Identification Help Needed!!

[KateR]

Hi Everyone, My husband and I found this little wonder while walking on the shore of Lake Ontario right outside of Toronto today. I am attaching the best pic I can with the space restrictions, I hope it is enough. To describe a little further the image in the pic, the interior of the ridges are crystalized, almost like a geode and you can see a raised "spine" that runs down the center. We don't know what it is, how old it is and if its a rare find or a common item for the area. We're not familiar with fossils and are not from the area. Any information would be greatly appreciated. Thanks in advance!

[jpc]

Hi and welcome.  It is an orthocone ammonoid.  Google that and see what you get.  A sea shell related to modern nautilus from well before the age of dinosaurs.  These things were split up in sections and we are seeing a cross section.  Pretty common in the area of Toronto.  But this is a nice example.   

[KateR]

Hi, Thanks so much for the information. I looked it up and absolutely looks like that's what it is. Very cool. It's almost impossible to wrap my head around how old it is. I really appreciate the info!  Kate

[Rockwood]

2 hours ago, jpc said:

Hi and welcome.  It is an orthocone ammonoid.  Google that and see what you get.  A sea shell related to modern nautilus from well before the age of dinosaurs.  These things were split up in sections and we are seeing a cross section.  Pretty common in the area of Toronto.  But this is a nice example.   

How is it differentiated from a nautiloid ?

[Pemphix]

Orthoceras sp. (Nautiloid) ("ancestor" of modern nautilus).

Occurs in Paleozoic marine Sediments.

Typical for ordovician age (around 485-443 Mio years ago).

 

Best regards,

Pemphix

[Monica]

Hi KateR!

 

Yes, what you have is indeed an orthoconic nautiloid.  I've been fossil-hunting along the rivers close to Lake Ontario here in the Greater Toronto Area since the summer, and I've found quite a few - it's definitely my most common find.  I really like your specimen, though, because you've stated that there is a raised "spine" running down the centre of the fossil - this is the siphuncle, which was a strand of tissue connecting the animal's chambers that was probably used to empty water from these chambers, which would have aided in the animal's buoyancy.

 

As for being amazed at how old the specimen is - I am, too!  The rocks around this area are around 460-440 million years old!!!

 

Thanks for sharing!

 

Monica

 

PS - As for the differences between ammonoids and nautiloids, I think there are 2 distinguishing characteristics: 1. the location of the siphuncle (ammonoids - closer to the outside; nautiloids - closer to the centre), and 2. the chamber walls/septa (ammonoids - very convoluted; nautiloids - very simple/straight and only slightly curved).  For these 2 reasons, I believe we can say what you have is a nautiloid.

[KateR]

Thanks Monica, That's awesome information. I can't believe the rocks around these parts are that old either. Really quite amazing, and an incredible thing to find when your not looking for it.  

[Fossildude19]

Welcome to the Forum.

 

Nice Orthocone cephalopod.

Regards,

 

 

 

 

 

[jpc]

2 hours ago, KateR said:

Thanks Monica, That's awesome information. I can't believe the rocks around these parts are that old either. Really quite amazing, and an incredible thing to find when your not looking for it.  

...and when you get up north of Toronto a fair bit you get into what geologists call the Canadian Shield.  The rocks there are much much older.  

[Monica]

5 hours ago, jpc said:

...and when you get up north of Toronto a fair bit you get into what geologists call the Canadian Shield.  The rocks there are much much older.  

Very true, jpc - in the summer we rent a cottage that's almost 3 hours north of Toronto, and my daughter was very disappointed this past summer when I told her that we wouldn't be able to look for fossils for a week while we were up there because the rocks in the area are too old for fossils (although she did have a great time looking for pretty rocks instead ).