''Pteranodon sternbergi'' is an extinct
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of the
pteranodontid
The Pteranodontidae are a family of large pterosaurs from the Late Cretaceous of North America and possibly other continents including Europe and Africa. The family was named in 1876 by Othniel Charles Marsh. Pteranodontids had a distinctive, elon ...
pterodactyloid
Pterodactyloidea ( ; derived from the Greek words ''πτερόν'' (''pterón'', for usual ''ptéryx'') "wing", and ''δάκτυλος'' (''dáktylos'') "finger") is one of the two traditional suborders of pterosaurs ("wing lizards"), and contai ...
pterosaur
Pterosaurs are an extinct clade of flying reptiles in the order Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 million to 66 million years ago). Pterosaurs are the earli ...
genus ''
Pteranodon
''Pteranodon'' (; from and ) is a genus of pterosaur that included some of the largest known flying reptiles, with ''P. longiceps'' having a wingspan of over . They lived during the late Cretaceous geological period of North America in presen ...
'' from the
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...
geological period of
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
. ''P. sternbergi'' was among the largest pterosaurs, with a wingspan of up to in males. It has been argued that ''P. sternbergi'' should be classified in a separate genus, ''Geosternbergia'', but this has not been followed by most other researchers.
Discovery and history
The first fossils of ''Pteranodon sternbergi'' were collected by American paleontologist
George F. Sternberg in 1952 from the lower portion of the
Niobrara Formation
The Niobrara Formation , also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is com ...
. The fossils of the animal looked similar to those of the species ''
Pteranodon longiceps
''Pteranodon'' (; from and ) is a genus of pterosaur that included some of the largest known flying reptiles, with ''P. longiceps'' having a wingspan of over . They lived during the late Cretaceous geological period of North America in presen ...
'', but the crests were set upright and in a slightly different position. In 1958, Sternberg and paleontologist
Myrl V. Walker published a study about this peculiar find.
In 1966, American paleontologist
John Christian Harksen assigned the specimens found as a new species of ''Pteranodon'' called ''P. sternbergi'' due to its distinct upright crest that set it apart from ''P. longiceps''.
Halsey W. Miller however, concluded a revision of the different species of ''Pteranodon'' in 1971, and created three different
subgenera
In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus.
In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...
. One of which was ''Sternbergia'', which consisted of the ''Pteranodon'' specimens with upright crests. ''P. sternbergi'' was assigned to this subgenus along with another species called ''P. walkeri'', but Miller then found out that the name ''Sternbergia'' had been preoccupied, so he changed it into ''Geosternbergia'' instead.
Paleontologists like
S. Christopher Bennett consider ''P. sternbergi'' to be older than ''P. longiceps'', and therefore the direct ancestor of that species.
[
]
The most complete example of the species, currently in the collections of the University of Alberta Laboratory for Vertebrate Paleontology as specimen number UALVP 24238, is a partially-articulated sub-adult fossil with a wingspan of about . The skeleton is missing only parts of the skull and the ends of the wings and feet, was discovered in 1974 near Utica, Kansas
Utica is a city in Ness County, Kansas, United States. As of the 2020 census, the population of the city was 99.
History
The first post office in Utica was established in 1879.
Utica was named by early pioneer C.W. Bell who was from Utica ...
. The fossil was found by Richard C. Fox and Allen Lindoe in rocks belonging to the lower part of the Smoky Hill Chalk Member of the Niobrara Formation
The Niobrara Formation , also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is com ...
. These rocks date to the late Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by ...
or early Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...
stage, about 86 million years ago. In 2010
The year saw a multitude of natural and environmental disasters such as the 2010 Haiti earthquake, the Deepwater Horizon oil spill, and the 2010 Chile earthquake. The 2009 swine flu pandemic, swine flu pandemic which began the previous year ...
, a paper by Alexander W.A. Kellner argued that this specimen was different enough from ''G. sternbegi'' that it should be re-classified as its own genus and species, which he named ''Dawndraco kanzai''. This generic name combined the Dawn deity of the Iroquois
The Iroquois ( ), also known as the Five Nations, and later as the Six Nations from 1722 onwards; alternatively referred to by the Endonym and exonym, endonym Haudenosaunee ( ; ) are an Iroquoian languages, Iroquoian-speaking Confederation#Ind ...
with a Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
''draco'', "dragon
A dragon is a Magic (supernatural), magical legendary creature that appears in the folklore of multiple cultures worldwide. Beliefs about dragons vary considerably through regions, but European dragon, dragons in Western cultures since the Hi ...
". The specific name Specific name may refer to:
* in Database management systems, a system-assigned name that is unique within a particular database
In taxonomy, either of these two meanings, each with its own set of rules:
* Specific name (botany), the two-part (bino ...
refers to the Kanza tribe of Kansas
Kansas ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named a ...
.[ Kellner thought that several features of the skeleton supported his hypothesis that ''D. kanzai'' was a unique species, most notably its unique snout, which does not strongly taper towards the tip as in female ''Pteranodon'' specimens, with the upper and lower margins running almost parallel instead. Kellner thought this meant the specimen must have had a crest running along the length of the snout. However, a re-examination of the fossil published in 2017 by Elizabeth Martin-Silverstone and colleagues argued that the differences in the snout were more likely due to male pteranodontids having longer, broader bills than the more complete female specimens Kellner used for comparison. Martin-Silverstone concluded that "''Dawndraco''" was simply a male ''P. sternbergi'' with a very long bill with a gradual taper.]
''P. sternbergi'' fossils are known from the Niobrara and Sharon Springs Formations of the central United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
. ''Geosternbergia'' existed as a group for more than four million years during the late Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by ...
