Pteranodon

*Pteranodon longiceps*

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***Pteranodon*** (pronounced /tɨˈrænədɒn/; from Greek πτερ- "wing" and αν-οδων "toothless"), from the Late Cretaceous of North America (Kansas, Alabama, Nebraska, Wyoming, and South Dakota), was one of the largest pterosaur genera, with a wingspan of up to 9 metres (30 ft). *Pteranodon* is known from more fossil specimens than any other pterosaur, with about 1,200 specimens known to science, many of them well preserved with complete skulls and articulated skeletons, and was an important part of the animal community present in the Western Interior Seaway.

*Pteranodon* was a reptile, but not a dinosaur. All dinosaurs are diapsid reptiles with an upright stance, and by definition Dinosauria consists of the groups Saurischia and Ornithischia, which excludes Pterosauria. While the advanced pterodactyloid pterosaurs like *Pteranodon* had a semi-upright stance, this evolved independently of the upright stance in dinosaurs, and pterosaurs lacked the distinctive adaptations in the hip associated with the dinosaurian posture. However, dinosaurs and pterosaurs may have been closely related, and most paleontologists place them together in the group Ornithodira, or "bird necks".

## Description

*Pteranodon* was among the largest pterosaurs, with the wingspan of most adults ranging between three and six meters (9–20 ft). While most specimens are found crushed, enough fossils exist to put together a detailed description of the animal.

Unlike earlier pterosaurs such as *Rhamphorhynchus* and *Pterodactylus*, *Pteranodon* had toothless beaks, similar to those of modern birds. *Pteranodon* beaks were made of solid, bony margins that projected from the base of the jaws. The beaks were long, slender, and ended in sharp points. The upper jaw was longer than the lower jaw. The upper jaw was curved upward; while this has normally been attributed only to the upward-curving beak, one specimen (UALVP 24238) has a curvature corresponding with the beak actually widening towards the tip. While the tip of the beak is not known in this specimen, the level of curvature suggests it would have been extremely long. This led Bennett (1994) to suggest that the upward curve was not entirely due to a curved beak, but rather indicated an *Anhanguera*-like sloping crest on the front of the beak (premaxilla). However, further specimens would be necessary to determine the actual structure of the beak in *P. sternbergi*. Some specimens of both *P. sternbergi* and *P. longiceps* do preserve the beak tips, and lack any premaxillary crests.

The most distinctive characteristic of *Pteranodon* is its primary cranial crest. These crests consisted of skull bones (frontals) projecting upward and backward from the skull. The size and shape of these crests varied due to a number of factors, including age, sex, and species. Male *Pteranodon sternbergi*, the older species, had a more vertical crest with a broad forward projection, while their descendants, *Pteranodon longiceps*, evolved a narrower, more backwards-projecting crest. Females of both species were smaller, and bore small, rounded crests. See the Paleobiology section below for more on crests and their function.

Other distinguishing characteristics that set *Pteranodon* apart from other pterosaurs include narrow neural spines on the vertebrae, plate-like bony ligaments strengthening the vertebrae above the hip, and a short tail in which the last few vertebrae are fused into a rod.

There are two species of *Pteranodon* currently recognized as valid: *Pteranodon longiceps* (the type species) and *Pteranodon sternbergi*. The species differ only in the shape of the crest in adult males (described above), and possibly in the angle of certain skull bones.

*Pteranodon* fossils are known from the Niobrara and Pierre Formations of the central United States. *Pteranodon* existed as a group for over four million years during the late Coniacian - early Campanian stages of the Cretaceous period. It is present in most layers of the Niobrarra Formation except for the upper two; in 2003, Kenneth Carpenter surveyed the distribution and dating of fossils in this formation, demonstrating that *Pteranodon sternbergi* existed there from 88-85 million years ago, while *P. longiceps* existed between 86-84.5 million years ago. A possible third species is known from the Sharon springs member of the Pierre Shale Formation in Kansas, Wyoming and South Dakota, dating to between 81.5 and 80.5 million years ago.

