Tullimonstrum gregarium
MAZON CREEK FOSSILS
The plant and animal fossils of the Mazon Creek shale are among the most important fossils that have been found in Illinois. They are known as the Mazon Creek fossils because they were originally found along Mazon Creek in northeastern Illinois.
Most preserved organisms are fossils of the hard parts of organisms (shells, bones, teeth, etc.). This means that in most fossil deposits only animals that have hard parts are preserved. This leaves scientists to speculate about biodiversity throughout geologic time, and imparts a biodiversity bias toward those organisms with hard parts.
Because of the unique conditions of fossilization, Mazon Creek fossils have both hard and softer parts preserved. Many soft-bodied organisms that were previously unknown to science are preserved as imprints in these shale deposits.
The approximate age for the Tullymonster is 300 million years old, making them from the Pennsylvania period (Late Carboniferous).
Tullymonster
This organism was a long marine nektonic carnivore, with 8 sharp teeth and triangular dorsal and horizontal fins. It lived in the shallow oceans that covered the area during the time of the Late Carboniferous. During that time, swampy conditions transitioned the area between times of dry land, freshwater, and brackish sea water incursions. This is evidenced by the marine and freshwater organisms preserved in the shale and coal beds. Tullymonster is the Illinois state fossil.
The plant and animal fossils of the Mazon Creek shale are among the most important fossils that have been found in Illinois. They are known as the Mazon Creek fossils because they were originally found along Mazon Creek in northeastern Illinois.
Most preserved organisms are fossils of the hard parts of organisms (shells, bones, teeth, etc.). This means that in most fossil deposits only animals that have hard parts are preserved. This leaves scientists to speculate about biodiversity throughout geologic time, and imparts a biodiversity bias toward those organisms with hard parts.
Because of the unique conditions of fossilization, Mazon Creek fossils have both hard and softer parts preserved. Many soft-bodied organisms that were previously unknown to science are preserved as imprints in these shale deposits.
The approximate age for the Tullymonster is 300 million years old, making them from the Pennsylvania period (Late Carboniferous).
Tullymonster
This organism was a long marine nektonic carnivore, with 8 sharp teeth and triangular dorsal and horizontal fins. It lived in the shallow oceans that covered the area during the time of the Late Carboniferous. During that time, swampy conditions transitioned the area between times of dry land, freshwater, and brackish sea water incursions. This is evidenced by the marine and freshwater organisms preserved in the shale and coal beds. Tullymonster is the Illinois state fossil.
Marine nektonic organism.
http://www.museum.state.il.us/exhibits/symbols/fossil.html