Here's something kind'a cool. Brought a fossil home from the
shop at work yesterday. Nobody knew what it was or how old
it might be. Guesses where anything from a spine to proto-teeth
of some herbivore.
Turns out nobody was even close. From an EMail I received back earlier today:
Hi Ron,
This is almost certainly an orthoconic nautiloid shell. The preservation is similar
to Tyndall Limestone (the material that has been used to face a lot of government
buildings in the prairie provinces), which would suggest that the specimen is
Ordovician in age (more than 440 million years old). This particular group of
animals had a very long fossil record, which makes it difficult to narrow down
the age of the rock precisely. A lot of this type of rock was brought into the
province by glaciers that swept in from the east, and slabs of Tyndall stone can
be found as field-stones over much of southern Saskatchewan. It is likely that your
specimen comes from one of these slabs.
The coiled shape that you are seeing is either the outside of the shell, or something
called a cameral deposit. Orthoconic nautiloids had a long, tubular shells that were
divided into many chambers. Each time the squid-like organism grew, it would add
a new chamber onto the end of the shell. When the animal died, the shell would have
infilled with sediment; later on, the shell dissolves more easily than the sediment that
is present on both the inside and outside of the shell, leaving this sort of characteristic
shape. The tight packing of the “coils” seen in your specimen might suggest that it is a
dense part of the shell called a cameral deposit – this is a thickened part of the shell
that was laid down along the cord that ran from one chamber to the next (usually in the
center of each chamber, used to pump fluid in and out of chambers). If this is the case,
you can wet the surface of your slab, and you may be able to see the outline of the outer
shell. These shells can be surprisingly large – we have some at the museum that are
more than four feet long, and four to six inches in diameter.
I have attached a few pictures of nautiloids to help put some of this information into context.
If there is anything else that I can do to help you out with this specimen, please let me know.
All the best,
-Ryan
Anyway...off to go shovelling...
shop at work yesterday. Nobody knew what it was or how old
it might be. Guesses where anything from a spine to proto-teeth
of some herbivore.
Turns out nobody was even close. From an EMail I received back earlier today:
Hi Ron,
This is almost certainly an orthoconic nautiloid shell. The preservation is similar
to Tyndall Limestone (the material that has been used to face a lot of government
buildings in the prairie provinces), which would suggest that the specimen is
Ordovician in age (more than 440 million years old). This particular group of
animals had a very long fossil record, which makes it difficult to narrow down
the age of the rock precisely. A lot of this type of rock was brought into the
province by glaciers that swept in from the east, and slabs of Tyndall stone can
be found as field-stones over much of southern Saskatchewan. It is likely that your
specimen comes from one of these slabs.
The coiled shape that you are seeing is either the outside of the shell, or something
called a cameral deposit. Orthoconic nautiloids had a long, tubular shells that were
divided into many chambers. Each time the squid-like organism grew, it would add
a new chamber onto the end of the shell. When the animal died, the shell would have
infilled with sediment; later on, the shell dissolves more easily than the sediment that
is present on both the inside and outside of the shell, leaving this sort of characteristic
shape. The tight packing of the “coils” seen in your specimen might suggest that it is a
dense part of the shell called a cameral deposit – this is a thickened part of the shell
that was laid down along the cord that ran from one chamber to the next (usually in the
center of each chamber, used to pump fluid in and out of chambers). If this is the case,
you can wet the surface of your slab, and you may be able to see the outline of the outer
shell. These shells can be surprisingly large – we have some at the museum that are
more than four feet long, and four to six inches in diameter.
I have attached a few pictures of nautiloids to help put some of this information into context.
If there is anything else that I can do to help you out with this specimen, please let me know.
All the best,
-Ryan
Anyway...off to go shovelling...
