Therizinosauridae
Encyclopedia
Therizinosauridae is a family
of advanced herbivorous or omnivorous theropod dinosaur
s. Therizinosaurid fossil
remains have been recovered from mid-late Cretaceous
Period deposits from Mongolia
, China
, and the United States
.
in 1954 to contain the enigmatic Therizinosaurus cheloniformis
, which Maleev originally thought to be a species of giant "turtle
-like lizard." It was long considered a strange, probably carnivorous, species. Relatives of Therizinosaurus were later found but not recognized as such for some time. These more complete specimens were herbivores, and had a bizarre mixture of what looked to early researchers like a mix between ornithischia
n and "prosauropod" dinosaurs. Collectively, these were included in the family Segnosauridae, or "slow lizards", due to their heavy bodies, short legs, and presumably slow, ground sloth
-like lifestyle. Subsequent studies found that segnosaurids were neither prosauropods nor ornithischians, but actually bizarre theropods, and that the previously enigmatic Therizinosaurus was also a member of this group. Since the family Therizinosauridae was named earlier than Segnosauridae, the later name became a junior synonym of the former, despite the fact that Therizinosaurus was a new addition to the segnosaurid group.
Therizinosauridae was first given a phylogenetic definition by Paul Sereno
in 1998, who defined it as all dinosaurs closer to Erlikosaurus
than to Ornithomimus
. As the relationship of therizinosaurids to other theropods clarified and more members of the larger therizinosaur
group were found, a more restrictive definition has come to be preferred for the family-level name Therizinosauridae. Sereno himself, for example, re-defined the name in 2005 as the clade
containing Therizinosaurus cheloniformis
, Nothronychus mckinleyi
, and Neimongosaurus yangi
.
presented here follows a 2007 phylogenetic analysis by Phil Senter.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of advanced herbivorous or omnivorous 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...
s. Therizinosaurid fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
remains have been recovered from mid-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 deposits from 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...
, 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 the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
Classification
The family Therizinosauridae was coined by Evgeny MaleevEvgeny Maleev
Evgeny Aleksandrovich Maleev was a Russian paleontologist who named the armoured dinosaur Talarurus, the fearsome Tarbosaurus, and the enigmatic Therizinosaurus. Maleev did research on Tarbosaurus brains by cutting open fossilized braincases with a diamond saw...
in 1954 to contain the enigmatic Therizinosaurus cheloniformis
Therizinosaurus
Therizinosaurus is a genus of very large theropod dinosaur. Therizinosaurus lived in the late Cretaceous Period , and was one of the last and largest representatives of its unique group, the Therizinosauria...
, which Maleev originally thought to be a species of giant "turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
-like lizard." It was long considered a strange, probably carnivorous, species. Relatives of Therizinosaurus were later found but not recognized as such for some time. These more complete specimens were herbivores, and had a bizarre mixture of what looked to early researchers like a mix between 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'...
n and "prosauropod" dinosaurs. Collectively, these were included in the family Segnosauridae, or "slow lizards", due to their heavy bodies, short legs, and presumably slow, ground sloth
Ground sloth
Ground sloths are a diverse group of extinct sloths, in the mammalian superorder Xenarthra. Their most recent survivors lived in the Antilles, where it has been proposed they may have survived until 1550 CE; however, the youngest AMS radiocarbon date reported is 4190 BP, calibrated to c. 4700 BP...
-like lifestyle. Subsequent studies found that segnosaurids were neither prosauropods nor ornithischians, but actually bizarre theropods, and that the previously enigmatic Therizinosaurus was also a member of this group. Since the family Therizinosauridae was named earlier than Segnosauridae, the later name became a junior synonym of the former, despite the fact that Therizinosaurus was a new addition to the segnosaurid group.
