Nothronychus
Encyclopedia
Nothronychus is a genus
of theropod dinosaur
classified in the group Therizinosauria, from the Cretaceous
of North America
.
The type species
of this dinosaur, Nothronychus mckinleyi, was described by James Kirkland and Douglas G. Wolfe in 2001
. It was recovered near New Mexico
's border with Arizona
, in an area known as the Zuni Basin, from rocks assigned to the Moreno Hill Formation
, dating to the late Cretaceous
period (mid-Turonian
stage), around 91 million years ago. A second specimen, described in 2009 as a second species, Nothronychus graffami, was found in the Tropic Shale Formation
of Utah
, dating to the early Turonian, between one million and a half million years older than N. mckinleyi.
The name Nothronychus, is derived from Greek
, meaning "slothful claw."
Nothronychus was a herbivorous theropod with a beak
, a bird-like hip (resembling that of the non-related ornithischia
ns) and four-toed feet, with all four toes facing forward.
Nothronychus was a member of the Coelurosauria
, the theropod group of carnivorous dinosaurs that includes carnivores such as Tyrannosaurus
. However, more specifically, Nothronychus was a part of the sub-group Maniraptora
, theropods which evolved into omnivores and, in the case of Nothronychus and its family, plant-eaters. It was biped
al and walked more upright than its carnivore ancestors. N. graffami weighed about a tonne, were 4.5–6 m (15–20 ft) long and stood 3-3.6 m (10–12 ft) tall, while N. mckinleyi was only slightly smaller.
A reconstruction of 40 to 50 percent of its skeleton, from the two separate species, allowed scientists to describe these dinosaurs as having leaf-shaped teeth with circular roots, long necks, long arms with dexterous hands and, measured over the curve, up to thirty centimeter (12 in) long curved claws on their fingers, large "pot-bellied" abdomens, stout hind legs, and relatively short tails. N. mckinleyi was different from N. graffami in being less robust as well as details of the tail vertebrae, and a more bent lower arm bone (ulna
).
at the Haystack Butte site. A therizinosaur ischium (a hip bone) had originally been mistaken for a squamosal
, a part of the skull crest of the newly discovered ceratopsia
n Zuniceratops
. However, closer examination revealed the true identity of the bone, and soon more parts of the skeleton were found. The New Mexico team, led by paleontologists Jim Kirkland and Doug Wolfe, published their find in the Journal of Vertebrate Paleontology
on 22 August 2001, making it the type specimen of the new species Nothronychus mckinleyi. The Arizona Republic newspaper, however, was first to announce the name on 19 June 2001, in a column by R.E. Molnar
. The generic name is derived from Greek νωθρός, nothros, "heavy" or "slothful", en ὄνυξ, onyx, "claw". The specific name honours rancher Bobby McKinley on whose land the find was made. The holotype
, specimen MSM P2106, consists of two skull fragments, a braincase, some vertebrae and parts of the shoulder girdle, forelimbs, pelvis and hindlimbs.
A second, more complete therizinosaur specimen, UMNH VP 16420, was discovered from the Tropic Shale
formation (dating to the early Turonian stage) of southern Utah in 2000 by Merle Graffam, a resident of Big Water, Utah. The area around Big Water had been subject to several expeditions by teams from the Museum of Northern Arizona
(MNA), and was known for its abundance of marine reptile fossils, especially plesiosaur
s. During part of the late Cretaceous period, the region had been submerged under a shallow sea, the Western Interior Seaway
, and preserves extensive marine deposits. Graffam's initial discovery (a large, isolated toe bone) came as a surprise to scientists, as it clearly belonged to a land-dwelling dinosaur, rather than a plesiosaur. However, the location of the bone at the time would have been nearly 100 kilometers from the Cretaceous shoreline. An excavation of the area by an MNA crew revealed more of the skeleton, and the scientists found that it was a therizinosaur, and the first example of that group to be found in the Americas. All previous therizinosaur fossils had come from China
and Mongolia
. It is the most complete therizinosaurid specimen known but lacks the skull.
