Jian changmaensis
First non-avian dinosaur from the Xiagou Formation's bird-rich site.
Jian changmaensis is a species of microraptorine theropod dinosaur that lived during the Early Cretaceous (Aptian age) in what is now the Xiagou Formation of China. The genus Jian contains only this species, known solely from a pectoral girdle and a partial forelimb. It is one of several non-avian dinosaurs described from this formation, which has produced more than one hundred bird fossils.
The fossil material was uncovered in 2008 from exposures of the Xiagou Formation in the Changma Basin, near Changma village in northwestern Gansu Province. The specimen, cataloged as GSGM-D050 and housed permanently at the Gansu Geological Museum, consists of an articulated section of the skeleton: the scapulocoracoid (pectoral girdle) along with the humerus, radius, and ulna of the forelimb. An initial report appeared in a 2010 conference abstract. In 2025, Ling-Qi Zhou and colleagues formally named and described Jian changmaensis as a new genus and species of microraptorine, designating GSGM-D050 as the holotype. The genus name Jian refers to Jiān, a one-winged bird from Chinese legend, while the species name changmaensis points to the type locality.
Jian is considered a medium-sized microraptorine, falling between smaller forms like *Wulong* (known from an immature specimen), *Zhongjianosaurus*, and small *Microraptor*, and larger relatives such as *Sinornithosaurus* and *Changyuraptor*. Its size is comparable to large *Microraptor* specimens and a subadult *Sinornithosaurus*. The scapula and coracoid are firmly fused, indicating the holotype was a skeletally mature individual. Additionally, the bone surfaces lack the grooved and pitted textures associated with vascular canals seen in actively growing animals. Autapomorphies of *Jian changmaensis* include a coracoid-to-humerus ratio greater than that of any other microraptorine; distal condyles of the humerus located primarily on the cranial surface of the bone (less cranially oriented in related species); and a prominent foramen near the top of the radius when viewed from below.
Quick Facts
- Genus
- Jian
- Species
- changmaensis
Facts from the source article.
Lore & Background
The fossil material of Jian changmaensis was discovered in 2008 in outcrops of the Xiagou Formation, part of the Changma Basin near Changma village in northwest Gansu Province, China. The specimen, accessioned as GSGM-D050 in the Gansu Geological Museum, consists of an articulated pectoral girdle (scapulocoracoid) and partial forelimb (humerus, radius, and ulna). It was initially reported in a 2010 conference abstract and formally described as a new genus and species in 2025 by Ling-Qi Zhou and colleagues. The generic name Jian references Jiān, a one-winged bird in Chinese legend; the specific name changmaensis refers to the type locality.
Jian changmaensis is considered a medium-sized microraptorine, similar in size to large Microraptor specimens and a subadult Sinornithosaurus.
Reader's Guide
Jian changmaensis holds significance as the first non-avian dinosaur described from the Xiagou Formation, a deposit that has yielded over 100 bird fossils. Its discovery expands the known diversity of microraptorine theropods from the Early Cretaceous of China and provides insight into the paleoecology of the region. Notably, accumulations of shattered bird bones resembling owl pellets have been found at the same site, and as the only non-bird and one of the largest microraptorines from the locality, Jian may have been the producer of these bone masses, suggesting a possible predatory or scavenging role. Phylogenetic analysis places Jian within the Microraptorinae, in an unresolved polytomy with Hesperonychus, Microraptor, and Zhongjianosaurus, highlighting ongoing questions about the relationships among derived microraptorines. The species contributes to understanding the morphological variation within this group, particularly in the pectoral girdle and forelimb anatomy.
Did You Know?
- Jian changmaensis is the only species in the genus Jian.
- The holotype specimen (GSGM-D050) consists only of a pectoral girdle and partial forelimb.
- Jian may have produced accumulations of shattered bird bones found at the Xiagou Formation site.
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