– early Campanian
The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...
stages of the Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
period. The genus is present in the lower the Niobrarra Formation except for the upper two; in 2003, Kenneth Carpenter
Kenneth Carpenter (born 21 September 1949) is an American paleontologist. He is the former director of the USU Eastern Prehistoric Museum and author or co-author of books on dinosaurs and Mesozoic life. His main research interests are armore ...
surveyed the distribution and dating of fossils in this formation, demonstrating that ''Pteranodon sternbergi'' existed there from 88 to 85 million years ago, while the species later named ''G. maiseyi'' existed between 81.5 and 80.5 million years ago.
Description
Size
''Pteranodon sternbergi'' was among the largest pterosaurs, with the wingspan of most adults ranging between . No complete skulls of adult males have been found, but a nearly complete lower jaw has been estimated at long.[Zimmerman, H., Preiss, B., and Sovak, J. (2001). ''Beyond the Dinosaurs!: sky dragons, sea monsters, mega-mammals, and other prehistoric beasts'', Simon and Schuster. .] While most specimens are found crushed, enough fossils exist to put together a detailed description of the animal. ''P. sternbergi'' differs from its close relative ''Pteranodon longiceps'' mainly due to its earlier time period and broader, more upright crest.[
]
Skull and beak
The upright cranial crest of ''P. sternbergi'' is its distinctive characteristic. 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 ''P. sternbergi'', the older species of the two described to date, had a larger vertical crest with a broad forward projection, while ''G. maiseyi'' had a short, rounded vertical crest and was generally smaller. Females of both species were smaller and bore small, rounded crests.[ The crests were probably mainly display structures, though they may have had other functions as well.][
Unlike the earlier pterosaurs, such as the rhamphorhynchids and the pterodactylids, ''P. sternbergi'' had a toothless ]beak
The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for pecking, grasping, and holding (in probing for food, eating, manipulating and ...
that was made of solid, bony margins that projected from the base of the jaws, similar to modern-day bird
Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
s. The structure of the beaks were long, slender, and ended in thin, sharp points. Its maxilla
In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...
was also found to be longer than the mandible
In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla).
The jawbone i ...
, and was curved upward.
Classification
''Pteranodon sternbergi'' is one of the two widely recognized species of ''Pteranodon
''Pteranodon'' (; from and ) is a genus of pterosaur that included some of the largest known flying reptiles, with ''P. longiceps'' having a wingspan of over . They lived during the late Cretaceous geological period of North America in presen ...
''. Alexander Kellner has argued that ''Pteranodon sternbergi'' should be classified in a separate genus, ''Geosternbergia'',[ but other pterosaur researchers have regarded this split as unwarranted and continued to classify it as a species of ''Pteranodon''.] Kellner also classified a specimen previously identified as ''Pteranodon longiceps'' as a second species of ''Geosternbergia'', ''G. maiseyi''.[
Below is a ]cladogram
A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...
showing the phylogenetic placement of this species within Pteranodontia
Pteranodontia is an extinct group of ornithocheiroid pterodactyloid pterosaurs. It lived during the Late Cretaceous (Turonian to Maastrichtian stages) of North America, South America, Europe and Africa. They were some of the most advanced pterosa ...
from Andres and Myers (2013).
Both species previously referred to ''Geosternbergia'' were separately included as those of ''Pteranodon'' (''P. sternbergi'' and ''P. maiseyi'') based on phylogenetic analysis in 2024.
Paleobiology
Sexual variation
Adult ''P. sternbergi'' specimens may 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 alongside 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 concept that they represent females and males, and that ''P. sternbergi'' was sexually dimorphic
Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
. Skulls from the larger size class preserve large, upward 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, toward the tip of the beak, which is not seen in smaller specimens.
The gender 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 represent males.[
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 gender of immature specimens difficult to establish from partial remains.]
The fact that females appear to have outnumbered males two to one suggests that, as with modern animals with size-related sexual dimorphism, such as sea lion
Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly. Together with the fur seals, they make up the family Otariidae, eared seals. ...
s and other pinniped
Pinnipeds (pronounced ), commonly known as seals, are a widely range (biology), distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammals. They comprise the extant taxon, extant families Odobenidae (whose onl ...
s, ''P. sternbergi'' might have been polygynous
Polygyny () is a form of polygamy entailing the marriage of a man to several women. The term polygyny is from Neoclassical Greek πολυγυνία (); .
Incidence
Polygyny is more widespread in Africa than in any other continent. Some scholar ...
, with a few males competing for association with groups consisting of large numbers of females. Similar to modern pinnipeds, ''P. sternbergi'' may have competed 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 ''P. sternbergi'' 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. If this hypothesis
A hypothesis (: hypotheses) is a proposed explanation for a phenomenon. A scientific hypothesis must be based on observations and make a testable and reproducible prediction about reality, in a process beginning with an educated guess o ...
is correct, it also is likely that male ''P. sternbergi'' played little to no part in rearing the young; such a behavior is not found in the males of modern polygynous animals who father many offspring at the same time.[
]
See also
* List of pterosaur genera
This list of pterosaurs is a comprehensive listing of all Genus, genera that have ever been included in the order Pterosauria, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considere ...
* Timeline of pterosaur research
This timeline of pterosaur research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, and Biological taxonomy, taxonomic revisions of pterosaurs, the famed flying reptiles of the Mesozoic Era (ge ...
* Pterosaur size
References
{{Portal bar, Paleontology, United States
Late Cretaceous pterosaurs of North America
Pteranodontia
Taxa named by Alexander Kellner
Fossil taxa described in 1978