''Dilong'' (帝龍, which means 'emperor dragon') is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of basal
tyrannosauroid
Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent b ...
dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
.
The only species is ''Dilong paradoxus''. It is from the
Lower
Lower may refer to:
*Lower (surname)
*Lower Township, New Jersey
*Lower Receiver (firearms)
*Lower Wick Gloucestershire, England
See also
*Nizhny
Nizhny (russian: Ни́жний; masculine), Nizhnyaya (; feminine), or Nizhneye (russian: Ни́ ...
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
Yixian Formation
The Yixian Formation (; formerly transcribed as Yihsien Formation) is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans the late Barremian and early Aptian stages of the Early Cretaceous. It is known for its ex ...
near Lujiatun, Beipiao, in the western
Liaoning
Liaoning () is a coastal province in Northeast China that is the smallest, southernmost, and most populous province in the region. With its capital at Shenyang, it is located on the northern shore of the Yellow Sea, and is the northernmost ...
province of
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
. It lived about 126 million years ago.
Discovery
![Dilong](https://upload.wikimedia.org/wikipedia/commons/8/8e/Dilong.jpg)
''Dilong'' was described by
Xu Xing and colleagues in 2004.
The name is derived from the
Chinese
Chinese can refer to:
* Something related to China
* Chinese people, people of Chinese nationality, citizenship, and/or ethnicity
**''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation
** List of ethnic groups in China, people of ...
帝 ''dì'' meaning 'emperor' and 龙 / 龍 ''lóng'' meaning 'dragon'. "Di", "emperor", refers to the relationship of this animal to ''
Tyrannosaurus
''Tyrannosaurus'' is a genus of large theropoda, theropod dinosaur. The species ''Tyrannosaurus rex'' (''rex'' meaning "king" in Latin), often called ''T. rex'' or colloquially ''T-Rex'', is one of the best represented theropods. ''Tyrannosa ...
rex'', the "king" tyrannosaurid. "Long" is used to name Chinese dinosaurs in much the same way that the Latin ''-saur'' is in the West. The specific name, ''paradoxus'', is a
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
isation of the
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
παράδοξον meaning 'against received wisdom'.
Description
![Dilong paradoxus size 01](https://upload.wikimedia.org/wikipedia/commons/1/1e/Dilong_paradoxus_size_01.jpg)
The type specimen is IVPP 14243 (
Institute of Vertebrate Paleontology and Paleoanthropology The Institute of Vertebrate Paleontology and Paleoanthropology (IVPP; ) of China is a research institution and collections repository for fossils, including many dinosaur and pterosaur specimens (many from the Yixian Formation). As its name suggest ...
in
Beijing
}
Beijing ( ; ; ), alternatively romanized as Peking ( ), is the capital of the People's Republic of China. It is the center of power and development of the country. Beijing is the world's most populous national capital city, with over 21 ...
), a nearly complete, semi-articulated, skull and skeleton. Referred material includes IVPP 1242, a nearly complete skull and presacral vertebrae, TNP01109 (
Tianjin Museum of Natural History), a partial skull, and IVPP V11579, another skull which may belong to ''D. paradoxus'', or to a related species.
The type specimen of ''Dilong'' was about in length, but it is thought to be a juvenile and may have been over long when fully grown. Gregory S. Paul estimated that a long individual would have weighed .
Feathers
![Dilong TJV 50](https://upload.wikimedia.org/wikipedia/commons/6/6c/Dilong_TJV_50.JPG)
''Dilong paradoxus'' had a covering of simple
feather
Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and a premier ...
s or
protofeathers
A feathered dinosaur is any species of dinosaur possessing feathers. While this includes all species of birds, there is a hypothesis that many, if not all non-avian dinosaur species also possessed feathers in some shape or form.
It has been su ...
. The feathers were seen in fossilized skin impressions from near the
jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...
and tail. They are not identical to modern
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
feathers, lacking a central shaft and most likely used for warmth, since they could not have enabled flight. Adult tyrannosaurs, found in
Alberta
Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
and
Mongolia
Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...
have skin impressions which appear to show the pebbly scales typical of other dinosaurs. Xu et al. (2004) speculated that the tyrannosauroids may have had different skin coverings on different parts of their bodies—perhaps mixing scales and feathers. They also speculated that feathers may correlate negatively with body size—that juveniles may have been feathered, then shed the feathers and expressed only scales as the animal became larger and no longer needed insulation to stay warm.
