Study Group Chairman John Good opened the meeting and attendees introduced themselves. John mentioned that help would be needed next Friday to help set up for the Chicagoland Show at DuPage County Fairgrounds over Memorial Day Weekend. There is still room for more cases and Dorothy Auler has application forms. Cases get $10 and demonstrators get $25 for ESCONI. Karen Nordquist then reported on the exciting weekend at The Field Museum where Saturday May 12 was a theropod symposium with many young paleontologists talking about different aspects of the large meat-eaters including a new tyrannosaur Eotyrannus. Sunday was the talk by Phil Currie on the dinosaur bird connection followed by a roundtable by several of the symposium participants. The Aulers have again donated material for a silent auction tonight. Andy did not have anything to add on Mazon Creek. Karen Nordquist mentioned that while at Mazon Creek with the Lizzadro Museum a Conservation Policeman stopped the group and warned not to dig for fear of a $50 fine and a ban from the area. They have already fined and banned some people.

Field Trip Chairman John Good then reported about upcoming Field Trips. The May 20 trip is at Coal City at 9:00 for a visit to Braceville. Please do not climb up the hills and no alcohol. June 2 and 3 the trip is to Marion Kentucky for fluorite. On June 23 and 24 we will go to Buffalo Iowa for Devonian material and then to Alexandria Missouri for geodes on Sunday (there is also a museum at Augustana College near there also). Dave Bergmann has been there and talked about some of the minerals and fossils found there. From July 14-22 we will be going to Canada for amethyst collecting. He is trying to get into Manteno and Lehigh and will post developments on the web site. Contact John for more information and to sign up. He will also look into LaSalle and Lone Star if people are interested. Labor Day is agate collecting. Karl Everett is working on a trip to Sylvania for the 3^rd weekend in September. This trip would be the same weekend as our September Paleo meeting. Don Auler then talked about the Ishpenning trip on August 3 and 4 with a Sunday trip to the kona dolomite quarry. Here you can find 2,2 BYA stromatolites formed by ancient algae. Dorothy Auler then mentioned that Wendy Taylor at the Field Museum has offered members free tickets to Members’ Night next week. John Catalani then presented an excellent program on his favorites, the Nautiloids. He mentioned that the early blue-green algae are now known as cyanobacteria and they oxidized the iron and were the first to make oxygen. They are the most important critters to live because without them the rest of life would not have happened.

John first showed us a video of divers searching for a live chambered nautilus. They are found 1,000 feet below the surface and can not be kept in aquariums. They used a robot device to go down and take films of the animals in the dark. Their ancestors were heavy shelled bottom dwellers that went extinct. They have sharp beaks to crush shells and could take off a finger. John said they also eat the shells for calcium for their own growth. John provided us with handouts with some of the information that he would present. They have evolved over the years and there are two genera today. He showed us a cut nautilus that still had the siphuncle in it. This one has a small siphuncle but some of the Ordovician ones had one that filled about a third of its shell. No one knows what else it might have done with such a large siphuncle besides move gas and liquid into and from the chambers (its main function). Why the nautiloids are still around and the ammonites are not is an interesting area he will talk about later. The paper nautilus (it is an egg case that is coiled) is not a nautilus and is a member of another group with octopi. A good book is "In Search of the Nautilus" by Peter Ward, an expert on this animal. He wrote an interesting story of a trilobite death at the beak of a nautilus – it was probably fast and noisy. These nautiloids are probably a reason that trilobites developed hard shells, spines, 360-degree eyes, and enrollment. Nautiloids keep a negative buoyancy with gas so that they can move up and down easily. As the chambers are made they are filled with fluid to hold its structure. Then they remove the fluid that is replaced with gas (mostly carbon dioxide). During the night it will move up to the reef to eat and them return to the depths during the day (maybe a 600 meter trip). Those chambers strengthen the shell. The fancy convoluted chamber walls of ammonites were believed to have been for strength. But it was actually to get the fluid out faster with more surface area. There are some who believed that ammonites were like snails. Another said that the octopods are shellless ammonites and so ammonites are still around. There are many theories around.

