A fossil of the species was discovered in the fifties by rancher Warren H. Condray of Wells, KS. He notified senator Frank Carlson who directed him to the chancellor of the University of Kansas, Franklin David Murphy. Murphy sent the preparator of the paleontology of vertebrates department of the natural history museum of the university, Russell R. Camp, to investigate the matter. In July 1955 Camp, with help from Condray, recovered the skeleton of a dinosaur. It was further prepared by Camp and Glenn H. Marihugh. In 1961 the find was described and named by Theodore H. Eaton jr., also from the University of Kansas, as the type species Silvisaurus condrayi. The generic name is derived from Latin silva, "wood", in reference to the probably densely forested habitat of the animal. The specific name honours Condray. To date, Silvisaurus includes only the type species.
The holotype, KU 10296, was found in exposures of the Terracota Clay Member of the Dakota Formation (late Albian-early Cenomanian) in Kansas, and consists of an incomplete skeleton with skull. It includes the mandible, eight neck vertebrae, ten dorsal vertebrae, a sacrum of six sacral vertebrae, three tail vertebrae, a left pubis fragment, the lower end of the right femur, and a toe phalanx. Additionally disarticulated plates and spikes from the body armour were discovered. The condition of the fossil was poor as the bones had been exposed at the bottom of a dry riverbed and had been weathered and trampled by cattle. Some elements were only present as impressions or natural casts.
Based on the remains, the animal is estimated to have been approximately 4 metres (13 ft) in length. Its skull measures 33 centimetres (13 in) in length and is 25 centimetres (9.8 in) wide. The bony secondary palate is poorly developed in Silvisaurus, the dentary includes at least twenty-five teeth, the basal tubera of the basioccipital are bulbous, and each premaxilla holds eight to nine teeth.
The presence of teeth at the front of the jaw suggests that this may have been a relatively primitive nodosaur, since most later forms had a toothless beak instead. In addition to the usual rounded and polygonal osteoderms, Silvisaurus may have also sported bony spines on its shoulders and tail. The head contained large air passages, which may have been used for loud vocalisations, presumably for communication.
This taxon represents a relatively primitive nodosaurid, and Vickaryous et al. (2004) have stated that "Sauropelta edwardsorum, Silvisaurus condrayi, and Pawpawsaurus campbelli form a basal polytomy nested deep to Cedarpelta."
Acantholipan is a genus of herbivorous nodosaurid dinosaur from Mexico from the early Santonian age of the Late Cretaceous. It includes one species, Acantholipan gonzalezi.Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0.9 Ma (million years ago). The Albian is preceded by the Aptian and followed by the Cenomanian.Ankylosaurinae
Ankylosaurinae is a subfamily of ankylosaurid dinosaurs, existing from the Early Cretaceous about 105 million years ago until the end of the Late Cretaceous, about 66 mya. Many genera are included in the clade, such as Ankylosaurus, Pinacosaurus, Euoplocephalus, and Saichania.Bienosaurus
Bienosaurus (meaning "Bien's lizard") is a genus of thyreophoran dinosaur from the Lower Jurassic (probably Sinemurian) Lower Lufeng Formation in Yunnan Province in China.Bissektipelta
Bissektipelta is a genus of herbivorous ankylosaurid dinosaur from the Upper Cretaceous of Uzbekistan. Bissektipelta is monospecific, containing only the species B. archibaldi.Cedarpelta
Cedarpelta is an extinct genus of herbivorous basal ankylosaurid ankylosaur, based on material recovered from the Lower Cretaceous of North America. The skull lacks extensive cranial ornamentation, a trait which has been interpreted as plesiomorphic for ankylosaurs.Dakota Formation
The Dakota Formation (also Dakota Sandstone) is a geologic formation composed of sedimentary rocks deposited in the late-Early to early-Late Creteceous Western Interior Seaway. F.B. Meek and F.V. Hayden first applied the name to red sandstone exposures along the Missouri River near Dakota City, Nebraska. Dakota Formation is a primary usage in the Great Plains, while Dakota or Dakota Sandstone is used in the context of the Mancos Shale members of the Southwest. The Dakota Group classification is employed along the territory of the Dakota Hogback in Colorado and Wyoming, but includes additional older ages of formations than are usually included elsewhere under the Dakota name.
