I am from a rock 110 million year old sandstone from Richmond,
Iwas formed in an ancient shallow sea that covered the central part
of Australia. Ripple marks and the rock type show this
area was a shoreline.
As the tide changes the shoreline comes in and out of the water so
creatures dig tunnels...
to retreat into when the shore dries out
to assist in getting food
My flower-shaped tunnel on the right and is is a trace fossil.
A trace fossil is a
structure that is left behind by an ancient creature.
From looking a modern shorelines and comparing you can see I was a
worm-like creature because the tunnel shape is similar to tunnels made by
modern worm-like creatures.
The other trace fossil on the left is probably a crab
track. It looks a lot like modern crab tracks (click
the link if you want to find out more)
Often we do not know what the creature looked like but can make some
guesses based on the tunnels of creatures still living in shallow
If the trace fossil shape does not match that of a living creature then we
make a guess - no more - as to what it might have looked like.
We have no way to confirm this guess!
Some people claim that we know a lot about the ancient past but if you
look about you most things you see are made of soft body parts and are not
located in a place where they might be buried and become a fossil.
What are your chances, where you are sitting now, of becoming a fossil? -
Lets face it chances are pretty slim!
Most creatures are unlikely to ever become fossils
maybe 90% of ancient life. We don't really know!
Most soft bodied creatures in particular, leave no fossil record, we don't
know anything about them and never will.
Our "fossil record" is based on creatures that just happened to live in
places where it was easier to become a fossil for example...
by being buried in a just the right kind of sediment,
being covered in a volcanic ash fall,
getting caught and buried in a flood or landslide
falling into a preserving chemical like a tarpit, alkaline lake,
getting stuck in tree sap
being frozen or desicated
Our "fossil record" is
based mostly on creatures that had some hard durable large solid body
parts or as shown here on guesses based on the traces that they left
While the sea is long gone there are some very ancient rivers such as the
Finke River in the Northern Territory that show clear evidence that they
once flowed into this ancient salty sea.
Remarkably the Finke River contains fresh water sharks and skates,
creatures that adapted from salt to fresh water as the sea dried up.
We have some amazing things in Australia!
The Finke River is one of the oldest rivers in the world and flows into a
sea that no longer exists. These living fossils deserve our protection.