Dolichorhynchops
Encyclopedia
Dolichorhynchops is an extinct genus
of polycotylid plesiosaur
from the Late Cretaceous
(early Turonian
to late Campanian
stage) of North America
, containing three species
, D. osborni, D. herschelensis and D. tropicensis. Dolichorhynchops was an oceangoing prehistoric reptile. Its Greek
generic name means "long-nosed eye," perhaps because its eyes seem placed rather far forward on its lengthy snout.
The holotype specimen of Dolichorhynchops osborni was discovered in the upper Smoky Hill Chalk
Logan County, Kansas, by George F. Sternberg, as a teenager, in around 1900. The remains were collected by him and his father, Charles H. Sternberg, and then sold to the University of Kansas (Lawrence, Kansas). KUVP 1300 was prepared and mounted by H.T. Martin under the supervision of Dr. Samuel Wendell Williston
, who described and named it in 1902. A more detailed description and photographs were provided by Williston 1903). The specimen has been on display in the KU Museum of Natural History since that time.
In 1918, Charles H. Sternberg found a large mosasaur, Tylosaurus
, with the remains of a plesiosaur in its stomach. The mosasaur specimen is currently mounted in the United States National Museum (Smithsonian) and the plesiosaur remains are stored in the collections. Although these important specimens were briefly reported by C. H. Sternberg (1922), the information was lost to science until 2001. This specimen was rediscovered and described by Everhart (2004a). It is the basis for the story line in the 2007 National Geographic IMAX
documentary
Sea Monsters: A Prehistoric Adventure
, and a book by the same name (Everhart, 2007).
George Sternberg found a second, less complete specimen of D.osborni in 1926. In his effort to sell the specimen to a museum, Sternberg took detailed photographs of the skull. The specimen was eventually mounted in plaster and was acquired by the Harvard Museum of Comparative Zoology. MCZ 1064 was on display there until some time in the 1950s. This specimen was never completely described although the skull was figured by O'Keefe (2004). (See also Everhart, 2004b)
The specimen of D. osborni on exhibit at the Sternberg, FHSM VP-404 was found by Marion Bonner near Russell Springs in Logan County in the early 1950s. It is, perhaps, the most complete specimen of this species known. It is just under 10 feet in length. The skull was crushed flat but is in very good condition. This specimen was initially reported by Sternberg and Walker (1957), and then was the subject of a Masters thesis by Orville Bonner (1964). Note that it was described by Bonner as "Trinacromerum osborni" which was the accepted genus name at the time.
Two very large specimens of a polycotylid plesiosaur (KUVP 40001 and 40002)were collected from the Pierre Shale of Wyoming and later reported on by Adams in her 1977 Masters thesis. Later (1997), she officially described (1997) as a new species of Trinacromerum (T. bonneri). Unknown to her at the time, Carpenter (1996) had revised the Polycotylidae and separated Dolichorhynchops from Trinacromerum. Thus the species would revert back to Dolichorhynchops bonneri, but there is some question as to whether or not the specimens represent a separate species or just larger individuals of D. osborni. The question has yet to be resolved.
Until recently, all known specimens of D. osborni in Kansas had been collected from the upper layers of the Smoky Hill Chalk
(Campanian age). Everhart (2003) reported the first remains from the lower chalk (Late Coniacian-Santonian in age). In 2005, the remains of the earliest known D. osborni were discovered in the Fort Hays Limestone in Jewell County, Kansas. This is the first record of a polycotylid plesiosaur in this formation (Everhart, Decker and Decker, 2006).
. It was discovered in the Bearpaw Formation
of Saskatchewan
, Canada
, a Late Cretaceous
(late Campanian
to Maastrichtian
) rock formation. The fossil was found close to the town of Herschel
in south-western Saskatchewan, from which the species name is derived. The rock formation it was found in consists of sandstone
s, mudstone
s and shale
s laid down in the Western Interior Seaway
, just before it began to revert to dry land.
The type specimen of D. herschelensis was discovered in a disarticulated state (i.e. the bones were scattered about the discovery site). The skull
, lower jaw, rib
s, pelvis
and shoulder blades were all recovered, but the spine
was incomplete, so the exact number of vertebrae the living animal would have had is unknown. All four limbs are missing, with the exception of 9 small Phalanges
(finger bones) and a small number of limb bones found close by which may belong to the animal in question.
The specimen is believed to be an adult, due to the fusion of certain bones (it is generally assumed—not necessarily strictly correctly so—that other animals' skulls, much as humans', consist of dissociated bones interconnected by cartilage fontanelles that do not entirely close until full maturity). It is also believed to have been substantially smaller than its close relative, D. osborni, as some juvenile specimens of D. osborni are larger than the adult specimen of D. herschelensis. Assuming that only a few vertebrae are missing from the skeleton, the animal is estimated to be about 2.5 to 3 metres in length. The snout is long and thin, with numerous tooth sockets. However, very few of the thin, sharp teeth remain.
