Paleontologists have discovered what they say is a new species of early-diverging neornithischian dinosaur that was part of the Jurassic Yanliao Biota in northern China.
The skeleton of Pulaosaurus qinglong in left lateral view. Image credit: Hailong Zhang.
Named Pulaosaurus qinglong, the newly-identified dinosaur species lived in what is now China during the Jurassic period, around 160 million years ago.
The ancient reptile was part of the so-called Yanliao Biota, a Middle-to-Late Jurassic-aged ecosystem that included dinosaurs, mammals, amphibians, insects and lizards, as well as plants.
“The Yanliao Biota is one of the most significant Mesozoic, terrestrial lagerstätte in China, with an age that ranges from 168 to 157 million years and is comprised of fossil assemblages from the Jiulongshan and the Tiaojishan Formations,” said senior author Dr. Xing Xu, a paleontologist with the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences and Yunnan University, and colleagues.
“In total, there have been 54 genera and 58 species of vertebrates reported from the Yanliao Biota, including nine species of non-avian dinosaurs.”
“Because the Yanliao Biota preserves large amounts of vertebrate material from many species, it offers insight to major paleobiological events, such as the temporal origin of birds and the early evolution of mammals.”
“However, non-avian dinosaurs found in the Yanliao Biota are all small-bodied theropods whereas Ornithischia is represented by only one species, which may possibly be from the Jehol Biota.”
“This is in stark contrast to other contemporaneous Chinese terrestrial faunas such as the Shishugou and Shaximiao faunas where body size and taxonomic composition are more variable.”
Pulaosaurus qinglong belongs to Neornithischia (new ornithischians), a group of dinosaurs with the order Ornithischia.
First established in 1985, neornithischians had a thicker layer of asymmetrical enamel on the inside of their lower teeth.
“Neornithischia is a significant group of dinosaurs whose earliest origin may be dated back to the Middle Jurassic, represented by several early-diverging species including Sanxiasaurus, Agilisaurus, Hexinlusaurus found in China,” the paleontologists said.
“Besides China, there have been reports of neornithischian fossils from the Middle Jurassic of Eastern Europe, Scotland and layers from other geological times and countries.”
“Neornithischia diverges rapidly into a number of species in the Cretaceous period.”
The well-preserved specimen of Pulaosaurus qinglong was found in the Tiaojishan Formation of Qinglong in China’s Hebei province.
“The fossil is comprised of a nearly complete skeleton prepared on a brownish-red sandstone slab,” the researchers said.
“The specimen preserves most of the skull and a complete postcranial skeleton.”
According to the scientists, Pulaosaurus qinglong was a small-bodied neornthischian.
“The total length of this specimen is approximately 72.2 cm (i.e., the length from the rostral end of the skull to the caudal end of the last preserved caudal vertebrate) while its skull length is about 8 cm,” they said.
The discovery of the new species sheds new light on the biodiversity of Yanliao Biota and the phylogeny of early-diverging neornithischians.
“A phylogenetic analysis places Pulaosaurus qinglong at the base of Neornithischia close to Agilisaurus, which is the earliest-diverging neornithischian,” the authors said.
“The new species represents the first neornithischian found in the Yanliao Biota, and helps to fill the temporal and geographical gap in the distribution of Neornithischia within China.”
“A pair of arytenoids are preserved in the Pulaosaurus qinglong holotype and represents the second case of an ossified laryngeal apparatus among non-avian dinosaurs.”
“The arytenoids of Pulaosaurus qinglong indicates that ossified laryngeal apparatuses were present in Neornithischia, thus suggesting that the ossified laryngeal apparatus could be widespread across Dinosauria.”
“As the morphology of Pulaosaurus qinglong arytenoids resembles the arytenoids of extant birds, it is possible for the new species to have an avian-like vocalization.”
The discovery of Pulaosaurus qinglong is reported in a paper in the journal PeerJ.
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Y. Yang et al. 2025. A new neornithischian dinosaur from the Upper Jurassic Tiaojishan Formation of northern China. PeerJ 13: e19664; doi: 10.7717/peerj.19664