## Classification

### Species

A number of species of *Pteranodon* have been named since the 1870s, though most are now considered to be junior synonyms of two or three valid species. The best-supported is the type species, *P. longiceps*, based on a well-preserved specimen including the first-known skull found by S.W. Williston. This individual had a wingspan of 7 mteres. Other valid species include the possibly larger *P. sternbergi*, with a wingspan originally estimated at 9 metres. *P. occidentalis*, *P. velox*, *P. umbrosus*, *P. harpyia* and *P. comptus* are considered to be nomina dubia by Bennett (1994) and others. All are probably synonymous with the more well-known *Pteranodon*species.

*Pteranodon sternbergi* is the only known species of *Pteranodon* with an upright-crest. The lower jaw of *P. sternbergi* was 1.25 meters (4 ft) long. It was collected by George F. Sternberg in 1952 and described by John Christian Harksen in 1966, from the lower portion of the Niobrara Formation. It was older than *P. longiceps* and is considered by Bennett to be the direct ancestor of the later species.

### List of species and synonyms

Because the key distinguishing characteristic Marsh noted for *Pteranodon* was its lack of teeth, any toothless pterosaur jaw fragment, wherever it was found in the world, tended to be attributed to *Pteranodon* during the late 19th and early 20th centuries. This resulted in a plethora of species and a great deal of confusion. The name became a wastebasket taxon, rather like the dinosaur *Megalosaurus*, to label any pterosaur remains that could not be distinguished other than by the absence of teeth. Species (often dubious ones now known to be based on sexual variation or juvenile characters) have been reclassified a number of times, and several sub-genera were erected in the seventies by Halsey Wilkinson Miller to hold them in various combinations, further confusing the taxonomy (subgenera include *Longicepia*, *Occidentalia*, and *Geosternbergia*). Notable authors who have discussed the various aspects of *Pteranodon* include Bennett, Padian, Unwin, Kellner, and Wellnhofer. Two species, *P. orogensis* and *P. orientalis*, are not actually pteranodontids and have been renamed *Bennettazhia oregonensis* and *Bogolubovia orientalis* respectively.

Status of names listed below follow a survey by Bennett, 1994 unless otherwise noted.

## History of discovery

*Pteranodon* was the first pterosaur found outside of Europe. Its fossils were first found by Othniel Charles Marsh in 1870, in the Late Cretaceous Smoky Hill Chalk of western Kansas. These chalk beds were deposited at the bottom of what was once the Western Interior Seaway, a large shallow sea over what is now midsection of the North American continent. These first specimens, YPM 1160 and YPM 1161, consisted of partial wing bones, as well as a tooth from the prehistoric fish *Xiphactinus*, which Marsh mistakenly believed to belong to his new pterosaur (all known pterosaurs up to that point had teeth). In 1871, Marsh named the find *Pterodactlyus oweni*, assigning it to the well-known (but much smaller) European genus *Pterodactylus*. Marsh also collected more wing bones of the large pterosaur in 1871. Realizing that the name *Pterodactylus oweni* had in 1864 already been used for a specimen of the European *Pterodactylus*, Marsh re-named his North American pterosaur *Pterodactylus occidentalis*, or "Western wing finger," in his 1872 description of the new specimen. He also named two additional species, based on size differences: *Pterodactylus ingens* (the largest specimen so far), and *Pterodactlyus velox* (the smallest).

Meanwhile, Marsh's rival Edward Drinker Cope had also unearthed several specimens of the large North American pterosaur. Based on these specimens, Cope named two new species, *Ornithochirus umbrosus* and *Ornithochirus harpyia*, in an attempt to assign them to the large European genus *Ornithocheirus*. However, as he misspelled the name (forgetting the 'e'), he accidentally created an entirely new genus. Cope's paper naming his ''*Ornithochirus* species was published in 1872, just five days after Marsh's paper. This resulted in a dispute, fought in the published literature, over whose names had priority in what were obviously the same species. Cope conceded in 1875 that Marsh's names did have priority over his, but maintained that *Pterodactylus umbrosus* was a distinct species (but not genus) from any that Marsh had named previously. Re-evaluation by later scientists has supported Marsh's case, and found that Cope's assertion that *P. umbrosus* was a larger, distinct species were wrong.

