Quetzalcoatlus

Quetzalcoatlus Temporal range: Late Cretaceous (Maastrichtian), 68–66 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Skeletal reconstruction of Q. lawsoni
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Order:	†Pterosauria
Suborder:	†Pterodactyloidea
Family:	†Azhdarchidae
Subfamily:	†Quetzalcoatlinae
Genus:	†Quetzalcoatlus Lawson, 1975
Type species
†Quetzalcoatlus northropi Lawson, 1975
Other species
†Q. lawsoni Andres and Langston Jr., 2021
Synonyms
Pteranodon gigas Lawson, 1972

Quetzalcoatlus (/kɛtsəlkoʊˈætləs/) is a genus of azhdarchid pterosaur that lived during the Maastrichtian age of the Late Cretaceous in North America. The first specimen, recovered in 1971 from the Javelina Formation of Texas, United States, consists of several wing fragments and was described as Quetzalcoatlus northropi in 1975 by Douglas Lawson. The first part of the name refers to the Aztec serpent god of the sky, Quetzalcōātl, while the second part honors Jack Northrop, designer of a tailless fixed-wing aircraft. The remains of a second species were found between 1972 and 1974, also by Lawson, around 40 km (25 mi) from the Q. northropi locality. In 2021, these remains were assigned the name Quetzalcoatlus lawsoni by Brian Andres and (posthumously) Wann Langston Jr.

Quetzalcoatlus northropi has gained fame as a candidate for the largest flying animal ever discovered, though estimating its size has been difficult due to the fragmentary nature of the only known specimen. Wingspan estimates over the years have ranged from 5.2–25.8 m (17–85 ft), though this has more recently been narrowed down to around 10–11 m (33–36 ft) based on extrapolations from more complete members of the Azhdarchidae, the family to which Quetzalcoatlus belongs. The smaller and more complete Q. lawsoni had a wingspan of around 4.5 m (15 ft). The proportions of Quetzalcoatlus were typical of azhdarchids, with a very long neck and beak, shortened non-wing digits that were well adapted for walking, and a very short tail.

Historical interpretations of the diet of Quetzalcoatlus have ranged from scavenging to skim-feeding like the modern skimmer bird. However, more recent research has found that it most likely hunted small prey on the ground, in a similar way to storks and ground hornbills. This has been dubbed the terrestrial stalking model and is thought to be a common feeding behavior among large azhdarchids. On the other hand, the second species, Q. lawsoni, appears to have been associated with alkaline lakes, and a diet of small aquatic invertebrates has been suggested. Similarly, while Q. northropi is speculated have been fairly solitary, Q. lawsoni appears to have been highly gregarious (social).

For years it was uncertain how Quetzalcoatlus took off. Early models using a bipedal (two-legged) posture, such as that of Sankar Chatterjee and R.J. Templin in 2004, were heavily reliant on a relatively low body weight (about 70 kg (150 lb) in Chatterjee and Templin's case) and struggled to explain how takeoff was achieved. Based on the work of Mark P. Witton and Michael Habib in 2010, it now seems likely that pterosaurs, especially larger taxa such as Quetzalcoatlus, launched quadrupedally (from a four-legged posture), using the powerful muscles of their forelimbs to propel themselves off the ground and into the air.