Tylosaurus
Encyclopedia
Tylosaurus was a mosasaur
, a large, predatory marine lizard closely related to modern monitor lizards and to snakes.
s, fish, and other genera
of mosasaurs, it was a dominant predator of the Western Interior Seaway
during the Late Cretaceous
. Tylosaurus proriger was among the largest of all the mosasaurs (along with Hainosaurus
and Mosasaurus
hoffmannii), reaching maximum lengths of 15 meters
or more (49+ ft). A distinguishing characteristic of Tylosaurus is its elongated, cylindrical premaxilla (snout) from which it takes its name and which may have been used to ram and stun prey and also in intraspecific combat. Stomach contents associated with specimens of Tylosaurus proriger indicate that this ferocious mosasaur had a varied diet, including fish, sharks, smaller mosasaurs, plesiosaurs, and flightless diving birds such as Hesperornis
. In some paleoenvironments, Tylosaurus seems to have preferred shallow, nearshore waters (as with the Eutaw Formation
and Mooreville Chalk Formation
of Alabama), while favoring deeper water farther out from shore in other environments (as with the Niobrara Chalk of the western U.S.).
Like many other mosasaurs, the early history of this taxon
is complex and involves the infamous rivalry
between two early American paleontologists, Edward Drinker Cope
and Othniel Charles Marsh
. Originally, the name "Macrosaurus" proriger was proposed by Cope for a fragmentary skull and thirteen vertebrae collected from near Monument Rocks in western Kansas
in 1868. It was placed in the collections of the Harvard Museum of Comparative Zoology. Only a year later, Cope redescribed the same material in greater detail and referred it, instead, to the English mosasaur taxon Liodon. Then, in 1872, Marsh named a more complete specimen as a new genus, Rhinosaurus ("nose lizard"), but soon discovered that this name had already been used for a different animal. Cope suggested that Rhinosaurus be replaced by yet another new name, Rhamposaurus which also proved to be preoccupied. Marsh finally erected Tylosaurus later in 1872, to include the original Harvard material as well as additional, more complete specimens which had also been collected from Kansas. A giant specimen of T. proriger, recovered in 1911 by C. D. Bunker near Wallace, Kansas is one of the largest skeleton of Tylosaurus ever found. It is currently on display at the University of Kansas
Museum of Natural history.
In 1918, Charles H. Sternberg found a Tylosaurus, with the remains of a plesiosaur in its stomach. The specimen is currently mounted in the United States National Museum (Smithsonian) and the plesiosaur remains are stored in the collections. Although these important specimens were briefly reported by C. H. Sternberg (1922), the information was lost to science until 2001. This specimen was rediscovered and described by Everhart (2004a). It is the basis for the story line in the new (2007) National Geographic IMAX movie - Sea Monsters, and a book by the same name (Everhart, 2007).
A photograph of a Tylosaurus skull was taken by George F. Sternberg
about 1926 after he collected and prepared the specimen. It was discovered in the Smoky Hill Chalk
of Logan County, Kansas. Sternberg offered the specimen to the Smithsonian and included a photograph in his letter to Charles Gilmore. Copies of the original photos are in the archives of the Sternberg Museum of Natural History (FHSM). The specimen is FHSM VP-3, the exhibit specimen in the same museum.
and lower to middle Campanian
of North America (Kansas, Alabama, Nebraska, etc.); Tylosaurus nepaeolicus (Cope, 1874 ), from the Santonian of North America (Kansas); Tylosaurus haumuriensis (Hector, 1874; =Taniwhasaurus oweni), from the lower to middle Campanian of New Zealand
; Tylosaurus kansasensis Everhart, 2005 , from the late Coniacian
of Kansas.
