Venenosaurus
Encyclopedia
Venenosaurus named after the Poison Strip Member of the Cedar Mountain Formation
in Utah
, where the fossils were discovered by a Denver Museum of Natural History volunteer Tony DiCroce in 1998. Venenosaurus dicrocei was first described as a new species in 2001 by Virginia Tidwell, Kenneth Carpenter
, and Suzanne Meyer. Venenosaurus is a relatively small (probably around 10 m (33 ft) long) titanosauriform sauropod, known from an incomplete skeleton of an adult and a juvenile. The holotype
is DMNH
40932 Denver Museum of Natural History. The specimen consisted of tail vertebrae, the left scapula
, right radius
, left ulna
, metacarpals, forefoot phalanges
, right pubis
, left and right ischia, metatarsals
, chevrons
, and rib
s.
(Aptian-Albian) Poison Strip Member of the Cedar Mountain Formation in Grand County, Utah
. The Denver Museum of Natural History opened a small Cedar Mountain Formation
quarry in Eastern Utah. This quarry has produced diverse dinosaur fossils including sauropods, theropods, and ornithopods of varying states of growth. Of the sauropod remains from the quarry only one individual was fully grown. Carbonate
growths appear on bones in the quarry from which Venenosaurus was extracted.
, while still being distinct.
' s noted that many dorsal rib fragments belonging to the species had been discovered.
is deceptively slender despite appearing robust. The proximal end is only 22% of the width rendering it more slender than the radii of Alamosaurus
, Chubutisaurus
, Opisthocoelicaudia
, and Saltasaurus. The ratio of the radius' least circumference to length produces a ratio of .33, more gracile than the radius of Camarasaurus lewisi and C. grandis. Cedarosaurus, however, has a slightly more gracile ration of .31. The team finds that Brachiosaurus brancai' s radius is the closest anatomical match to that of Venenosaurus. The metacarpals of Venenosaurus are long and slender. With the exception of the incomplete first metacarpal, all of the right metacarpals are known. Metatarsal I is the shortest and most robust of the three recovered metatarsals. Cedarosaurus had a more gracile ulna
and radius than Venenosaurus. Metatarsal II is more gracile in Cedarosaurus.
proportions. Its hips most closely resemble those of Brachiosaurus.
articulations" challenges "traditional descriptive terminology" for such features. Tidwell et al. opined that "more precise identification of anterior and posterior articular face morphology" need to be devised. The researchers described a vertebra from near the base of the tail that was well preserved. Only its prezygapophyses were missing. Tidwell et al. claimed its physical characteristics were unique among sauropods.
The seven middle and distal tail vertebral centra were short, distinguishing it from titanosaurs like Andesaurus
, Malawisaurus
, Aeolosaurus
, Alamosaurus
, and Saltasaurus
. Two of the recovered middle tail vertebrae preserve partial neural spines. These spines are angled anteriorly when the vertebrae are aligned. These vertebrae resemble those of Cedarosaurus
, Aeolosaurus
, and Gondwanatitan
. The vertebrae are located at a transitional position from anterior to posterior caudal vertebrae. The authors estimated them to be the eleventh and twelfth vertebrae.
The authors documented a single posterior tail vertebra that was well preserved. Its neural spine was reduced in size and resembled a rod facing the rear of the animal that ended with the rear of the centrum. Venenosaurus had unusual lateral fossae, which looked like deep depressions in the outside walls of the vertebral centra. Some fossae are divided into two chambers by a ridge inside the depression. In most sauropods the fossae would form pneumatic openings leading to the interior of the centrum, rather than just being a depression. Less well-developed, but similar fossae are known from Cedarosaurus. Fossae that similarly resemble shallow depressions are known from Saltasaurus, Alamosaurus, Aeolosaurus, Gondwanatitan, and Malawisaurus. These taxa differ, however, in that their fossae are even shallower, lack the division into chambers, and do not extend as far into the vertebral columns as those of Venenosaurus.
The proximal caudal vertebrae is extremely diagnostic for sauropods. Derived titanosaurs had biconvex vertebrae. The primitive condition is either amphiplaty or amphicoely. Venenosaurus may have had a condition intermediate between the two. The possession of amphiplatyan caudal centra with anteriorly facing neural spines is a unique identifier of this species. Sometimes the form of central articulations change within a single individual's vertebral column.
Cedar Mountain Formation
The Cedar Mountain Formation is the name given to distinctive sedimentary rocks in eastern Utah that occur between the underlying Morrison Formation and overlying Naturita Formation . It is composed of non-marine sediments, that is, sediments deposited in rivers, lakes and on flood plains...
in 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...
