Mazon Creek Fossil Fauna
Tully Monsters, and "Y" and "H" Animals
The "Tully Monster"
In 1955, a Lockport, IL, pipefitter, Francis Tully, brought a puzzling Pit 11 find to George Langford and Dr. Richardson at the Field Museum. Richardson, equally perplexed, called the discovery a “monster.” The name stuck and it was published as such: Tullimonstrum gregarium. At the time of description in 1966, critical evidence for assigning it to a specific phylum was missing or not understood. It was thought to be an annelid worm, or possibly even a shell-less swimming mollusk. However, for 60 years it remained a complete mystery!
The Tully Monster is found only in Illinois and in 1989, it became the State Fossil. Since then, it has only further captured the public’s imagination.
A study led by Yale University (McCoy et al.), in cooperation with the Field Museum, the Burpee museum and others, looked at over 1200 specimens with state-of-the-art technology. In 2016, sixty years after it was first discovered, the Tully finally has a definition. It is a jawless fish on the lineage of lampreys and hagfish.
The Tully Monster is found only in Illinois and in 1989, it became the State Fossil. Since then, it has only further captured the public’s imagination.
A study led by Yale University (McCoy et al.), in cooperation with the Field Museum, the Burpee museum and others, looked at over 1200 specimens with state-of-the-art technology. In 2016, sixty years after it was first discovered, the Tully finally has a definition. It is a jawless fish on the lineage of lampreys and hagfish.
Tullimonstrum gregarium - Richardson, 1966
Tullimonstrum gregarium, Milwaukee Public Museum collection VP365807.1 and VP365807.2 (positive and negative halves)
Field Museum collection PE 81597 (T.Testa)
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J.Wittry collection
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Tullimonstrum gregarium, Milwaukee Public Museum collection VP367558.1-2 (positive and negative halves)
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Field Museum collection
Tullimonstrum gregarium, Milwaukee Public Museum collection VP366199.1-2 (positive and negative halves)
Field Museum collection
Tullimonstrum gregarium, Pit 11, Braidwood, IL - A.Young collection
Above and below: Chicago Academy of Sciences collection
Tullimonstrum gregarium, Pit 11, Braidwood, IL - A.Young collection
Tullimonstrum gregarium, Milwaukee Public Museum collection VP366202.1
Earth Science Club of Northern Illinois (ESCONI) member collection
Tullimonstrum gregarium, Milwaukee Public Museum collection VP25859
A juvenile Tullimonstrum gregarium with strange preservation - R.Rock collection
Tullimonstrum proboscis and "claw"
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Tullimonstrum gregarium, detail showing claw with teeth - Milwaukee Public Museum collection VP26070.1-2
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Field Museum collection
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Tullimonstrum gregarium - Milwaukee Public Museum collection VP36208
Tullimonstrum gregarium, proboscis with claw - J.Wittry collection, Figure 150.1 The Mazon Creek Fossil Fauna 2012
Above and below: Tullimonstrum gregarium, showing proboscis and claw - R.Rock collection
Tullimonstrum eye-bar
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Tullimonstrum gregarium, Milwaukee Public Museum VP366211.1-2 (positive and negative halves)
Field Museum collection
Tullimonstrum tail
Tullimonstrum gregarium tail section showing muscle banding, Pit 11, Braidwood, IL - A.Young collection
Incertae sedis - "Y" animal
Escumasia roryi - Nitecki and Solem, 1973
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Escumasia roryi, showing (eye?) pigment at the end of each arm, MPM P360288.1-2 (positive and negative halves )
Milwaukee Public Museum collection P360292
Hydrozoan - "H" animal
Etacystis communis - Nitecki and Schram, 1976
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Etacystis communis - Milwaukee Public Museum collection P2198.1-2 (positive and negative halves)
MPM P26274.1
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Etacystis communis - R.Rock collection
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