Classification
When ''Dilong'' was first described, it was considered one of the earliest and most primitive members of
Tyrannosauroidea
Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent b ...
, the group that includes the later, larger
tyrannosaurids
Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family (biology), family of coelurosaurian Theropoda, theropod dinosaurs that comprises two subfamilies containing up to thirteen genus, genera, including the eponymous ''Tyrannos ...
such as ''
Tyrannosaurus
''Tyrannosaurus'' is a genus of large theropoda, theropod dinosaur. The species ''Tyrannosaurus rex'' (''rex'' meaning "king" in Latin), often called ''T. rex'' or colloquially ''T-Rex'', is one of the best represented theropods. ''Tyrannosa ...
rex''. At least one later study, by Turner and colleagues in 2007, reanalyzed the relationships of coelurosaurian dinosaurs, including ''Dilong'', and found that it was not a tyrannosauroid. Rather, they placed ''Dilong'' two steps above the tyrannosauroids in their phylogeny; more advanced than ''
Coelurus
''Coelurus'' ( ) is a genus of coelurosaurian dinosaur from the Late Jurassic period (mid-late Kimmeridgian faunal stage, 155–152 million years ago). The name means "hollow tail", referring to its hollow tail vertebrae (Greek κοῖλο ...
'', but more primitive than the
Compsognathidae
Compsognathidae is a family of coelurosaurian theropod dinosaurs. Compsognathids were small carnivores, generally conservative in form, hailing from the Jurassic and Cretaceous Periods. The bird-like features of these species, along with other d ...
.
[Turner, A.H., Pol, D., Clarke, J.A., Erickson, G.M., and Norell, M. (2007). "Supporting online material for: A basal dromaeosaurid and size evolution preceding avian flight". ''Science'', 317: 1378-1381. ]
supplement
However, other studies continued to find ''Dilong'' as a tyrannosauroid, and some (such as Carr & Williamson 2010) found ''Dilong'' to fall within Tyrannosauroidea, not among the more advanced coelurosaurs.
Below is a cladogram containing most tyrannosauroids by Loewen ''et al.'' in 2013.
![Dilong skull American Museum of Natural History](https://upload.wikimedia.org/wikipedia/commons/4/4a/Dilong_skull_American_Museum_of_Natural_History.jpg)
In a 2014 study, ''Dilong'' was found to be a
proceratosaurid.
[ However, in an analysis by Brusatte ''et al.'' in 2016, both parsimony and ]Bayesian
Thomas Bayes (/beɪz/; c. 1701 – 1761) was an English statistician, philosopher, and Presbyterian minister.
Bayesian () refers either to a range of concepts and approaches that relate to statistical methods based on Bayes' theorem, or a followe ...
phylogenetic analyses placed ''Dilong'' outside of Proceratosauridae, as a slightly more advanced tyrannosauroid.
Paleobiology
Braincase
In human anatomy, the neurocranium, also known as the braincase, brainpan, or brain-pan is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calvaria or skul ...
scans indicate that ''Dilong'' had an S-shaped brain protected by thin meninges
In anatomy, the meninges (, ''singular:'' meninx ( or ), ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in th ...
, unlike ''Tyrannosaurus'' which has a more linear brain protected by thicker meninges; this is probably a size-related trait, as it is in crocodilia
Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest living ...
ns. The large flocculus of ''Dilong'' suggests it was agile and had good balance, while small olfactory tract
The olfactory tract is a bilateral bundle of afferent nerve fibers from the mitral and tufted cells of the olfactory bulb that connects to several target regions in the brain, including the piriform cortex, amygdala, and entorhinal cortex. It ...
s suggest that its sense of smell was not as refined as that of ''Tyrannosaurus'' and other more advanced tyrannosauroids.
See also
* Timeline of tyrannosaur research
This timeline of tyrannosaur research is a chronological listing of events in the history of paleontology focused on the tyrannosaurs, a group of predatory theropod dinosaurs that began as small, long-armed bird-like creatures with elaborate cr ...
References
External links
Original ''Nature'' article as a PDF
''New Scientist'' news article
{{Taxonbar, from=Q27439
Early Cretaceous dinosaurs of Asia
Feathered dinosaurs
Fossil taxa described in 2004
Tyrannosaurs
Taxa named by Xu Xing
Taxa named by Mark Norell
Yixian fauna