Owing to extensive terrestrial weathering of older rocks during the Jurassic and Triassic, the Dakota strata lie unconformably atop formations ranging in age from early Creteceous to Precambrian, and are among the oldest Cretaceous rocks in the northern Great Plains, including Kansas, Nebraska, Iowa, Minnesota, and Wisconsin. There, it consists of sandy, shallow-marine or beach deposits with intermittent, marine-influenced mud-flat sediments, and occasional stream deposits.The sandstones of the Dakota Formation form the Dakota Aquifer, an important water source in some areas of the Great Plains.Dongyangopelta
Dongyangopelta is an extinct genus of nodosaurid ankylosaurian dinosaur known from the "middle" Cretaceous Chaochuan Formation (Albian or Cenomanian stage) of Dongyang, Zhejiang Province, China. Dongyangopelta was first named by Rongjun Chen, Wenjie Zheng, Yoichi Azuma, Masateru Shibata, Tianliang Lou, Qiang Jin and Xingsheng Jin in 2013 and the type species is Dongyangopelta yangyanensis. It differs from Zhejiangosaurus, the second nodosaurid from southeast China, in the characters of presacral rod, ilium, and femur. Donyangopelta is distinguishable from Zhejiangosaurus only on the basis of the morphology of its pelvic shield.Hungarosaurus
Hungarosaurus tormai is a herbivorous nodosaurid ankylosaur from the Upper Cretaceous (Santonian) Csehbánya Formation of the Bakony Mountains of western Hungary. It is the most completely known ankylosaur from the Cretaceous of Europe. Ankylosaur material had been known from Europe since the 19th century, with finds having been previously made in England, Austria, western Romania, France, and northern Spain.Mongolostegus
Mongolostegus is a genus of stegosaur from the Early Cretaceous (Aptian-Albian) of Mongolia. The type and only species is M. exspectabilis, known from a single specimen previously under the nomen nudum Wuerhosaurus mongoliensis.Nodosauridae
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous period of what are now North America, Europe, Asia, Africa, and Antarctica.Nodosaurinae
Nodosaurinae is a group of ankylosaurian dinosaurs named in 1919 by Othenio Abel.Nodosaurus
Nodosaurus (meaning "knobbed lizard") is a genus of herbivorous ankylosaurian dinosaur from the Late Cretaceous, the fossils of which are found in North America.Pawpawsaurus
Pawpawsaurus, meaning "Pawpaw Lizard", is a nodosaurid ankylosaur from the Cretaceous (late Albian) of Tarrant County, Texas, discovered in May 1992. The only species yet assigned to this taxon, Pawpawsaurus campbelli, is based on a complete skull (lacking mandibles) from the marine Paw Paw Formation (Wachita Group).Peloroplites
Peloroplites (from Greek pelor "monster", and hoplites, "armoured soldier") is a genus of nodosaurid armored dinosaur from Lower Cretaceous rocks of Utah, United States. It is known from a partial skull and partial postcranial remains from the base of the Mussentuchit Member of the Cedar Mountain Formation, deposited during the Albian-Cenomanian boundary, about 104.46 to 98.37 million years ago, and was found in Emery County, Utah. It was named in 2008 by Kenneth Carpenter and colleagues.
Peloroplites was about 5 to 5.5 meters (16 to 18 ft) long, comparable to its approximate contemporary Sauropelta. It is one of the largest known nodosaurids, and came from a time when ankylosaurians in general were attaining large sizes.Polacanthinae
Polacanthinae is a grouping of ankylosaurs, possibly primitive nodosaurids. Polacanthines are late Jurassic to early Cretaceous in age, and appear to have become extinct about the same time a land bridge opened between Asia and North America.Polacanthines were somewhat more lightly armoured than more advanced ankylosaurids and nodosaurids. Their spikes were made up of thin, compact bone with less reinforcing collagen than in the heavily armoured nodosaurids. The relative fragility of polacanthine armour suggests that it may have been as much for display as defense.Sauropelta
Sauropelta ( SAWR-o-PEL-tə; meaning 'lizard shield') is a genus of nodosaurid dinosaur that existed in the Early Cretaceous Period of North America. One species (S. edwardsorum) has been named although others may have existed. Anatomically, Sauropelta is one of the most well-understood nodosaurids, with fossilized remains recovered in the U.S. states of Wyoming, Montana, and possibly Utah. It is also the earliest known genus of nodosaurid; most of its remains are found in a section of the Cloverly Formation dated to 108.5 million years ago.
It was a medium-sized nodosaurid, measuring about 5.2 metres (17.1 ft) long. Sauropelta had a distinctively long tail which made up about half of its body length. Although its body was smaller than a modern black rhinoceros, Sauropelta was about the same mass, weighing in at about 1,500 kilograms (3,300 lb). The extra weight was largely due to its extensive covering of bony armor, including the characteristically large spines projecting from its neck.Tatisaurus
Tatisaurus is a genus of ornithischian dinosaur from the Early Jurassic from the Lower Lufeng Formation in Yunnan Province in China. Little is known as the remains are fragmentary.Tianzhenosaurus
Tianzhenosaurus (Tianzhen + Greek sauros="lizard") is a genus of ankylosaurid dinosaurs discovered in Tianzhen County, at Kangdailiang near Zhaojiagou Village, in Shanxi Province, China, in the Late Cretaceous Huiquanpu Formation. Thus far, a virtually complete skull and postcranial skeleton have been assigned to the genus, which is monotypic (T. youngi Pang & Cheng, 1998).
This was a medium-sized ankylosaurian, the skull measuring 28 cm (11 in) in length, with a total body length around 4 m (13 ft).
Vickaryous et al. (2004) placed Tianzhenosaurus within the Ankylosauridae, nested as the sister group to Pinacosaurus. Some authors have suggested that Tianzhenosaurus is actually a junior synonym of Saichania chulsanensis.