Therizinosauridae was first given a phylogenetic definition by Paul Sereno
Paul Sereno
Paul Callistus Sereno is an American paleontologist from the University of Chicago who discovered several new dinosaur species on several continents. He has conducted excavations at sites as varied as Inner Mongolia, Argentina, Morocco, and Niger...
in 1998, who defined it as all dinosaurs closer to Erlikosaurus
Erlikosaurus
Erlikosaurus is a genus of herbivorous theropod dinosaur from the late Cretaceous Period, belonging to the Therizinosauridae. Its fossils, a skull and some post-cranial fragments, were found in the Bayan Shireh Formation of Mongolia, dating to around 90 million years ago.-Discovery and naming:The...
than to Ornithomimus
Ornithomimus
Ornithomimus is a genus of ornithomimid dinosaur from the Late Cretaceous Period of what is now North America.In 1890 Ornithomimus velox was named by Othniel Charles Marsh on the basis of a foot and partial hand from the Maastrichtian Denver Formation. Another seventeen species have been named since...
. As the relationship of therizinosaurids to other theropods clarified and more members of the larger therizinosaur
Therizinosaur
Therizinosaurs are theropod dinosaurs belonging to the clade Therizinosauria. Therizinosaur fossils have been found in Early through Late Cretaceous deposits in Mongolia, the People's Republic of China and Western North America...
group were found, a more restrictive definition has come to be preferred for the family-level name Therizinosauridae. Sereno himself, for example, re-defined the name in 2005 as the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
containing Therizinosaurus cheloniformis
Therizinosaurus
Therizinosaurus is a genus of very large theropod dinosaur. Therizinosaurus lived in the late Cretaceous Period , and was one of the last and largest representatives of its unique group, the Therizinosauria...
, Nothronychus mckinleyi
Nothronychus
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...
, and Neimongosaurus yangi
Neimongosaurus
Neimongosaurus is a genus of herbivorous therizinosaur theropod dinosaur known from the Upper Cretaceous of Nei Mongol, China....
.
Taxonomy
- Family Therizinosauridae
- EnigmosaurusEnigmosaurusEnigmosaurus is a genus of therizinosauroid theropod dinosaur from the Late Cretaceous of Mongolia, central Asia...
- ErliansaurusErliansaurusErliansaurus is a genus of therizinosauroid theropod dinosaur from the Late Cretaceous of China.A fossil of Erliansaurus was found near Sanhangobi in Inner-Mongolia. The type species, Erliansaurus bellamanus, was described by Xu Xing, Zhang Xiaohong, Paul Sereno, Zhao Xijin, Kuang Xuewen, Han Jun...
- ErlikosaurusErlikosaurusErlikosaurus is a genus of herbivorous theropod dinosaur from the late Cretaceous Period, belonging to the Therizinosauridae. Its fossils, a skull and some post-cranial fragments, were found in the Bayan Shireh Formation of Mongolia, dating to around 90 million years ago.-Discovery and naming:The...
- NanshiungosaurusNanshiungosaurusNanshiungosaurus is a genus of therizinosaurian theropod dinosaur from the Cretaceous of China.Two species have been named in the genus: the type species Nanshiungosaurus brevispinus and Nanshiungosaurus bohlini.-Discovery and naming:...
- NeimongosaurusNeimongosaurusNeimongosaurus is a genus of herbivorous therizinosaur theropod dinosaur known from the Upper Cretaceous of Nei Mongol, China....
- NothronychusNothronychusNothronychus 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...
- SegnosaurusSegnosaurusSegnosaurus is a genus of herbivorous theropod dinosaur belonging to the Therizinosauridae from the Cretaceous of Mongolia.-Discovery and naming:...
- SuzhousaurusSuzhousaurusSuzhousaurus is a genus of herbivorous therizinosauroid theropod dinosaur from the Early Cretaceous-age Xinminpu Group of the Yujingzi Basin, Gansu, China.-Discovery and naming:...
- TherizinosaurusTherizinosaurusTherizinosaurus is a genus of very large theropod dinosaur. Therizinosaurus lived in the late Cretaceous Period , and was one of the last and largest representatives of its unique group, the Therizinosauria...
(typeBiological typeIn biology, a type is one particular specimen of an organism to which the scientific name of that organism is formally attached...
)
- Enigmosaurus
Phylogeny
The cladogramCladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
presented here follows a 2007 phylogenetic analysis by Phil Senter.