While the first *Pteranodon* wing bones were collected by Marsh and Cope in the early 1870s, the first *Pteranodon* skull was found on May 2, 1876, along the Smoky Hill River in Wallace County (now Logan County), Kansas, USA, by Samuel Wendell Williston, a fossil collector working for Marsh. A second, smaller skull soon followed. These skulls showed that the North American pterosaur was different than any European species, in that they lacked teeth. Marsh recognized that this major difference, describing the specimens as "distinguished from all previously known genera of the order Pterosauria by the entire absence of teeth." Marsh recognized that this warranted a new genus, and he coined the name *Pteranodon* ("wing without tooth") in 1876. Marsh also reclassified all the previously named North American species from *Pterodactylus* to *Pteranodon*, with the larger skull, YPM 1117, referred to the new species *Pteranodon longiceps*. He also named an additional species, *Pteranodon gracilis*, based on a wing bone that he mistook for a pelvic bone. He realized his mistake, and re-classified this specimen in a separate genus, which he named *Nyctosaurus*.

## Paleobiology

### Diet

The diet of *Pteranodon* is known to have included fish; fossilized fish bones have been found in the stomach area of one *Pteranodon*, and a fossilized fish bolus has been found between the rami of another *Pteranodon*, specimen AMNH 5098.

### Flight

The wing shape of *Pteranodon* suggests that it would have flown rather like a modern-day albatross. This is a suggestion based on the fact that the *Pteranodon* had a high aspect ratio (wingspan to chord length) similar to that of the albatross — 9:1 for *Pteranodon*, compared to 8:1 for an albatross. Albatrosses spend long stretches of time at sea fishing, and utilize a flight pattern called "dynamic soaring" which exploits the vertical gradient of wind speed near the ocean surface to travel long distances without flapping, and without the aid of thermals (which do not occur over the open ocean the same way they do over land). However, most scientists do agree that *Pteranodon* could flap their wings and fly with power. These two flight styles would not have been mutually exclusive in *Pteranodon*, or in pterosaurs in general.

### Crest

*Pteranodon* was notable for its skull crest, though the function of the crest has been a subject of debate. However, most explanations have focused on the blade-like, backward pointed crest of male *P. longiceps*, and ignored the wide range of variation across age and gender. The fact that the crests vary so much rules out most practical functions other than for use in mating displays.

George Francis Eaton, in 1910, proposed two possible functions for the crest: as an aerodynamic counterbalance, and as a muscle attachment point. He suggested that the crest might have anchored large, long jaw muscles, but admitted that this function alone could not explain the large size of some crests. Bennett (1992) agreed with Eaton's own assessment that the crest was too large and variable to have been a muscle attachment site. Eaton had suggested that a secondary function of the crest might have been as a counterbalance against the long beak, reducing the need for heavy neck muscles to control the orientation of the head. Wind tunnel tests showed that the crest did function as an effective counterbalance to a degree, but Bennett noted that the hypothesis again focuses only on the long crests of male *P. longiceps*, not on the larger crests of *P. sternbergi* and very small crests of females. Bennett found that the crests of females had no counterbalancing effect, and that the crests of male *P. sternbergi* would, by themselves, have a negative effect on the balance of the head. Side to side movement of the crests would actually have required more, not less, neck musculature to control.

In 1943, Dominik von Kripp suggested that the crest may have served as a rudder, an idea embraced by several later researchers. One researcher, Ross S. Stein, even suggested that the crest may have supported a membrane of skin connecting the backward-pointing crest to the neck and back, increasing its surface area and effectiveness as a rudder. The rudder hypothesis again does not take into account females or *P. sternbergi*, which had an upward-pointing, not backward-pointing crest. Bennett also found that even in its capacity as a rudder, the crest would not provide nearly as much directional force as simply maneuvering the wings. The suggestion that the crest was an air brake, and that the animals would turn their heads to the side in order to slow down, suffers from a similar problem. Additionally, the rudder and air brake hypotheses do not explain why such large variation exists in crest size even among adults.

Alexander Kellner suggested that the large crests of the pterosaur *Tapejara*, as well as other species, might be used for heat exchange, allowing these pterosaurs to absorb or shed heat and regulate body temperature, which would also account for the correlation between crest size and body size. However, there is no evidence of extra blood vessels in the crest for this purpose, and the large, membranous wings filled with blood vessels would have served that purpose much more effectively.

