Bactrosaurus
Encyclopedia
Bactrosaurus is a genus
of herbivorous
dinosaur
that lived in east China
during the late Cretaceous
, about 70 mya. The position Bactrosaurus occupies in the Cretaceous makes it one of the earliest known hadrosaurs, and although it is not known from a full skeleton, Bactrosaurus is one of the best known of these early hadrosaurs, making its discovery a significant finding.
.
It was an early relative of Lambeosaurus
, and shows a number of iguanodont
-like features, including three stacked teeth for each visible tooth, small maxillary
teeth, and an unusually powerful build for a hadrosaur. It shows features intermediate between those of the two main hadrosaurid groups, and may represent an ancestral form that evolved from an earlier iguanodontid dinosaur.
Bactrosaurus was originally described as lacking a crest, which would be typical for an iguanodont, but anomalously primitive for a lambeosaurine like itself. However subsequent study of Bactrosaurus remains uncovered pieces of what appear to be the base of an incompletely preserved crest.
In 2003, evidence of tumor
s, including hemangioma
s, desmoplastic fibroma, metastatic cancer, and osteoblastoma
was discovered in fossilized Bactrosaurus skeletons. Rothschild et al. tested dinosaur vertebrae for tumors using computerized tomography and fluoroscope screening. Several other hadrosaurids, including Brachylophosaurus, Gilmoreosaurus, and Edmontosaurus, also tested positive. Although more than 10,000 fossils were examined in this manner, the tumors were limited to Bactrosaurus and closely related genera. The tumors may have been caused by environmental factors or genetic propensity.
in the Gobi Desert
of China
were composed of partial skeletons of six individual B. johnsoni. The specimens collected appear to come from a variety of age groups, from individuals that may be hatchlings to full-sized adults. The fossils were described in 1933 by Charles W. Gilmore
, who named the new animal Bactrosaurus, or "club lizard", in reference to the large club-shaped neural spines projecting from some of the vertebrae.
No complete remains have yet to be uncovered, but Bactrosaurus is still better known than most of the early hadrosaurs. Known parts of the anatomy of Bactrosaurus include the limbs, pelvis, and most of the skull (although the crest is notably absent).
Contemporaries
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 herbivorous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
that lived in east China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
during the late Cretaceous
Cretaceous
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...
, about 70 mya. The position Bactrosaurus occupies in the Cretaceous makes it one of the earliest known hadrosaurs, and although it is not known from a full skeleton, Bactrosaurus is one of the best known of these early hadrosaurs, making its discovery a significant finding.
Description
A typical Bactrosaurus would have been 6 metres (19.7 ft) long and 2 metres (6.6 ft) high when standing on all fours, and weighed 1.1 to 1.5 t (2,425.1 to 3,306.9 lb), with an 80 centimetres (2.6 ft) femurFemur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
.
It was an early relative of Lambeosaurus
Lambeosaurus
Lambeosaurus is a genus of hadrosaurid dinosaur that lived about 76 to 75 million years ago, in the Late Cretaceous Period of North America. This bipedal/quadrupedal, herbivorous dinosaur is known for its distinctive hollow cranial crest, which in the best-known species resembled a hatchet...
, and shows a number of iguanodont
Iguanodont
Iguanodonts were herbivorous dinosaurs that lived from the mid-Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, Ouranosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodonts were one of the first groups of dinosaurs to be found...
-like features, including three stacked teeth for each visible tooth, small maxillary
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
teeth, and an unusually powerful build for a hadrosaur. It shows features intermediate between those of the two main hadrosaurid groups, and may represent an ancestral form that evolved from an earlier iguanodontid dinosaur.
Bactrosaurus was originally described as lacking a crest, which would be typical for an iguanodont, but anomalously primitive for a lambeosaurine like itself. However subsequent study of Bactrosaurus remains uncovered pieces of what appear to be the base of an incompletely preserved crest.
In 2003, evidence of tumor
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
s, including hemangioma
Hemangioma
A hemangioma of infancy is a benign self-involuting tumor of endothelial cells, the cells that line blood vessels. It usually appears during the first weeks of life and sometimes resolves by age 10. In more severe case hemangioma may have permanency, if not treated by a physician...
s, desmoplastic fibroma, metastatic cancer, and osteoblastoma
Osteoblastoma
Osteoblastoma is an uncommon osteoid tissue-forming primary neoplasm of the bone.It has clinical and histologic manifestations similar to those of osteoid osteoma; therefore, some consider the two tumors to be variants of the same disease, with osteoblastoma representing a giant osteoid osteoma...
was discovered in fossilized Bactrosaurus skeletons. Rothschild et al. tested dinosaur vertebrae for tumors using computerized tomography and fluoroscope screening. Several other hadrosaurids, including Brachylophosaurus, Gilmoreosaurus, and Edmontosaurus, also tested positive. Although more than 10,000 fossils were examined in this manner, the tumors were limited to Bactrosaurus and closely related genera. The tumors may have been caused by environmental factors or genetic propensity.
Discovery
The first Bactrosaurus remains recovered from the Iren Dabasu FormationIren Dabasu Formation
The Iren Dabasu Formation is a Mesozoic geologic formation. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.-Ornithischians:-Saurischians:-References:...
in the Gobi Desert
Gobi Desert
The Gobi is a large desert region in Asia. It covers parts of northern and northwestern China, and of southern Mongolia. The desert basins of the Gobi are bounded by the Altai Mountains and the grasslands and steppes of Mongolia on the north, by the Hexi Corridor and Tibetan Plateau to the...
of China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
were composed of partial skeletons of six individual B. johnsoni. The specimens collected appear to come from a variety of age groups, from individuals that may be hatchlings to full-sized adults. The fossils were described in 1933 by Charles W. Gilmore
Charles W. Gilmore
Charles Whitney Gilmore was an American paleontologist, who named dinosaurs in North America and Mongolia, including the Cretaceous sauropod Alamosaurus, Alectrosaurus, Archaeornithomimus, Bactrosaurus, Brachyceratops, Chirostenotes, Mongolosaurus, Parrosaurus, Pinacosaurus, Styracosaurus and...
, who named the new animal Bactrosaurus, or "club lizard", in reference to the large club-shaped neural spines projecting from some of the vertebrae.
No complete remains have yet to be uncovered, but Bactrosaurus is still better known than most of the early hadrosaurs. Known parts of the anatomy of Bactrosaurus include the limbs, pelvis, and most of the skull (although the crest is notably absent).
See also
Related animals- GilmoreosaurusGilmoreosaurusGilmoreosaurus is the name given to a genus of dinosaur from the Cretaceous of Asia. The type species is Gilmoreosaurus mongoliensis. It is believed to be a hadrosaur or iguanodont from the Iren Dabasu Formation of Mongolia, dating to 70 Ma ago. Additional specimens have been described as distinct...
Contemporaries
- ArchaeornithomimusArchaeornithomimusArchaeornithomimus is a genus of ornithomimosaurian theropod dinosaur from the Late Cretaceous of China, 70 million years ago....