Nyctosaurus
Encyclopedia
Nyctosaurus is a genus
of pterodactyloid pterosaur
, the remains of which have been found in the Niobrara Formation
of the mid-western United States
, which, during the late Cretaceous Period, was covered in an extensive shallow sea. The genus Nyctosaurus has had numerous species referred to it, though how many of these may actually be valid requires further study. At least one species possessed an extraordinarily large antler-like cranial crest.
. It had relatively long wings, similar in shape to modern seabirds. However, it was smaller overall than Pteranodon, with an adult wingspan of 2 meters and a maximum weight of about 1.86 kg. The overall body length was 37 cm. Some specimens preserve a distinctive crest, at least 55 cm tall in old adults, relatively gigantic compared to the rest of the body and over three times the length of the head. The crest is composed of two long, grooved spars, one pointed upward and the other backward, arising from a common base projecting up and back from the back of the skull. The two spars were nearly equal in length, and both were nearly as long or longer than the total length of the body. The upward-pointing crest spar was at least 42 cm long (1.3 ft) and the backward-pointing spar was at least 32 cm long (1 ft).
The jaws of Nyctosaurus were long and extremely pointed. The jaw tips were thin and needle sharp, and are often broken off in fossil specimens, giving the appearance that one jaw is longer than the other, though in life they were probably equal in length.
Nyctosaurus is the only pterosaur to have lost its clawed "fingers", with the exception of the wing finger (of which however the fourth phalanx
was lost), which is likely to have impaired its movement on the ground, leading scientists to conjecture that it spent almost all of its time on the wing and rarely landed. In particular, the lack of claws with which to grip surfaces would have made climbing or clinging to cliffs and tree trunks impossible for Nyctosaurus.
A few scientists had initially hypothesized that this crest, which resembles an enormous antler
, may have supported a skin "headsail" used for stability in flight. While there is no fossil evidence for such a sail, studies have shown that a membranous attachment to the bony crest would have imparted aerodynamic advantages. However, in the actual description of the fossils, paleontologist Christopher Bennett argued against the possibility of a membrane or soft tissue extension to the crest. Bennett noted that the edges of each prong were smooth and rounded, and showed no evidence for any soft-tissue attachment points. He also compared Nyctosaurus with large-crested tapejarids, which do preserve soft tissue extensions supported by prongs, and showed that in those species, the attachment points were obvious, with jagged edges where the transition from bone to soft tissue occurred. Bennett concluded that the crest was most likely used solely for display, citing similar structures in modern animals. The 2009 study by Xing and colleagues testing the aerodynamics of the giant crest with a "headsail" also tested the aerodynamics of the same crest with no sail, and found that it added no significant negative factors, so a crest with no headsail would not have hindered normal flight. It is more likely that the crest acted mainly for display, and that any aerodynamic effects it may have had were secondary. Bennett also argued that the crest was probably not a sexually dimorphic character, as in most crested pterosaurs, including the related Pteranodon, both sexes are crested and it is only the size and shape of the crest that differs. The apparently non-crested Nyctosaurus specimens therefore probably came from sub-adults.
The function of a very large headcrest such as the one possessed by Nyctosaurus is still a great mystery. It is theorized that a headsail would be able to harness the dynamic winds and add power to its flight. When it was in contact with water, whether skimming the water with its beak, dragging its wings, at rest or some combination of the like, the areas of surface contact would function like the keel of a boat pushing against the water medium and controlling its course. The loss of digits I, II, and III further streamlined the wing and support the use of sailing
in some form.
, part of the Niobrara Formation
. Specifically, they are found only within a narrow zone characterised by the abundance of ammonite
fossils belonging to the species Spinaptychus sternbergi. These limestone deposits were laid down during a marine regression
of the Western Interior Seaway
that lasted between 85 and 84.5 million years ago. Therefore, Nyctosaurus was a relatively short-lived species, unlike its relative Pternodon, which is found throughout almost all of the Niobrara layers into the overlying Pierre Shale Formation, and existed between 88 and 80.5 million years ago.