The Utah specimen studied by the MNA team was found to be closely related to N. mckinleyi, though it differed in build (being heavier) and age (about half a million years older). The MNA specimen was first announced in two 2002 talks during the 54th meeting of the Rocky Mountain Geological Society of America. It was later discussed in an issue of Arizona Geology as a distinct species from N. mckinleyi, but not named. The specimen was classified and named as the new species Nothronychus graffami by Lindsay Zanno and colleagues in the journal Proceedings of the Royal Society B
on 15 July 2009. N. graffami was named for Graffam, who discovered the original specimens. A reconstructed skeleton of N. graffami went on display at the MNA in September 2007.
. A cladistic analysis in 2010 recovered N. graffami as the sister species of N. mckinleyi.
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 theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
classified in the group Therizinosauria, 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
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
.
The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of this dinosaur, Nothronychus mckinleyi, was described by James Kirkland and Douglas G. Wolfe in 2001
2001 in paleontology
-Newly named insects:-Newly named bony fishes:-Newly named amphibians:-Newly named turtles:-Ichthyosaurs:-Newly named basal lepidosauromorphs:-Newly named plesiosaurs:-Newly named sphenodonts:-Newly named basal archosauromorphs:...
. It was recovered near New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
's border with Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, in an area known as the Zuni Basin, from rocks assigned to the Moreno Hill Formation
Moreno Hill Formation
The Moreno Hill Formation is a geological formation in New Mexico whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-Dinosaurs:-References:...
, dating to 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...
period (mid-Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
stage), around 91 million years ago. A second specimen, described in 2009 as a second species, Nothronychus graffami, was found in the Tropic Shale Formation
Tropic Shale Formation
The Tropic Shale Formation is a Mesozoic geologic formation. Dinosaur remains are among the fossils that have been recovered from the formation, including Nothronychus graffami.-References:...
of Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
, dating to the early Turonian, between one million and a half million years older than N. mckinleyi.
The name Nothronychus, is derived from Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
, meaning "slothful claw."
Nothronychus was a herbivorous theropod with a beak
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
, a bird-like hip (resembling that of the non-related ornithischia
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
ns) and four-toed feet, with all four toes facing forward.
Description
Coelurosauria
Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. In the past, it was used to refer to all small theropods, although this classification has been abolished...
, the theropod group of carnivorous dinosaurs that includes carnivores such as Tyrannosaurus
Tyrannosaurus
Tyrannosaurus meaning "tyrant," and sauros meaning "lizard") is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex , commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, with a much wider range than other...
. However, more specifically, Nothronychus was a part of the sub-group Maniraptora
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea...
, theropods which evolved into omnivores and, in the case of Nothronychus and its family, plant-eaters. It was biped
Biped
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning "two feet"...
al and walked more upright than its carnivore ancestors. N. graffami weighed about a tonne, were 4.5–6 m (15–20 ft) long and stood 3-3.6 m (10–12 ft) tall, while N. mckinleyi was only slightly smaller.
A reconstruction of 40 to 50 percent of its skeleton, from the two separate species, allowed scientists to describe these dinosaurs as having leaf-shaped teeth with circular roots, long necks, long arms with dexterous hands and, measured over the curve, up to thirty centimeter (12 in) long curved claws on their fingers, large "pot-bellied" abdomens, stout hind legs, and relatively short tails. N. mckinleyi was different from N. graffami in being less robust as well as details of the tail vertebrae, and a more bent lower arm bone (ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
).
Discovery and species
The first fossil evidence later attributed to Nothronychus was discovered by a team of paleontologists working in the Zuni Basin of New MexicoNew Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
at the Haystack Butte site. A therizinosaur ischium (a hip bone) had originally been mistaken for a squamosal
Squamosal
The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...
, a part of the skull crest of the newly discovered ceratopsia
Ceratopsia
Ceratopsia or Ceratopia is a group of herbivorous, beaked dinosaurs which thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7...
n Zuniceratops
Zuniceratops
Zuniceratops was a ceratopsian dinosaur from the mid Turonian of the Late Cretaceous Period of what is now New Mexico, United States...
