Trilobite Pygidiums from the BAS - Zacanthoides Walapai

[Arizona Chris]

HI all,

 

Here is the last piece of the trilobites write up from our "SW Site" (Stevens Way, Ashfork, Az.) featuring the interesting pygidiums of the Zacanthoides Walapai trilobites we found in huge abundance in the Bright Angel shale.  Ill post a few nice shots here, and at the end a link to the full (monstrous) write up on our paleo web site.  Thanks for looking!

 

The most common fossil found in the green shales at our SH locality are trilobite pygidiums for the Zacanthoides Walapai species. They are joined by assorted cranidiums, thorax and rib segments, and hordes of hyolithids, and a very rare coralomorph. Generally low diversity such as this site suggests has been attributed to a stressed environment, with perhaps low food sources, aggressive wave action, or an influx of fresh water from the nearby deltas. This was a shallow sea outbound from the deposits known as the Tapeats Sandstone which marked shore, delta and beach deposits. Combined with the deeper water Muav Limestone, this trio of formations is known as the Tonto Group. All three can be found outside the Grand Canyon to the south in small limited areas such as here, yielding an opportunity to explore the paleo fauna without hiking miles and thousands of feet into the Grand Canyon.

 

A few images that are special:

 

The full write up can be found here:

 

http://www.schursastrophotography.com/paleo/Fossilfotos-4f.html

 

 

[Fossildude19]

Very cool! 

Thanks for posting this.  

Regards,

[Arizona Chris]

Thanks Tim!  On the second image here, just below the two pygidii is a hypostome. 

[MeargleSchmeargl]

Coolio! Always love the ol' roly polies!