With the above hypotheses ruled out, the best supported hypothesis for crest function seems to be as a sexual display. This is consistent with the size variation seen in fossil specimens, where juveniles and females have small crests and males large, elaborate, variable crests.

### Sexual variation

Adult *Pteranodon* specimens can be divided into two distinct size classes, small and large, with the large size class being about one and a half times larger than the small, and the small being twice as common as the large. Both size classes lived along side each other, and while researchers had previously suggested that they represent different species, Christopher Bennett showed that the differences between them are consistent with the idea that they represent males and females, and that *Pteranodon* species were sexually dimorphic. Skulls from the larger size class preserve large, upwards and backward pointing crests, while the crests of the smaller size class are small and triangular. Some larger skulls also show evidence of a second crest that extended long and low along toward the tip of the beak, which is not seen in smaller specimens.

The sex of the different size classes was determined not from the skulls, but from the pelvic bones. Contrary to what may be expected, the smaller size class had disproportionately large and wide-set pelvic bones. Bennett interpreted this as indicating a more spacious birth canal, through which eggs would pass. He concluded that the small size class with small, triangular crests represent females, and the larger, large-crested specimens are male.

Note that the overall size and crest size also corresponds to age. Immature specimens are known from both females and males, and immature males often have small crests similar to adult females. Therefore, it seems that the large crests only developed in males when they reached their large, adult size, making the sex of immature specimens difficult to establish from partial remains.

The fact that females appear to have outnumbered males two to one suggests that, like modern animals with size-related sexual dimorphism such as sea lions and other pinnipeds, *Pteranodon* were polygynous, with a few males presiding over, and competing for, large numbers of females. Like modern pinnipeds, *Pteranodon* may have fought to establish territory on rocky, offshore rookeries, with the largest, and largest-crested, males gaining the most territory and having more success mating with females. The crests of male *Pteranodon* would not have been used in competition, but rather as "visual dominance-rank symbols", with display rituals taking the place of physical competition with other males. It is also likely that male *Pteranodon* played little to no part in rearing the young; such a behavior is not found in the males of modern polygynous animals.

### Locomotion

The terrestrial locomotion of *Pteranodon*, especially whether it was bipedal or quadrupedal, has historically been the subject of debate. Today, most pterosaur researchers agree that pterosaurs were quadrupedal, thanks largely to the discovery of several pterosaur trackways. The possibility of swimming has been discussed briefly in two papers (Bennett 2001 and Bramwell & Whitfield 1974), and has been studied in detail at Michigan State University through the use of quantitative morphometrics and an extant phylogenetic bracket (a morphologically comparative technique invented by Larry Witmer).

## JPInstitute.com Description

First thing, Pteranodon is not a dinosaur, it is a flying reptile. A really big flying reptile! When it spread its wings, it could reach from the front to the back of a school bus. Just imagine something that big flying around. It didn't have feathers, but it may have had a covering of fur, sort of like a bat.

Members of the pterosaur family lived through much of the Mesozoic, some with wingspans close to 50 feet. Pteranodon, as you can tell by the translation of its name, had no teeth. It probably used the long crest on the back of its head to help it steer while flying. There is still some debate about whether these reptiles could actually fly or if they were primarily gliders, but the consensus seems to be that they could take off with little or no wind.

Their diet was probably fish and scavenged remains of dead animals. Quite a few Pteranodon skeletons have been found in Kansas in the central part of the U.S. This would have been the shore of a shallow sea when these creatures were alive, supporting the theory that they were fish eaters.

## Dinosaur Field Guide Description

Pteranodon ("wings without teeth') is probably the best known of the more advanced pterosaurs, called pterodactyls ("winged fingers"). There are several species of Pteranodon, each with a distinctive crest on the back of the head. All species of Pteranodon, however, had long, slender beaks that were totally toothless. They probably ate fish that they caught while skimming over the water. Pteranodon is known from thousands of fossils, most of which are just broken fragments but some of which are complete skeletons. It had a wingspan of at least 26 feet- possibly 33 feet for the largest specimens which made it one of the largest of all
flying creatures in the history of Earth. For many decades, it was the largest pterosaur known, but larger ones have since been discovered. (Quetzalcoatlus had a wingspan of 36 feet/lI m, and Ornithocheirus had a wingspan of up to 43 feet/13 m!) Pteranodon flew above the seas of Kansas during the Late Cretaceous. Although it must have come to land to roost and lay its eggs, it does not appear to have lived much on the mainland. Therefore, pictures showing it flying over the heads of tyrant dinosaurs, horned dinosaurs, and/or duckbill dinosaurs are most likely wrong.

