In diagrams, It is common to depict geological periods to be directly on top of each other with fossils of that period within them. When looking for evidence of this, I have only found examples of trilobites and shells. However it is common to see this sort of ordering depicted with dinosaurs in them http://www.globalchange.umich.edu/globalchange1/current/lectures/complex_life/fossil_record.html

In high school my teacher said that at the grand canyon we find no fossils at the bottom, further up we find shells, above that we find jellyfish, then fish, then reptiles, then mammals. After doing research I found out that this was not the case. Now I suspect that diagrams that depict this ordering of the fossil record with dinosaurs maybe deception or at least a representation of the fossil record that can be easily misinterpreted by laymen.

So are there any examples of this ordering with dinosaurs? eg Jurassic layer with Jurassic fossils, then on top of that layer there is a Cretaceous layer with Cretaceous fossils?

Note: I know the wording of the question is quite terrible. Feel free to edit it.

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    $\begingroup$ Welcome to Earth Science Stack Exchange! I don't completely follow your question — would it help to draw what you mean? It sounds a bit like your teacher may have been talking about when types of animal first appeared. For example, shelly fossils have appeared in strata since they first appeared, they aren't confined to a particular zone. $\endgroup$
    – Matt Hall
    Feb 12, 2015 at 18:23
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    $\begingroup$ @RayKay as a rule of thumb, when you find out that "firm evidence for evolution turns out to be false", it's either not really false, whoever told you the evidence doesn't know what he is talking about, you yourself misunderstood it, or it wasn't firm evidence to begin with. $\endgroup$
    – Gimelist
    Feb 13, 2015 at 5:04
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    $\begingroup$ I still didn't understand your question by the way. However, the answer given here explains how this works pretty well. $\endgroup$
    – Gimelist
    Feb 13, 2015 at 23:58
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    $\begingroup$ The correspondence of chimpanzee and human DNA is so far from what you originally asked that it makes no sense to mention it here. As a general point, I would say that many aspects of evolution are very complex so to say that a layperson finds it difficult to judge the veracity of nuanced details is stating the obvious. You seem to be searching for answers and trying to apply logic. This is admirable. However, if you really want to understand these issues in enough detail to meaningfully contribute to them, perhaps you should consider some further study in the fields that interest you. $\endgroup$
    – geordie
    Feb 15, 2015 at 1:20
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    $\begingroup$ Also on Skeptics. $\endgroup$
    – HDE 226868
    Feb 15, 2015 at 1:57

1 Answer 1


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 does not render correlations involving dinosaurs less valid.

Consider a hypothetical case where some dinosaur footprints are found in a mudstone layer. The mudstone also contains distinctive grains of pollen. In the layer above the mudstone we see no more dinosaur footprints but we still have the same pollen grains. These pollen have been found in other strata (perhaps on the other side of the world!) while the dinosaur foot prints are much more rare. In this case we will be able to correlate these to rock layers much more widely using the pollen than from the dinosaur prints. However, if the mudstone layer is the youngest geological unit known to contain the fossil remnants of that particular dinosaur species (assuming it had a distinctive footprint) then we can assume that the species became extinct. Extinctions are very useful for correlating the relative age of geological units, therefore the last appearance of the dinosaur footprints will provide a tighter age control than the pollen (which persists in the rock record).

I should add that stratigraphic corrections based on the fossil record can be very complex. The scientists who study the fossil record (palaeontologists) spend decades trying to decipher the exact details of the evolution of life on this planet preserved in rocks. Due to the complexity of this science it is very easy for a layperson to get confused or make false assessments.

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    $\begingroup$ @RayKay I am both a science teacher and have had experience in this kind of geological exploration (and used to work with fossil progressions). The stratigraphic record can be affected by many factors resulting in the loss of some of the record - there are, as Geordie mentioned, many complications of the layers. $\endgroup$
    – user889
    Feb 15, 2015 at 20:37

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