incertae sedis

strange body plan / Tullimonstrum / Tully monster

• "It appears that Tullimonstrum represents an extinct and previously unknown phylum" (Johnson and Richardson 1969: 119).
• "[...] Illinois have yielded some of the most spectacular fossils known to science. Collectively known as Mazon Creek fossils. [...] specimens are spectacular as objects of mystery, because their relationships and identity continue to frustrate paleontologists, though they are well preserved. Perhaps the most mysterious of these fossils, and one whose mystery has long intrigued researchers at Field Museum, is the so-called Tully monster" (Beall 1990: 24).
• "The jury is hung on this case, and without additional data, will remain hung. The intrigue of the Tully monster continues" (Beall 1990: 29).

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Beall, Bret S. 1990. The mystery of the monster. Field Museum of Natural History Bulletin, 61(1): 24-29. [a006654fx]

Johnson, Ralph Gordon and Eugene Stanley Richardson. 1969. Pennsylvanian invertebrates of the Mazon Creek Area, Illinois: The morphology and affinities of Tullimonstrum. Fieldiana: Geology, 12(8): 119-149. [a006653fx]

wiki: Tullimonstrum // Link
ISGS: Illinois' State Fossil Tullimonstrum gregarium // Link

via:
Discovery Channel: Tierra de dinosaurios: Chicago.