Quetzalcoatlus was a pterodactyloid
pterosaurPterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight...
known from the
Late CretaceousThe Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
of North America (
MaastrichtianThe Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
stage, about 68–65.5 million years ago), and one of the largest known flying animals of all time. It was a member of the
AzhdarchidaeAzhdarchidae is a family of pterosaurs known primarily from the late Cretaceous Period, though an isolated vertebrae apparently from an azhdarchid is known from the early Cretaceous as well...
, a family of advanced toothless pterosaurs with unusually long, stiffened necks. Its name comes from the
MesoamericaMesoamerica is a region and culture area in the Americas, extending approximately from central Mexico to Belize, Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica, within which a number of pre-Columbian societies flourished before the Spanish colonization of the Americas in the 15th and...
n feathered serpent god
QuetzalcoatlQuetzalcoatl is a Mesoamerican deity whose name comes from the Nahuatl language and has the meaning of "feathered serpent". The worship of a feathered serpent deity is first documented in Teotihuacan in the first century BCE or first century CE...
.
Description
Skull material (from the unnamed smaller species) shows that
Quetzalcoatlus had a very sharp and pointed beak, contrary to some earlier reconstructions that showed a blunter snout, based on the inadvertent inclusion of jaw material from another pterosaur species, possibly a
tapejaridTapejaridae are a family of pterodactyloid pterosaurs from the early Cretaceous period. Members are currently known from Brazil and China, where the most primitive genera are found, indicating that the family has an Asian origin....
or a form related to
TupuxuaraTupuxuara is a genus of large, crested, toothless pterodactyloid pterosaur.The genus was in 1988 named and described by Alexander Kellner and Diogenes de Almeida Campos. The type species is Tupuxuara longicristatus. The genus name refers to a familiar spirit from the mythology of the Tupi...
. A skull crest was present but its exact form and size are still unknown.
Size
When it was first discovered, scientists estimated that the largest
Quetzalcoatlus fossils came from an individual with a wingspan as large as 15.9 meters (52.2 feet), choosing the middle of three extrapolations from the proportions of other pterosaurs that gave an estimate of 11, 15.5 and 21 meters respectively (36 feet, 50.85 feet, 68.9 feet). In 1981, further study lowered these estimates to 11–12 meters (36–39 feet). More recent estimates based on greater knowledge of azhdarchid proportions place its wingspan at 10–11 meters (33–36 ft).
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. While some studies have historically found extremely low weight estimates for
Quetzalcoatlus, as low as 70 kilograms (154.3 lb) for a 10-meter individual, a majority of estimates published since the 2000s have been higher, and the tend toward 200–250 kg (440.9–551.2 lb).
Discovery and species
The first
Quetzalcoatlus fossils were discovered in
TexasTexas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
, from the
MaastrichtianThe Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
Javelina FormationThe Javelina Formation is a geological formation in Texas. Dating has shown that the strata date to the mid-late Maastrichtian stage of the Late Cretaceous, with the middle part of the formation dated to about 69 million years ago plus or minus 1 Ma and the top situated near the K-Pg boundary,...
at
Big Bend National ParkBig Bend National Park is a national park located in the U.S. state of Texas. Big Bend has national significance as the largest protected area of Chihuahuan Desert topography and ecology in the United States, which includes more than 1,200 species of plants, more than 450 species of birds, 56...
(dated to around 68 million years ago) in 1971 by a geology graduate student from the University of Texas at Austin's
Jackson School of GeosciencesThe Jackson School of Geosciences at The University of Texas at Austin unites the Department of Geological Sciences with two research units, the Institute for Geophysics and the Bureau of Economic Geology....
,
Douglas A. LawsonDouglas A. Lawson is a geologist, paleontologist, and computer scientist.In 1971, Lawson discovered a partial wing Douglas A. Lawson (born 1947) is a geologist, paleontologist, and computer scientist.In 1971, Lawson discovered a partial wing Douglas A. Lawson (born 1947) is a geologist,...
. 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
wingspanThe wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...
. Lawson discovered a second site of the same age, about forty kilometers from the first, where between 1972 and 1974 he and Professor Wann Langston Jr. of the
Texas Memorial MuseumThe Texas Memorial Museum is the main exhibit hall of the Texas Natural Science Center at the University of Texas at Austin in Austin, Texas, USA....
unearthed three fragmentary skeletons of much smaller individuals. Lawson in 1975 announced the find in an article in
ScienceScience is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....
