Madison County, NY Identification

[historianmichael]

I found these fossils while collecting at several locations in Madison County, NY. I have no clue what it could be. Any help would be greatly appreciated.

 

 

[ynot]

Welcome to TFF!

Neat looking fossils.

I have no idea what they are.

[Rockwood]

What is the scale ?

Is the finger print a fingerprint or part of the fossil plate ? 

[Vieira]

Maybe a starfish fragment?

[Fossildude19]

Welcome to the Forum.

 

They are thoracic segments of the trilobite Dipleura dekayi. 

 

[Jeffrey P]

I agree with Tim.

[GeschWhat]

2 hours ago, Fossildude19 said:

They are thoracic segments of the trilobite Dipleura dekayi. 

I never would have guessed trilo-bit. What beautiful detail!

[Walt]

 

Did he lose his head?

 

 

[Rockwood]

That would make it a big trilobite, and the post smaller than it looks ?

Scale  

[historianmichael]

Upon second glance, I think I would agree that the second photo is of the dipleura. The first photo seems different however. The tiny dot pattern comes up, rather than goes into the material, as you would ordinarily find with the skin of a trilobite. Is it perhaps the imprint of a thoracic segment? Here is another photo with scale added.

 

 

 

Edited August 17, 2018 by historianmichael

[FossilDAWG]

In this specimen the actual shell material has dissolved, leaving a mold or impression.  The sediment that filled the pores therefore stands out as little bumps or pillars.

 

Don

[piranha]

The articulating half ring shows it is flipped over in ventral aspect. 

 

[Fossildude19]

2 hours ago, Walt said:

Did he lose his head?

Yes, he did.  

I'm not positive that is the cephalon that goes with the thorax and pygidium, but it is probable, as these are molt fossils.

When the trilos would shed their exoskeleton, they would separate at the junction of the thorax and cephalon. Then they would crawl out of the body molt.  

[piranha]

18 minutes ago, Fossildude19 said:

When the trilos would shed their exoskeleton, they would separate at the junction of the thorax and cephalon. Then they would crawl out of the body molt.  

 

 

Trilobites employed many different methods of exuviation.  Most would displace the free cheeks, others at different points along the thorax or the pygidium.  Olenellids had no facial sutures so they displaced the hypostome and rostral plate in order to moult ventrally.  Here is an excellent paper on this topic:

 

Daley, A.C., & Drage, H.B. 2016

The fossil record of ecdysis, and trends in the moulting behaviour of trilobites. 

Arthropod Structure & Development, 45(2):71-96   PDF LINK

[Walt]

thank you guys! 

[Fossildude19]

6 minutes ago, piranha said:

 

 

Trilobites employed many different methods of exuviation.  Most would displace the free cheeks, others at different points along the thorax or the pygidium.  Olenellids had no facial sutures so they displaced the hypostome and rostral plate in order to moult ventrally.  Here is an excellent paper on this topic:

 

Daley, A.C., & Drage, H.B. 2016

The fossil record of ecdysis, and trends in the moulting behaviour of trilobites. 

Arthropod Structure & Development, 45(2):71-96   PDF LINK

 

Thanks for clarifying that, Scott!

Also, thank you for the paper.