, where the fossils were discovered by a Denver Museum of Natural History volunteer Tony DiCroce in 1998. Venenosaurus dicrocei was first described as a new species in 2001 by Virginia Tidwell, Kenneth Carpenter
Kenneth Carpenter
Kenneth Carpenter is a paleontologist. He is the museum director of the USU Eastern Prehistoric Museum and author or co-author of a number of books on dinosaurs and Mesozoic life...
, and Suzanne Meyer. Venenosaurus is a relatively small (probably around 10 m (33 ft) long) titanosauriform sauropod, known from an incomplete skeleton of an adult and a juvenile. 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...
is DMNH
Denver Museum of Nature and Science
The Denver Museum of Nature & Science is a municipal natural history and science museum in Denver, Colorado. It is a resource for informal science education in the Rocky Mountain region. A variety of exhibitions, programs, and activities help museum visitors learn about the natural history of...
40932 Denver Museum of Natural History. The specimen consisted of tail vertebrae, the left scapula
Scapula
In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....
, right radius
Radius
In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...
, left ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
, metacarpals, forefoot 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...
, right pubis
Pubis (bone)
In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
, left and right ischia, metatarsals
Metatarsus
The metatarsus or metatarsal bones are a group of five long bones in the foot located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the medial side : the first, second, third, fourth, and fifth...
, chevrons
Chevron (anatomy)
A chevron is one of a series of bones on the ventral side of the tail in many reptiles, dinosaurs , and some mammals such as kangaroos and manatees....
, and 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.
Geological and environmental context
The Venenosaurus type specimen was found in the Early CretaceousCretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
(Aptian-Albian) Poison Strip Member of the Cedar Mountain Formation in Grand County, Utah
Grand County, Utah
Grand County is a county located in the U.S. state of Utah. As of 2000 the population was 8,485, and by 2005 had been estimated at 8,743. It was named for the Colorado River, which at the time of statehood was known as the Grand River. Its county seat and largest city is Moab.-Geography:According...
. The Denver Museum of Natural History opened a small Cedar Mountain Formation
Cedar Mountain Formation
The Cedar Mountain Formation is the name given to distinctive sedimentary rocks in eastern Utah that occur between the underlying Morrison Formation and overlying Naturita Formation . It is composed of non-marine sediments, that is, sediments deposited in rivers, lakes and on flood plains...
quarry in Eastern Utah. This quarry has produced diverse dinosaur fossils including sauropods, theropods, and ornithopods of varying states of growth. Of the sauropod remains from the quarry only one individual was fully grown. Carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
growths appear on bones in the quarry from which Venenosaurus was extracted.
Anatomy
The scientists who first described V. dicrocei observed that the new species most closely resembles CedarosaurusCedarosaurus
Cedarosaurus was a nasal-crested macronarian dinosaur genus from the Early Cretaceous Period . It was a sauropod which lived in what is now Utah...
, while still being distinct.
Body
The describers of V. dicroceiLimbs
The radiusRadius
In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...
is deceptively slender despite appearing robust. The proximal end is only 22% of the width rendering it more slender than the radii of Alamosaurus
Alamosaurus
Alamosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now North America. It was a large quadrupedal herbivore. Isolated vertebrae and limb bones indicate that it reached sizes comparable to Argentinosaurus and Puertasaurus, which would make it the...
, Chubutisaurus
Chubutisaurus
Chubutisaurus is a genus of dinosaur from the Early Cretaceous Period. It lived in South America. It is classified as a sauropod, specifically one of the titanosaurs. The type species, C. insignis, was described by del Corro in 1975. Its fossils were found in the Cerro Barcino Formation, Albian...
, Opisthocoelicaudia
Opisthocoelicaudia
Opisthocoelicaudia was 12-metre-long sauropod dinosaur of the Late Cretaceous Period discovered in Mongolia in 1965 by Polish and Mongolian scientists in what is now the Gobi Desert...
, and Saltasaurus. The ratio of the radius' least circumference to length produces a ratio of .33, more gracile than the radius of Camarasaurus lewisi and C. grandis. Cedarosaurus, however, has a slightly more gracile ration of .31. The team finds that Brachiosaurus brancai
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
and radius than Venenosaurus. Metatarsal II is more gracile in Cedarosaurus.
Pelvis
Venenosaurus shows a mixture of titanosaur and non-titanosaur ischium-to-pubisPubis (bone)
In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
proportions. Its hips most closely resemble those of Brachiosaurus.
