Article Spotlight: A new neornithischian dinosaur from the Upper Jurassic Tiaojishan Formation

A new neornithischian dinosaur from the Upper Jurassic Tiaojishan Formation of northern China

The Middle and Late Jurassic Yanliao Biota is different from other contemporaneous fossil assemblages in that it lacks neornithischian dinosaurs. Here, we report a new, early-diverging neornithischian, Pulaosaurus qinglong gen. et sp. nov., from the Upper Jurassic Tiaojishan Formation of Qinglong, Hebei Province, of northern China.

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This study introduces Pulaosaurus ginglong gen. et sp. nov., a newly discovered early-diverging neornithischian dinosaur from the Upper Jurassic Tiaojishan Formation in Qinglong, Hebei Province, China. The holotype specimen (IVPP V30936) is a nearly complete skeleton, providing significant insights into the morphology, phylogeny, and paleobiology of early neornithischians.

Key Findings:

Morphology:

Pulaosaurus exhibits a mix of basal and derived traits, such as five premaxillary teeth, a jugal boss, a nuchal crest, and ossified laryngeal elements.

The specimen preserves rare hyolaryngeal structures, including ceratobranchials and arytenoids, suggesting potential bird-like vocalization capabilities.

Phylogenetic Analysis:

Phylogenetic analyses place Pulaosaurus as one of the earliest-diverging neornithischians, closely related to Agilisaurus.

The results highlight mosaic evolution in neornithischians, with some derived traits appearing early in the clade.

Biogeographic Significance:

The discovery fills a temporal and geographic gap in the fossil record of neornithischians in China, linking Middle Jurassic taxa from southwestern China to Early Cretaceous taxa from northeastern China.

It challenges previous hypotheses about the geographic isolation of the Yanliao Biota, indicating greater biodiversity than previously recognized.

Paleobiological Insights:

The ossified laryngeal apparatus in Pulaosaurus is only the second reported in non-avian dinosaurs, suggesting such structures may have been widespread.

The arytenoids resemble those of birds, implying advanced vocal capabilities, though the larynx likely functioned as a sound modulator rather than the primary vocal source.

Gut Contents:

The specimen preserves possible plant seeds in the abdominal cavity, hinting at herbivory, though further study is needed for confirmation.

Conclusion:

Pulaosaurus ginglong represents a critical addition to understanding early neornithischian evolution, bridging gaps in the fossil record and offering new insights into the diversity and paleobiology of Jurassic dinosaurs. The study underscores the importance of the Yanliao Biota and calls for re-evaluation of hyolaryngeal elements in other dinosaur specimens.

DOI: 10.7717/peerj.19664

A new neornithischian dinosaur from the Upper Jurassic Tiaojishan Formation of northern China

The Middle and Late Jurassic Yanliao Biota is different from other contemporaneous fossil assemblages in that it lacks neornithischian dinosaurs. Here, we report a new, early-diverging neornithischian, Pulaosaurus qinglong gen. et sp. nov., from the Upper Jurassic Tiaojishan Formation of Qinglong, Hebei Province, of northern China.