The Tully Monster (Tullimonstrum gregarium), so far apparently unique to Illinois, was a soft-bodied invertebrate that lived in shallow tropical coastal waters of muddy estuaries during the Pennsylvanian geological period, about 300 million years ago. The Tully Monster had fins not unlike a cuttlefish and a long proboscis with eight small sharp teeth with which it may have probed actively for small creatures and edible detritus in the muddy bottom. It was part of the ecological community represented in the unusually rich group of soft-bodied organisms represented among the assemblage called the Mazon Creek fossils from their site in Grundy County, Illinois. Tully Monster, state fossil of Illinois 430 x 272 px Copyright © 2004 U-Haul International, Inc. ... Official language(s) English Capital {{{Capital}}} Largest city Chicago Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 25th 149,998 km² 340 km 629 km 4. ... Invertebrate is a term coined by Jean-Baptiste Lamarck to describe any animal without a spinal column. ... An estuary is a semi-enclosed coastal body of water which has a free connection with the open sea and within which sea water mixes with fresh water. ... The Pennsylvanian is a geologic (sub)period lasting from roughly 325 million years before the present (BP) to 286 million years BP. As with most other geologic periods, the rock beds that define the period are well identified, but the exact date of the start and end are uncertain by... The geologic time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth. ... A fin is a surface used to produce thrust or to steer while traveling in water, air, or other fluid media. ... Families Sepiadariidae Sepiidae Cuttlefish are animals of the order Sepiida, and are marine cephalopods, small relatives of squids and nautilus. ... In general, a proboscis (from Greek pro before and baskein to feed) is an elongated appendage from the head of an animal. ... Types of teeth Molars are used for grinding up foods Carnassials are used for slicing food. ... The term is used to describe animals without skeleton, roughly coresponding to the group Vermes as proposed by Carl von Linné. All animals have muscles, but since muscles can only pull, never push, a number of animals have developed hard parts that the muscles can pull on, commonly called skeletons. ... The Mazon Creek fossils are conservation lagerstätten found near Chicago, Illinois. ... Grundy County is a county located in the state of Illinois. ...

The formation of the Mazon Creek fossils is unusual. When the creatures died, they were rapidly buried in silty outwash. The bacteria that began to decompose the plant and animal remains in the mud produced carbon dioxide in the sediments around the remains. The carbon dioxide combined with iron from the groundwater around the remains, forming encrusting nodules of siderite ('ironstone'), which created a hard permanent 'cast' of the animal which slowly further decayed, leaving a carbon film on the cast. Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... Groundwater is water which may be flowing within aquifers below the water table. ... Siderite is also the name of a type of iron meteorite. ...

The combination of rapid burial and rapid formation of siderite resulted in excellent preservation of the many animals and plants that ended up in the mud. As a result, the Mazon Creek fossils are one of the world's major Lagerstätten, or concentrated fossil assemblages. Lagerstätten (German, singular: Lagerstätte, literally: place(s) of storage or resting place(s)) are sedimentary deposits that exhibit extraordinary fossil richness or completeness. ...

Amateur collector Francis Tully found the first of these fossils in 1958. He took the strange creature to the Field Museum, but paleontologists remain stumped as to what phylum Tullimonstrum belongs. In 1989 Tullimonstrum gregarium was officially designated the State Fossil of Illinois. A fossil Ammonite Fossils (from Latin fossus, literally having been dug up) are the mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms. ... 1958 (MCMLVIII) was a common year starting on Wednesday of the Gregorian calendar. ... Field Museum of Natural History, Chicago The Field Museum of Natural History, in Chicago, Illinois, USA, sits on Lake Shore Drive next to Lake Michigan, part of a scenic complex called known as the Museum Campus which includes Soldier Field, the football stadium that is the home of the Chicago... A paleontologist carefully chips rock from a column of dinosaur vertebrae. ... Phylum (plural: phyla) is a taxon used in the classification of animals, adopted from the Greek phylai the clan-based voting groups in Greek city-states. ... 1989 (MCMLXXXIX) is a common year starting on Sunday of the Gregorian calendar. ... Though every state in the United States has a State Bird and a State Flower, not every state in the United States has a State Fossil. ...

External links

• Tullimonstrum described.
• A particularly well-preserved Tullimonstrum in the Illinois State Museum.
• Illinois State Geological Survey surveys Tullimonstrum.
• Tully Monsters described and illustrated.