Tullimonstrum
| Tullimonstrum gregarium Temporal range:
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| Fossil of Tullimonstrum gregarium (part and counterpart) | |
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| (unranked): | Stem Petromyzontiformes
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| Genus: | Tullimonstrum
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| T. gregarium Eugene S. Richardson, Jr., 1966
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Tullimonstrum gregarium, colloquially known as the Tully Monster, was a soft-bodied vertebrate that lived in shallow tropical coastal waters of muddy estuaries during the Pennsylvanian geological period, about 300 million years ago. Examples of Tullimonstrum have been found only in the Mazon Creek fossil beds of Illinois, United States.
Etymology
Tullimonstrum gregarium takes its genus name from its discoverer, Francis Tully. Appropriately, "tull" is also Norwegian for "nonsense",[2] whereas the species name, gregarium, means "common" and reflects its abundance.[3] The term 'monster' relates to the creature's outlandish appearance and strange body plan.
Description
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Tullimonstrum probably reached lengths of up to 35 centimetres (14 in); the smallest individuals are about 8 cm (3.1 in) long.[2]
Tullimonstrum had a pair of fins like those of a cuttlefish, which were situated at the tail end of its body. The organism also possibly featured vertical, ventral fins (though the fidelity of preservation of fossils of its soft body makes this difficult to determine), and typically featured a long proboscis with up to eight small sharp teeth on each "jaw", with which it may have actively probed 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 found among the assemblage called the Mazon Creek fossils from their site in Grundy County, Illinois.[4] The absence of hard parts in the fossil implies that the animal did not possess organs composed of bone, chitin or calcium carbonate.[2] There is evidence of serially repeated internal structures.[2] Its head is poorly differentiated.[2] A transverse bar-shaped structure, which was either dorsal or ventral, terminates in two round organs which are associated with dark material similar to the pigmentation often found in eyes. Their form and structure is suggestive of a camera-type construction.[2]
Affinity
In 2016 a morphological study showed that "Tullimonstrum" was in fact a stem-lamprey, closely related to modern lampreys and thus a member of the phylum Chordata [1]. This affinity was attributed based on pronounced cartilaginous arcualia, a dorsal fin and asymmetric caudal fin, keratinous teeth, a single nostril, and tecal cartilages like in lampreys. It also has many features not found in lampreys due it its specialized ecological niche.
Ecology
Tullimonstrum was probably a free-swimming carnivore that dwelt in open marine water, and was occasionally washed to the near-shore setting in which it was preserved.[2]
Taphonomic setting
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 slowed further decay, leaving a carbon film on the cast.
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.
The proboscis is rarely preserved in its entirety; it is complete in around 3% of specimens. However some part of the organ is preserved in about 50% of cases.[2]
History
Amateur collector Francis Tully found the first of these fossils in 1958. He took the strange creature to the Field Museum of Natural History, but paleontologists were stumped as to what phylum Tullimonstrum belongs to.
A 1966 satire pretended that modern representatives were to be found in Africa.[5][6] In 1989 Tullimonstrum gregarium was officially designated the State Fossil of Illinois.[3][7]
See also
References
- ^ a b McCoy, Victoria E.; Saupe, Erin E.; Lamsdell, James C.; Tarhan, Lidya G.; McMahon, Sean; Lidgard, Scott; Mayer, Paul; Whalen, Christopher D.; Soriano, Carmen; Finney, Lydia; Vogt, Stefan; Clark, Elizabeth G.; Anderson, Ross P.; Petermann, Holger; Locatelli, Emma R.; Briggs, Derek E. G. (2016). "The 'Tully monster' is a vertebrate". Nature.
- ^ a b c d e f g h Johnson, Ralph Gordon; Richardson, Eugene Stanley, Jr. (March 24, 1969). "Pennsylvanian Invertebrates of the Mazon Creek Area, Illinois: The Morphology and Affinities of Tullimonstrum". Fieldiana Geology. 12 (8): 119–149. OCLC 86328.
{{cite journal}}: CS1 maint: multiple names: authors list (link) [1] - ^ a b Mikulic, Donald G.; Kluessendorf, Joanne (1997). "Illinois' State Fossil—Tullimonstrum gregarium" (PDF). Geobit. 5. OCLC 38563956.
- ^ Richardson, Eugene Stanley, Jr. (January 7, 1966). "Wormlike Fossil from the Pennsylvanian of Illinois". Science. 151 (3706): 75–76. Bibcode:1966Sci...151...75R. doi:10.1126/science.151.3706.75-a. PMID 17842092.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Kloss, Gerald (June 18, 1968). "The Great Dancing Worm Hoax". The Milwaukee Journal. Retrieved March 31, 2012.
- ^ Rory, E. Scumas (1969). The Dancing Worm of Turkana. Vanishing Press. OCLC 191964063.
- ^ "State Symbol: Illinois State Fossil — Tully Monster (Tullimonstrum gregarium)". Illinois State Museum. Retrieved March 31, 2012.
External links
- "The Tully Monster", a video by the Field Museum of Natural History
- Mazon Creek Paleobotany References by the Field Museum of Natural History