Cryodrakon

of Cryodrakon refers to the Greek god of the north wind, Boreas The generic name Cryodrakon is derived from the Ancient Greek words κρύος (kryos, meaning "cold") and δράκων (drakon, meaning "dragon"), while the specific name boreas refers to the Greek god the north wind, Boreas. Hence, Cryodrakon boreas could be translated as "cold dragon of the north winds". Habib had previously considered the name Cryodrakon viserion, as a reference to the ice dragon in Game of Thrones. ==Discovery and history==

Since 1972, bones of large pterosaurs (flying reptiles) belonging to the family Azhdarchidae have been reported from Alberta. These were the first pterosaur fossils discovered in Canada. They were sometimes referred to as Quetzalcoatlus sp., indicating an uncertain species of Quetzalcoatlus, or were just assigned to Quetzalcoatlus without specifying anything. This partial skeleton, specimen TMP 1992.83, lacks the skull and consists of a fourth cervical (neck) vertebra, a rib, a humerus, a pteroid (wing) bone, a fourth metacarpal, a tibia and a metatarsal. In 2019, specimen TMP 1992.83 received a new separate genus and type species, Cryodrakon boreas, and became the holotype of this new pterosaur. Cryodrakon boreas was named and described by paleontologists David Hone, François Therrien, and Michael Habib. Through comparisons with other azhdarchid taxa, Hone and colleagues concluded that all azhdarchid material from Alberta could be referred to a single distinct taxon. Therefore, they assigned all the known azhdarchid remains from the Dinosaur Park Formation to Cryodrakon boreas. The specimens consisted of numerous cervical vertebrae, a scapulocoracoid, an ulna, several fourth metacarpals, wing finger phalanges and a femur. These bones represent individuals of various biological ages, among them juveniles and a large mature exemplar. However, most of the bones are from medium-sized individuals. In their 2019 study, only the cervical vertebrae were described in detail, since bones from other parts of the body had already been treated in 2005. ==Description==

The majority of the fossil remains of Cryodrakon, among them its holotype bones, most likely represented young and subadult individuals. Their dimensions are similar to those of Quetzalcoatlus sp. (now known as the species Q. lawsoni A fully-grown Cryodrakon would have most likely been of similar size to Q. northropi, based on the size of its remains. A wingspan of about has been estimated for adult individuals. The previously mentioned specimen TMP 1980.16.1367 of Cryodrakon is also comparable in size to the holotype of Arambourgiania, which measured around , indicating that Cryodrakon would have also been of similar size to this pterosaur. but more recent estimates have been more moderate, ranging from , mostly due to the fragmentary nature of its remains. This would Arambourgiania equal to or even slightly smaller in size than Cryodrakon. In terms of body structure, Cryodrakon was proportionally similar to Quetzalcoatlus and other long-necked advanced members of the Azhdarchidae, though its somewhat more robust bones may indicate that it was slightly heavier. Cryodrakon is distinguished from all other known azhdarchids by two features of its neck vertebrae. The lateral pneumatic fossae or pneumatophores, a pair of small openings leading to air pockets on either side of the neural canal, were positioned near the lower edge of the neural canal, while those of other azhdarchids (with the purported exception of Eurazhdarcho) were positioned higher up. The second distinguishing feature related to its postexapophyses, large bony knobs adjacent to the protruding rear connection surface of each vertebra, the cotyle. The postexapophyses of Cryodrakon were prominent in width but short in length, clearly separated from the cotyle, and their facets were directed downwards. ==Classification==

'' was the pterosaur to which all azhdarchid remains from the Dinosaur Park Formation were once referred to (A), Arambourgiania (C), and Quetzalcoatlus lawsoni'' (D), with known parts in gray In its description, Hone and colleagues placed Cryodrakon in the family Azhdarchidae. No exact cladistic analysis had been given to clarify its precise relationship with other azhdarchids. However, the describers were confident that it did not belong in the basalmost (most primitive) position within Azhdarchidae due to the lack of distinct cervical zygapophyses in its middle cervicals. Additionally, based on the geological age of its fossil remains, Cryodrakon would have been one of the oldest known North American azhdarchids. In 2023, a study by paleontologist Rubi Pêgas et al. also recovered Cryodrakon within Quetzalcoatlinae, but differed from Andres in its specific position within the subfamily. In her analysis, she found Cryodrakon as the basalmost member of Quetzalcoatlinae. her study is shown in the second cladogram below. Topology 1: Andres (2021). Topology 2: Pêgas et al. (2023). }} }} }} }} == Paleobiology ==

Cryodrakon is thought to have been capable of flight, Some specimens of Cryodrakon show signs of being eaten by other archosaurs, either due to predation or scavenging. The holotype partial skeleton of Cryodrakon was found to have been scavenged by a dromaeosaurid, possibly Saurornitholestes langstoni. Aside from tooth marks, a broken tooth was found in one of the bones, which, according to the authors, meant that the thin-walled bone of Cryodrakon "must have been very tough." == Paleoenvironment==

The Dinosaur Park Formation, where fossils of Cryodrakon have been excavated, preserves many fossils from alluvial and coastal plain environments. Both of these environments would have experienced high precipitation, warm temperatures, and high humidity, with conditions becoming more swamp-like as time progressed. There was a great diversity of herbivorous dinosaurs including both lambeosaurine and saurolophine hadrosaurs, centrosaurine and chasmosaurine ceratopsians, and nodosaurid and ankylosaurid ankylosaurs, which could have been able to feed on different vegetation levels from one another. The predatory niches were occupied by small maniraptoran theropods (including dromaeosaurids and troodontids), medium-sized juvenile tyrannosaurids, and fully grown tyrannosaurids. ==See also==