Siamosaurus

*Siamosaurus suteethorni*

***Siamosaurus***, meaning "Siamese lizard", (SIE-ah-moe-SORE-us) is an extinct genus of spinosaurid which existed during the early Cretaceous period, Thailand. The exact size of this dinosaur is currently unknown, however most estimates suggest that it was around 9.1 metres (30 ft) in length and 2-3 tons in weight.

Little is known about *Siamosaurus*. Its teeth closely resembled those of its relative species; like *Spinosaurus aegypticus*, its diet is presumed to be mainly consisted of aquatic animals; like large fish & crocodymorphs; albeit it is known that the spinosaurids were generalist carnivores; indicating siasmosaurus would be able to hunt/search for the terrestrial prey as well. This carnivore generalism seems to be the case as some of the siasmosaurus remains found to be with the direct assosication with sauropod remains

## History

Éric Buffetaut and his colleague Rucha Ingavat discovered teeth from Phu Pratu Teema, Sao Khua Formation. By 1983, it was unknown which animal these were from, but they were determined to be either from an "unusual theropod, or some unknown crocodilian". In 1986, a reassessment found them as a new genus, *Siamosaurus*. The epithet is after Varavudh Suteethorn and the genus means "Siamese lizard".

## Description

Size estimates vary because it is so incomplete. Postcrania and teeth SM2016-1-147 and SM2016-1-165 are in the Sirindhorn Museum in Thailand, with a caudal series possibly referable described by a dissertation by Samathi. SM-PW9B-11 to 17, SM-PW9B, SM-PW9A-unnumbered, SM-PW9-unnumbered and SM 2017-1-176 were called "Phuwing spinosaurid B" by Samathi, being similar to *Camarillasaurus* and *Baryonyx*. Two partial skeletons and a tooth are also referable.

## Paleobiology

Siamosaurus bears signs of being a generalist carnivore. Isolate tooth crowns found in direct associated with sauropod material indicate that it was either a predator of them or an opportunistic scavenger.

## Habitat and behavior

According to a 2010 publication by Roman Amiot and his colleagues found that oxygen isotope ratios in spinosaurid remains suggest semiaquatic lifestyles. Further comparisons between spinosaurid teeth and those of a contemporary theropod, crocodile and turtle showed that they were more similar to those of crocodilians and turtles than was originally believed, further supporting the notion that *Siamosaurus* and some species of spinosaurids were likely semi-aquatic. *Siamosaurus* specimens tend to have the largest difference to theropods and *Spinosaurus* had the smallest. The results of the tests concluded that some spinosaurids had lifestyles similar to crocodilians and hippopotamuses and spent most of their daily life in water.

Its indicated or suggested semiaquatic adaptations might suggests that *Siamosaurus* was able to live alongside other theropods without competing for food, since they lived in different habitats and possessed different diets and ecological niches. This would have however encouraged Siamosaurs to breed more which may or may not have reduced aquatic animal species populations and probably forced the animal onto more terrestrial prey items, as indicated by the sauropod remains direct association with Siamosaurus.

*Siamosaurus* and *Ichthyovenator* are the two primary spinosaurid species that live in south east Asia. How they migrated there or why they lived there is unknown. There seems to be no identifiable advantages living there, other than maybe the lack of larger spinosaurids and larger carnivores.

## Appearance in other media

### *Jurassic Park*

* Siamosaurus appeared in the Jurassic World toys.

## References

1. ↑ https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0147031
2. ↑ http://novataxa.blogspot.com/2012/04/1986-siamosaurus-suteethorni.html?m=1
3. ↑ http://bionames.org/references/b59a520799fa193c4549b19075d59f3b
4. ↑ http://www.sdm.dmr.go.th/db/datafossils\_detailf.php?id=00000000000000219641
5. ↑ http://www.sdm.dmr.go.th/db/datafossils\_detailf.php?id=00000000000000219713
6. ↑ http://www.sdm.dmr.go.th/db/datafossils\_detailf.php?id=00000000000000219621
7. ↑ http://www.sdm.dmr.go.th/db/datafossils\_detailf.php?id=00000000000000219641
8. ↑ https://www.researchgate.net/publication/260714806\_The\_evolution\_of\_large-bodied\_therood\_dinosaurs\_during\_the\_Mesozoic\_in\_Asia
9. ↑ https://bonndoc.ulb.uni-bonn.de/xmlui/handle/20.500.11811/8088
10. ↑ https://www.semanticscholar.org/paper/The-%E2%80%9C%CF%87%E2%80%9D-of-the-Matter%3A-Testing-the-Relationship-and-Sales-Lacerda/4dc98d4c53064e319f3070ba0bc36471caa6cf64
11. ↑ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4734717/
12. ↑ https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0152634
13. ↑ https://www.readcube.com/articles/10.1371/journal.pone.0147031