Serpulids in the Permian Ft. Apache Limestone

[Arizona Chris]

Well, here is the latest microfossil work on the acid residues of about 35 pounds in limestone collected a few weeks ago at our new Highline trail locality east of Payson.  In all, we found perhaps a score of these fossils, mixed in  with hordes of gastropods.  They are pretty tiny, and definitely classify as microfossils.  Every shot here is a stack of at least 5 frames of varying focus, the one killer serpulid tube at 45x is a stack of a dozen images.  The background is a nice blue paint sample chip from Home Depot.  They have all colors and they are free!

 

Serpulids worm tubes from the Permian Fort Apache Limestone East of Payson - Serpula Spirorbis sp.

 

Live serpulid from Canada:

 

Over two dozen serpulid tubes have been found so far in the acid fines from the second site we have found in the Fort Apache Limestone. Serpulids have been around since the Ordovician and are indeed a very ancient lineage. These worms build small coiled tubes attached to either hard surfaces such as shells or other small invertebrate hard parts, or on the leaves of sea weeds. We have found both types in this formation. They are small, barely visible to the naked eye, yet their coiled tubes are very diagnostic when sorting the silicified remains under magnification. Here are a few of the better preserved specimens found from about 35 pounds of rock from the latest locality east of Payson.

 

Note: captions are below images.  

 Section of spiny Urchin spine, with three serpulids attached permanently. This view shows the coiled tube on the lower left corner. 10x view.

 

 

Side view of flattened spine, showing two more. Flattening occurs when the sediment containing the fossils are compacted before lithification.

 

 

 A collection of loose Spirorbis serpulids. They would have lived on the bottom of the leaves of sea weeds and when the weed died, the serpulid tubes fall to the bottom to be fossilized. Seen here at 7x magnification. The head of a straight pin is just below.

 

 

 Close up at 45x of the tube spiral that is at the bottom of the above image. You can clearly see the opening coiling over the top of the earlier tube dwelling. It is preserved in nearly pure silica.

 

 

 Bottom side of same specimen, 45x. Note how it is flat - this is the side that attached to the sea weed and grew against it. The serpulid essentially glued itself on to the leaf, forming a flat on the weed side.

 

 

[Al Dente]

Nice. Are all of these flat on one side? if not, a couple might be ammonoids. Ammonoids have an inflated protoconch and two that I have circled look like they have this feature.

 

 

[Arizona Chris]

Al, your right - I took a look again this morning at those two and they are not flat on the back.  Baby ammonites?????

[Al Dente]

1 hour ago, Arizona Chris said:

Al, your right - I took a look again this morning at those two and they are not flat on the back.  Baby ammonites?????

Too old for ammonites but could be ammonoids. Some gastropods will also have an inflated protoconch.

 

Here's an example I found online showing an ammonoid protoconch.

[Arizona Chris]

Al, there are plenty of nautiloids in this formation.  We have found both orthocone and coiled types, so it is likely that is what these are.  Some are the size of dinner plates!

[FossilDAWG]

The shell microstructure of all fossils previously considered to be Paleozoic or early Mesozoic serpulids indicates that they are not in fact serpulids (which are polychaete annelids) but instead belong to the microchonchids, a different group of organisms possibly related to lophophorids such as bryozoans and brachiopods.  See this thread for an interesting discussion of the issue.  The problem is that with nothing to go on but a small coiled shell affized to other objects, the possibilities for convergent evolution are endless. 

 

Don

[Arizona Chris]

Whatever you may call them, I find them fascinating.  They look identical to the same age Permian spriorbis we find in great abundance in the same aged Supai formation brackish water deposits in Christopher Creek, at the now defunct uranium mine.  This is a treasure trove of plant fossils, and many spirorbis types (or look alikes) cover the bottoms of fern and cordiates leaves.  While all the older references refer them to serpulids, paleontological nomenclature is constantly under review, and Im not surprised at all that paleozoic serpulids have been reclassified.  Thank you for your insightful input!