The cephalopods are part of Mollusca and are divided into three groups: Nautiloids (including extinct Nautiloids and extant nautiloids); Ammonites (that are extinct); and Coleocidea which include squid, octopus and cuttlefish today. Some nautiloids have about 90. Early Cambrian nautiloids gave rise to all of them around now. The straight shelled ones are the most common. A diagram of one showed the basic parts, the phragmocone including the empty chambers, and the living chamber. The source of nautiloids is not known for sure yet and there are several theories. The formation of the siphuncle (the key part) is an important part of the puzzle. In Nautilus the siphuncle is always in the center, but it can be anywhere on nautiloids. The septal wall has a hooked part called the septal neck (connecting ring) and they vary in the different animals. There is a wide range in design of the connecting ring that are distinctive for the different types. There are lateral growth lines. On some there are longitudinal lines on the shell on one side that are believed to help break up the image as seen by predators. Some are red on top and white from the bottom to disguise them. The siphon is a tube made of 2 flaps of skin in the front of the animal that helps it move around.

The nautilus has a hood called an operculum that covers its top. There are only a few fossils that show it connected to the shell so these parts had been named separately (jaws). The jaws are very strong and some are made of calcium phosphate. There are many shell forms for nautiloids. Some are straight, some curved, and others coil in different ways. Some are heteromorph with some coils early on and then a straightened section at the end. Ornamentation plays several roles. Some have crenellated ridges or ribs for shell strength. It may also break up the flow of water around the shell so that it can move through the water faster. It might also help to lessen the damage done when broken. There is not much known about the soft part morphology. The straight shelled ones probably had 8-10 arms (squid and cuttlefish have 8 arms and 2 tentacles with suction cups). Some of the others that led to Nautilus probably had up to 90 small arms. The shell where the animal was hatched (about 1 inch when comes out of egg) is very smooth and then there is like a break in the shell where it starts to grow. Then it starts to make adult shell and camouflage. There could be millions of Nautiloids around today. A pellicle moves the fluid in the chambers to the siphuncle. The Nautiloid does stop growing and you can find an adult by looking at the growth rings. All of a sudden there are 3 very narrow lines as they make final adjustments. They may live 20-30 years. The Nautilus males are bigger. In Ammonites the female may be 125 times bigger than the male.

The original cephalopods were Plectronoceratus from the Upper Cambrian in China. Then there was a gaggle of cephalopods near the end of the Cambrian. The Ellesmerocerida are the only group that made it past the Cambrian and evolved into the five superorders: Endoceratoidae (big guys), Actinoceratoidea, Discosoratoidea (rare), Orthoceratoidea (some lost their shells to lose weight), and Nautilatoidea. There are several strategies for buoyancy. Coiling is the best way with chambers with gas above the body. The truncated straight shelled ones had gas filled chambers above the living chamber. They used to think that these lived with the opening down and the cone sticking straight up. They know better now after finding deposits that balanced the lift of the gas within the chambers. There were a variety of life styles. Some floated and filter fed, some ate trilobites, and some flat ones probably burrowed in the mud (like a flounder, but they could not swim). Some had real small chambers and probably stayed on the bottom. Nautiloids appeared in the Late Cambrian and Ammonites appeared in the Devonian. The Ammonites disappeared at the end of the Cretaceous and the Nautiloids suffered some set backs but are still around today. They may even be diversifying a lot again today. Nautilus breeds slowly with half a dozen eggs. They stay down low at about 1000 meters. The Ammonites only breed once with many eggs and then die (like squid). They were eating up in the plankton near the surface when the meteorite hit and acidified the top of the water. The Nautiloids were deep and got through the extinction. There are other theories about the extinction. The Ammonites were specialized food eaters and were more vulnerable. The Ammonites grew quicker and had thinner shells compared to Nautiloids. To kill something you have to interrupt the food chain or reproduction.

There are 2 living species of Nautiloids today (Nautilus and Allonautilus). There is one species that even has fur. They are all in the South Pacific. John then showed a series of slides showing the diversity of Nautiloids from Platteville (Ordovician at 455 MYA). There were several new species included. He had several examples to show us from his collection, including a 6 foot long straight Nautiloid.

The meeting was adjourned for more discussion, the silent auction, and refreshments.

Respectfully Submitted Karen Nordquist, Secretary

Related Web Sites

Cephalopods - Present and Past  

Fifth International Symposium, a meeting in Vienna, Austria

http://www.geolba.ac.at/ecepha.htm

Ammonoidea 

 Information about the biology of ammonoids from The Cephalopod Page.

http://is.dal.ca/~ceph/TCP/ammon.html