. That same year, in a subsequent letter to the same journal, he made the original large specimen, TMM 41450-3, the
holotypeA holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
of a new genus and species,
Quetzalcoatlus northropi. The genus name refers to the
AztecThe Aztec people were certain ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl language and who dominated large parts of Mesoamerica in the 14th, 15th and 16th centuries, a period referred to as the late post-classic period in Mesoamerican chronology.Aztec is the...
feathered serpent god
QuetzalcoatlQuetzalcoatl is a Mesoamerican deity whose name comes from the Nahuatl language and has the meaning of "feathered serpent". The worship of a feathered serpent deity is first documented in Teotihuacan in the first century BCE or first century CE...
. The specific name honors
John Knudsen NorthropJohn Knudsen "Jack" Northrop was an American aircraft industrialist and designer, who founded the Northrop Corporation in 1939.-Entering aviation:...
, the founder of
NorthropNorthrop Corporation was a leading United States aircraft manufacturer from its formation in 1939 until its merger with Grumman to form Northrop Grumman in 1994. The company is known for its development of the flying wing design, although only a few of these have entered service.-History:Jack...
, who was interested in large tailless
flying wingA flying wing is a tailless fixed-wing aircraft which has no definite fuselage, with most of the crew, payload and equipment being housed inside the main wing structure....
aircraft designs resembling
Quetzalcoatlus. 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 KellnerAlexander Wilhelm Armin Kellner is a Liechtensteinian/Brazilian paleontologist, a leading expert in the field of the study of pterosaurs....
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 meters (18 ft).
The holotype specimen of
Q. northropi has yet to be discovered and described. Where the known remains overlap, it has been considered by Mark Witton and colleagues (2010) to be indistinguishable from its
RomaniaRomania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...
n contemporary
HatzegopteryxHatzegopteryx is a genus of azhdarchid pterosaur, known from incomplete remains found in Transylvania. The skull fragments, left humerus, and other fossilized remains indicate it was among the largest pterosaurs. The skeleton of Hatzegopteryx has been considered identical to the known remains of...
. If
Q. northropi is complete enough to be distinguished from other pterosaurs (i.e., if it is not a
nomen dubiumIn zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
),
Hatzegopteryx may represent the same animal. It is likely that huge pterosaurs such as
Q. northropi would have had very large, transcontinental ranges, making its presence in both North America and Europe unsurprising. Mark Witton
et al. pointed out that the skull material of
Hatzegopteryx and
Q. sp. differ enough that they cannot be regarded as the same animal, making it likely that
Q. sp., if not identical to
Quetzalcoatlus northropi, represents a distinct genus.
An azhdarchid neck vertebra, discovered in 2002 from the Maastrichtian age
Hell Creek FormationThe Hell Creek Formation is an intensely-studied division of Upper Cretaceous to lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana...
, 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 tyrannosaur specimen. Despite this association with the remains of a large carnivorous
dinosaurDinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
, 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 - 5.5m (16.5 – 18 ft).
Paleobiology
Quetzalcoatlus was abundant in Texas during the
Lancian-Geology:Terrestrial sedimentary strata from the Judithian to the Lancian are generally regressive through-out the entire sequence, so the preserved changes in fossil communities represent not only phylogenetic changes but ecological zones from the submontane habitats to near-sea level coastal...
in a fauna dominated by
AlamosaurusAlamosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now North America. It was a large quadrupedal herbivore. Isolated vertebrae and limb bones indicate that it reached sizes comparable to Argentinosaurus and Puertasaurus, which would make it the...
. The
Alamosaurus-
Quetzalcoatlus association probably represents semi-arid inland plains.
Quetzalcoatlus had precursors in North America and its apparent rise to widespreadness may represent the expansion of its preferred habitat rather than an immigration event, as some experts have suggested.
Feeding
There have been a number of different ideas proposed about the lifestyle of
Quetzalcoatlus. Because the area of the fossil site was four hundred kilometers removed from the coastline and there were no indications of large rivers or deep lakes nearby at the end of the Cretaceous, Lawson in 1975 rejected a
fish-eatingA piscivore is a carnivorous animal which eats primarily fish. Piscivory was the diet of early tetrapods , insectivory came next, then in time reptiles added herbivory....
lifestyle, instead suggesting that
Quetzalcoatlus scavenged like the
Marabou StorkThe Marabou Stork, Leptoptilos crumeniferus, is a large wading bird in the stork family Ciconiidae. It breeds in Africa south of the Sahara, occurring in both wet and arid habitats, often near human habitation, especially waste tips...