The ecosystem preserved in this zone was unique in its abundance of vertebrate life. Nyctosaurus shared the sky with the bird Ichthyornis
and with Pteranodon longiceps, though the second Niobrara Pteranodon species, P. sternbergi, had disappeared from the fossil record by this point. In the waters of the Western Interior Seaway
below swam mosasaur
s (Clidastes
, Ectenosaurus
and Tylosaurus
), the flightless diving bird Parahesperornis
, and a wide variety of fish, including swordfish-like Protosphyraena
, the predatory Xiphactinus
and the shark Cretolamna.
The first Nyctosaurus fossils were described in 1876 by Othniel Charles Marsh
, based on fragmentary material, holotype
YPM 1178, from the Smoky Hill River
site in Kansas
. Marsh referred the specimen to a species of his new genus Pteranodon, as Pteranodon gracilis. Later that year, Marsh reclassified the species in its own genus, which he named Nyctosaurus, meaning "night lizard" or "bat lizard", in reference to the wing structure somewhat paralleling those of bat
s. In 1881, Marsh incorrectly assumed the name was preoccupied and changed it into Nyctodactylus, which thus is now a junior synonym. In 1902, Samuel Wendell Williston
described the most complete skeleton then known (P 25026) discovered in 1901 by H. T. Martin. In 1903, Williston named a second species, N. leptodactylus, but this is today considered identical to N. gracilis.
In 1953, Llewellyn Ivor Price
named a partial humerus
, DMGM 258-R found in Brazil
, N. lamegoi; the specific name honours the geologist
Alberto Ribeiro Lamego. This species has an estimated wingspan of four metres; it is today generally considered to be a form different from Nyctosaurus, but has not yet been assigned its own genus name.
In 1972 a new skeleton, FHSM VP-2148, in 1962 discovered by George Fryer Sternberg, was named N. bonneri; it is today generally seen as identical to N. gracilis.
In 1978 Gregory Brown prepared the most complete Nyctosaurus skeleton currently known, UNSM 93000.
In 1984 Robert Milton Schoch renamed Pteranodon nanus (Marsh 1881), "the dwarf", Nyctosaurus nanus. The question of this species validity is currently pending further study.
In the early 2000s, Kenneth Jenkins of Ellis, Kansas
collected two specimens of Nyctosaurus which were the first to demonstrate conclusively that not only was this species crested, the crest in mature specimens was very large and elaborate. The specimens were purchased by a private collector in Austin
, Texas
. Despite being in private hands rather than a museum collection, paleontologist Chris Bennett was able to study the specimens and gave them the manuscript reference numbers KJ1 and KJ2 (for Kenneth Jenkins). Bennett published a description of the specimens in 2003. Despite the unusual crests, the specimens were otherwise indistinguishable from other specimens of Nyctosaurus. However, the then-currently named species were extremely similar and Bennett declined to refer them to a specific one pending further study of the differences, or lack therof, between species of Nyctosaurus.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of pterodactyloid pterosaur
Pterosaur
Pterosaurs 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...
, the remains of which have been found in the Niobrara Formation
Niobrara Formation
The Niobrara Formation, also called the Niobrara Chalk , is a geologic formation in North America that was laid down between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian ages of the Late Cretaceous. It is composed of two structural units, the Smoky Hill Chalk Member...
of the mid-western United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, which, during the late Cretaceous Period, was covered in an extensive shallow sea. The genus Nyctosaurus has had numerous species referred to it, though how many of these may actually be valid requires further study. At least one species possessed an extraordinarily large antler-like cranial crest.
Description
Nyctosaurus was similar in anatomy to its close relative and contemporary, PteranodonPteranodon
Pteranodon , from the Late Cretaceous geological period of North America in present day Kansas, Alabama, Nebraska, Wyoming, and South Dakota, was one of the largest pterosaur genera and had a maximum wingspan of over...
