Permian Scaphopods II Juvenile Teleoconchs (cf. Plagioglypta canna) from the Fort Apache Limestone East of Payson

Updated  10/27/17

Scaphopod Teleoconchs in the Fort Apache Limestone


For over a decade, this particular fossil gave us a lot of trouble when trying to identify its affiliation. We had listed it as "problematica" and until more fossils could be obtained, even its phylum was in doubt. Recent collection of large amounts of material from the Fort Apache Limestone at the Highway 260 site has enabled us to nail down this obscure fossil. At first, we had considered Tentaculitids or Cornulititids however the morphology wasn't quite right, and the fact that they were extinct in the late lower Permian made this untenable. I still felt strongly that this still was some type of bizarre scaphopod, so I contacted a well known Scaphopod expert at the Museum of Natural History in Rotterdam in the Netherlands for help. Jordy van der Beek ( was glad to help us and so we sent him more information and lots of photos of what we had. A few days later, he responded and knew exactly what we had found. These were the juvenile portion of a growing scaphopod known as a "Teleoconch". They are seldom fossilized, however the unusual conditions in the Fort Apache Sea greatly favors the preservation of very tiny and juvenile mollusks. Here was something new and quite unexpected! Now lets explain what a teleoconch is, and discuss its features.

So exactly what is a "Teleoconch"?

Scaphopods have three growth phases out of the egg. First, a protoconch is a tiny ovoid shaped microscopic animal which swims in the plankton and feeds on even smaller micro plankton. Then it settles down to the bottom and starts to grow its cone shape. This phase, called the "teleoconch" is curved, has slightly angled transverse ribbing and is very small indeed - usually less than half an inch. Finally, the little scaphopods "program" changes and it switches to the adult phase. The transverse ribs stop forming and are replaced with the smooth or linearly ribbed adult exterior pattern. At some point, the teleoconch breaks off and leaves the small end open to allow the current to flow through the mollusk for its final configuration. And you can find the the juveniles and discarded teleoconchs preserved in the sediments as these small curved cone shaped fossils.

Explanation Diagrams and photos

 Adult scaphopod at left here, at the top of the curving shell is the transversely ribbed teleoconch region, which in most cases is lost when the adults are full size. Not all scaphopods have such a distinct teleoconch, some are smooth. Plagioglypta had the ribbing.

(Click to enlarge)

 Protoconchs on right and several phases of teleoconch seen here as it changes to the adult phase on the left. (Steiner)

 SEM images of several teleoconchs of scaphopods. Clearly, there is a rapid growth phase after the protoconch settles down followed by the generation of transverse ribbing. (Steiner)

 SEM images of extant scaphopods in their teleoconch phase. In reality, these conchs are nearly as transparent as glass. (see below image)

 An extant juvenile scaphopod living in the sea today, this teleoconch is transparent and the internal animal can be seen clearly. Note the transverse ribs on the exterior.

Our recent Finds

Our techniques for collection of fossil material is to first, collect limestones that show a visible traces of internal silicified fossils on their surfaces starting to dissolve out.   Those will always contain more within, and these are collected and packed out on our backs for several miles back to the Jeep.  Back in our paleo lab, we dissolve the limestone in large plastic tubs with a dilution of 10% muriatic acid obtained at ACE hardware store in town.  The next day, the acid fines are washed and sorted with three or four different size sieves and dried in flat Teflon coated metal pans in the sun.  Sorting is done one teaspoon at a time of the fines, under a stereo microscope.  Specimens are picked out with needle fine tweezers, or wet toothpicks. 

The s found are always less than half an inch in size, and most are broken fragments of the tubes which contained the animal.  However, a good number of them were found complete and are stunning to see with a good LED high intensity side light under the scope.  They are hollow, thin walled and are preserved as complete casts of the original conch in a white amorphous silica.  Their exterior is covered with numerous transverse rings at a slight angle to the conch, all touching with no space in between, however one did show the transition to the adult smooth configuration.

Juvenile Scaphopod Morphology

 Here is one specimen which shows the transverse rings on the left side in the teleoconch changing to the more smooth exterior shell of the adult phase on the right.
The Images

Photos of our specimens were taken with an AmScope trinocular zoom microscope and an AmScope 10 megapixel color CMOS camera.  A dozen or more images of each specimen were obtained with varied focus, and the image sets were focus stacked with Picolay for the final sharp image.  Final touch up and the scale addition were done in Adobe Photoshop. The magnification is listed on each image next to the scale.

 A gaggle of a few of the more complete specimens. Most are less than 1 cm long, and represent juveniles or early adults. 7x
 20x close up of one of the more complete specimens. Some of the smallest ribs are worn off on the left, but they continue in force on the right. Note how the conch is curved and the transverse ribs are skewed.
 45x close up of the transverse rings morphology in the above specimen.
 Another typical specimen at 20x. This one was actually flattened on the left side.
 20x third example.
 End on view at 45x shows the wall thickness of an average sized specimen. It is filled with sand and has no internal partitions.
 30x view of the smallest mostly complete specimen we found. It is really tiny!
 Compare a pin head above to the average size we found at both sites.

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