Paleontologists have described two new species of azhdarchid pterosaurs from fossils found in the Late Cretaceous Bayanshiree Formation in Mongolia’s Gobi Desert.
Life restoration of the Bayanshiree azhdarchid pterosaurs: the co-existence between Gobiazhdarcho tsogtbaatari and Tsogtopteryx mongoliensis in the Bayanshiree paleoenvironment, with a group of Gobihadros mongoliensis nearby. Image credit: Zhao Chuang.
The two new species lived in Mongolia during the Late Cretaceous epoch, between 96 and 90 million years ago.
Named Gobiazhdarcho tsogtbaatari and Tsogtopteryx mongoliensis, both flying reptiles belong to a cosmopolitan family of toothless, probably terrestrial-foraging pterosaurs called Azhdarchidae.
“Pterosaurs, the first vertebrate group to evolve powered flight, exhibit a fossil record stretching from the Late Triassic to the Cretaceous-Paleogene boundary, and an impressive diversity,” said Shihezi University paleontologist Xuanyu Zhou and colleagues from the Museu de Zoologia da USP and Hokkaido University Museum.
“Within pterosaurs, Azhdarchidae represents a very particular clade. At present, it includes at least 17 nominal species.”
“Characterized mainly by their elongate cervical vertebrae with vestigial neural spines, azhdarchids are an almost ubiquitous presence in Turonian-Maastrichtian pterosaur assemblages worldwide, being the most diverse and widespread group of pterosaurs during the Late Cretaceous.”
“Similar to other azhdarchoids, they sported edentulous jaws and seem to have been relatively terrestrial in lifestyle compared to other pterosaurs.”
“Azhdarchids are well-known especially for including the largest flying creatures ever, comprising some gigantic forms with 10-11-m-wingspans such as Quetzalcoatlus northropi, Arambourgiania philadelphiae, and Hatzegopteryx thambema, as well as the 9-m-wingspan Thanatosdrakon amaru.”
Type specimens of Gobiazhdarcho tsogtbaatari and Tsogtopteryx mongoliensis were collected in the 1990s from two different localities of the Bayanshiree Formation (also spelled Bayan Shireh, Baynshire, Bayshiree, or Baysheen Shireh Formation), which is located in the eastern region of the Gobi Desert, in Mongolia.
“The Bayanshiree azhdarchids comprise two specimens: the Bayshin Tsav azhdarchid (Tsogtopteryx mongoliensis), represented by an almost complete mid-cervical; and the Burkhant azhdarchid (Gobiazhdarcho tsogtbaatari), comprising an atlantoaxis, a cervical III, and a partial mid-cervical,” the paleontologists said.
“These specimens were collected by the Hayashibara Museum of Natural Sciences-Mongolian Paleontological Center Joint Paleontological Expedition in 1993 and 1995 from, respectively, the Bayshin Tsav and Burkhant localities.”
According to the team, Gobiazhdarcho tsogtbaatari represents a medium-sized (3.0-3.5 m in wingspan) early member of a Quetzalcoatlus–Arambourgiania lineage.
Tsogtopteryx mongoliensis is an early member of a Hatzegopteryx-lineage and, surprisingly, seems to represent a small form under 2 m in wingspan.
“It is interesting to note that Tsogtopteryx mongoliensis represents one of the smallest known azhdarchid species so far, only behind the 1.6-m-wingspan Hornby azhdarchid, from the Campanian of Canada,” the researchers said.
The discovery of these two new species fills in important temporal gaps in the evolutionary history of azhdarchid pterosaurs.
“Our results shed fresh light on the diversity and phylogeny of azhdarchid pterosaurs,” the scientists said.
“They also reinforce the reoccurring pattern of co-existence between multiple, differently-sized azhdarchid species from a same deposit.”
A paper on the findings was published online this week in the journal PeerJ.
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R.V. Pêgas et al. 2025. Azhdarchid pterosaur diversity in the Bayanshiree Formation, Upper Cretaceous of the Gobi Desert, Mongolia. PeerJ 13: e19711; doi: 10.7717/peerj.19711
