You might have a stain left or some of the shape as a ...

6

You are correct when you say it is mostly a matter of getting your eye in and getting used to the shapes and types of rock you need to be looking at. Hopefully however the below information will help you find a few more fossils or at least be of interest to you. The main fossil bearing beds in Lyme Regis are from the Jurassic period and formed in a warm sea,...

6

Photosynthesis has not stopped. It happens all the time, splitting water and carbon dioxide, and producing oxygen and carbohydrates. Likewise, organic matter rots and decomposes all the time, requiring oxygen and releasing carbon dioxide. The Keeling curve actually illustrates this quite nicely: most of the land mass where this happens lies in the north, and ...

6

Firstly, I'd like to state that so far there is no evidence that a civilization similar to ours has appeared on Earth before us. It might be apparent that we as a species have left quite a significant geological footprint, (if we didn't Archeologists would be out of a job!), and as of yet we've discovered no evidence to indicate a civilization that cannot ...

6

Typically this is accomplished through radiometric dating. While this is a complex field and the article I've provided a link for explains it better than I could here, the short answer is that different elements' isotopes decay to at a known rate, and by measuring the quantities of the isotopes in question (which are chosen depending on the approximately ...

6

Stromatolites have indeed been used in palaeoclimatic investigations. Here are a couple of papers I found through Google Scholar: Paul I. Abell, Stanley M. Awramik, Robert H. Osborne, Sterling Tomellini, Plio-pleistocene lacustrine stromatolites from lake Turkana, Kenya: Morphology, stratigraphy and stable isotopes, Sedimentary Geology, Volume 32, Issues 1–...

6

I agree with commentator @John, this is a fossil coral. The coral animal (the polyp) builds a column, and as it ages it closes off the bottom and extends the upper lip. In some of the views you see the column structure. In others you see the arrangement of polyps. It looks like the cells of the coral are filled in with calcite, which probably made the ...

6

Most likely plesiosaur. That fluted structure is indicative of marine reptile teeth. My first guess was mosasaur but their are a lot of plesiosaurs from that formation so I would go with that. It is obviously a shed tooth which makes it harder. shark teeth flare out at the base becasue they attach differently than marine reptile teeth, sharks need more ...

6

Leonardo was wrong about this. It is not due to sea level dropping (except in very isolated cases), it's due to the land rising. Sedimentary rocks that form in sea beds are often uplifted by tectonic processes to form mountains and plateaus. See e.g. https://en.wikipedia.org/wiki/Sedimentary_rock

5

This is a really bad question, because all three can lack fossils, or all three can have fossils. The definition of "minerals" is also a bit unclear, because fossils are also made out of minerals. I'll assume that by minerals they mean non-biogenic minerals. Let's go through each one of them: a clastic sedimentary rock This rock will have minerals, ...

5

It's an entelodont, South Dakota is famous for it's Oligocene mammalian faunas which include entelodonts such as Archaeotherium and Daeodon. here is an http://i.ebayimg.com/images/i/181202162847-0-1/s-l1000.jpg for comparison: Thanks to the guys at fossilforum, they knew in less than a day. this question could have stayed on here for a year so i was ...

5

That is because the chemical reactivity of $^{18}\text{O}$ is slightly higher than that of $^{16}\text{O}$. For that reason, the biochemical reactions that produce calcium carbonate in foraminifera prefer $^{18}\text{O}$ over $^{16}\text{O}$. However, the temperature dependence arise from the fact that the difference in reactivity is smaller when ...

5

things need to be exposed to bacteria to rot, amber produces a perfect form fitting seal and has several antimicrobial properties to boot killing off bacteria that is already present. Even microbes trapped in amber become preserved. This makes a lot of sense when you realize the resin evolved to seal injuries in trees if it did not prevent the spread of ...

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