Alum Bluff Group Eco-Sketches

[typhis]

I made these drawings back in 1993 when I had a shell show exhibit called "Fossil Fauna of the Alum Bluff Group." I won several major awards at shows throughout Florida for my exhibit, but over the years the display cases and backboards have mildewed, the labels have been lost, and a number of the specimens have been donated to FLMNH. I scanned my original drawings a while back, as acid was beginning to discolor the paper. Most of the captions came straight from my original display backboards, but I have had to reconstruct the contents of a few that were lost. Hope you enjoy them!

Alum Bluff Near-Shore Sand (Chipola Fm.)

In front is an adult Orthaulax gabbi, an unusual strombid which was quite common in the Chipola Formation, apparently preferring a limestone and coral reef environment. Also in front is the small herbivore, Calliostoma grammaticum. A large empty shell of Melongena sculpturata has become home to several Actinobalanus floridanus barnacles. In the rear are two specimens of Siphocrypraea chilona with their mantles partially withdrawn to reveal their color pattern.

Brackish Water Sandy Beach (Chipola Fm.)

The Chipola beach site was located near the mouth of a river, and as such, yields a wide variety of species including genera that are only found today in brackish water environments. In this picture, you can see a number of bivalve species that have washed up on the sandy beach, including two coquinas (Donax trueloides), Armimiltha chipolana, Macrocallista sp. (similar to today's Sunray Venus), and Linga glenni. Gastropods that have washed ashore include Oliva liodes, Tegula exoluta, and the rarer of the two Falsilyria species, F. anoptos. A number of species, like F. anoptos, can be found with their color patterns still visible. Small shark teeth can also be found throughout the formation.

Limy Lower Beds (Chipola Fm.)

Inhabitants of the basal beds: A hermit crab (Petrochirus sp.) has taken up residence in an empty shell of Phalium aldrichi. P. aldrichi is a close relative of today's Scotch Bonnet. Also in the foreground is a specimen of Trigonostoma serilium crawling over the limerock. Behind are two specimens of Nodipecten condylomatus, who, ulinke most bivalves, resided on the surface. In the rear are Cymatium ritteri (a member of the Hairy Triton family); a spiny urchin (unnamed species); and two small heads of coral Goniopora hilli. In some places, corals can be found growing directly attached to the underlying Chattahootchee Limestone.

Oak Grove Sand

The Oak Grove Sand is now considered a facies of the Chipola Formation. Its fauna is not nearly as diverse as the other sites in the Alum Bluff Group. Here you can see the large moon snail, Neverita eucallosa, crawling on the surface. This species would have spent most of its life burrowing underneath the fine sand searching for bivalve prey. The drill holes near the umbos of the two bivalves, Lirophora glytocema and Anodontia santarosana, were most likely caused by a fatal run-in with N. eucallosa. Another predator, the muricid Vokesimurex gilli, is also out looking for prey. In the corner of the picture, an abandoned oyster shell (Ostrea pauciplicata) has become home to a small coral (Astrangia sp.?). A small shark patrols in the background.

Offshore Coral Patch Reef (Chipola Fm.)

I lost the original write-up that went with this one, so I am trying to reconstruct it as best I can. Unfortunately, I can't remember the names of all the corals anymore, as I donated most of my good coral heads to FLMNH (and lost their original labels). I think the genera of the two large ones in the rear are Montastrea and Porites, however.

In the foreground, a Shame-faced Crab (Calappa sp.) has just eaten a moon snail (Neverita chipolana) by using its claws to break away the shell of its prey. Behind the crab is an abandoned shell of Pterynotus hoerlei, an exotic and extremely rare carnivore that is only found in the Chipola reef facies. A specimen of Cerithium burnsii, common throughout the upper beds of the formation, crawls by in the foreground on the right. Behind the cerith, a Cassis delta is on the prowl looking for an echinoderm meal. A single valve of the winged oyster, Pteria chipolana, lies in the coral rubble nearby. In the background, a parrot fish uses its hard grinding teeth to scrape off bits of coral from the large coral heads, while a pair of barracudas patrols the reef in the distance.

Shallow Back Reef (Chipola Fm.)

The Chipola back reef: In the foreground is Zoila willcoxii, perhaps the most common cowry in the Chipola Formation. Modern relatives of this shell feed on sponges. An empty test (outer skeleton) of Clypeaster concavus rests on the bottom. During life, this sea biscuit would have been covered with short brown spines. Solitary corals (Antillophyllia chipolana) and calcareous algae (various types) are abundant, and can be seen here growing attached to rocks. In the center is the Thorny Oyster, Spondylus chipolanus. Crawling over a small head of coral in the rear is a specimen of Morum chipolanum, which is being watched by a small butterfly fish. Fish fossils such as vertebrae and otoliths are common finds throughout the Chipola Formation.

