Sarahsaurus
Encyclopedia
Sarahsaurus is a genus
of basal
sauropodomorph dinosaur
which lived during the lower Jurassic period in what is now northeastern Arizona
, USA.
Sarahsaurus is known from a nearly complete articulated holotype
skeleton
referred to as TMM 43646-2, another partial skeleton known as TMM 43646-3, and a nearly complete but poorly preserved skull
known as MCZ 8893. This last specimen was previously described and referred to as Massospondylus sp. All specimens of Sarahsaurus were collected from the Early Jurassic
Kayenta Formation
near Gold Spring, Arizona, which is Sinemurian
to Pliensbachian
in age.
Sarahsaurus was first described by Timothy B. Rowe, Hans-Dieter Sues
and Robert R. Reisz
in 2011
and the type species
is Sarahsaurus aurifontanalis. The generic name honours Sarah (Mrs Ernest) Butler, and sauros (Greek), for "lizard". The specific name is derived from aurum (Latin), "gold", and fontanalis (Latin), "of the spring" in reference to Gold Spring, Arizona, where the holotype was found. Sarahsaurus is the third basal sauropodomorph dinosaur to have been identified in North America
. (The other two are Anchisaurus
[here including Ammosaurus
] from the Early Jurassic of the Connecticut River Valley and Seitaad
of the later Navajo Sandstone
of Early Jurassic Utah.) It is thought to have appeared through a dispersal event that originated in South America and was separate from those of the other two sauropodomorphs. The animal is notable for possessing very large, powerful hands, suggesting that it was an omnivore.
In a cladistic analysis, presented by Apaldetti and colleagues in November 2011, Sarahsaurus was found to be most closely related to Ignavusaurus
within Massopoda
.
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 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:...
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...
which lived during the lower Jurassic period in what is now northeastern Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
, USA.
Sarahsaurus is known from a nearly complete articulated 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...
skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
referred to as TMM 43646-2, another partial skeleton known as TMM 43646-3, and a nearly complete but poorly preserved skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
known as MCZ 8893. This last specimen was previously described and referred to as Massospondylus sp. All specimens of Sarahsaurus were collected from the Early Jurassic
Early Jurassic
The Early Jurassic epoch is the earliest of three epochs of the Jurassic period...
Kayenta Formation
Kayenta Formation
The Kayenta Formation is a geologic layer in the Glen Canyon Group that is spread across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah. This rock formation is particularly prominent in southeastern Utah, where it is seen in the...
near Gold Spring, Arizona, which is Sinemurian
Sinemurian
In the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
to Pliensbachian
Pliensbachian
The Pliensbachian is an age of the geologic timescale or stage in the stratigraphic column. It is part of the Early or Lower Jurassic epoch or series and spans the time between 189.6 ± 1.5 Ma and 183 ± 1.5 Ma . The Pliensbachian is preceded by the Sinemurian and followed by the Toarcian.The...
in age.
Sarahsaurus was first described by Timothy B. Rowe, Hans-Dieter Sues
Hans-Dieter Sues
Hans-Dieter Sues is a German-born paleontologist who is Senior Scientist and Curator of Vertebrate Paleontology at the National Museum of Natural History of the Smithsonian Institution in Washington, DC. He received his education at Johannes Gutenberg-Universität Mainz , University of Alberta, and...
and Robert R. Reisz
Robert R. Reisz
Robert Rafael Reisz is a Canadian paleontologist and specialist in the study of early amniote and tetrapod evolution.Robert Reisz was born August 27, 1947, in Oradea, Romania. He received his B.Sc. , M.Sc. and Ph.D. from McGill University as Robert L. Carroll’s first doctoral graduate...
in 2011
2011 in paleontology
-Lobopods:-Arachnids:-Insects:-Newly named jawless vertebrates:-Newly named acanthodian:-Newly named cartilaginous fishes:-Newly named bony fishes:-Newly named lepospondyls:-Newly named temnospondyls:-Newly named lissamphibians:...
and the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
is Sarahsaurus aurifontanalis. The generic name honours Sarah (Mrs Ernest) Butler, and sauros (Greek), for "lizard". The specific name is derived from aurum (Latin), "gold", and fontanalis (Latin), "of the spring" in reference to Gold Spring, Arizona, where the holotype was found. Sarahsaurus is the third basal sauropodomorph dinosaur to have been identified in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. (The other two are Anchisaurus
Anchisaurus
Anchisaurus is a genus of basal sauropodomorph, and was an early herbivorous dinosaur. Until recently it was classed as a member of Prosauropoda. The name comes from the Greek αγχι/agkhi...
[here including Ammosaurus
Ammosaurus
Ammosaurus is a genus of sauropodomorph dinosaur from the Early and Middle Jurassic Period of North America. At 4 meters in length, it was small compared to some other members of its suborder, which included the largest animals ever to walk the Earth...
] from the Early Jurassic of the Connecticut River Valley and Seitaad
Seitaad
Seitaad is a genus of sauropodomorph dinosaur which lived during the lower Jurassic period in what is now southern Utah, USA.Seitaad is known from an articulated partial postcranial holotype skeleton referred to as UMNH VP 18040. The skeleton is missing its head, neck and tail...
of the later Navajo Sandstone
Navajo Sandstone
Navajo Sandstone is a geologic formation in the Glen Canyon Group that is spread across the U.S. states of northern Arizona, northwest Colorado, and Utah; as part of the Colorado Plateau province of the United States...
of Early Jurassic Utah.) It is thought to have appeared through a dispersal event that originated in South America and was separate from those of the other two sauropodomorphs. The animal is notable for possessing very large, powerful hands, suggesting that it was an omnivore.
In a cladistic analysis, presented by Apaldetti and colleagues in November 2011, Sarahsaurus was found to be most closely related to Ignavusaurus
Ignavusaurus
Ignavusaurus is a genus of basal sauropodomorph dinosaur that lived during the Early Jurassic in what is now present-day Lesotho. Its fossils were found in the upper Elliot Formation which is probably Hettangian in age. It was described on the basis of a partial, well preserved articulated skeleton...
within Massopoda
Massopoda
The Massopoda is a clade of sauropodomorph dinosaurs which lived during the Late Triassic to the Late Cretaceous periods. Massopoda, which was first named by paleontologist Adam M...
.