Turonian echinoid

[PFOOLEY]

I recently found an echinoid in the Prionocyclyus hyatti ammonite zone of the Upper Cretaceous (Middle Turonian) Semilla Sandstone Member of the Carlile Shale.

 

 

 

These creatures are not common and until now...

 

  

 

...I have only found fragments.

 

 

After a quick clean and some photos, I wonder if there is enough diagnostic material left on this crushed and eroded specimen. 

 

  

 

  

 

scale= 1/4"

 

I do not know much about echinoderms, but I am very much interested in learning more.  Is there enough of this creature to label a genus?

 

Thank you for your help.

[Mikrogeophagus]

I'd say it's worth comparing to Mecaster batnensis which can be found in similarly aged formations in Texas. I've seen @LSCHNELLE pull one from the uppermost south bosque which I believe is the same Prionocyclyus hyatti ammonite zone. From your pics they look a little similar as well. 

[PFOOLEY]

Thank you @EPIKLULSXDDDDD...I appreciate it. I will start there.

[Jeffrey P]

Great find! Congrats Mike. I imagine you were quite pumped to find that. Best wishes and luck with the ID, etc.

[PFOOLEY]

34 minutes ago, Jeffrey P said:

Great find! Congrats Mike. I imagine you were quite pumped to find that. Best wishes and luck with the ID, etc.

 

Thank you, Jeffrey! I was indeed pumped...more pieces to the puzzle, more learning, more goals.

 

I've already had some very positive, short discussions with Dr. Lucas regarding this Semilla spatangoid...I know it seems like it's just an echinoid, but there are currently zero echinoderms documented from this interval...and only a few others from the Cretaceous of NM. The Middle Turonian of New Mexico has really been an awesome place to be an amateur paleontologist...crazy how the Universe works. 

[PFOOLEY]

I was fortunate enough to find a few more specimens of this genus of echinoid...

 

...this specimen was the most complete of the four additional specimens.

 

 

 

scale = 1/4"

 

The other three.

 

[JohnJ]

Mike, are any of the apical system details preserved when viewed under a microscope?

[PFOOLEY]

The smallest of these new specimens offers the best chance at being able to see those plates. When I get an opportunity, I will get over to the lab and take a peek. That will be very helpful for determining whether they are Mecaster or Hemiaster.

[PFOOLEY]

I snagged this...

 

  

 

"The apical disc, as in other irregular echinoids, is composed of five ocular plates (green) and up to four plates (yellow). The ocular plates are pierced by a microscopic perforation that houses the tip of the radial water vessel; ocular plates are always situated at the tip of each ambulacrum. The plates are generally larger and are pierced by a much larger circular pore, the gonopore. It is through this opening that the echinoid sheds its gametes into the water column. One of these plates, G2, is larger and perforated by a mass of small holes, the madrepores. This plate is also known as the madreporite. It is the external opening for the internal system of water vessels that include the tube-feet."

 

Hemiaster differs from Mecaster in having an ethmophract apical disc...

 

 

rather than a semi-ethmolytic (disc)...

 

 

or ethmolytic disc. 

 

 

 

......from the The Echinoid Directory  

[PFOOLEY]

Thank you @Mikrogeophagus and @JohnJ for your input...

 

 

Lucas and Foley (2023)

THE CRETACEOUS ECHINOID MECASTER FROM THE TURONIAN OF THE SOUTHEASTERN SAN JUAN BASIN, NEW MEXICO

 

27-MECASTER.pdf

 

...still some room for assigning a species.

 

[Jared C]

2 hours ago, PFOOLEY said:

Thank you @Mikrogeophagus and @JohnJ for your input...

 

 

Lucas and Foley (2023)

THE CRETACEOUS ECHINOID MECASTER FROM THE TURONIAN OF THE SOUTHEASTERN SAN JUAN BASIN, NEW MEXICO

 

27-MECASTER.pdf 725.88 kB · 1 download

 

...still some room for assigning a species.

 

Congrats on the pub!!

[PFOOLEY]

49 minutes ago, Jared C said:

Congrats on the pub!!

 

Thank you, Jared. 

[Mikrogeophagus]

Huge congrats!!! I enjoyed reading that

[JohnJ]

Great work, Mike!

[old bones]

Congratulations on the publication, Mike! 

[jpc]

woo hooo!

 

[PFOOLEY]

17 hours ago, Mikrogeophagus said:

Huge congrats!!!...

 

Thank you for the suggestion! 

[PFOOLEY]

5 hours ago, JohnJ said:

Great work, Mike!

 

Thank you, John! There is still some work to be done on these creatures...just need to find some more, better preserved, specimens. 

[PFOOLEY]

5 hours ago, old bones said:

Congratulations on the publication, Mike! 

 

Thank you, Julianna! 

[PFOOLEY]

17 minutes ago, jpc said:

woo hooo!

 

...indeed. Thank you, sir.