Guanlong (冠龍) is an extinct genus of proceratosaurid Tyrannosauroidea dinosaur from the Late Jurassic (Oxfordian) Shishugou Formation of China. It was first described in 2006 by Xu Xing and colleagues, who found it to represent a new taxon related to Tyrannosaurus. The name is derived from Chinese language, translating as "crown dragon". Two individuals are currently known, consisting of a partially complete adult and a nearly complete juvenile.
Discovery
Guanlong was discovered in the
Dzungaria area of China by a joint expedition by scientists from the Institute of Vertebrate Paleontology and Paleoanthropology and George Washington University, and named by Xu Xing and others in 2006.
Guanlong comes from the Chinese words for "crown", 冠 (Hanyu Pinyin: guān), and "dragon", 龍 (Hanyu Pinyin: lóng), referring to the crest. The specific epithet (五彩),
wucaii (Hanyu Pinyin: wǔcǎi), means "multicoloured" and refers to the colours of rock of the Wucaiwan (五彩灣, "5-colored bay", "multicolored bay"), the multi-hued badlands where the creature was found.
At present,
Guanlong is known from two specimens, one discovered on top of the other, with three other individual theropod dinosaurs, in the Shishugou Formation. The
holotype (IVPP V14531) is a reasonably complete, partially articulated adult skeleton, and was the one on top. Another, immature specimen, the
paratype IVPP V14532, is known from fully articulated and nearly complete remains. It was presumed to have been trampled, after death, by the adult. The crest on the skull of the immature specimen is notably smaller and restricted to the forward portion of the snout, while the adult has a larger and more extensive crest. The crests of both specimens are thin, delicate structures that likely served as display organs, possibly for events like mating.
Description
Guanlong was a relatively small theropod, reaching in length and in body mass.
[Holtz, Thomas R. Jr. (2008) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages Supplementary Information
] Its fossils were found in the Shishugou Formation dating to about 160 million years ago, in the
Oxfordian stage of the
Late Jurassic period,
92 million years before its well-known relative
Tyrannosaurus. This bipedal
theropod shared many traits with its descendants, and also had some unusual ones, like a large crest on its head. Unlike later tyrannosaurs,
Guanlong had three long fingers on its hands. Aside from its distinctive crest, it would have resembled its close relative
Dilong paradoxus, and like
Dilong may have had a coat of primitive
.
Classification
A 2013 study found
Guanlong to be in a clade with both
Proceratosaurus and
Kileskus. Together they formed the family Proceratosauridae with a clade containing
Sinotyrannus,
Juratyrant and
Stokesosaurus.
However, in 2014 another study was published, instead finding
Stokesosaurus and
Juratyrant outside the family, which only included
Guanlong,
Proceratosaurus,
Kileskus and
Sinotyrannus.
Below is a simplified cladogram of the later analysis, from Fiorillo & Tykoski, 2014.
In 2024, the describers of Alpkarakush recovered Dilong and proceratosaurids ( Proceratosaurus and Guanlong) outside Tyrannosauroidea based on their phylogenetic analysis.
Paleobiology
The age of the two individuals were determined using a
histological analysis. The adult was shown to have matured at 7 years of age, and died at the age of 12. The juvenile died at 6, and was still growing. As the individuals are different ages, it can be seen some of the changes that happened during growth. In the juvenile, the crest is restricted to the snout, which is proportionally shorter. The orbit is also larger, the
hand comparatively larger, the lower leg is longer, the
pubic bone has a less expanded end, and other features found in more derived
and tyrannosauroids.
Guanlong possessed a cranial crest, which may have been used for display. It is similar to those of Dilophosaurus and Monolophosaurus, and like those it was highly pneumatic. However, it was more delicate than in the other genera, and also proportionately larger and more elaborate. Structures in Dilophosaurus and Monolophosaurus have also been suggested to be for species recognition, but the more gracile crest of Guanlong is more likely for display purposes.
See also
-
Timeline of tyrannosaur research
External links
