1) Differentiate precisely between a chemically altered (petrified) fossil and a cast fossil.
A petrified fossil and a cast fossil seem to be the same to me. They are both mineral replica of the original organism...





http://www.geocities.com/asdfasdf23135/index_fossil.JPG
2) For the above chart of index fossils, I don't know which is the name of the fossil and what does the other represent? For example, the second one, Pecten jeffersonius, MOLLUSCA, Pelecypoda, scallop, which is the name of the fossil and what does each of the above terms represent? For the "Tertiary-Quaternary" at the end, is it saying that this is a index fossil of both the Tertiary and Quaternary Periods?

3) For the first one (Oleneothyris harlani), unlike the other three, there is nothing written after BRACHIOPODA, why?

I didn't take biology so this stuff is a pain for me! Can someone explain? I would really appreciate! :)

1) A cast fossil is when the organisms is completely removed, leaving a void in the rock (a cast of the organism). Chemically altered fossils occur when the minerals in the original organism are replaced. That is a pretty crap definition. I'm sure someone can explain it better - too early i nthe morning for overly coherent thoughts...

2) The top line gives the scientific name. This is the Genus and species (note that the genus always starts with a capital letter, the species with a small letter). Humans are Homo sapiens. Genus: Homo, species: sapien.

The line in capitals is the phylum. Any terms after that are orders (may be classes - not 100% on that).

In brackets we have the common names (if available, e.g. scallop) and the age range in which they are found, not just when they are zone fossils.

3) Bracipods is a common name, as well as a phylum name (ok, technically, Brachipoda is the phylum name...)

Hope that helps.

Jon

1) A cast fossil is when a mold is filled with minerals/sediments, so it is still a mineral replica of the organism...and now I am puzzled...I can't tell how cast fossil and petrified fossil are different...

2) So for example, the second picture, Genus: Pecten? Species: jeffersonius?
Why doesn't the third picture have the name for "Species"?

The word after the CAPTIALS, does anyone know if they represent "classes"? (since I have found that class is right below phylum, i.e. kingdom, phylum, class, order, family, genus, and species)

3) For the first picture, if BRACHIOPODA is the phylum name, why doesn't it have a "class" name after it?

Thanks for explaning!

1) A cast fossil is when a mold is filled with minerals/sediments, so it is still a mineral replica of the organism...and now I am puzzled...I can't tell how cast fossil and petrified fossil are different...

2) So for example, the second picture, Genus: Pecten? Species: jeffersonius?
Why doesn't the third picture have the name for "Species"?

The word after the CAPTIALS, does anyone know if they represent "classes"? (since I have found that class is right below phylum, i.e. kingdom, phylum, class, order, family, genus, and species)

3) For the first picture, if BRACHIOPODA is the phylum name, why doesn't it have a "class" name after it?

Thanks for explaning!

1) I'm not a palaeontologist, more a carbonate sedimentologist, but the only way I can think of is to get a thin section of the fossil. If the fossil is a cast, no biological strucutres will be visible. The fossil will be made of crystals of the replacing mineral. If the fossil is petrified (i.e. remineralised in-situ) then the biological structures will still be visible. For example: A brachipod shell in thin section is made of lots of wavy lines, so if it has been re-mineralised then these will be retained: http://www.geo.utexas.edu/courses/416M_Banner/carbonate%20topics/topicc2/skeletalgrains/thinsection/brachiopod.jpg

The above picture is also good as it shows a void that has been filled in with sparry (crystalline) calcite (the very obvious crystals in the centre). If the fossil is a cast the shell will look like this instead.

2) See three. And Pelecypoda is a class (quick google search is all that's needed)

3) No idea - perhaps the author of the pictures felt they didn't need to put one in as all brachipods looks very similar :)

For this organism, as an example,

Crinoid
ECHINODERMATA, Crinoidea
(sea "lily" stem, Mississippian)

Is the following the correct interpretation of it??
Species: (Not given)
Genus: Crinoid
Phylum: ECHINODERMATA
Class: Crinoidea
English common name: sea "lily" stem
Time period: Mississippian

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Also, is Mammal = Mammalia? Is mammal/mammalia a "class"?

rdjon pretty much covered the answers, but I was hoping to clarify #1 a bit.
cast= take an object, and surround it in mud/clay. Then remove the object (via decomposition, let's say) - you are left with a mud/clay model of the original. A hollow space formed to the shape of the living thing which is no longer around.
Then fill that space w/ minerals that form stone, and today, you have a cast fossil - something that only provides useful information about the shape of the creature; it's outside.

With a petrified fossil, the biological stuff is replaced with minerals one bit at a time. So each organ is swapped for rock piece by piece. This provides a detailed internal reconstruction of the living thing - the rock forms to much smaller hollow spaces down to the size of individual cells, and preserves the shape of more than just the outside of the thing fossilized.
That's what he meant by "in situ" - the thing itself was fossilized in place.