Seashells And Fossils?

[2gould]

I appologize in advance if this question is too basic, but it has been bugging me for awhile. There are a lot of definitions of fossils out there so I just chose the Wikipedia definition which states that a fossil is "mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms."

As such, do the seashells you encounter just strolling on the beach count as fossils?? I just figured that seashells were seashells and fossils were different. However, on this site I see pictures of fossilized seashells, so now I don't know what to think. Is there a process by which a common seashell becomes fossilized, at which point it then becomes a "fossil"?

I hope my question is clear and I would appreciate any clarification if possible...I am totally a newbie...haha

Charley

[Gatorman]

Well I personally would not consider a seashell a fossil unless I knew it came from ancient deposits. And I know that if I go into a Sink hole in the middle of Florida and find shells i know they are fossil. But the ones on the beaches may not be.

[jkfoam]

2gould,

Interesting question and one that keeps appearing on a fairly regular basis.

I always like to go back to R.C. Moore's definition in his opening paragraph in "Invertebrate Fossils". I quote

"Fossils are the remains or traces of animals or plants which have been preserved by natural causes in the earths crust. The term fossil origionally referred to anything dug from the earth. Since organisms living at the present time are not considered fossils when they become buried, many paleontologist arbitraily exclude from classification as fossils all organisms which have been buried since the beginning of historic times."

JKFoam

[Guest solius symbiosus]

I tend to think that the original organism has to undergo some amount of diagenesis. Too, I don't consider trace fossils as fossils; hence the "trace".

EDIT: I should add that there are some exceptions, e.g., original material found in some examples(Mastodons, Ammonites, ...)

[kauffy]

i would say for one of those seashells to become a fossil it must undergo a process of being buried, and its original material being replaced by mineralisation/petrification ect (i would also consider frozen mammoth remains and bog wood ect to be fossils).... its often with shells though that they begin as calcium carbonate and after mineralisation are still calcium carbonate...the seashells you find on a beach are almost always modern (bar a few exceptions when offshore deposits, or cliff exposures have washed them onto the beach) sometimes it is easy to find out whether your shells are a fossil, obviously if you find some that have rock attatched or they are surrounded by rock (the matrix) if you are still unsure whether your shells are fossils or not, you can consult a paleontologist at a museum or uni, or you can find information from a local library about the modern seashells from the area and compare the ones you found, if you cant find a modern one it may infact be a fossil....keep in mind though that some shells that are found as fossils can also be found in the same area still living for example at Calvert Cliffs MD.

but i would not call an shell i found on a beach to be a fossil until mineralisation and the fossilisation process has occurd

Fossilised shells can be quite detailed and look almost like they died yesterday! but they often have no coloration.....

hope some of this information helps.....i was just blabbing

Chris

[Guest Nicholas]

i would say for one of those seashells to become a fossil it must undergo a process of being buried, and its original material being replaced by mineralisation/petrification ect (i would also consider frozen mammoth remains and bog wood ect to be fossils).... its often with shells though that they begin as calcium carbonate and after mineralisation are still calcium carbonate...the seashells you find on a beach are almost always modern (bar a few exceptions when offshore deposits, or cliff exposures have washed them onto the beach) sometimes it is easy to find out whether your shells are a fossil, obviously if you find some that have rock attatched or they are surrounded by rock (the matrix) if you are still unsure whether your shells are fossils or not, you can consult a paleontologist at a museum or uni, or you can find information from a local library about the modern seashells from the area and compare the ones you found, if you cant find a modern one it may infact be a fossil....keep in mind though that some shells that are found as fossils can also be found in the same area still living for example at Calvert Cliffs MD.

but i would not call an shell i found on a beach to be a fossil until mineralisation and the fossilisation process has occurd

Fossilised shells can be quite detailed and look almost like they died yesterday! but they often have no coloration.....

hope some of this information helps.....i was just blabbing

Chris

I tend to agree with you Chris on this one. I believe that this also applies to dried remains, I've come across people who have dried sea sponges until they are hard and almost rock like and then tried to pass them off as fossils. I've also heard of dried seahorses being passed off as fossils... To me for a fossil to occur the replacement of minerals much be evident. There are some exceptions like everyone said above of ancient life preserved so perfectly that there is no mineralization, etc...

[2gould]

Thank you for all your great replies! You confirmed my suspicion but gave me the reasoning behind it. Thank you very much!

[CURT]

I appologize in advance if this question is too basic, but it has been bugging me for awhile. There are a lot of definitions of fossils out there so I just chose the Wikipedia definition which states that a fossil is "mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms."

As such, do the seashells you encounter just strolling on the beach count as fossils?? I just figured that seashells were seashells and fossils were different. However, on this site I see pictures of fossilized seashells, so now I don't know what to think. Is there a process by which a common seashell becomes fossilized, at which point it then becomes a "fossil"?

I hope my question is clear and I would appreciate any clarification if possible...I am totally a newbie...haha

Charley

The remains of an organism must be at least 11,000 years old to be considered a fossil, although most people would consider something 9,000 or 10,000 to be a fossil. Most shells on the beach are probably not very old, although they may look it from rolling around in the surf. Some beach shells can wash up from off shore formations, just as shark teeth, amber, and ice age mammals do, but it would be rare. I found a croc scute while beach walking after a sand replenishment project in Spring Lake, N.J. Most fossil shells come from ancient sea floor or lake bed deposits like those in Florida, Italy, Poland, etc, that have been dated to earlier geologic time periods. Many Tertiary period shells can look like they died yesterday, so even if you did find a fossil, it would be pretty hard to know for sure unless you knew it was extinct.

[Guest N.AL.hunter]

A fossil can be younger than 11000 yrs old. Mammoths from up north can be as young as 4000 yrs ago, but still are fossils, so the age is very arbitrary as to what a fossil is. we had a posting on this topic a couple of months ago.

[CURT]

A fossil can be younger than 11000 yrs old. Mammoths from up north can be as young as 4000 yrs ago, but still are fossils, so the age is very arbitrary as to what a fossil is. we had a posting on this topic a couple of months ago.

I read once that a fossil can be as young as 100 years if the animal is extinct. The dodo was given as an example. Anyone else ever hear that?