A little help?

[Sinestia]

As mentioned in my opal post this was also in the mystery box and was looking for any ideas. About the size of a deck of cards. 

[Ludwigia]

Imprint of a gastropod.

[Daniel Fischer]

I agree with @Ludwigia, a trace fossil of a gastropod and also probably an amonite but I don't know amonite species

[Sinestia]

25 minutes ago, Daniel Fischer said:

I agree with @Ludwigia, a trace fossil of a gastropod and also probably an amonite but I don't know amonite species

Thank you guys, I was also thinking amonite. On a side note, it is very dense and heavy for its size. Is this normal?

[Rockwood]

59 minutes ago, Daniel Fischer said:

I agree with @Ludwigia, a trace fossil of a gastropod and also probably an amonite but I don't know amonite species

Careful, trace fossil refers to the result of an activity. I've had to accept imprint as a mold, but I don't think this one will fly. 

I think the center of the fossil is what distinguishes it from a cephalopod, but I'll let someone who understands it better explain that.

[Fossildude19]

Gastropod imprint. I see no evidence of ammonites. No sutures. 

[caterpillar]

Gastropod imprint for me too.

Take a look at Pleurotomaria

[Daniel Fischer]

1 hour ago, Rockwood said:

Careful, trace fossil refers to the result of an activity. I've had to accept imprint as a mold, but I don't think this one will fly. 

I think the center of the fossil is what distinguishes it from a cephalopod, but I'll let someone who understands it better explain that.

Thank you for letting me know that, I thought that trace fossils are all of the imprint fossil.

[val horn]

It looks like there are lumpers and spliters:  everybody is right, or wrong:

 

(The fossils of bones, teeth, and shells are called body fossils. Most dinosaur fossils are collections of body fossils. Trace fossils are rocks that have preserved evidence of biological activity. They are not fossilized remains, just the traces of organisms.Feb 22, 2004

fossil | National Geographic Society

https://www.nationalgeographic.org › encyclopedia › fossil)

 

It seems that there is a difference of opinion as to how many different types of fossils exist, if there are only two types than external and internal molds are classified with the body fossils. If you allow three types of fossils than you add in replacement fossils for external and internal molds.  Others offer more categories

 

Updated April 10, 2018
By Claire Gillespie , sciencing.com
(Fossils, the remains of prehistoric organisms or other evidence of prehistoric life, tell you a great deal about what the world was like millions or even billions of years ago. Five different types of fossils are body fossils, molds and casts, petrification fossils, footprints and trackways, and coprolites. )

 

To give Rockwood his due, discussion is  clearer if molds and casts are in there own category 

 

[Randyw]

4 hours ago, val horn said:

Updated April 10, 2018
By Claire Gillespie , sciencing.com
(Fossils, the remains of prehistoric organisms or other evidence of prehistoric life, tell you a great deal about what the world was like millions or even billions of years ago. Five different types of fossils are body fossils, molds and casts, petrification fossils, footprints and trackways, and coprolites. )

Personally I like this grouping. It would make it easy for me and I like easy

[BobWill]

This looks like a good time for the latest iteration of my infamous "list."

Compiled and corrected many times with help from many professionals and terms added and removed many times.

I use material like this for educational hand-outs whenever Dallas Paleontological Society has a table at fossil-related events.

Feel free to use or change it however you like:

 

                                   32  WAYS  FOSSILS  ARE  PRESERVED
                                     
                                       DUPLICATION
1    Internal Mold  (minerals in contact with inner surface solidify then original dissolves)
2    External Mold  (minerals in contact with outer surface solidify then original dissolves)
3    Natural Cast   (solidifying minerals fill cavity in sediment left when original dissolves)

                                  

                                      MINERALIZATION
4    Permineralization    (space between cells fills with minerals that solidify)
5    Petrification    (space between cells fills with silica binding to cellulose)
                              
                                 CHEMICAL CHANGES
6    Replacement    (cells replaced with new minerals that solidify)
7    Recrystallization    (replacement when the new minerals are a crystal form)
8    Carbonization    (thin carbon film formed by chemical change)
9    Coalification    (carbonization occurring by much slower processes)
10  Hardened plant resin  (amber or cobalt)
                                                