, but then on the carcasses of titanosaur
sauropodsSauropoda , or the sauropods , are an infraorder of saurischian dinosaurs. They had long necks, long tails, small heads , and thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land...
such as
AlamosaurusAlamosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now North America. It was a large quadrupedal herbivore. Isolated vertebrae and limb bones indicate that it reached sizes comparable to Argentinosaurus and Puertasaurus, which would make it the...
. Lawson had found the remains of the giant pterosaur while searching for the bones of this dinosaur, which formed an important part of its ecosystem.
In 1996, Thomas Lehman and Langston rejected the scavenging hypothesis, pointing out that the lower jaw bent so strongly downwards that even when it closed completely a gap of over five centimeters remained between it and the upper jaw, very different from the hooked beaks of specialized scavenging birds. They suggested that with its long neck vertebrae and long toothless jaws
Quetzalcoatlus fed like modern-day
skimmerThe Skimmers, Rynchopidae, are a small family of tern-like birds in the order Charadriiformes, which also includes the waders, gulls and auks. The family comprises three species found in South Asia, Africa, and the Americas....
s, catching fish on the wing while cleaving the waves with its beak. While this skim-feeding view became widely accepted, it was not subjected to scientific research until 2007 when a study showed that for such large pterosaurs it was not a viable method because the energy costs would be too high due to excessive
dragIn fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...
. In 2008 pterosaur workers Mark Paul Witton and
Darren NaishDarren Naish is a vertebrate palaeontologist and science writer. He obtained a geology degree at the University of Southampton and later studied vertebrate palaeontology under British palaeontologist David Martill at the University of Portsmouth, where he obtained both an M. Phil...
published an examination of possible feeding habits and ecology of azhdarchids. Witton and Naish noted that most azhdarchid remains are found in inland deposits far from seas or other large bodies of water required for skimming. Additionally, the beak, jaw, and neck anatomy are unlike those of any known skimming animal. Rather, they concluded that azhdarchids were more likely terrestrial stalkers, similar to modern
storkStorks are large, long-legged, long-necked wading birds with long, stout bills. They belong to the family Ciconiidae. They are the only family in the biological order Ciconiiformes, which was once much larger and held a number of families....
s, and probably hunted small vertebrates on land or in small streams. Though
Quetzalcoatlus, like other pterosaurs, was a quadruped when on the ground,
Quetzalcoatlus and other azhdarchids have fore and hind limb proportions more similar to modern running
ungulateUngulates are several groups of mammals, most of which use the tips of their toes, usually hoofed, to sustain their whole body weight while moving. They make up several orders of mammals, of which six to eight survive...
mammals than to their smaller cousins, implying that they were uniquely suited to a terrestrial lifestyle.
Flight
The nature of flight in
Quetzalcoatlus and other giant azhdarchids is poorly understood. Their method of flight depends largely on their weight, which has been controversial, with widely differing masses favored by different scientists. Some researchers have suggested that these animals employed slow,
soaringGliding flight is heavier-than-air flight without the use of thrust. It is employed by gliding animals and by aircraft such as gliders. The most common human application of gliding flight is in sport and recreation using aircraft designed for this purpose...
flight, while others have concluded that their flight was fast and dynamic. In 2010, Donald Henderson argued that the mass of
Q. northropi has been underestimated, even the highest estimates, and that it was too massive to have achieved powered flight. Henderson argued that it may have been flightless.
Paul MacCreadyPaul B. MacCready, Jr. was an American aeronautical engineer. He was the founder of AeroVironment and the designer of the human-powered aircraft that won the Kremer prize...
undertook an aerodynamics experiment testing the flight of
Quetzalcoatlus in 1986. He constructed a model flying machine or
ornithopterAn ornithopter is an aircraft that flies by flapping its wings. Designers seek to imitate the flapping-wing flight of birds, bats, and insects. Though machines may differ in form, they are usually built on the same scale as these flying creatures. Manned ornithopters have also been built, and some...
with a simple computer functioning as an
autopilotAn autopilot is a mechanical, electrical, or hydraulic system used to guide a vehicle without assistance from a human being. An autopilot can refer specifically to aircraft, self-steering gear for boats, or auto guidance of space craft and missiles...
. The model successfully flew with a combination of soaring and wing flapping; however, the model was half scale based on a then-current weight estimate of around 80 kg, far lower than more modern estimates of over 200 kg.
(Also, see below.)