. However, closer examination revealed the true identity of the bone, and soon more parts of the skeleton were found. The New Mexico team, led by paleontologists Jim Kirkland and Doug Wolfe, published their find in the Journal of Vertebrate Paleontology
Journal of Vertebrate Paleontology
The Journal of Vertebrate Paleontology was founded in 1980 at the University of Oklahoma by Dr. Jiri Zidek. It is a scientific journal that publishes original contributions on all aspects of the vertebrate paleontology, including vertebrate origins, evolution, functional morphology, taxonomy,...
on 22 August 2001, making it the type specimen of the new species Nothronychus mckinleyi. The Arizona Republic newspaper, however, was first to announce the name on 19 June 2001, in a column by R.E. Molnar
Ralph Molnar
Ralph E. Molnar is a paleontologist who had been Curator of Mammals at the Queensland Museum and more recently associated with the Museum of Northern Arizona. He is also a research associate at the Texas natural Science Centre. He co-authored descriptions of the dinosaurs Muttaburrasaurus, Kakuru,...
. The generic name is derived from Greek νωθρός, nothros, "heavy" or "slothful", en ὄνυξ, onyx, "claw". The specific name honours rancher Bobby McKinley on whose land the find was made. The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
, specimen MSM P2106, consists of two skull fragments, a braincase, some vertebrae and parts of the shoulder girdle, forelimbs, pelvis and hindlimbs.
A second, more complete therizinosaur specimen, UMNH VP 16420, was discovered from the Tropic Shale
Tropic Shale Formation
The Tropic Shale Formation is a Mesozoic geologic formation. Dinosaur remains are among the fossils that have been recovered from the formation, including Nothronychus graffami.-References:...
formation (dating to the early Turonian stage) of southern Utah in 2000 by Merle Graffam, a resident of Big Water, Utah. The area around Big Water had been subject to several expeditions by teams from the Museum of Northern Arizona
Museum of Northern Arizona
The Museum of Northern Arizona is a museum in Flagstaff, Arizona, USA, that was established as a repository for Native American artifacts and natural history specimens from the Colorado Plateau.The museum was founded in 1928 by zoologist Dr. Harold S...
(MNA), and was known for its abundance of marine reptile fossils, especially plesiosaur
Plesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
s. During part of the late Cretaceous period, the region had been submerged under a shallow sea, 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...
, and preserves extensive marine deposits. Graffam's initial discovery (a large, isolated toe bone) came as a surprise to scientists, as it clearly belonged to a land-dwelling dinosaur, rather than a plesiosaur. However, the location of the bone at the time would have been nearly 100 kilometers from the Cretaceous shoreline. An excavation of the area by an MNA crew revealed more of the skeleton, and the scientists found that it was a therizinosaur, and the first example of that group to be found in the Americas. All previous therizinosaur fossils had come from China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
and Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
. It is the most complete therizinosaurid specimen known but lacks the skull.
The Utah specimen studied by the MNA team was found to be closely related to N. mckinleyi, though it differed in build (being heavier) and age (about half a million years older). The MNA specimen was first announced in two 2002 talks during the 54th meeting of the Rocky Mountain Geological Society of America. It was later discussed in an issue of Arizona Geology as a distinct species from N. mckinleyi, but not named. The specimen was classified and named as the new species Nothronychus graffami by Lindsay Zanno and colleagues in the journal Proceedings of the Royal Society B
Proceedings of the Royal Society
Proceedings of the Royal Society is the parent title of two scientific journals published by the Royal Society, whereas its initial journal, Philosophical Transactions, is now devoted to special thematic issues...
on 15 July 2009. N. graffami was named for Graffam, who discovered the original specimens. A reconstructed skeleton of N. graffami went on display at the MNA in September 2007.
Phylogeny
Nothronychus mckinleyi was in 2001 assigned to the TherizinosauridaeTherizinosauridae
Therizinosauridae is a family of advanced herbivorous or omnivorous theropod dinosaurs. Therizinosaurid fossil remains have been recovered from mid-late Cretaceous Period deposits from Mongolia, China, and the United States.-Classification:...
. A cladistic analysis in 2010 recovered N. graffami as the sister species of N. mckinleyi.