. The specific name is derived from the name of the Tropic Shale, in which the two specimens of D. tropicensis were found. It is known from the holotype
MNA
V10046, an almost complete, well-preserved skeleton
including the most of the skull
and from the referred specimen MNA V9431, fragmentary postcrania
l elements. It was collected by the Museum of Northern Arizona
from a single locality within the Tropic Shale of Utah
, dating to the early Turonian
stage of the early Late Cretaceous
, about 93.5-91 million years ago. D. tropicensis extends the known stratigraphic range for Dolichorhynchops back by approximately 7 million years. Previously three additional polycotylid taxa, Eopolycotylus
, Palmulasaurus
and Trinacromerum
, have been named from the same formation, two of which are corrently endemic to the Tropic Shale.
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 polycotylid plesiosaur
Plesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
from the Late Cretaceous
Late Cretaceous
The 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...
(early Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
to late Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
stage) of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, containing three species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, D. osborni, D. herschelensis and D. tropicensis. Dolichorhynchops was an oceangoing prehistoric reptile. Its Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
generic name means "long-nosed eye," perhaps because its eyes seem placed rather far forward on its lengthy snout.
D. osborni
Smoky Hill Chalk
The Smoky Hill Chalk Member of the Niobrara Chalk formation is a Cretaceous conservation Lagerstätte, or fossil rich geological formation, known primarily for its exceptionally well-preserved marine reptiles. The Smoky Hill Chalk Member is the uppermost of the two structural units of the Niobrara...
Logan County, Kansas, by George F. Sternberg, as a teenager, in around 1900. The remains were collected by him and his father, Charles H. Sternberg, and then sold to the University of Kansas (Lawrence, Kansas). KUVP 1300 was prepared and mounted by H.T. Martin under the supervision of Dr. 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...
, who described and named it in 1902. A more detailed description and photographs were provided by Williston 1903). The specimen has been on display in the KU Museum of Natural History since that time.
In 1918, Charles H. Sternberg found a large mosasaur, Tylosaurus
Tylosaurus
Tylosaurus was a mosasaur, a large, predatory marine lizard closely related to modern monitor lizards and to snakes.-Paleobiology:...
, with the remains of a plesiosaur in its stomach. The mosasaur specimen is currently mounted in the United States National Museum (Smithsonian) and the plesiosaur remains are stored in the collections. Although these important specimens were briefly reported by C. H. Sternberg (1922), the information was lost to science until 2001. This specimen was rediscovered and described by Everhart (2004a). It is the basis for the story line in the 2007 National Geographic IMAX
IMAX
IMAX 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
Documentary film
Documentary films constitute a broad category of nonfictional motion pictures intended to document some aspect of reality, primarily for the purposes of instruction or maintaining a historical record...
Sea Monsters: A Prehistoric Adventure
Sea Monsters: A Prehistoric Adventure
Sea Monsters: A Prehistoric Adventure is a film by National Geographic which is set in the Earth's prehistoric past. The film features state-of-the-art three dimensional photographic and computer generated characters/animals. The setting alternates between prehistory and modern day times in which...
, and a book by the same name (Everhart, 2007).
George Sternberg found a second, less complete specimen of D.osborni in 1926. In his effort to sell the specimen to a museum, Sternberg took detailed photographs of the skull. The specimen was eventually mounted in plaster and was acquired by the Harvard Museum of Comparative Zoology. MCZ 1064 was on display there until some time in the 1950s. This specimen was never completely described although the skull was figured by O'Keefe (2004). (See also Everhart, 2004b)
The specimen of D. osborni on exhibit at the Sternberg, FHSM VP-404 was found by Marion Bonner near Russell Springs in Logan County in the early 1950s. It is, perhaps, the most complete specimen of this species known. It is just under 10 feet in length. The skull was crushed flat but is in very good condition. This specimen was initially reported by Sternberg and Walker (1957), and then was the subject of a Masters thesis by Orville Bonner (1964). Note that it was described by Bonner as "Trinacromerum osborni" which was the accepted genus name at the time.
Until recently, all known specimens of D. osborni in Kansas had been collected from the upper layers of the Smoky Hill Chalk
Smoky Hill Chalk
The Smoky Hill Chalk Member of the Niobrara Chalk formation is a Cretaceous conservation Lagerstätte, or fossil rich geological formation, known primarily for its exceptionally well-preserved marine reptiles. The Smoky Hill Chalk Member is the uppermost of the two structural units of the Niobrara...
(Campanian age). Everhart (2003) reported the first remains from the lower chalk (Late Coniacian-Santonian in age). In 2005, the remains of the earliest known D. osborni were discovered in the Fort Hays Limestone in Jewell County, Kansas. This is the first record of a polycotylid plesiosaur in this formation (Everhart, Decker and Decker, 2006).
D. herschelensis
D. herschelensis was described as a new species by Tamaki Sato in 20052005 in paleontology
-New taxa:-New taxa:-Xiphosurans:* Fossils of Lunataspis, the earliest known xiphosuran, are discovered in Canada. It was not given a formal description until 2008, however.-New taxa:-Newly named dinosaurs:...
