Just what is a fossil?

Saurexallopus, a four toed dinosaur or bird trace fossil

Last week on facebook I shared someone’s photo of a museum display that proclaimed “fossil. n.: any evidence of life more than 7,000 years old.”

I had a bit of a lively debate discussing what exactly a fossil would be.  The best they could come up with was that a fossil is something turned to stone by pressure and time with no organic material remaining.

Most educational sites are much more careful to use a definition that is accurate, I rather like the acrostic Stories in Stone uses to explain how something qualifies for the title Fossil:

Petrified Araucaria mirabilis Cone; Patagonia, Argentina

Found

Only in

Sedimentary

Stones

Indicating

Life

Although even that will show to miss some real fossils.

Museums seem to be more forceful trying to make fossils prove their claim that the earth must be old.  Here’s what the Natural History Museum of San Diego says about them:

Fossils are the remains and/or traces of prehistoric life. The critical factor is age. Fossils have to be older than 10,000 years, the generally accepted temporal boundary marking the end of the last Pleistocene glacial event.

OK, they don’t care about the pressurization (very wise) or organic remains, they just try to make them so old the Bible must be lying.  Wikipedia’s Fossil page was honest enough to admit that claiming fossils MUST be 10,000 years old is “arbitrary” [which means they just decided it should be that without a good reason].

So what is a fossil really?  Here are the types of things scientists call fossils (from Enchanted Learning):

• mold fossils(like when you press a toy into playdough and pull it back out)
  

  Fossil Homeosaurus maximiliani Paris, Galleries of Paleontology and Compared Anatomy

• cast fossils (when something else fills in that shape)
• trace fossils = ichnofossils (fossilized nests, gastroliths, burrows, footprints, etc.)
• true form fossils (fossils of the actual animal or animal part)

This last one, where the animal or plant is still there (more or less) is divided into these sub-types:

• unaltered preservation (like insects or plant parts trapped in amber, a hardened form of tree sap)
• permineralization=petrification (in which rock-like minerals seep in slowly and replace the original organic tissues with silica, calcite or pyrite, forming a rock-like fossil – can preserve hard and soft parts – most bone and wood fossils are permineralized)

Did you catch that?  Those dino bones we love to visit are petrified just like the teddy bear in the spring.  And as we know, they stink, so there is still organic material in there that wasn’t replaced by minerals.

Tree bark fossil called Lepidodendron, 005411 (Photo credit: Black Country Museums)

• carbonization=coalification (in which only the carbon remains in the specimen – otherelements, like hydrogen, oxygen, and nitrogen are removed)

Sometime I will get around to all the amazing things we find in coal.  Notice that coal is made from a living thing (a plant) that has lost other elements leaving only the carbon behind.

• recrystalization (hard parts either revert to more stable minerals or small crystals turn into larger crystals)

Do we have trouble with fossils just because we believe God made the world only about 6,000 years ago?  Not a bit.  We would if we didn’t believe in a global catastrophe, but the Bible carefully explains that to us as well.

On the 17th day of the second month, when Noah was 600 years old, the springs under the earth broke through the ground, and water flowed out everywhere. The sky also opened like windows and rain poured down. The rain fell on the earth for 40 days and 40 nights. That same day Noah went into the boat with his wife, his sons Shem, Ham, and Japheth, and their wives.

Every living thing on earth died—every man and woman, every bird, and every kind of animal. All the many kinds of animals and all the things that crawl on the ground died. Every living, breathing thing on dry land died. In this way God wiped the earth clean—he destroyed every living thing on the earth—every human, every animal, everything that crawls, and every bird. All that was left was Noah and his family and the animals that were with him in the boat.  Genesis 7:11,21-23