                                    DESICCATION
11   Remains preserved in a Peat Pit
12   Remains preserved in a Tar Pit
13   Remains preserved in Frozen Tundra
14   Remains preserved by Mummification
                                          
                    ICHNOFOSSILS OR TRACE FOSSILS
15   Tracks (foot prints, tail dragging,  swimming traces)
16   Claw marks
17   Infilled burrows
18   Coprolites or droppings
19   Cololite or intestinal contents
20   Feeding traces
21   Urolites or urine splatters
22   Regurgitaliths or vomit
23   Body rests
24   Gastroliths or stomach contents
25   Bite marks
26   Layered bio-accretionary structures (stromatolites)
27   Termite mounds
28   Banded Iron Formations  (periods of presence or absence of microbes)
                                                           
                                             OTHERS
29   Adpression      (compression, impression)
30   Resin Inclusion   (Life trapped in resin which hardens into amber or copal)
31   Bioimmuration   (preservation due to organic overgrowth)
32   Unaltered remains

[DPS Ammonite]

Bob, here are my comments.

 

1 and 2: original does not have to dissolve. It only needs to be moved to clearly see a mold. I have oysters with both valves from Post Oak Creek that came apart revealing and internal mold, steinkern.

 

4 and 5: definitions need to be swapped. A permineralized fossil has organic material (not necessarily only cellulose), a petrified fossil does not. 

https://ucmp.berkeley.edu/paleo/fossilsarchive/permin.html

 

6 and 3 really close. What is difference? I usually call both casts. It is not always clear if the process is a bit by bit replacement or if the original is totally dissolved away before any replacement or filling begins.

 

7: I think that you are saying that a mineral crystallized. For example fibrous calcite recrystallizes into one giant single crystal of the body fossil.

 

10: copal not cobalt.

 

17: Don’t need to say infilled. Burrows can be hollow.

 

You can have an organism preserved in wax such as paraffin.

 

Chemical or distillation traces such as oil and gas are common.

 

 

[BobWill]

4 hours ago, DPS Ammonite said:

Bob, here are my comments.

 

1 and 2: original does not have to dissolve. It only needs to be moved to clearly see a mold. I have oysters with both valves from Post Oak Creek that came apart revealing and internal mold, steinkern.

 

4 and 5: definitions need to be swapped. A permineralized fossil has organic material (not necessarily only cellulose), a petrified fossil does not. 

https://ucmp.berkeley.edu/paleo/fossilsarchive/permin.html

 

6 and 3 really close. What is difference? I usually call both casts. It is not always clear if the process is a bit by bit replacement or if the original is totally dissolved away before any replacement or filling begins.

 

7: I think that you are saying that a mineral crystallized. For example fibrous calcite recrystallizes into one giant single crystal of the body fossil.

 

10: copal not cobalt.

 

17: Don’t need to say infilled. Burrows can be hollow.

 

You can have an organism preserved in wax such as paraffin.

 

Chemical or distillation traces such as oil and gas are common.

 

 

Thanks John. You have helped with this list a lot before, I believe the difference between 3 and 6 is that 3 is not a chemical alteration, just minerals filling a cavity, while 6 involves individual cells being replaced. I think it was Tom Dill who suggested this was a chemical process but I haven't looked deeper.

 

I'll have to look up where I got the information for 4 & 5. I will fix the issue with copal, burrows and 1 & 2. I had no idea fossils could be preserved in wax. Where has this been observed and where should that be listed, with the "OTHERS."

 

If I include oil and gas, how about coal, and which heading would they fall under?

[DPS Ammonite]

Preservation in paraffin is similar to that by oil, tar and asphalt.

 

http://petrifiedwoodmuseum.org/ChemicalPreservation.htm

 

I would call preservation of organisms in paraffin, oil, tar and asphalt as impregnation in hydrocarbons. I would get the tar pits out of the desiccation category. I would add a separate desiccation/mummification category by itself.

 

https://ucmp.berkeley.edu/paleo/fossilsarchive/drydes.html

 

Paraffin, oil, tar and asphalt are chemical trace fossils by themselves sometimes without any recognizable organisms. Coal without obvious identifiable fossil organisms could be considered a chemical trace fossil also.

Take preservation in frozen tundra out of desiccation. Say preservation in ice, tundra and glaciers. Some pieces of meat that are not desiccated are eaten by pack dogs and intrepid people.