. It had relatively long wings, similar in shape to modern seabirds. However, it was smaller overall than Pteranodon, with an adult wingspan of 2 meters and a maximum weight of about 1.86 kg. The overall body length was 37 cm. Some specimens preserve a distinctive crest, at least 55 cm tall in old adults, relatively gigantic compared to the rest of the body and over three times the length of the head. The crest is composed of two long, grooved spars, one pointed upward and the other backward, arising from a common base projecting up and back from the back of the skull. The two spars were nearly equal in length, and both were nearly as long or longer than the total length of the body. The upward-pointing crest spar was at least 42 cm long (1.3 ft) and the backward-pointing spar was at least 32 cm long (1 ft).
The jaws of Nyctosaurus were long and extremely pointed. The jaw tips were thin and needle sharp, and are often broken off in fossil specimens, giving the appearance that one jaw is longer than the other, though in life they were probably equal in length.
Nyctosaurus is the only pterosaur to have lost its clawed "fingers", with the exception of the wing finger (of which however the fourth phalanx
Phalanx bones
In anatomy, phalanx bones are those that form the fingers and toes. In primates such as humans and monkeys, the thumb and big toe have two phalanges, while the other fingers and toes consist of three. Phalanges are classified as long bones.The phalanges do not have individual names...
was lost), which is likely to have impaired its movement on the ground, leading scientists to conjecture that it spent almost all of its time on the wing and rarely landed. In particular, the lack of claws with which to grip surfaces would have made climbing or clinging to cliffs and tree trunks impossible for Nyctosaurus.
Life history
Nyctosaurus, like its relative Pteranodon, appears to have grown very rapidly after hatching. Fully adult specimens are no larger than some immature specimens such as P 25026 (pictured below), indicating that Nyctosaurus went from hatching to adult size (with wingspans of 2m or more) in under a year. Some sub-adult specimens have been preserved with their skulls in nearly pristine condition, and lack any trace of a head crest, indicating that the distinctively large crest only began to develop after the first year of life. The crest may have continued to grow more elaborate as the animal aged, though no studies have examined the age of the fully adult, large-crested specimens. These individuals may have been 5 or even 10 years old at the time of their deaths.Crest function
Only five relatively complete Nyctosaurus skulls have been found. Of those, one is juvenile and does not possess a crest (specimen FMNH P 25026), and two are more mature and may show signs of having had a crest but are too badly crushed to say for sure (FHSM 2148 and CM 11422). Two specimens (KJ1 and KJ2) described in 2003, however, preserved an enormous double-pronged crest.A few scientists had initially hypothesized that this crest, which resembles an enormous antler
Antler
Antlers are the usually large, branching bony appendages on the heads of most deer species.-Etymology:Antler originally meant the lowest tine, the "brow tine"...
, may have supported a skin "headsail" used for stability in flight. While there is no fossil evidence for such a sail, studies have shown that a membranous attachment to the bony crest would have imparted aerodynamic advantages. However, in the actual description of the fossils, paleontologist Christopher Bennett argued against the possibility of a membrane or soft tissue extension to the crest. Bennett noted that the edges of each prong were smooth and rounded, and showed no evidence for any soft-tissue attachment points. He also compared Nyctosaurus with large-crested tapejarids, which do preserve soft tissue extensions supported by prongs, and showed that in those species, the attachment points were obvious, with jagged edges where the transition from bone to soft tissue occurred. Bennett concluded that the crest was most likely used solely for display, citing similar structures in modern animals. The 2009 study by Xing and colleagues testing the aerodynamics of the giant crest with a "headsail" also tested the aerodynamics of the same crest with no sail, and found that it added no significant negative factors, so a crest with no headsail would not have hindered normal flight. It is more likely that the crest acted mainly for display, and that any aerodynamic effects it may have had were secondary. Bennett also argued that the crest was probably not a sexually dimorphic character, as in most crested pterosaurs, including the related Pteranodon, both sexes are crested and it is only the size and shape of the crest that differs. The apparently non-crested Nyctosaurus specimens therefore probably came from sub-adults.