Vertebrae
The researchers who named Venenosaurus observed that the growing known diversity "of sauropod caudal centrumBody of vertebra
The body is the largest part of a vertebra, and is more or less cylindrical in shape. For vertebrates other than humans, this structure is usually called a centrum....
articulations" challenges "traditional descriptive terminology" for such features. Tidwell et al. opined that "more precise identification of anterior and posterior articular face morphology" need to be devised. The researchers described a vertebra from near the base of the tail that was well preserved. Only its prezygapophyses were missing. Tidwell et al. claimed its physical characteristics were unique among sauropods.
The seven middle and distal tail vertebral centra were short, distinguishing it from titanosaurs like Andesaurus
Andesaurus
Andesaurus is a genus of basal titanosaurian sauropod dinosaur which existed during the middle of the Cretaceous Period in South America. Like most sauropods, it would have had a small head on the end of a long neck and an equally long tail...
, Malawisaurus
Malawisaurus
Malawisaurus was a genus of sauropod dinosaur . It lived in what is now Africa, specifically Malawi, during the Aptian age of the Early Cretaceous Period. It is one of the few titanosaurs for which skull material has been found.It was named by Louis L. Jacobs and colleagues, and was originally...
, Aeolosaurus
Aeolosaurus
Aeolosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. Like most sauropods, it would have been a quadrupedal herbivore with a long neck and tail...
, Alamosaurus
Alamosaurus
Alamosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now North America. It was a large quadrupedal herbivore. Isolated vertebrae and limb bones indicate that it reached sizes comparable to Argentinosaurus and Puertasaurus, which would make it the...
, and Saltasaurus
Saltasaurus
Saltasaurus is a genus of titanosaurid sauropod dinosaur of the Late Cretaceous Period. Relatively small among sauropods, though still massive by the standards of modern creatures, Saltasaurus was characterized by a diplodocid-like head...
. Two of the recovered middle tail vertebrae preserve partial neural spines. These spines are angled anteriorly when the vertebrae are aligned. These vertebrae resemble those of Cedarosaurus
Cedarosaurus
Cedarosaurus was a nasal-crested macronarian dinosaur genus from the Early Cretaceous Period . It was a sauropod which lived in what is now Utah...
, Aeolosaurus
Aeolosaurus
Aeolosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. Like most sauropods, it would have been a quadrupedal herbivore with a long neck and tail...
, and Gondwanatitan
Gondwanatitan
Gondwanatitan was a titanosaurian sauropod dinosaur. Gondwanatitan was found in Brazil, at the time part of the southern supercontinent Gondwana , in the late Cretaceous Period . Like some other sauropods, Gondwanatitan was tall and ate tough shoots and leaves off of the tops of trees. G...
. The vertebrae are located at a transitional position from anterior to posterior caudal vertebrae. The authors estimated them to be the eleventh and twelfth vertebrae.
The authors documented a single posterior tail vertebra that was well preserved. Its neural spine was reduced in size and resembled a rod facing the rear of the animal that ended with the rear of the centrum. Venenosaurus had unusual lateral fossae, which looked like deep depressions in the outside walls of the vertebral centra. Some fossae are divided into two chambers by a ridge inside the depression. In most sauropods the fossae would form pneumatic openings leading to the interior of the centrum, rather than just being a depression. Less well-developed, but similar fossae are known from Cedarosaurus. Fossae that similarly resemble shallow depressions are known from Saltasaurus, Alamosaurus, Aeolosaurus, Gondwanatitan, and Malawisaurus. These taxa differ, however, in that their fossae are even shallower, lack the division into chambers, and do not extend as far into the vertebral columns as those of Venenosaurus.
The proximal caudal vertebrae is extremely diagnostic for sauropods. Derived titanosaurs had biconvex vertebrae. The primitive condition is either amphiplaty or amphicoely. Venenosaurus may have had a condition intermediate between the two. The possession of amphiplatyan caudal centra with anteriorly facing neural spines is a unique identifier of this species. Sometimes the form of central articulations change within a single individual's vertebral column.
Reference
- Tidwell, V., Carpenter, K. & Meyer, S. 2001. New Titanosauriform (Sauropoda) from the Poison Strip Member of the Cedar Mountain Formation (Lower Cretaceous), Utah. In: Mesozoic Vertebrate Life. D. H. Tanke & K. Carpenter (eds.). Indiana University Press, Eds. D.H. Tanke & K. Carpenter. Indiana University Press. 139-165.