A closely related genus, Hainosaurus
("Haine lizard", named after the Haine River in Belgium
) is known from the Cretaceous
of North America and Europe. Both Tylosaurus and Hainosaurus are grouped together into the subfamily Tylosaurinae and are referred to informally as "tylosaurines" or "tylosaurs." Bell placed the tylosaurines together with the plioplatecarpine mosasaurs (Platecarpus, Plioplatecarpus, etc.) in an informal monophyletic grouping which he called the "Russellosaurinae."
of indeterminate classification whose carcass appeared to have been deposited in a bathyal or outer shelf environment that later became Alaska's Matanuska Formation
. Every element of its skeleton not found in a concretion
bore many closely spaced ovualar conical depressions ranging in diameter from 2.12 to 5.81 mm and 1.64 to 3.62 deep. These depressions are probably bite marks. The depressions are not symmetrical enough for gastropod drill marks and are not shaped like sponge borings. None of the preserved fish fossils of the Matanuska Formation fit the size or geometry of the borings. The size and spacing and shape by contrast, however, closely resembles the teeth of Tylosaurus proriger. The apparent tooth marks are unlikely to have occurred before the carcass was washed out to sea since that would have punctured the body, preventing the build up of bloating gases that allowed the carcass to drift out to sea in the first place. The distribution of bite marks corresponds inversely to the presence of flesh in the animal. For instance, lower limb bones sustained the most damage because there was the least amount of flesh shielding the bones at those locations. The concretions formed as the flesh chemically reacted to the seafloor on the largest parts of the animal where the scavenging mosasaur would be unable to fully wrap its jaws around the carcass. Bones pulled free from the carcass were buried in the mud and preserved in mudstone.
Tylosaurus, as a a large mosasaur, is frequently depicted in popular culture. It has featured in National Geographic's Sea Monsters: A Prehistoric Adventure
, Sea Monsters - A Walking with Dinosaurs Trilogy, and Dinosaur Revolution
, among others.
A 34 ft. long Tylosaurus found in Kansas
by Alan Komrosky in 2009 is now on display at the Museum of World Treasures
in Wichita
, Kansas.
Mosasaur
Mosasaurs are large extinct marine lizards. The first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764...
, a large, predatory marine lizard closely related to modern monitor lizards and to snakes.
Paleobiology
Along with plesiosaurs, sharkShark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s, fish, and other genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of mosasaurs, it was a dominant predator of the Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
during the Late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. Tylosaurus proriger was among the largest of all the mosasaurs (along with Hainosaurus
Hainosaurus
Hainosaurus is an extinct genus of marine lizard belonging to the mosasaur family. It was one of the largest mosasaurs, though its size has been revised more than once. At first it was estimated to be , and the largest mosasaurid. During the 1990s, its size was revised to long; more recently,...
and Mosasaurus
Mosasaurus
Mosasaurus is a genus of mosasaur, carnivorous, aquatic lizards, somewhat resembling flippered crocodiles, with elongated heavy jaws. The genus existed during the Maastrichtian age of the Cretaceous period , around 70-65 millions years ago in the area of modern Western Europe and North America...
hoffmannii), reaching maximum lengths of 15 meters
Metre
The metre , symbol m, is the base unit of length in the International System of Units . Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole , its definition has been periodically refined to reflect growing knowledge of metrology...
or more (49+ ft). A distinguishing characteristic of Tylosaurus is its elongated, cylindrical premaxilla (snout) from which it takes its name and which may have been used to ram and stun prey and also in intraspecific combat. Stomach contents associated with specimens of Tylosaurus proriger indicate that this ferocious mosasaur had a varied diet, including fish, sharks, smaller mosasaurs, plesiosaurs, and flightless diving birds such as Hesperornis
Hesperornis
Hesperornis is a genus of flightless aquatic birds that spanned the first half of the Campanian age of the Late Cretaceous period . One of the lesser-known discoveries of the paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an important early find in the history of avian...
. In some paleoenvironments, Tylosaurus seems to have preferred shallow, nearshore waters (as with the Eutaw Formation
Eutaw Formation
The Eutaw Formation is a geological formation in North America, within the U.S. states of Alabama, Georgia, and Mississippi. The strata date from the late Coniacian to the early Santonian stage of the Late Cretaceous. It consists of the upper Tombigbee Sand Member and an unnamed lower member...
and Mooreville Chalk Formation
Mooreville Chalk Formation
The Mooreville Chalk Formation is a geological formation in North America, within the U.S. states of Alabama and Mississippi. The strata date back to the early Santonian to the early Campanian stage of the Late Cretaceous. The chalk was formed by pelagic sediments deposited along the eastern edge...
of Alabama), while favoring deeper water farther out from shore in other environments (as with the Niobrara Chalk of the western U.S.).