The function of a very large headcrest such as the one possessed by Nyctosaurus is still a great mystery. It is theorized that a headsail would be able to harness the dynamic winds and add power to its flight. When it was in contact with water, whether skimming the water with its beak, dragging its wings, at rest or some combination of the like, the areas of surface contact would function like the keel of a boat pushing against the water medium and controlling its course. The loss of digits I, II, and III further streamlined the wing and support the use of sailing
Sailing
Sailing is the propulsion of a vehicle and the control of its movement with large foils called sails. By changing the rigging, rudder, and sometimes the keel or centre board, a sailor manages the force of the wind on the sails in order to move the boat relative to its surrounding medium and...
in some form.
Wing loading and speed
Sankar Chatterjee and R.J. Templin used estimates based on complete Nyctosaurus specimens to determine weight and total wing area, and to calculate its total wing loading. They also estimated its total available flight power based on estimated musculature. Using these calculations, they estimated the cruising speed of Nyctosaurus gracilis as 9.6 meters/second (34.5 kilometers/hour or 21.4 miles/hour).Ecology
All known Nyctosaurus fossils come from the Smokey Hills Chalk of KansasKansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...
, part of the Niobrara Formation
Niobrara Formation
The Niobrara Formation, also called the Niobrara Chalk , is a geologic formation in North America that was laid down between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian ages of the Late Cretaceous. It is composed of two structural units, the Smoky Hill Chalk Member...
. Specifically, they are found only within a narrow zone characterised by the abundance of ammonite
Ammonite
Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...
fossils belonging to the species Spinaptychus sternbergi. These limestone deposits were laid down during a marine regression
Marine regression
Marine regression is a geological process occurring when areas of submerged seafloor are exposed above the sea level. The opposite event, marine transgression, occurs when flooding from the sea covers previously exposed land....
of the Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
that lasted between 85 and 84.5 million years ago. Therefore, Nyctosaurus was a relatively short-lived species, unlike its relative Pternodon, which is found throughout almost all of the Niobrara layers into the overlying Pierre Shale Formation, and existed between 88 and 80.5 million years ago.
The ecosystem preserved in this zone was unique in its abundance of vertebrate life. Nyctosaurus shared the sky with the bird Ichthyornis
Ichthyornis
Ichthyornis is a genus of toothed seabirds from the Late Cretaceous of North America. Its fossil remains are known from the chalks of Alberta, Alabama, Kansas, New Mexico, Saskatchewan, and Texas, in strata that were laid down in the Western Interior Seaway during the Turonian-Campanian ages,...
and with Pteranodon longiceps, though the second Niobrara Pteranodon species, P. sternbergi, had disappeared from the fossil record by this point. In the waters of the Western Interior Seaway
Western Interior Seaway
The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves, Laramidia and Appalachia, during most of the mid- and late-Cretaceous Period...
below swam mosasaur
Mosasaur
Mosasaurs are large extinct marine lizards. The first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764...
s (Clidastes
Clidastes
Clidastes is an extinct genus of mosasaur lizard from marine environments of the Late Cretaceous.Clidastes was an agile and fast swimmer that cruised the surface or shallow waters hunting for fish, flying reptiles and anything that got too close.- Appearance :Clidastes was the smallest of the...
, Ectenosaurus
Ectenosaurus
Ectenosaurus is a genus of mosasaur from the Late Cretaceous period....
and Tylosaurus
Tylosaurus
Tylosaurus was a mosasaur, a large, predatory marine lizard closely related to modern monitor lizards and to snakes.-Paleobiology:...
), the flightless diving bird Parahesperornis
Parahesperornis
Parahesperornis is a prehistoric flightless bird genus from the Late Cretaceous. Its range in space and time may have been extensive, but its remains are rather few and far between, at least compared with its contemporary relatives in Hesperornis. Remains are known from central North America,...
, and a wide variety of fish, including swordfish-like Protosphyraena
Protosphyraena
Protosphyraena is a fossil genus of swordfish-like marine fish, that throve worldwide during the Upper Cretaceous Period . Though fossil remains of this taxon have been found in both Europe and Asia, it is perhaps best known from the Smoky Hill Member of the Niobrara Chalk Formation of Kansas...
