Andy Hay gave a very good overview of how to tell the differences between many of the Mazon Creek animals. He showed us many overheads from his studies how difficult it is to distinguish many times because of the quality of the fossils found. Many of the drawings were from Ida Thompson’s book. He showed us several segmented bristle worms that differed by their bristles and teeth, which often are not preserved. Some of them even look like centipedes or millipedes. The best way is by the general shape of the body. These include the worm named for ESCONI called Esconites. It is difficult to distinguish the lobster-like shrimp Mamayocaris from Anthracarus (with longer antenna). The tail and antenna are different but are often not preserved. Andy told us that new fossils are not accepted now unless the type specimen is in a museum. This is because in the past, some new type fossils were in private collections and could become inaccessible to scientist. Another duo that is hard to tell is the Paleocaris and Acanthotelson shrimps. They look alike except for the fact that Paleocaris has a larger size segment in the middle of its body. The fantail of Paleocaris differs from the sharp tail of Acanthotelson also, but they are often not preserved. Dithyrocaris is interesting because usually only the beautiful carapace is preserved. It looks like a horseshoe crab. Two other shrimp, Betotelson and Tyrannophorites, are very similar except for a long shell protrusion over the eyes of Belotelson. In addition, the legs of Tyrannophontes are longer. Belotelson is on of the most common shrimp found in Pit 11. Sometimes only the carapace is found. Essoidia is a tiny shrimp found in an arched shape and is often just a ghost on the concretion. Eurypterids are desired by everyone but are very rare. It is hard to find one with all the appendages on it. Many think that the Eurypterids caused the end of the trilobites. The most common horseshoe crab is Euproops, but is often found without its telson. Andy showed us a Smithixerxes, an early relative of insects, the paratype of which Andy donated to the Smithsonian Museum. The common centipedes found in Mazon Creek are Scutigerida (with beautiful long legs) and the most common millipede is the Geophillda. They can be confused with some of the shrimp. It can be difficult to tell an insect wing from a leaf. The wing of a coal age cockroach can look a lot like a Cyclopteris leaf. This may be an example of animal mimicry to protect it from predators. Clams can be differentiated from their beaks. Edmondia can be fairly easy to tell with both shells opened up together. Septimyalina is often found attached to leaves or plants. The Solemya can be found in the black shale near LaSalle. The common tiny fish is Elonichtyhys and is found in the black shale at the Olgesby Quarry and can be about 8 inches long.

Several members then talked about the fossils that they had brought. Bealis had two large cases that included a wide range of animals including fish and insects. We looked under the microscope at the tiny amphibian jaw with 6 teeth that he brought with him. The meeting was adjourned for refreshments.

Respectfully Submitted Karen Nordquist, Secretary