trilobite pygidium from Etobicoke Creek

[Monica]

Hi all!

 

I just got back from a little hunt with the kids along Etobicoke Creek here in Mississauga, Ontario (Georgian Bay Formation, Upper Ordovician), and I'm wondering if I perhaps found a trilobite pygidium?  Here are some pictures:

 

Front of rock (lots of little branching bryozoans and some crinoid bits):

 

Back of rock (where the possible trilobite pygidium is located - circled in red):

 

Close-up of possible trilobite pygidium:

 

What do you think?  And, if it is indeed a trilobite pygidium, can it be identified any further?

 

Thanks in advance!

 

Monica

 

 

[Kane]

I would label it Flexicalymene senaria.

 

Image from Ludvigsen (1979) Fossils of Ontario - Part 1: The Trilobites.

[Tidgy's Dad]

Certainly a trilobite pygidium. 

And nice bryozoans too. 

Good day's hunting. 

[Monica]

2 hours ago, Kane said:

I would label it Flexicalymene senaria.

 

Image from Ludvigsen (1979) Fossils of Ontario - Part 1: The Trilobites.

 

Thanks, Kane!  I was hoping that it was a trilo-bit, but I try not to get my hopes up so as to avoid disappointment. 

 

[Monica]

2 hours ago, Tidgy's Dad said:

Certainly a trilobite pygidium. 

And nice bryozoans too. 

Good day's hunting. 

 

Thanks for chiming in, Adam!  I'm happy with this find, too - I brought it home because of all the little bryozoans on it (I don't usually find so many on one rock so I thought it was worthy of the trip home for a little wash and a closer look) and the trilobite bum was a bonus.   I also brought home a piece of rock with two beat-up orthoconic nautiloids on it (they're not in the best condition, but one of them tapers quite nicely which is unusual for what I usually find, so I might end up keeping it...or I might bring it back to the creek - I'm still undecided), a couple of loose orthoconic nautiloids (one is a bit beat-up and the other is covered with a bryozoan, but I can't resist bringing cephalopods home - I feel drawn to them, which is why Viola calls me "The Cephalopod Queen" ), as well as a rock with a bunch of gastropods on it cut in various ways, but one is cut in a beautiful longitudinal section, so it's a keeper. 

[Tidgy's Dad]

9 minutes ago, Monica said:

 

Thanks for chiming in, Adam!  I'm happy with this find, too - I brought it home because of all the little bryozoans on it (I don't usually find so many on one rock so I thought it was worthy of the trip home for a little wash and a closer look) and the trilobite bum was a bonus.   I also brought home a piece of rock with two beat-up orthoconic nautiloids on it (they're not in the best condition, but one of them tapers quite nicely which is unusual for what I usually find, so I might end up keeping it...or I might bring it back to the creek - I'm still undecided), a couple of loose orthoconic nautiloids (one is a bit beat-up and the other is covered with a bryozoan, but I can't resist bringing cephalopods home - I feel drawn to them, which is why Viola calls me "The Cephalopod Queen" ), as well as a rock with a bunch of gastropods on it cut in various ways, but one is cut in a beautiful longitudinal section, so it's a keeper. 

Sounds like you had a great day out! 

I love encrusting bryozoans. 

The gastropods sound interesting. 

So, if you're The Cephalopod Queen, that makes Viola, The Princess of what ?

[Kane]

34 minutes ago, Monica said:

 

Thanks, Kane!  I was hoping that it was a trilo-bit, but I try not to get my hopes up so as to avoid disappointment. 

 

Doesn't hurt to keep your hopes up as the Georgian Bay Fm reports up to six trilobite genera according to Ludvigsen: 

 

Although it should be noted that Isotalo (2015) in Ordovician Trilobites of Southern Ontario, Canada and the Surrounding Region lists two species: Flexicalymene granulosa and Isotelus maximus. I would probably need to look at your specimen's features a bit more keenly to determine if it is F. senaria or F. granulosa. 

 

To be on the safe side, I would revise my previous ID label and call it Flexicalymene sp. pending a bit more finer-grained examination of the diagnostic details.  

 

[Ludwigia]

Nice little piggy I've circled something in your first pic that could also belong to a trilobite. Perhaps a cross section of the pleura?

 

[Monica]

2 hours ago, Tidgy's Dad said:

Sounds like you had a great day out! 

I love encrusting bryozoans. 

The gastropods sound interesting. 

So, if you're The Cephalopod Queen, that makes Viola, The Princess of what ?

 

Viola loves all kinds of "shells" (i.e. brachiopods and bivalves), so I'd probably call her "The Princess of Shells."

 

(fyi: I just asked Viola what she thinks she's the princess of, and she said "The Princess of Candy"!    She definitely loves candy more than the rest of us in the house, so perhaps that would be the best title for her. )

[Monica]

2 hours ago, Kane said:

Doesn't hurt to keep your hopes up as the Georgian Bay Fm reports up to six trilobite genera according to Ludvigsen: 

 

Although it should be noted that Isotalo (2015) in Ordovician Trilobites of Southern Ontario, Canada and the Surrounding Region lists two species: Flexicalymene granulosa and Isotelus maximus. I would probably need to look at your specimen's features a bit more keenly to determine if it is F. senaria or F. granulosa. 

 

To be on the safe side, I would revise my previous ID label and call it Flexicalymene sp. pending a bit more finer-grained examination of the diagnostic details.  

 

 

I'm okay with just giving my little trilo-bum a genus - Flexicalymene sp. is good enough for me!  Thanks a bunch! 

 

[Monica]

2 hours ago, Ludwigia said:

Nice little piggy I've circled something in your first pic that could also belong to a trilobite. Perhaps a cross section of the pleura?

 

 

I think you're right, Roger!  And I think I see a similar item near the top of my first picture, too - good eye! 

[Tidgy's Dad]

3 minutes ago, Monica said:

 

Viola loves all kinds of "shells" (i.e. brachiopods and bivalves), so I'd probably call her "The Princess of Shells."

 

(fyi: I just asked Viola what she thinks she's the princess of, and she said "The Princess of Candy"!    She definitely loves candy more than the rest of us in the house, so perhaps that would be the best title for her. )

The Princess of Candy, eh? 

How Sweet! 

[Monica]

Just now, Tidgy's Dad said:

The Princess of Candy, eh? 

How Sweet! 

 

She's very sweet...when she isn't angry about something... (I like to describe her as "feisty" )

[Tidgy's Dad]

Just now, Monica said:

 

She's very sweet...when she isn't angry about something... (I like to describe her as "feisty" )

Just the adjective I use for Tidgy. 

My feisty Princess of Dandelions. 

[subsonicdrone]

nice finds!

i like the detail on the bryozoans

[ynot]

Congratulations on finally finding a trilobite at that location, hope the next is whole!

[Monica]

On 4/1/2018 at 8:36 PM, subsonicdrone said:

nice finds!

i like the detail on the bryozoans

Thanks!  I, too, like how the individual pores can be seen on the broyzoans 

 

On 4/1/2018 at 8:44 PM, ynot said:

Congratulations on finally finding a trilobite at that location, hope the next is whole!

Thanks, Tony!  This is indeed my first Flexicalymene sp. trilo-bit found at my local haunt, although I did find a couple of rusophycus there as well as a very beat-up Isotelus sp. along the same creek in the past.  I'm definitely hoping to find a nice, complete trilo here in my area one day...