''Venenosaurus'' ( ) was a

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', ' lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their ...

dinosaur. The name literally means "poison lizard", and it was named so after the

Poison Strip The Cedar Mountain Formation is the name given to a distinctive sedimentary geologic formation in eastern Utah, spanning most of the early and mid- Cretaceous. The formation was named for Cedar Mountain in northern Emery County, Utah, where Willi ...

Member of the

Cedar Mountain Formation The Cedar Mountain Formation is the name given to a distinctive sedimentary geologic formation in eastern Utah, spanning most of the early and mid- Cretaceous. The formation was named for Cedar Mountain in northern Emery County, Utah, where Will ...

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

, United States, 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 (born September 21, 1949, in Tokyo, Japan) is a 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 ...

, and Suzanne Meyer. ''Venenosaurus'' is a relatively small

titanosauriform Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...

sauropod, measuring long and weighing . It is known from an incomplete skeleton of an adult and a juvenile. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

is DMNH 40932 Denver Museum of Natural History. The specimen consisted of tail

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

e, the left

scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eith ...

, right

radius In classical geometry, a radius (plural, : radii) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', ...

, left

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

metacarpals In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ar ...

, forefoot phalanges, right pubis, left and right

ischia Ischia ( , , ) is a volcanic island in the Tyrrhenian Sea. It lies at the northern end of the Gulf of Naples, about from Naples. It is the largest of the Phlegrean Islands. Roughly trapezoidal in shape, it measures approximately east to ...

metatarsals The metatarsal bones, or metatarsus, 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 me ...

, chevrons, and

rib In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ches ...

Geological and environmental context

The ''Venenosaurus'' type specimen was found in the Early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

(Aptian-Albian) Poison Strip Member of the Cedar Mountain Formation in

Grand County, Utah Grand County is a county on the east central edge of the U.S. state of Utah, United States. As of the 2010 United States Census, the population was 9,225. Its county seat and largest city is Moab. History Evidence of indigenous occupation ...

. The

Denver Museum of Natural History 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 mus ...

opened a small

quarry in Eastern Utah. This quarry has produced diverse dinosaur fossils including sauropods,

theropods Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally ca ...

, and

ornithopods Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world ...

of varying states of growth. Of the sauropod remains from the quarry only one individual was fully grown.

Carbonate A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate ...

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 ''

Cedarosaurus ''Cedarosaurus'' (meaning "Cedar lizard" - named after the Cedar Mountain Formation, in which it was discovered) was a nasal-crested macronarian dinosaur genus from the Early Cretaceous Period (Valanginian). It was a sauropod which lived in what ...

'', while still being distinct.

Limbs

The

of ''Venenosaurus'' is more slender than the radii of ''

Alamosaurus ''Alamosaurus'' (; meaning "Ojo Alamo lizard") is a genus of opisthocoelicaudiine titanosaurian sauropod dinosaurs, containing a single known species, ''Alamosaurus sanjuanensis'', from the late Cretaceous Period of what is now southern North A ...

'', ''

Chubutisaurus ''Chubutisaurus'' (meaning " Chubut lizard") 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, ''Chubutisaurus insignis'', w ...

'', ''

Opisthocoelicaudia ''Opisthocoelicaudia'' is a genus of sauropod dinosaur of the late Cretaceous, Late Cretaceous Period discovered in the Gobi Desert of Mongolia. The type species is ''Opisthocoelicaudia skarzynskii''. A well-preserved skeleton lacking only the ...

'', 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 ratio of .31. The team found that ''

Brachiosaurus brancai ''Giraffatitan'' (name meaning "titanic giraffe") is a genus of sauropod dinosaur that lived during the late Jurassic Period (Kimmeridgian–Tithonian stages) in what is now Lindi Region, Tanzania. It was originally named as an African species o ...

'''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

and radius than ''Venenosaurus''.

Pelvis

''Venenosaurus'' shows a mixture of titanosaur and non-titanosaur

ischium The ischium () form ...

-to- pubis proportions. Its hips most closely resemble those of ''Brachiosaurus''.

Vertebrae

The vertebrae in the middle and toward the end of the tail were short, distinguishing it from

titanosaurs Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...

like ''

Andesaurus ''Andesaurus'' ( ; "Andes lizard") is a genus of basal titanosaurian sauropod dinosaur which existed during the middle of the Cretaceous Period in South America. Like most sauropods, belonging to one of the largest animals ever to walk the Eart ...

'', ''

Malawisaurus ''Malawisaurus'' (meaning "Malawi lizard") is an extinct genus of titanosaurian sauropod dinosaur. It is known from the Dinosaur Beds of northern Malawi, which probably date to the Aptian stage of the Early Cretaceous. The type species is ''M. di ...

'', ''

Aeolosaurus ''Aeolosaurus'' (; "Aeolus' lizard") 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. ''Aeolos ...

'', ''

'', and ''

Saltasaurus ''Saltasaurus'' (which means "lizard from Salta") is a genus of saltasaurid dinosaur of the Late Cretaceous period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, ''Saltasaurus'' was characterized by ...

''. The neural spines in the middle tail vertebrae are angled toward the front of the animal. These vertebrae resemble those of ''

'', ''

'', and ''

Gondwanatitan ''Gondwanatitan'' (meaning "giant from Gondwana") was a titanosaurian sauropod dinosaur. ''Gondwanatitan'' was found in Brazil, at the time part of the southern supercontinent Gondwana, in the late Cretaceous Period (70 mya). Like some other ...

''. The vertebrae are located at a transitional position from anterior to posterior caudal vertebrae. ''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 vertebrae near the base of the tail are extremely useful for classifying sauropods. Derived titanosaurs had vertebrae that were convex on the front and back. Primitive sauropods had vertebrae that were either flat on both ends ( amphiplaty) or concave on both ( 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.

Footnotes

Sources

* Tidwell, V., Carpenter, K. & Meyer, S. 2001. "New Titanosauriform (Sauropoda) from the Poison Strip Member of the Cedar Mountain Formation (Lower Cretaceous), Utah." In: D. H. Tanke & K. Carpenter (eds.). ''Mesozoic Vertebrate Life''. Indiana University Press. 139–165. {{Taxonbar, from=Q144253 Early Cretaceous dinosaurs of North America Macronarians Fossil taxa described in 2001 Taxa named by Kenneth Carpenter Paleontology in Utah