Callawayasaurus
Encyclopedia
Callawayasaurus is a genus
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 plesiosaur
Plesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...

 from 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...

 Elasmosauridae
Elasmosauridae
Elasmosauridae was the family of plesiosaurs. They had the longest necks of the plesiosaurs and survived from the Late Triassic to the end of the Cretaceous. They had a diet of fish and shelless cephalopods.-Size:...

. When the first Callawayasaurus fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 was first discovered by Samuel Paul Welles
Samuel Paul Welles
Samuel Paul Welles was an American palaeontologist, who was Research Associate at the Museum of Palaeontology, University of California, Berkeley. He took part in excavations at the 'Placerias Quarry' in 1930 and the Shonisaurus discoveries of 1954 and later, in what is now the Berlin-Ichthyosaur...

 in 1962, he described it as Alzadasaurus colombiensis before it was moved into its current genus by Kenneth Carpenter
Kenneth Carpenter
Kenneth Carpenter is a paleontologist. He is the museum director of the USU Eastern Prehistoric Museum and author or co-author of a number of books on dinosaurs and Mesozoic life...

 in 1999.

Etymology

Callawayasaurus (Callaway) is named in honor of the paleontologist, Jack M. Callaway, editor of Ancient Marine Reptiles who, as Carpenter put it, "in his brief career as a vertebrate paleontologist, did much to improve our understanding of marine reptiles". The familiar suffix, -saurus comes from the Greek sauros (σαυρος), meaning "lizard" or "reptile."

Description

The first 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...

 of Callawayasaurus to be found was 35 cm long, while the animal as a whole grew up to 8 m long. The nares of Callawayasaurus are elongated and positioned over the 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...

, which has 3-5 teeth.
The neck
Neck
The neck is the part of the body, on many terrestrial or secondarily aquatic vertebrates, that distinguishes the head from the torso or trunk. The adjective signifying "of the neck" is cervical .-Boner anatomy: The cervical spine:The cervical portion of the human spine comprises seven boney...

 contains 56 vertebrae which are relatively short compared to other elasmosaurids. Callawayasaurus fossils have no pectoral bars; in common with other plesiosaurs such as Terminonatator
Terminonatator
Terminonatator is a genus of elasmosaurid plesiosaur from the Late Cretaceous of Saskatchewan, Canada. It is known from a skull and partial skeleton from a young adult, found in the Campanian-age Bearpaw Formation near Notukeu Creek in Ponteix...

. They also lack postaxial accessory facets
Zygapophysial joint
A zygapophysial joint is a synovial joint between the superior articular process of one vertebra and the inferior articular process of the vertebra directly above it...

.

Another nearly complete 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...

 was found to be slightly more robust than 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
Specimen
A specimen is a portion/quantity of material for use in testing, examination, or study.BiologyA laboratory specimen is an individual animal, part of an animal, a plant, part of a plant, or a microorganism, used as a representative to study the properties of the whole population of that species or...

. This subtle change may indicate sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...

.

Distribution

The fist Callawayasaurus remains were found in the Paja Formation
Paja Formation
The Paja Formation is a Mesozoic geologic formation. Plesiosaur remains are among the fossils that have been recovered from its strata....

 near Leiva
Villa de Leyva
Villa de Leyva is a colonial town and municipality, in the Boyacá department of Colombia, part of the subregion of the Ricaurte Province. The town is located some 40 km west of Tunja and has a population of about 9,600 people...

, Boyaca
Boyacá Department
Boyacá is one of the 32 Departments of Colombia, and the remnant of one of the original nine states of the "United States of Colombia".Boyacá is centrally located within Colombia, almost entirely within the mountains of the Eastern Cordillera to the border with Venezuela, although the western end...

 Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

.
The species name for the type, "columbiensis", means "from Columbia."
Callawayasaurus are known from the Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...

 faunal stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...

 of the early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 period, which extended from 125 to 112 million years ago.

External links

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