. It was discovered in the Bearpaw Formation
Bearpaw Formation
The Bearpaw Formation, also called the Bearpaw Shale, is a sedimentary rock formation found in northwestern North America. It is exposed in the U.S. state of Montana, as well as the Canadian provinces of Alberta and Saskatchewan, east of the Rocky Mountains...
of Saskatchewan
Saskatchewan
Saskatchewan is a prairie province in Canada, which has an area of . Saskatchewan is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, and on the south by the U.S. states of Montana and North Dakota....
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, a Late Cretaceous
Late Cretaceous
The 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...
(late Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
to Maastrichtian
Maastrichtian
The 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...
) rock formation. The fossil was found close to the town of Herschel
Herschel, Saskatchewan
-External links:*******-Footnotes:...
in south-western Saskatchewan, from which the species name is derived. The rock formation it was found in consists of sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
s, mudstone
Mudstone
Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
s and shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
s laid down in 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...
, just before it began to revert to dry land.
The type specimen of D. herschelensis was discovered in a disarticulated state (i.e. the bones were scattered about the discovery site). The skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
, lower jaw, rib
Rib
In vertebrate anatomy, ribs are the long curved bones which form the rib cage. In most vertebrates, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax...
s, pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
and shoulder blades were all recovered, but the spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
was incomplete, so the exact number of vertebrae the living animal would have had is unknown. All four limbs are missing, with the exception of 9 small Phalanges
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...
(finger bones) and a small number of limb bones found close by which may belong to the animal in question.
The specimen is believed to be an adult, due to the fusion of certain bones (it is generally assumed—not necessarily strictly correctly so—that other animals' skulls, much as humans', consist of dissociated bones interconnected by cartilage fontanelles that do not entirely close until full maturity). It is also believed to have been substantially smaller than its close relative, D. osborni, as some juvenile specimens of D. osborni are larger than the adult specimen of D. herschelensis. Assuming that only a few vertebrae are missing from the skeleton, the animal is estimated to be about 2.5 to 3 metres in length. The snout is long and thin, with numerous tooth sockets. However, very few of the thin, sharp teeth remain.
D. tropicensis
D. tropicensis was first named by Rebecca Schmeisser McKean in 20112011 in paleontology
-Lobopods:-Arachnids:-Insects:-Newly named jawless vertebrates:-Newly named acanthodian:-Newly named cartilaginous fishes:-Newly named bony fishes:-Newly named lepospondyls:-Newly named temnospondyls:-Newly named lissamphibians:...
. The specific name is derived from the name of the Tropic Shale, in which the two specimens of D. tropicensis were found. It is known from the 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...
MNA
Museum of Northern Arizona
The Museum of Northern Arizona is a museum in Flagstaff, Arizona, USA, that was established as a repository for Native American artifacts and natural history specimens from the Colorado Plateau.The museum was founded in 1928 by zoologist Dr. Harold S...
V10046, an almost complete, well-preserved skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
including the most of the skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
and from the referred specimen MNA V9431, fragmentary postcrania
Postcrania
Postcrania[p] in zoology and vertebrate paleontology refers to all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g...
l elements. It was collected by the Museum of Northern Arizona
Museum of Northern Arizona
The Museum of Northern Arizona is a museum in Flagstaff, Arizona, USA, that was established as a repository for Native American artifacts and natural history specimens from the Colorado Plateau.The museum was founded in 1928 by zoologist Dr. Harold S...
from a single locality within the Tropic Shale of Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
, dating to the early Turonian
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.5 ± 0.8 Ma and 89.3 ± 1 Ma...
stage of the early Late Cretaceous
Late Cretaceous
The 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...
, about 93.5-91 million years ago. D. tropicensis extends the known stratigraphic range for Dolichorhynchops back by approximately 7 million years. Previously three additional polycotylid taxa, Eopolycotylus
Eopolycotylus
Eopolycotylus is an extinct genus of plesiosaur....
, Palmulasaurus
Palmulasaurus
Palmulasaurus is a genus of polycotylid plesiosaur from the Late Cretaceous of Utah. It was originally described as Palmula, but the name was occupied by a genus of Cretaceous foraminifer first described in 1833....
and Trinacromerum
Trinacromerum
Trinacromerum is an extinct genus of sauropterygian reptile belonging to the plesiosaur suborder. It lived during the Late Cretaceous period in what is now Kansas. It was 3 meters long. Its teeth show it fed on small fish....
, have been named from the same formation, two of which are corrently endemic to the Tropic Shale.
In popular culture
- Dolichorhynchops osborni appeared in the National Geographic documentaryDocumentary filmDocumentary films constitute a broad category of nonfictional motion pictures intended to document some aspect of reality, primarily for the purposes of instruction or maintaining a historical record...
Sea Monsters: A Prehistoric AdventureSea Monsters: A Prehistoric AdventureSea Monsters: A Prehistoric Adventure is a film by National Geographic which is set in the Earth's prehistoric past. The film features state-of-the-art three dimensional photographic and computer generated characters/animals. The setting alternates between prehistory and modern day times in which...
. It acted as the main protagonist. It was depicted living in groups, giving birth in shallow coves, and relying mostly on speed to escape its many predators.