In popular culture
Quetzalcoatlus has been featured in documentaries, both in cinemas and on television, since the 1980s. The Smithsonian project to build a working model of
Q. northropi was the subject of the 1986
IMAXIMAX is a motion picture film format and a set of proprietary cinema projection standards created by the Canadian company IMAX Corporation. IMAX has the capacity to record and display images of far greater size and resolution than conventional film systems...
documentary
On the WingOn the Wing is a 1986 IMAX film featuring a half-sized robotic Quetzalcoatlus that demonstrates principles of animal flight.The film is narrated by F. Murray Abraham....
, shown at the National Air and space museum in
Washington, D.C.Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
. It has also been featured in television programs such as the
BBCThe British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
's
Walking with DinosaursWalking with Dinosaurs is a six-part documentary television miniseries that was produced by BBC, narrated by Kenneth Branagh, and first aired in the United Kingdom, in 1999. The series was subsequently aired in North America on the Discovery Channel in 2000, with Branagh's voice replaced with that...
in 1999 and Dangerous, Ltd.'s
Clash of the DinosaursClash of the Dinosaurs is a four-part television mini-series produced by Dangerous LTD for Discovery Channel. The show premiered on December 13, 2009 with a double-episode.-Featured genera:* Ankylosaurus* Deinonychus* Parasaurolophus...
in 2009. The later program featured traits invented by the producers to heighten entertainment value, including a depiction of
Quetzalcoatlus with the ability to use ultraviolet vision to locate dinosaur urine when hunting in the air. It was also depicted in the 2011 documentary
March of the Dinosaurs, where it was erroneously depicted as a clawless, bipedal scavenger, and in the 2009 series
Animal ArmageddonAnimal Armageddon is an American paleontology-based documentary television miniseries that originally aired from to on Animal Planet. All the prehistoric scenes are created 100% in Lightwave...
, where it was correctly portrayed with pycnofibres.
In June 2010, several life-sized models of
Q. northropi were put on display on London's
South BankSouth Bank is an area of London, England located immediately adjacent to the south side of the River Thames. It forms a long and narrow section of riverside development that is within the London Borough of Lambeth to the border with the London Borough of Southwark and was formerly simply known as...
as the centerpiece exhibit for the
Royal SocietyThe Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
’s 350th anniversary exhibition. The models, which included both flying and standing individuals with wingspans of 30 feet (9.1 m), were intended to help build interest in science among the public. The models were created by scientists from the
University of PortsmouthThe University of Portsmouth is a university in Portsmouth, Hampshire, England. The University was ranked 60th out of 122 in The Sunday Times University Guide...
, including David Martill, Bob Loveridge and Mark Witton, and engineers Bob and Jack Rushton from Griffon Hoverwork. The display presented to the public the most accurate pterosaur models constructed at the time, taking into account anatomical and footprint evidence based on skeletal and trace fossils from related pterosaurs.
In modern technology designs
In 1985, the U.S.
Defense Advanced Research Projects AgencyThe Defense Advanced Research Projects Agency is an agency of the United States Department of Defense responsible for the development of new technology for use by the military...
(DARPA) and
AeroVironmentAeroVironment Inc. is a technology company in Monrovia, California, and Simi Valley, California, that is primarily involved in energy systems, electric vehicle systems, and unmanned aerial vehicles . Paul B. MacCready, Jr., a famous designer of human powered aircraft, founded the company in 1971...
used
Quetzalcoatlus northropi as the basis for an experimental
ornithopterAn ornithopter is an aircraft that flies by flapping its wings. Designers seek to imitate the flapping-wing flight of birds, bats, and insects. Though machines may differ in form, they are usually built on the same scale as these flying creatures. Manned ornithopters have also been built, and some...
UAV. They produced a half-scale model weighing 40 pounds (18.1 kg), with a wingspan of 18 feet (5.5 m). Coincidentally, Douglas A. Lawson, who discovered
Q. northropi in Texas in 1971, named it for
John "Jack" NorthropJohn Knudsen "Jack" Northrop was an American aircraft industrialist and designer, who founded the Northrop Corporation in 1939.-Entering aviation:...
, a famous developer of tailless
flying wingA flying wing is a tailless fixed-wing aircraft which has no definite fuselage, with most of the crew, payload and equipment being housed inside the main wing structure....
aircraft in the 1940s. The replica of
Q. northropi incorporates a "flight control system/autopilot which processes pilot commands and sensor inputs, implements several feedback loops, and delivers command signals to its various servo-actuators." It is on exhibit at the
National Air and Space MuseumThe National Air and Space Museum of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1976. Located in Washington, D.C., United States, it is a center for research into the history and science of aviation and...
.