BROOKSELLA & AGATES--- COULEE ROCK SHOW; LA CROSSE, WISCONSIN

 It was a great day in La Crosse and I was ready to go, large coffee in hand.  The Coulee Rock Club did an outstanding job,  Congratulations.

The Onalaska Omni Center is a great place for smaller venues.

In my last posting I described my happiness is being able to wander around a spring edition (May 23-21) of the RMAG Promotions spring show at the Denver Crown Plaza Airport Convention Center.  It was really nice to buy a few minerals and take tantalizing peeks at some really fine specimens out of my price range.  But then my excitement really soared when I discovered that a trip to my ole stomping grounds of La Crosse, Wisconsin, coincided with the annual show of the Coulee Rock Club.  I was aware the show existed due to a couple of lectures at past shows; however, the coinciding dates was pure serendipity. Although small in members, the club has an outstanding and impressive cadre of show organizers and workers.  Their show was held on a two-day weekend (June 4-5) in a great venue—the Onalaska Omni Center. Dealers, along with Club activities for juniors/pebble pups/children, occupied most of the space. 

Kiddies, spin the wheel.
 

Although flint knapping was not participatory it attracted a large crowd of youngsters all day--watching in awe.

However, the Club did leave room for perhaps the most popular show event, the Silent Auction.  A long table held perhaps 15-20 stations that were changed on a regular rotation and successful bidders were quite pleased with their purchases--especially the younger members (who are the future members of our clubs).  I was actually amazed at the variety of items open for bidding with a number of different well-preserved early Paleozoic fossils that would give any kid a good start on a personal fossil collection.  In addition, there were a number of minerals, some well crystallized, from numerous states and a few foreign countries (but also unlabeled as to origin).  A few minerals had some old and quite fragile identification cards.  In other words, something for everyone, especially the younger rockhounds. 

 

I picked up an item or two, especially if bids were not coming in on a regular basis. I soon parted with the purchases by gifting to younger rockhounds who could not attend the Show:

Geodes and calcite crystals to grade school rockhounds.

Unfortunately this coiled Cretaceous ammonite (Placenticeras) was incomplete but had a beautiful display of suture lines.  My best guess is the critter was collected from the Pierre Shale (pretty certain) from South Dakota, perhaps Wyoming. Goes to an adult fossil hound.

 

OK, we don't need to know about locality information on this trilobite from a dealer.  My guess is Morocco 😁😁😁 Is there any reconstruction???

Crinoids are much more common at Midwest shows that in the West.  But no locality information!

All gars (Fish) have "lots of" sharp teeth.  Here is a saber tooth gar.  No locality infornation.

Mineral specimens were sparse. Kyanite.

Sulfur.  Hard to tell if it was made last week or "long ago".  No information on locality or age. 

THE KEEPERS: 1) a visit with Doug Moore, formally with the University of Wisconsin System--biologist, but now one of the premier agate collectors and photographers in the country (HQ at Stevens Point, WI).  Doug had for sale a fantastic variety of agates, mostly Lake Superior and Fairburn.  He also sells some of his majestic photographs (my poster is at the framer so the photos below are substitutes).

 

Thin slice of Dryhead Agate. Nabbed from Pinterest.com. 

Photo from Art Gala night at 2016 Agate Expo.

THE KEEPERS: 2) I picked up an interesting circular "glob" of reddish-orange sandstone (~10 cm x 12 cm). It was pretty ugly and no one topped my bid of a buck.  I though it was an internal mold of a Cambrian jellyfish although it came without much information (zoophycos).  But a little research indicated that it was not a Cambrian jellyfish (although I was in good company as the famous paleontologist Charles Walcott (1896, 1898), he of Burgess Shale fame, described them as fossil medusa [the free swimming life cycle] of Cnidarians--the corals and jellyfish). That is interpretation number 2.

What I came up with my search was an enigmatic critter (or is it a critter) named Brooksella, that are collected from the Cambrian Conasauga Formation of the Coosa River Valley of Alabama and Georgia. They are known as star cobbles due to their lobate structure (3-15 lobes). Ciampaglio and others (2006) described  the morphology of Brooksella as most consistent with a siliceous (hexactinellid) sponge. So that is interpretation number two, a fossil sponge.

Now here comes interpretation number three, a non critter! Nolan and others (2016) examined a number of specimens and determined that "Brooksella’s composition and internal structure are similar to concretions from the Conasauga: quartz grains with minor amounts of calcite and small, oxidized, root-like holes partly filled with iron oxide and barite crystals. In situ Brooksella were rare and were oriented with their “oscula” and lobes downward, rather than upward if this was a once-living sponge. Furthermore, shale laminations were displaced by the growth of the putative sponge. We therefore think that the sponge designation is insufficiently supported, and we favor a concretional mode of formation for Brooksella."

What does all this mean? The popular literature seems to favor sponges.  In summary I really like the following from the web site of The Paleontological Research Institution (www.priweb.org.) They note that "texts and images on this website have Creative Commons-NonCommercial ShareAlike 4.0 International licenses."  I thank them for the right to copy and redistribute the material.

Shales and concretions in the middle Cambrian Conasauga Formation of northeastern Alabama and northwestern Georgia contain body and trace fossils showing the preservation of diverse soft-bodied organisms, as well as many mineralized skeletons. These include algae, sponges, arthropods, brachiopods, echinoderms, mollusks, and trace fossils. Some of the most curious Conasauga fossils are "star cobbles," referred to the genus Brooksella. These enigmatic fossils have been variously thought of as medusae (jellyfi sh), algae, trace fossils, or inorganic structures. Recent research suggests, however, that they are most likely sponges with siliceous (SiO2) skeletons.

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"Star cobbles" (Brooksella) from the Cambrian Conasauga Formation. Fossils are 2.5–centimeters (1–2 inches) across. Images from Walcott (1898; Monographs of the U.S.G.S, 30); public domain

REFERENCES CITED

 Ciampaglio, C.N., L.E. Babcock, C.L. Wellman, A.R. York, & H.K. Brunswick. 2006. Phylogenetic affinities and taphonomy of Brooksella from the Cambrian of Georgia and Alabama, USA. Palaeoworld 15: 256-265.

Ciampaglio, C.N., C. Wellman, H. Brunswick, A. York & L.E. Babcock. 2005. Reinterpretation of Brooksella from the Conasauga Formation (Cambrian) of Georgia and Alabama, USA. in The Fourth International Symposium on the Cambrian System and the Tenth Field Conference of the Cambrian Stage Subdivision Working Group, Nanjing, August 18-24, 2005, abstracts and short papers. Acta Micropalaeontologica Sinica 22(Supplement): 21-23.

Ciampaglio, C.N. & L.E. Babcock. 2006. Reinterpretation of Brooksella from the Conasauga Formation (Cambrian) of Georgia and Alabama, USA. Geological Society of America Abstracts with Programs 38(3): 4-5.

Nolan, Morrison, S.Walker, & A. Sharma, Ajay. 2016. RE-EVALUATION OF THE MIDDLE CAMBRIAN SPONGE, BROOKSELLA ALTERNATA , FROM THE CONASAUGA FORMATION, GEORGIA AND ALABAMA, U.S.A. Geological Society of America Abstracts with Programs 48 (7). 

Walcott, Charles. 1896. Fossil jelly fishes from the Middle Cambrian terrane: Proceedings of the United States National Museum. 18 (1086). 

Walcott, Charles. 1898. Fossil Medusae: Monographs of the United States Geological Survey. 30.