Discovery
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
is complex and involves the infamous rivalry
Bone Wars
The Bone Wars, also known as the "Great Dinosaur Rush", refers to a period of intense fossil speculation and discovery during the Gilded Age of American history, marked by a heated rivalry between Edward Drinker Cope and Othniel Charles Marsh...
between two early American paleontologists, Edward Drinker Cope
Edward Drinker Cope
Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen...
and Othniel Charles Marsh
Othniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...
. Originally, the name "Macrosaurus" proriger was proposed by Cope for a fragmentary skull and thirteen vertebrae collected from near Monument Rocks in western Kansas
Kansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...
in 1868. It was placed in the collections of the Harvard Museum of Comparative Zoology. Only a year later, Cope redescribed the same material in greater detail and referred it, instead, to the English mosasaur taxon Liodon. Then, in 1872, Marsh named a more complete specimen as a new genus, Rhinosaurus ("nose lizard"), but soon discovered that this name had already been used for a different animal. Cope suggested that Rhinosaurus be replaced by yet another new name, Rhamposaurus which also proved to be preoccupied. Marsh finally erected Tylosaurus later in 1872, to include the original Harvard material as well as additional, more complete specimens which had also been collected from Kansas. A giant specimen of T. proriger, recovered in 1911 by C. D. Bunker near Wallace, Kansas is one of the largest skeleton of Tylosaurus ever found. It is currently on display at the University of Kansas
University of Kansas
The University of Kansas is a public research university and the largest university in the state of Kansas. KU campuses are located in Lawrence, Wichita, Overland Park, and Kansas City, Kansas with the main campus being located in Lawrence on Mount Oread, the highest point in Lawrence. The...
Museum of Natural history.
A photograph of a Tylosaurus skull was taken by George F. Sternberg
George F. Sternberg
George Fryer Sternberg was a paleontologist best known for his discovery in Gove County, Kansas of the "fish-within-a-fish" of Xiphactinus audax. He was the son of Charles Hazelius Sternberg and nephew of Brig. Gen. George M. Sternberg...
about 1926 after he collected and prepared the specimen. It was discovered in the Smoky Hill Chalk
Smoky Hill Chalk
The Smoky Hill Chalk Member of the Niobrara Chalk formation is a Cretaceous conservation Lagerstätte, or fossil rich geological formation, known primarily for its exceptionally well-preserved marine reptiles. The Smoky Hill Chalk Member is the uppermost of the two structural units of the Niobrara...
of Logan County, Kansas. Sternberg offered the specimen to the Smithsonian and included a photograph in his letter to Charles Gilmore. Copies of the original photos are in the archives of the Sternberg Museum of Natural History (FHSM). The specimen is FHSM VP-3, the exhibit specimen in the same museum.
Species
Though many species of Tylosaurus have been named over the years, only a few are now recognized by scientists as taxonomically valid. They are as follows: Tylosaurus proriger (Cope, 1869), from the SantonianSantonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series. It spans the time between 85.8 ± 0.7 mya and 83.5 ± 0.7 mya...
and lower to middle Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
of North America (Kansas, Alabama, Nebraska, etc.); Tylosaurus nepaeolicus (Cope, 1874 ), from the Santonian of North America (Kansas); Tylosaurus haumuriensis (Hector, 1874; =Taniwhasaurus oweni), from the lower to middle Campanian of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
; Tylosaurus kansasensis Everhart, 2005 , from the late Coniacian
Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series and spans the time between 89.3 ± 1 Ma and 85.8 ± 0.7 Ma...
of Kansas.
A closely related genus, Hainosaurus
Hainosaurus
Hainosaurus is an extinct genus of marine lizard belonging to the mosasaur family. It was one of the largest mosasaurs, though its size has been revised more than once. At first it was estimated to be , and the largest mosasaurid. During the 1990s, its size was revised to long; more recently,...