### Fun Facts

Pteranodon is often shown incorrectly with teeth, or with the tail of a Rhamphorhynchus. The Pteranodon briefly seen at the end of The Lost World: Jurassic Park is shown (correctly) with no teeth, but the Pteranodon in Jurassic Park Ill are shown with beakfuls of them (no doubt the result of InGen's genetic manipulations)!

### Trivia

When Pteranodon was first discovered, it became very famous. While all the pterosaurs found previously were the size of a seagull or smaller, Pteranodon was much bigger than any flying animal today.

## Links

http://web.archive.org/web/20040214170211fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_ptera.html#

## References

Template:References

1. ↑ 1.0 1.1 1.2 Bennett, S.C. (2000). "Inferring stratigraphic position of fossil vertebrates from the Niobrara Chalk of western Kansas." *Current Research in Earth Sciences: Kansas Geological Survey Bulletin*, **244**(Part 1): 26 pp.
2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 Bennett, S.C. (1994). "Taxonomy and systematics of the Late Cretaceous pterosaur *Pteranodon* (Pterosauria, Pterodactyloida)." *Occasional Papers of the Natural History Museum, University of Kansas*, **169**: 1-70.
3. ↑ Carpenter, K. (2003). "Vertebrate Biostratigraphy of the Smoky Hill Chalk (Niobrara Formation) and the Sharon Springs Member (Pierre Shale)." *High-Resolution Approaches in Stratigraphic Paleontology*, **21**: 421-437. DOI: 10.1007/978-1-4020-9053-0
4. ↑ 4.0 4.1 Template:Cite book
5. ↑ Zimmerman, H., Preiss, B., and Sovak, J. (2001). *Beyond the Dinosaurs!: sky dragons, sea monsters, mega-mammals, and other prehistoric beasts*, Simon and Schuster. ISBN 0-689-84113-2.
6. ↑ Cope, E.D. (1875). "The Vertebrata of the Cretaceous formations of the West." *Report, U. S. Geological Survey of the Territories (Hayden)*, **2**: 302 pp., 57 pls.
7. ↑ Marsh, O.C. (1876a). "Notice of a new sub-order of Pterosauria." *American Journal of Science, Series 3*, **11**(65): 507-509.
8. ↑ Marsh, O.C., (1876b). "Principal characters of American pterodactyls." *American Journal of Science, Series 3*, **12**(72): 479-480.
9. ↑ Padian, K. (1983). "A functional analysis of flying and walking in pterosaurs." *Paleobiology*, **9**(3): 218-239.
10. ↑ 10.0 10.1 Eaton, G.F. (1910). "Osteology of *Pteranodon*." *Memoirs of the Connecticut Academy of Arts and Sciences*, **2**:1-38, pls. i-xxxi.
11. ↑ 11.0 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 Bennett, S.C. (1992). "Sexual dimorphism of *Pteranodon* and other pterosaurs, with comments on cranial crests." *Journal of Vertebrate Paleontology*, **12**(4): 422-434.
12. ↑ von Kripp, D. (1943). "Ein Lebensbild von *Pteranodon ingens* auf flugtechnischer Grundlage." *Nova Acta Leopoldina, N.F.*, **12**(83): 16-32 [in German].
13. ↑ Stein, R.S. (1975). "Dynamic analysis of *Pteranodon ingens*: a reptilian adaptation to flight." *Journal of Paleontology*, **49**: 534-548.
14. ↑ 14.0 14.1 Bramwell, C.D. and Whitfield, G.R. (1974). "Biomechanics of Pteranodon." *Philosophical Transactions Royal Society B*, *267'*.
15. ↑ Bennett, S.C. (2001). "The osteology and functional morphology of the Late Cretaceous pterosaur *Pteranodon*. General description of osteology." *Palaeontographica, Abteilung A*, **260**: 1-112.
16. ↑ Smith, A.C. (2007). "Pteranodont claw morphology and its implications for aquatic locomotion." Master's Thesis, Michigan State University.