Quetzalcoatlus

***Quetzalcoatlus*** /kɛtsəlkoʊˈætləs/ is a genus of pterosaur known from the Late Cretaceous period of North America (Maastrichtian stage); its members were among the largest known flying animals of all time. *Quetzalcoatlus* is a member of the Azhdarchidae, a family of advanced toothless pterosaurs with unusually long, stiffened necks. Its name comes from the Aztec feathered serpent god Quetzalcoatl, the feathered serpent. The type species is ***Q. northropi***, named by Douglas Lawson in 1975; the genus also includes the smaller species ***Q. lawsoni***, which was known for many years as an unnamed species before being named by Brian Andres and Wann Langston Jr. (posthumously) in 2021.

## Discovery and species

Cast of the holotype humerus
The first *Quetzalcoatlus* fossils were discovered in Texas, United States, from the MaastrichtianJavelina Formation at Big Bend National Park(dated to around 68 million years ago) in 1971 by Douglas A. Lawson, then a geology graduate student from the Jackson School of Geosciences at the University of Texas at Austin. The specimen consisted of a partial wing (in pterosaurs composed of the forearms and elongated fourth finger), from an individual later estimated at over 10 m (33 ft) in wingspan.

Lawson discovered a second site of the same age, about 40 km (25 mi) from the first, where between 1972 and 1974 he and Professor Wann Langston Jr. of the Texas Memorial Museumunearthed three fragmentary skeletons of much smaller individuals. Lawson in 1975 announced the find in an article in *Science*. That same year, in a subsequent letter to the same journal, he made the original large specimen, TMM 41450-3, the holotype of a new genus and species, *Quetzalcoatlus northropi*. The genus name refers to the Aztec feathered serpent god, Quetzalcoatl. The specific name honors John Knudsen Northrop, the founder of Northrop, who drove the development of large tailless flying wingaircraft designs resembling *Quetzalcoatlus*.
Skeletal reconstruction of *Q. lawsoni*.

At first it was assumed that the smaller specimens were juvenile or subadult forms of the larger type. Later, when more remains were found, it was realized they could have been a separate species. This possible second species from Texas was provisionally referred to as a *Quetzalcoatlus* sp. by Alexander Kellner and Langston in 1996, indicating that its status was too uncertain to give it a full new species name. The smaller specimens are more complete than the *Q. northropi* holotype, and include four partial skulls, though they are much less massive, with an estimated wingspan of 5.5 m (18 ft). This species was named *Q. lawsoni* in 2021, named after the genus' original describer.

The holotype specimen of *Q. northropi* had not been properly described and diagnosed until 2021 and until then the status of the genus *Quetzalcoatlus*was identified as problematic. Mark Witton and colleagues (2010) noted that the type species of the genus—the fragmentary wing bones comprising *Q. northropi*—represent elements which are typically considered undiagnostic to generic or specific level, and that this complicates interpretations of azhdarchid taxonomy. For instance, Witton *et al.* (2010) suggested that the *Q. northropi* type material is of generalized enough morphology to be near identical to that of other giant azhdarchids, such as the overlapping elements of the contemporary Romanian giant azhdarchid *Hatzegopteryx*. This being the case, and assuming *Q. northropi* can be distinguished from other pterosaurs (i.e., if it is not a *nomen dubium*), perhaps *Hatzegopteryx*should be regarded as a European occurrence of *Quetzalcoatlus*. However, Witton *et al.* also noted that the skull material of *Hatzegopteryx* and *Q. lawsoni* differ enough that they cannot be regarded as the same animal, but that the significance of this cannot be ascertained given uncertainty over the relationships of *Quetzalcoatlus*specimens. These issues can only be resolved by *Q. northropi* being demonstrated as a valid taxon and its relationships with *Q. lawsoni* being investigated. An additional complication to these discussions is the likelihood that huge pterosaurs such as *Q. northropi* could have made long, transcontinental flights, suggesting that locations as disparate as North America and Europe could have shared giant azhdarchid species. *Q. lawsoni*was found to be a valid taxon in 2021, and confirmed to belong to the same genus as *Q. northropi*.

An azhdarchid neck vertebra, discovered in 2002 from the Maastrichtian age Hell Creek Formation, may also belong to *Quetzalcoatlus*. The specimen (BMR P2002.2) was recovered accidentally when it was included in a field jacket prepared to transport part of a *Tyrannosaurus* specimen. Despite this association with the remains of a large carnivorous dinosaur, the vertebra shows no evidence that it was chewed on by the dinosaur. The bone came from an individual azhdarchid pterosaur estimated to have had a wingspan of 5–5.5 m (16–18 ft).

## Description

### Size[edit]

See also: Pterosaur size
Size comparison of a human to *Q. northropi* (green) and *Q. lawsoni* (blue)

When it was first named as a new species in 1975, scientists estimated that the largest *Quetzalcoatlus* fossils came from an individual with a wingspan as large as 15.9 m (52 ft). Choosing the middle of three extrapolations from the proportions of other pterosaurs gave an estimate of 11 m, 15.5 m, and 21 m, respectively (36 ft, 50.85 ft, 68.9 ft). In 1981, further advanced studies lowered these estimates to 11–12 m (36–39 ft).
Comparison of *Q. northropi*with a Cessna 172 light aircraft.

A life size restoration of *Q. northropi* at The Field Museum in Chicago.

More recent estimates based on greater knowledge of azhdarchid proportions place its wingspan at 10–11 m (33–36 ft). Remains found in Texas in 1971 indicate that this pterosaur had a minimum wingspan of about 11 m (36 ft).Generalized height in a bipedal stance, based on its wingspan, would have been at least 3 m (9.8 ft) high at the shoulder.

Body mass estimates for giant azhdarchids are extremely problematic because no existing species share a similar size or body plan, and in consequence, published results vary widely. Generalized weight, based on some studies that have historically found extremely low weight estimates for *Quetzalcoatlus*, was as low as 70 kg (150 lb) for a 10 m (32 ft 10 in) individual. A majority of estimates published since the 2000s have been substantially higher, around 200–250 kg (440–550 lb).

In 2021, Kevin Padian and his colleagues estimated that *Q. lawsoni* would have weighed 20 kg (44 lb) for individuals with a wingspan of 4.5 m (15 ft). In 2022, Gregory S. Paul estimated that *Q. lawsoni* had a wingspan of 5 m (16 ft), body length of 3.5 m (11 ft), and body mass of 65 kg (143 lb).