Suuwassea
Encyclopedia
Suuwassea is a genus
of diplodocoid
sauropod dinosaur
found in the Upper Jurassic strata of the Morrison Formation
, located in southern Carbon County
, Montana
, USA. The fossil remains were recovered in a series of expeditions during a period spanning the years 1999 and 2000, described by J.D. Harris and Peter Dodson
in 2004. They consist of a disarticulated but associated partial skeleton, including partial vertebral series and limb bones.
Since the fossil was found in an ancestral territory of the Native American
Crow
tribe, the etymology of the generic name is derived from a term in their language, suuwassa, “the first thunder heard in Spring”. The root suu, meaning “thunder” and wassa, “ancient”, are a nod to the “thunder lizard” moniker often applied to sauropods. The specific descriptor honours the deceased sponsor of the expeditions that recovered the fossil.
Suuwassea is a basal diplodocoid, estimated to have been 14 to 15 meters long (46 to 49 ft), characterized by skull and axial skeleton features it shares with Diplodocidae and Dicraeosauridae
though it is too primitive to pertain to any of the latter clades. The herbivore differs from dicraeosaurids in the unfused state of the frontal, and from diplodocids in the arrangement of bones around the foramen magnum, though it possesses a greater number of similarities with the latter than with clade Dicraeosauridae.
S. emilieae’s find is concurrent with other finds of medium-sized sauropods in Morrison Formation’s northern section contrary to the finds of large animals in the southern reaches. This size difference was possibly due to new environments created as the Middle Jurassic
Sundance Sea
retreated northward. This sauropod’s phylogenetic analysis puts in doubt a number of autapomorphic characters of both Diplodocidae and Dicraeosauridae, opening the possibility that these are plesiomorphies differentially retained by each family. The presence of dicraeosaurid characters on a Laurasian diplodocoid also raises the question of the origin and distribution of a purported ancestral diplodocoid: Laurasia
, Gondwana
, or both.
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 diplodocoid
Diplodocoidea
Diplodocoidea was a superfamily of sauropod dinosaurs, which included some of the longest animals of all time, including slender giants like Supersaurus, Diplodocus, Apatosaurus, and Amphicoelias...
sauropod 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...
found in the Upper Jurassic strata of the Morrison Formation
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...
, located in southern Carbon County
Carbon County, Montana
-National protected areas:* Bighorn Canyon National Recreation Area * Custer National Forest * Gallatin National Forest -Economy:During the early history of Carbon County, coal mining was the predominant industry...
, Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
, USA. The fossil remains were recovered in a series of expeditions during a period spanning the years 1999 and 2000, described by J.D. Harris and Peter Dodson
Peter Dodson
Peter Dodson is an American paleontologist who has published many papers and written and collaborated on books about dinosaurs. An authority on Ceratopsians, he has also authored several papers and textbooks on hadrosaurs and sauropods, and is a co-editor of The Dinosauria, widely considered the...
in 2004. They consist of a disarticulated but associated partial skeleton, including partial vertebral series and limb bones.
Since the fossil was found in an ancestral territory of the Native American
Native Americans in the United States
Native Americans in the United States are the indigenous peoples in North America within the boundaries of the present-day continental United States, parts of Alaska, and the island state of Hawaii. They are composed of numerous, distinct tribes, states, and ethnic groups, many of which survive as...
Crow
Crow Nation
The Crow, also called the Absaroka or Apsáalooke, are a Siouan people of Native Americans who historically lived in the Yellowstone River valley, which extends from present-day Wyoming, through Montana and into North Dakota. They now live on a reservation south of Billings, Montana and in several...
tribe, the etymology of the generic name is derived from a term in their language, suuwassa, “the first thunder heard in Spring”. The root suu, meaning “thunder” and wassa, “ancient”, are a nod to the “thunder lizard” moniker often applied to sauropods. The specific descriptor honours the deceased sponsor of the expeditions that recovered the fossil.
Suuwassea is a basal diplodocoid, estimated to have been 14 to 15 meters long (46 to 49 ft), characterized by skull and axial skeleton features it shares with Diplodocidae and Dicraeosauridae
Dicraeosauridae
Dicraeosauridae is a family of sauropod dinosaurs known from the Late Jurassic and Early Cretaceous of Africa and South America. Currently only three genera are recognised; the Jurassic South American genus Brachytrachelopan, the Jurassic African Dicraeosaurus and the South American Early...
though it is too primitive to pertain to any of the latter clades. The herbivore differs from dicraeosaurids in the unfused state of the frontal, and from diplodocids in the arrangement of bones around the foramen magnum, though it possesses a greater number of similarities with the latter than with clade Dicraeosauridae.
S. emilieae’s find is concurrent with other finds of medium-sized sauropods in Morrison Formation’s northern section contrary to the finds of large animals in the southern reaches. This size difference was possibly due to new environments created as the Middle Jurassic
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
Sundance Sea
Sundance Sea
The Sundance Sea was an epeiric sea that existed in North America during the mid to late Jurassic Period of the Mesozoic Era. It was an arm of what is now the Arctic Ocean, and extended through what is now western Canada into the central western United States...
retreated northward. This sauropod’s phylogenetic analysis puts in doubt a number of autapomorphic characters of both Diplodocidae and Dicraeosauridae, opening the possibility that these are plesiomorphies differentially retained by each family. The presence of dicraeosaurid characters on a Laurasian diplodocoid also raises the question of the origin and distribution of a purported ancestral diplodocoid: Laurasia
Laurasia
In paleogeography, Laurasia was the northernmost of two supercontinents that formed part of the Pangaea supercontinent from approximately...
, Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
, or both.