Shoal River Fm. Silt / Sand

Two turrets (Turritella waltonensis - rear) feed on organic matter which they separate from the mud and sand. The bivalve Glycymeris waltonensis can be seen boring below the surface, where most bivalves spend their lives hidden from view. Dog whelks (Nassarius waltonensis - on grass) live by sorting organic particles from the mud and sand, and also by scavenging dead matter. On the left is an empty shell of the extremely rare Distortio floridana. In front can be seen the egg cases of Conus waltonensis, and the tiny but beautiful Trigonostoma sphenoidostoma.

Silty Lagoonal Beds (Chipola Fm.)

In front are two specimens of the bivalve Yoldia frater, and a Portunus crab (very similar to the Blue Crabs of today). Just behind is Strombus aldrichi, a herbivore living in large colonies (in some areas of the formation, they can be found by the thousands). Strombus moves with a leaping motion, using its sickle-shaped operculum to aid in locomotion. In the rear can be seen a Talityphis obesus, and an Upside Down Jellyfish (Cassiopeia sp.). While soft animals such as jellyfish do not fossilize, there is no doubt that they were present. This genus was chosen as it can be found today in large numbers in quiet, muddy lagoonal areas such as this one.

[xonenine]

fantastic, like being taken on a tour in a submersible thanks for sharing your art and information

[Pagurus]

Thanks for posting these. It's terrific to see a representation of this ancient ecosystem. Did you have specimens of all of these when you set up the exhibit originally?

I'm kind of partial to the hermit crab. Nice pictures!

[typhis]

Yes, I used all of my own specimens as "models" for the drawings, though I did have to refer to photos in various modern shell books to know what to do about all the critters and parts that don't fossilize. Of course, for the crabs, all I have in my collection is small claws...never been lucky enough to find any more than that. My exhibit was 40 feet long...oak cases with thick glass...ugh. One day I really want to do a monster exhibit of all my worldwide fossil Muricidae (several hundred species), but I need new cases first and I don't know where I'd find the time to do all the necessary research to make it truly interesting........

[prem]

Very nice. As a kid, I often hunted the Jackson Bluff Formation (similar fauna to Alum Bluff) on the Ochlocknee River.

---Prem

[typhis]

By the dam, I assume? Did you ever get anything decent there? We boated up to the bluff by the dam a couple of times years & years ago, but the fossil layer was pretty yucky...I was thrilled to come away with a broken Typhis harrisi. Always wanted to collect the Cancellaria Zone from the "borrow pit" behind the dam where Mansfield got all of his really good stuff back in the '20s / '30s. I got to see a lot of that material when I was helping FLMNH curate it all. Alas, born too young...

[MikeR]

I have found decent material at the dam site however it not easy to collect (http://www.thefossilforum.com/index.php?/blog/101/entry-218-jackson-bluff-formation/). I asked Roger Portell last year about the burrow pit and he said it is still there but on the dam property so not generally accessible. It might be possible to hit Roger up to get FPS in if there is enough area to support a large group.

Mike

[typhis]

He took the FPS folks behind the dam not long ago for one of the meetings; we missed that trip unfortunately. Did you go on that one? They had a picture of the wall they were all hacking on in the FPS newsletter. I asked him about it in November; he said where they were at was still all Ecphora Zone and not Cancellaria Zone. So I'm not sure if that was the "borrow pit" or just a stray outcrop behind the dam. But he did mention that you couldn't fit many people digging on that wall at the same time.

I'd give anything to get some of the true C.Z. borrow pit material. The FGS collection has trays and trays of what most people would consider rare species, like Phyllonotus leonensis...I only have one of those that we got in APAC years ago right before it closed down, and it's in bad shape (had another and lost it...). People often sell Phyllonotus specimens on eBay that they call P. leonensis, but virtually none of them actually are (I know this because I've bought most of them, just in case!!!!!) Once you've seen a tray of the "real thing" from the FGS collection, the imposters really jump out at you.

At any rate, I love your Jackson Bluff specimen pictures. We didn't stay long (passing through on the way to Chipola), so we just scanned the surface of the boulders that had fallen down. Mostly bivalves...not even any good small stuff when we brought some home to break down.

[Auspex]

The art of interpretation; your fine images seem simple, but the impact is tremendous!