Siamosaurus
Encyclopedia
Siamosaurus is a genus
of theropod dinosaur
from Early Cretaceous
Thailand
. The size of the animal is unknown, but it may have reached a length of about 9.1 meters (30 ft). The type species
, Siamosaurus suteethorni, was formally described by Buffetaut and Ingavat in 1986. There is very little information on this Cretaceous meat-eater, but it is known from teeth that closely resemble those of Spinosaurus
; it may have eaten fish
.
ratios of spinosaurid bones indicates semiaquatic lifestyles. Isotope ratios from teeth from the spinosaurids Baryonyx
, Irritator
, Siamosaurus, and Spinosaurus
were compared with isotopic compositions from contemporaneous theropods, turtles, and crocodilians. The study found that, among theropods, spinosaurid isotope ratios were closer to those of turtles and crocodilians. Siamosaurus specimens tended to have the largest difference from the ratios of other theropods, and Spinosaurus tended to be have the least difference. The authors concluded that spinosaurids, like modern crocodilians and hippopotamuses, spent much of their daily lives in water. The authors also suggested that semiaquatic habits and piscivory
in spinosaurids can explain how spinosaurids coexisted with other large theropods: by feeding on different prey items and living in different habitats, the different types of theropods would have been out of direct competition.
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 theropod 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...
from 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...
Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
. The size of the animal is unknown, but it may have reached a length of about 9.1 meters (30 ft). 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...
, Siamosaurus suteethorni, was formally described by Buffetaut and Ingavat in 1986. There is very little information on this Cretaceous meat-eater, but it is known from teeth that closely resemble those of Spinosaurus
Spinosaurus
Spinosaurus is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. This genus was first known from Egyptian remains discovered in 1912 and described by German...
; it may have eaten fish
Piscivore
A piscivore is a carnivorous animal which eats primarily fish. Piscivory was the diet of early tetrapods , insectivory came next, then in time reptiles added herbivory....
.
Habitat
A 2010 publication by Romain Amiot and colleagues found that oxygen isotopeIsotopes of oxygen
There are three stable isotopes of oxygen that lead to oxygen having a standard atomic mass of 15.9994 u. 17 radioactive isotopes have also been characterized, with mass numbers from 12O to 28O, all short-lived, with the longest-lived being 15O with a half-life of 122.24 seconds...
ratios of spinosaurid bones indicates semiaquatic lifestyles. Isotope ratios from teeth from the spinosaurids Baryonyx
Baryonyx
Baryonyx is a genus of carnivorous saurischian dinosaur first discovered in clay pits just south of Dorking, England, and later reported from fossils found in northern Spain and Portugal. It is known to contain only one species, Baryonyx walkeri...
, Irritator
Irritator
Irritator is a genus of spinosaurid dinosaur that lived in the early Cretaceous Period , around 110 million years ago. Current estimations indicate a length of 8 meters . It was found in Brazil...
, Siamosaurus, and Spinosaurus
Spinosaurus
Spinosaurus is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. This genus was first known from Egyptian remains discovered in 1912 and described by German...
were compared with isotopic compositions from contemporaneous theropods, turtles, and crocodilians. The study found that, among theropods, spinosaurid isotope ratios were closer to those of turtles and crocodilians. Siamosaurus specimens tended to have the largest difference from the ratios of other theropods, and Spinosaurus tended to be have the least difference. The authors concluded that spinosaurids, like modern crocodilians and hippopotamuses, spent much of their daily lives in water. The authors also suggested that semiaquatic habits and piscivory
Piscivore
A piscivore is a carnivorous animal which eats primarily fish. Piscivory was the diet of early tetrapods , insectivory came next, then in time reptiles added herbivory....
in spinosaurids can explain how spinosaurids coexisted with other large theropods: by feeding on different prey items and living in different habitats, the different types of theropods would have been out of direct competition.
External links
- Siamosaurus in The Dinosaur Encyclopaedia at Dino Russ's Lair