Tully Monster
Encyclopedia
The Tully Monster so far apparently unique to Illinois
, USA, 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 a pair of fins
not unlike a cuttlefish
at the tail end of its body, and possibly vertical fins as well (though the fidelity of preservation of fossils of its soft body makes this difficult to determine), 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
found among the assemblage called the Mazon Creek fossils
from their site in Grundy County, Illinois. The absence of hard parts in the fossil implies that the animal did not possess organs composed of bone, chitin or calcium carbonate. There is evidence of serially-repeated internal structures. Its head is poorly differentiated. 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.
. Since it lacks any characters of the well-known modern phyla, it has been speculated that it is a stem group to one of the many phyla of worms that are poorly represented today. Similarities with Cambrian fossil organisms such as Vetustovermis and Opabinia
have also been noted.
The formation of the Mazon Creek fossils is unusual. When the creatures died, they were rapidly buried in silt
y outwash. The bacteria
that began to decompose the plant and animal remains in the mud produced carbon dioxide
in the sediment
s 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 decayed, 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 Lagerstätte
n, 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.
s in 1958. He took the strange creature to the Field Museum of Natural History
, but paleontologists
remain stumped as to what phylum
Tullimonstrum belongs to. In 1989 Tullimonstrum gregarium was officially designated the State Fossil
of Illinois.
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
, USA, was a soft-bodied
Soft-bodied organisms
The term "soft-bodied organism" is used to describe animals without skeleton, roughly corresponding 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,...
invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
that lived in shallow tropical coastal waters of muddy estuaries during the Pennsylvanian
Pennsylvanian
The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...
geological period
Geologic time scale
The geologic time scale provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth...
, about 300 million years ago.
Etymology
Tullimonstrum takes its name from its discoverer, Francis Tully. Appropriately, "tull" is also Norwegian for "nonsense". gregarium reflects its abundance. The term 'monster' relates to the creature's outlandish appearance and strange body planBody plan
A body plan is the blueprint for the way the body of an organism is laid out. An organism's symmetry, its number of body segments and number of limbs are all aspects of its body plan...
.
Description
Tullimonstrum probably reached lengths of up to 35 centimetres (13.8 in); the smallest individuals are about 8 cm (3.1 in) long.The Tully Monster had a pair of fins
FINS
FINS is a network protocol used by Omron PLCs, over different physical networks like Ethernet, Controller Link, DeviceNet and RS-232C....
not unlike a cuttlefish
Cuttlefish
Cuttlefish are marine animals of the order Sepiida. They belong to the class Cephalopoda . Despite their name, cuttlefish are not fish but molluscs....
at the tail end of its body, and possibly vertical fins as well (though the fidelity of preservation of fossils of its soft body makes this difficult to determine), and a long proboscis
Proboscis
A proboscis is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In simpler terms, a proboscis is the straw-like mouth found in several varieties of species.-Etymology:...
with eight small sharp teeth with which it may have probed actively for small creatures and edible detritus
Detritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
in the muddy bottom. It was part of the ecological community represented in the unusually rich group of soft-bodied organisms
Soft-bodied organisms
The term "soft-bodied organism" is used to describe animals without skeleton, roughly corresponding 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,...
found among the assemblage called the Mazon Creek fossils
Mazon Creek fossils
The Mazon Creek fossil beds are a conservation found near Morris, in Grundy County, Illinois. The fossil beds are located in ironstone concretions, formed approximately in the mid-Pennsylvanian epoch of the Carboniferous period...
from their site in Grundy County, Illinois. The absence of hard parts in the fossil implies that the animal did not possess organs composed of bone, chitin or calcium carbonate. There is evidence of serially-repeated internal structures. Its head is poorly differentiated. 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.
Affinity
There is insufficient evidence to align Tullimonstrum to the crown or even stem group of any phylumPhylum
In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....
. Since it lacks any characters of the well-known modern phyla, it has been speculated that it is a stem group to one of the many phyla of worms that are poorly represented today. Similarities with Cambrian fossil organisms such as Vetustovermis and Opabinia
Opabinia
Opabinia is an animal genus found in Cambrian fossil deposits. Its sole species, Opabinia regalis, is known from the Middle Cambrian Burgess Shale of British Columbia, Canada. Fewer than twenty good specimens have been described; 3 specimens of Opabinia are known from the Greater Phyllopod bed,...
have also been noted.
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.Taphonomic setting
Silt
Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...
y outwash. The bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
that began to decompose the plant and animal remains in the mud produced carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
in the sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
s around the remains. The carbon dioxide combined with iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
from the groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
around the remains, forming encrusting nodules of siderite
Siderite
Siderite is a mineral composed of iron carbonate FeCO3. It takes its name from the Greek word σίδηρος sideros, “iron”. It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus...
('ironstone'), which created a hard permanent 'cast' of the animal which slowed further decayed, 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 Lagerstätte
Lagerstätte
A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....
n, 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.
History
Amateur collector Francis Tully found the first of these fossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s in 1958. He took the strange creature to the Field Museum of Natural History
Field Museum of Natural History
The Field Museum of Natural History is located in Chicago, Illinois, USA. It sits on Lake Shore Drive next to Lake Michigan, part of a scenic complex known as the Museum Campus Chicago...
, but paleontologists
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
remain stumped as to what phylum
Phylum
In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....
Tullimonstrum belongs to. In 1989 Tullimonstrum gregarium was officially designated the State Fossil
State fossil
Most American states have made a state fossil designation, in many cases during the 1980s. It is common to designate one species in which fossilization has occurred, rather than a single specimen, or a category of fossils not limited to a single species....
of Illinois.
External links
- Tullimonstrum at the Illinois State Museum
- A particularly well-preserved Tullimonstrum at the Illinois State Museum
- Tullimonstrum at the Illinois State Geological Survey
- Tullimonstrum at Statefossils.com
- Mazon Creek references at the Field Museum of Natural History