Glacialisaurus
Encyclopedia
Glacialisaurus is a genus
of massospondylid
sauropodomorph dinosaur
. It lived during the Early Jurassic
period in what is now central Transantarctic Mountains
of Antarctica. It is known from the holotype
FMNH
PR1823, a partial hind limb (foot
) and from the referred material FMNH PR1822, a left femur
. It was discovered and collected in the tuffaceous siltstone
s and mudstone
s of the lower part of the Hanson Formation, in Mount Kirkpatrick
. It was first named by Nathan Smith and Diego Pol in 2007
and the type species is Glacialisaurus hammeri. The generic name, Glacialisaurus, is derived from the Latin
word glacialis, meaning "icy" or "frozen", in reference to the Beardmore Glacier
region in the Central Transantarctic Mountains
, where the fossil remains were found. The specific name, G. hammeri, honors Dr. William R. Hammer of Augustana College
, who made major contributions to both paleontology
and Antarctic research.
In their phylogenetic analysis of the relationships of Glacialisaurus, Smith and Pol found that it is a massospondylid, a non-eusauropod sauropodomorph more advanced than other forms such as Saturnalia
and Plateosaurus
. Features of its foot are similar to Lufengosaurus
(from the Early Jurassic of China
), and the phylogenetic study suggests that Lufengosaurus may have been a close relative of Glacialisaurus, whereas other massospondylids such as Coloradisaurus
and Massospondylus
found to be more basal
forms. Recent cladistic analyses by Yates (2007), Yates et al. (2010, 2011) and Novas et al. (2011) found the same results. The discovery of Glacialisaurus is important to the study of the early distribution of sauropod dinosaurs. The presence of this primitive sauropodomorph in the Hanson Formation (which has also yielded remains attributed to true sauropods) shows that both primitive and advanced members of this lineage existed side by side in the early Jurassic Period.
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 massospondylid
Massospondylidae
Massospondylidae is a family of massopod sauropodomorphs. Massospondylids are early sauropodomorph dinosaurs which existed in Asia, Africa and South America during the Late Triassic to the Early Jurassic periods...
sauropodomorph 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...
. It lived during the Early Jurassic
Early Jurassic
The Early Jurassic epoch is the earliest of three epochs of the Jurassic period...
period in what is now central Transantarctic Mountains
Transantarctic Mountains
The three largest mountain ranges on the Antarctic continent are the Transantarctic Mountains , the West Antarctica Ranges, and the East Antarctica Ranges. The Transantarctic Mountains compose a mountain range in Antarctica which extend, with some interruptions, across the continent from Cape Adare...
of Antarctica. 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...
FMNH
Field Museum of Natural History
The Field Museum of Natural History is located in Chicago, Illinois, USA. It sits on Lake Shore Drive next to Lake Michigan, part of a scenic complex known as the Museum Campus Chicago...
PR1823, a partial hind limb (foot
Foot
The foot is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made up of one or more segments or bones, generally including claws...
) and from the referred material FMNH PR1822, a left femur
Femur
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 discovered and collected in the tuffaceous siltstone
Siltstone
Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...
s and 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 of the lower part of the Hanson Formation, in Mount Kirkpatrick
Mount Kirkpatrick
Mount Kirkpatrick is a lofty, generally ice-free mountain in Antarctica's Queen Alexandra Range. Located 8 km west of Mount Dickerson, Mt. Kirkpatrick is the highest point in the Queen Alexandra Range, as well as in its parent range, the Transantarctic Mountains...
. It was first named by Nathan Smith and Diego Pol in 2007
2007 in paleontology
-newly named:-New taxa:-Newly named non-avian dinosaurs:Data courtesy of George Olshevky's dinosaur genera list.-Newly named birds:-New papers:...
and the type species is Glacialisaurus hammeri. The generic name, Glacialisaurus, is derived from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
word glacialis, meaning "icy" or "frozen", in reference to the Beardmore Glacier
Beardmore Glacier
The Beardmore Glacier in Antarctica is one of the largest glaciers in the world, with a length exceeding 160 km . The glacier is one of the main passages from the Ross Ice Shelf through the Queen Alexandra and Commonwealth ranges of the Transantarctic Mountains to the Antarctic Plateau, and was one...
region in the Central Transantarctic Mountains
Transantarctic Mountains
The three largest mountain ranges on the Antarctic continent are the Transantarctic Mountains , the West Antarctica Ranges, and the East Antarctica Ranges. The Transantarctic Mountains compose a mountain range in Antarctica which extend, with some interruptions, across the continent from Cape Adare...
, where the fossil remains were found. The specific name, G. hammeri, honors Dr. William R. Hammer of Augustana College
Augustana College (Illinois)
Augustana College is a private liberal arts college located in Rock Island, Illinois, United States. The college enrolls approximately 2,500 students. Covering of hilly, wooded land, Augustana is adjacent to the Mississippi River...
, who made major contributions to both paleontology
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
and Antarctic research.
In their phylogenetic analysis of the relationships of Glacialisaurus, Smith and Pol found that it is a massospondylid, a non-eusauropod sauropodomorph more advanced than other forms such as Saturnalia
Saturnalia (dinosaur)
Saturnalia is an extinct genus of basal sauropodomorph dinosaur known from the Triassic of Rio Grande do Sul, southern Brazil.-Discovery:Saturnalia was originally named on the basis of three partial skeletons...
and Plateosaurus
Plateosaurus
Plateosaurus is a genus of plateosaurid dinosaur that lived during the Late Triassic period, around 216 to 199 million years ago, in what is now Central and Northern Europe. Plateosaurus is a basal sauropodomorph dinosaur, a so-called "prosauropod"...
. Features of its foot are similar to Lufengosaurus
Lufengosaurus
Lufengosaurus is a genus of prosauropod dinosaur which lived during the Early Jurassic period in what is now southwestern China.-Discovery and species:...
(from the Early Jurassic 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...
), and the phylogenetic study suggests that Lufengosaurus may have been a close relative of Glacialisaurus, whereas other massospondylids such as Coloradisaurus
Coloradisaurus
Coloradisaurus is a genus of massospondylid sauropodomorph dinosaur. It lived during the Late Triassic period in what is now La Rioja Province, Argentina. It is known from the holotype PVL 5904, nearly complete skull...
and Massospondylus
Massospondylus
Massospondylus and ) is a genus of prosauropod dinosaur from the early Jurassic Period . It was described by Sir Richard Owen in 1854 from remains found in South Africa, and is thus one of the first dinosaurs to have been named...
found to be more basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
forms. Recent cladistic analyses by Yates (2007), Yates et al. (2010, 2011) and Novas et al. (2011) found the same results. The discovery of Glacialisaurus is important to the study of the early distribution of sauropod dinosaurs. The presence of this primitive sauropodomorph in the Hanson Formation (which has also yielded remains attributed to true sauropods) shows that both primitive and advanced members of this lineage existed side by side in the early Jurassic Period.