Augustasaurus
Encyclopedia
Augustasaurus is a genus
of aquatic sauropterygian reptile
belonging to the Pistosauria, a clade
containing plesiosaurs and their close relatives. Pistosaurus
and Augustasaurus were thougth to be the only known members of the family
Pistosauridae. However some recent cladistic analyses found Augustasaurus to be more advanced pistosaur, as a sister group of the order
Plesiosauria
. The only known species of Augustasaurus is Augustasaurus hagdorni , which was first described in 1997
.
of northwestern Nevada
, where its fossil
bones were first discovered. The second part of the name is the Greek
word sauros (σαυρος), which means "lizard
" or "reptile
." The type species, Augustasaurus hagdorni, was named in honor of the paleontologist Hans Hagdorn.
shares many general characteristics with its relative, Pistosaurus, such as tall, blade-like upper temporal arches. The skull's elongated rostrum
tapers to a dull point, the anterior premaxilla
ry and maxilla
ry teeth have been described as "fang
-like", and the squamosal
makes a box-like suspensorium.
The dorsal
neural spines
of Augustasaurus are low with rugose tops. Its coracoids are large plates similar to those in other plesiosaurs. However, the coracoid foramen are missing from Agustasaurus, in a way similar to those in the plesiosaur Corosaurus
. Its cervical ribs have anterior process, and like most plesiosaurs, Augustasaurus vertebrae have "thickened transverse processes".
of northwestern Nevada (United States
). The holotype
specimen was found in the Favret Formation
, which dates from the mid-Triassic period, of Pershing County, Nevada
.
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 aquatic sauropterygian reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
belonging to the Pistosauria, a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
containing plesiosaurs and their close relatives. Pistosaurus
Pistosaurus
Pistosaurus longaevus is an extinct genus of aquatic sauropterygian reptile closely related to plesiosaurs. Fossils have been found in France and Germany, and date to the Middle Triassic.- Appearance :...
and Augustasaurus were thougth to be the only known members of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Pistosauridae. However some recent cladistic analyses found Augustasaurus to be more advanced pistosaur, as a sister group of the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Plesiosauria
Plesiosauria
Plesiosauria is an order of Mesozoic marine reptiles. Plesiosaurs first appeared in the Early Jurassic Period and became especially common during the Jurassic Period, thriving until the K-T extinction at the end of the Cretaceous Period.The name "plesiosaur" is used to refer to the order...
. The only known species of Augustasaurus is Augustasaurus hagdorni , which was first described in 1997
1997 in paleontology
-newly named:-Newly named birds:-Dinosaurs:* Paleontologist Karen Chin receives a coprolite that was excavated during 1995 from strata dating back to the Maastrichtian in Saskatchewan, Canada. The specimen was about 17 inches long and contained fragments of bone...
.
Etymology
The first part of Augustasaurus name comes from the Augusta MountainsAugusta Mountains
The Augusta Mountains are a mountain range in Pershing County, Nevada....
of northwestern Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
, where its fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
bones were first discovered. The second part of the name is the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
word sauros (σαυρος), which means "lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
" or "reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
." The type species, Augustasaurus hagdorni, was named in honor of the paleontologist Hans Hagdorn.
Description
Augustasaurus skullSkull
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...
shares many general characteristics with its relative, Pistosaurus, such as tall, blade-like upper temporal arches. The skull's elongated rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....
tapers to a dull point, the anterior premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
ry and maxilla
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...
ry teeth have been described as "fang
Fang
Fang is a mammal's canine tooth.Fang may also refer to:* A snake's poison-injecting tooth: see snake venom* Fang people, in Central Africa* Fang language, spoken by Fang people...
-like", and the squamosal
Squamosal
The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...
makes a box-like suspensorium.
The dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
neural spines
Spine (zoology)
A spine is a hard, thorny or needle-like structure which occurs on various animals. Animals such as porcupines and sea urchins grow spines as a self-defense mechanism. Spines are often formed of keratin...
of Augustasaurus are low with rugose tops. Its coracoids are large plates similar to those in other plesiosaurs. However, the coracoid foramen are missing from Agustasaurus, in a way similar to those in the plesiosaur Corosaurus
Corosaurus
Corosaurus is an extinct genus of pistosauroid known from Wyoming of the USA.-Description:Corosaurus is known from the holotype UW 5485, a partial skeleton which includes the skull...
. Its cervical ribs have anterior process, and like most plesiosaurs, Augustasaurus vertebrae have "thickened transverse processes".
Distribution
Augustasaurus is known from the Augusta MountainsAugusta Mountains
The Augusta Mountains are a mountain range in Pershing County, Nevada....
of northwestern Nevada (United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
). 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...
specimen was found in the Favret Formation
Favret Formation
The Favret Formation is a Mesozoic geologic formation. Plesiosaur remains are among the fossils that have been recovered from its strata....
, which dates from the mid-Triassic period, of Pershing County, Nevada
Pershing County, Nevada
Pershing County is a county located in the U.S. state of Nevada. As of the 2000 census, the population was 6,693. Its county seat is Lovelock. The county was named after army general John J. Pershing . It was formed from Humboldt County in 1919, and the last county to be established in...
.
External links
- http://www.vertpaleo.org/publications/jvp/22-577-592.cfm
- http://www.plesiosaur.com/database/genusIndividual.php?i=32
- http://www.palaeos.com/Vertebrates/Units/220Lepidosauromorpha/220.400.html