("Haine lizard", named after the Haine River in Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
) is known from the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
of North America and Europe. Both Tylosaurus and Hainosaurus are grouped together into the subfamily Tylosaurinae and are referred to informally as "tylosaurines" or "tylosaurs." Bell placed the tylosaurines together with the plioplatecarpine mosasaurs (Platecarpus, Plioplatecarpus, etc.) in an informal monophyletic grouping which he called the "Russellosaurinae."
Scavenging of a hadrosaur carcass
The Talkeetna Mountains Hadrosaur was a hadrosauridHadrosaurid
Hadrosaurids or duck-billed dinosaurs are members of the family Hadrosauridae, and include ornithopods such as Edmontosaurus and Parasaurolophus. They were common herbivores in the Upper Cretaceous Period of what are now Asia, Europe and North America. They are descendants of the Upper...
of indeterminate classification whose carcass appeared to have been deposited in a bathyal or outer shelf environment that later became Alaska's Matanuska Formation
Matanuska Formation
The Matanuska Formation consists of more than of sedimentary strata exposed in the northern Chugach Mountains, Matanuska Valley, and southern Talkeetna Mountains of South-Central Alaska. The Matanuska Formation contains strata from Early Cretaceous to Late Cretaceous . Parts of the formation...
. Every element of its skeleton not found in a concretion
Concretion
A concretion is a volume of sedimentary rock in which a mineral cement fills the porosity . Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word 'concretion' is derived from the Latin con meaning 'together' and crescere meaning 'to grow'...
bore many closely spaced ovualar conical depressions ranging in diameter from 2.12 to 5.81 mm and 1.64 to 3.62 deep. These depressions are probably bite marks. The depressions are not symmetrical enough for gastropod drill marks and are not shaped like sponge borings. None of the preserved fish fossils of the Matanuska Formation fit the size or geometry of the borings. The size and spacing and shape by contrast, however, closely resembles the teeth of Tylosaurus proriger. The apparent tooth marks are unlikely to have occurred before the carcass was washed out to sea since that would have punctured the body, preventing the build up of bloating gases that allowed the carcass to drift out to sea in the first place. The distribution of bite marks corresponds inversely to the presence of flesh in the animal. For instance, lower limb bones sustained the most damage because there was the least amount of flesh shielding the bones at those locations. The concretions formed as the flesh chemically reacted to the seafloor on the largest parts of the animal where the scavenging mosasaur would be unable to fully wrap its jaws around the carcass. Bones pulled free from the carcass were buried in the mud and preserved in mudstone.
In popular culture
Sea Monsters: A Prehistoric Adventure
Sea Monsters: A Prehistoric Adventure is a film by National Geographic which is set in the Earth's prehistoric past. The film features state-of-the-art three dimensional photographic and computer generated characters/animals. The setting alternates between prehistory and modern day times in which...
, Sea Monsters - A Walking with Dinosaurs Trilogy, and Dinosaur Revolution
Dinosaur Revolution
Dinosaur Revolution is a four-part American nature documentary produced by Creative Differences, although it was believed to be a Pixar project when it was first revealed to the public due to a press release saying so. The first two episodes aired on Discovery Channel on September 4, 2011. The...
, among others.
A 34 ft. long Tylosaurus found in Kansas
Kansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...
by Alan Komrosky in 2009 is now on display at the Museum of World Treasures
Museum of World Treasures
The Museum of World Treasures is a world history museum in Wichita, Kansas, United States. Among the many items on display are Tyrannosaurus, Daspletosaurus, and Tylosaurus specimens , Egyptian mummies, signatures of all the American presidents, a section of the Berlin Wall, and the Scarecrow's...
in Wichita
Wichita, Kansas
Wichita is the largest city in the U.S. state of Kansas.As of the 2010 census, the city population was 382,368. Located in south-central Kansas on the Arkansas River, Wichita is the county seat of Sedgwick County and the principal city of the Wichita metropolitan area...
, Kansas.