, the predatory Xiphactinus
Xiphactinus
Xiphactinus was a large, 4.5 to 6 m long predatory bony fish that lived in the Western Interior Sea, over what is now the middle of North America, during the Late Cretaceous. When alive, the fish would have resembled a gargantuan, fanged tarpon...
and the shark Cretolamna.
Discovery and species
Othniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...
, based on fragmentary material, holotype
Holotype
A 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...
YPM 1178, from the Smoky Hill River
Smoky Hill River
The Smoky Hill River is a river in the central Great Plains of North America, running through the U.S. states of Colorado and Kansas.-Names:The Smoky Hill gets its name from the Smoky Hills region of north-central Kansas through which it flows...
site in Kansas
Kansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...
. Marsh referred the specimen to a species of his new genus Pteranodon, as Pteranodon gracilis. Later that year, Marsh reclassified the species in its own genus, which he named Nyctosaurus, meaning "night lizard" or "bat lizard", in reference to the wing structure somewhat paralleling those of bat
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
s. In 1881, Marsh incorrectly assumed the name was preoccupied and changed it into Nyctodactylus, which thus is now a junior synonym. In 1902, Samuel Wendell Williston
Samuel Wendell Williston
Samuel Wendell Williston was an American educator and paleontologist who was the first to propose that birds developed flight cursorially , rather than arboreally . He was also an entomologist, specialising in Diptera.-Early life:Williston was born in Boston, Massachusetts to Samuel Williston and...
described the most complete skeleton then known (P 25026) discovered in 1901 by H. T. Martin. In 1903, Williston named a second species, N. leptodactylus, but this is today considered identical to N. gracilis.
In 1953, Llewellyn Ivor Price
Llewellyn Ivor Price
Llewellyn Ivor Price was one of the first Brazilian paleontologists.-Biography:Price's work contributed not only to the development of Brazilian but also to global paleontology...
named a partial humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
, DMGM 258-R found in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, N. lamegoi; the specific name honours the geologist
Geologist
A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...
Alberto Ribeiro Lamego. This species has an estimated wingspan of four metres; it is today generally considered to be a form different from Nyctosaurus, but has not yet been assigned its own genus name.
In 1972 a new skeleton, FHSM VP-2148, in 1962 discovered by George Fryer Sternberg, was named N. bonneri; it is today generally seen as identical to N. gracilis.
In 1978 Gregory Brown prepared the most complete Nyctosaurus skeleton currently known, UNSM 93000.
In 1984 Robert Milton Schoch renamed Pteranodon nanus (Marsh 1881), "the dwarf", Nyctosaurus nanus. The question of this species validity is currently pending further study.
In the early 2000s, Kenneth Jenkins of Ellis, Kansas
Ellis, Kansas
Ellis is a city in Ellis County, Kansas, United States. As of the 2010 census, the city population was 2,062.- History :The Kansas Pacific Railway built a water station at the site of present-day Ellis in 1867 and then purchased the site under the Homestead Act. Three years later, in 1870, the U.S....
collected two specimens of Nyctosaurus which were the first to demonstrate conclusively that not only was this species crested, the crest in mature specimens was very large and elaborate. The specimens were purchased by a private collector in Austin
Austin
Austin is the capital of the U.S. state of Texas.Austin may also refer to:-In the United States:*Austin, Arkansas*Austin, Colorado*Austin, Chicago, Illinois*Austin, Indiana*Austin, Minnesota*Austin, Nevada*Austin, Oregon...
, Texas
Texas
Texas 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...
. Despite being in private hands rather than a museum collection, paleontologist Chris Bennett was able to study the specimens and gave them the manuscript reference numbers KJ1 and KJ2 (for Kenneth Jenkins). Bennett published a description of the specimens in 2003. Despite the unusual crests, the specimens were otherwise indistinguishable from other specimens of Nyctosaurus. However, the then-currently named species were extremely similar and Bennett declined to refer them to a specific one pending further study of the differences, or lack therof, between species of Nyctosaurus.
External links
- Nyctosauridae (scroll down) in The Pterosaur Database