Arizona Pennsylvanian Sponge Roots

[DPS Ammonite]

I have found many Pennsylvanian sponge roots in an isolated area of the Naco Formation near Payson, Arizona. The sub parallel root fibers range in size from 0.2 to 1.2 mm in diameter. The roots are often found growing/covering crinoid columnal sections. Near Pine and at my site the roots are found where Chaunactis olsoni sponges are the most common, but not the only sponge species present. Now I need to find a sponge with roots attached to ID the species of the roots. It is unknown if the silicified roots were originally silica or calcite.

 

I noticed that there are grooves from and matching the diameter of the roots in originally calcitic crinoid columnals and head pieces. What caused these grooves? Two hypothesis: the silica roots grew over the softer calcitic crinoid pieces rubbing grooves into them as the currents caused the roots to sway. Second: the roots had living tissue on the outside that secreted acid that caused the grooves. Knowledge of extant sponge anatomy might help answer this question.

 

Photo 1: average root diameter about 0.6 mm.

 

Photos 2 and 3: detail of first photo.

 

Photo 3: roots growing around section of crinoid columnals with grooves in columnals.

 

Dilliard, Kelly & Rigby, J. Keith. 2001. The new demosponges, Chaunactis olsoni and Haplistion nacoense, and associated sponges from the Pennsylvanian Naco Formation, Central Arizona. Brigham Young University Geology Studies. 46. 1-11. 
http://geology.byu.edu/Home/sites/default/files/geo_stud_vol_46_dilliard_rigby.pdf

@TqB

Edited June 27, 2021 by DPS Ammonite

[TqB]

An interesting occurrence - I haven't noticed anything like it. @Spongy Joe might have an answer - he's sometimes around.

 

If the sponge is the only silica fossil, it seems likely it was silica originally.

[DPS Ammonite]

The Naco in that area has lots of silicified crinoids, burrows, wood and brachiopods. All the sponges are silica too. Who knows if any of the sponges were calcareous.

[TqB]

6 hours ago, DPS Ammonite said:

The Naco in that area has lots of silicified crinoids, burrows, wood and brachiopods. All the sponges are silica too. Who knows if any of the sponges were calcareous.

Fair enough.

[TqB]

7 hours ago, DPS Ammonite said:

The Naco in that area has lots of silicified crinoids, burrows, wood and brachiopods. All the sponges are silica too. Who knows if any of the sponges were calcareous.

Do sponges other than hexactinellids have that type of root spicule? (I'll trawl the Treatise later.)

Edited June 27, 2021 by TqB