Giganotosaurus

*Giganotosaurus carolinii*

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***Giganotosaurus*** (meaning "giant southern lizard") is an extinct genus of carcharodontosaurid theropod dinosaurs that lived in the Cenomanian of Argentina 99.6 - 97 mya. The holotype was discovered in the Candeleros Formation of Patagonia in 1993, and is about 70% complete. The animal was named ***Giganotosaurus carolinii*** in 1995; the genus name translates as "giant southern lizard" and the specific name honors the discoverer, Rubén D. Carolini.

A dentary bone, a tooth and some tracks, discovered before the holotype, were later assigned to this animal. The genus attracted much interest and became part of a scientific debate about the maximum sizes of theropod dinosaurs.

## Description

The *Giganotosaurus* means "the giant southern lizard", as the *Megalosaurus* was the "giant lizard". It appeared superficially similar to other Carcharodontosaurs such as *Carcharodontosaurus and Mapusaurus*.

## Discovery

***Giganotosaurus carolinii*** was named after Ruben Carolini, an amateur fossil hunter, who discovered the fossils in the deposits of the Rio Limay Formation of Patagonia, southern Argentina, in 1993. It was published by Rodolfo Coria and Leonardo Selgado in the journal Nature in 1995.

The holotype specimen's (MUCPv-Ch1) skeleton was about 70% complete and included the skull, pelvis, leg bones, and most of the backbone. It is estimated at about 8.8 tonnes in weight, 3.5 meters tall at the hips, and 12.7 meters (41.6 feet) in length. A second specimen (MMCh-PV-95), was estimated at 2-5% larger. This larger *Giganotosaurus* specimen was estimated to represent an individual 12-13 meters long that was about 3.7 meter tall at the hips and weighed about 9.5 tonnes. The most complete skeleton was housed at the Royal Ontario Museum until March 17, 2013. The Specimen (MUCPv-Ch1) is 70 percent complete and is only missing its arms and feet.

## Classification

Coria and Salgado originally found Giganotosaurus to group more closely with the theropod clade Tetanurae than to more basal (Or "primitive") theropods such as ceratosaurs, due to shared features (synapomorphies) in the legs, skull, and pelvis. In 1996 Sereno and colleagues found *Giganotosaurus*, *Carcharodontosaurus*, and *Acrocanthosaurus* to be closely related within the superfamily Allosauroidea, and grouped them in the family Carcharodontosauridae. Features shared between these genera include the lacrimal and postorbital bones forming a broad "shelf" over the orbit, and the squared front end of the lower jaw.

## Paleobiology

*Giganotosaurus* lived in Argentina alongside giant sauropods such as *Limaysaurus* and *Andesaurus*. It's closest relatives were from the same continent, *Tyrannotitan* and *Mapusaurus*, and was also closely related to *Carcharodontosaurus* in Africa. It was a distant relative of *Allosaurus* from the Jurassic period. It had a massive skull, a long tail for extra balance to help support its massive head, fairly long and strong arms with three clawed fingers, and powerful back legs with three sharp talons on their toes. Most people speculate, considering the length and musculature of its legs, that *Giganotosaurus* could run even 30km/h. It had over 76 8-inch (20 centimeters), blade-like teeth that were built for slashing and bleeding out prey.

In 2005 Francois Terrier e.a. estimated that the bite force of *Giganotosaurus* was three times less than that of *Tyrannosaurus* and that the lower jaws were optimized for inflicting bleeding wounds; the point of the mandibula was reinforced to this purpose with a "chin" and broadened to handle smaller prey. The killing method of *Giganotosaurus* is killing by slicing through flesh and letting its prey bleed to death. An extremely brutal and unethical, but effective method. Titanosaur fossils, belonging to *Andesaurus* and *Limaysaurus*, have been recovered near the remains of Giganotosaurus, leading to speculation that these carnivores may have preyed on the giant herbivores. Fossils of the related carcharodontosaurid *Mapusaurus* grouped closely together may indicate pack hunting, a behavior that could possibly extend to *Giganotosaurus* itself.

In a study from 2021, A. J. Rowe and Snively estimated a bite force of 24,977 Newtons (~2.5 metric tons) for *Giganotosaurus*.

The original fossils of *Giganotosaurus* remain at the Carmen Funes Museum in Neuquen, Argentina, but replicas are common in other places, including the Australian Museum in Sydney.

## Paleoenvironment

*Giganotosaurus* was discovered in the Candeleros Formation, which was deposited during the Early Cenomanian age of the Late Cretaceous, approximately 98-97 million years ago.

## Notable Specimens

* **MUCPv-Ch1** is the holotype of *Giganotosaurus*, discovered in 1995, known from a partial skull, cervical, dorsal, sacral, and caudal vertebrae, ribs, hip bones, left and right femurs, left tibia nd fibula, and scapulae. Estimated at 12 - 12.7 m long.
* **MMCh-PV-95** is a large *Giganotosaurus* specimen, estimated to be 12 - 13 m long. Known from a dentary.

## JPInstitute.com Description

Giganotosaurus was one big carnivore. It may have been the biggest one of all, even bigger than T. rex. It lived in South America at a time when there were still large sauropods for it to eat. It had a very strong body and a mouth full of teeth like steak knives. Just its head alone was almost 6 feet (2 m) long.

A recent discovery in Argentina suggests that Giganotosaurus may have been as large as 46 feet (15 m). What is interesting is that there is another dinosaur found in North Africa, called Carcharodontosaurus that is almost identical - in fact, it may be the same genus. Since South America and Africa were still connected back then, it is possible they are very close relations.

Like T. rex, this dinosaur hunted in warm and swampy areas. Some of the sauropods of that time had armor on their backs in order to protect them from an attack from above and that kind of attack could only have come from a predator as large as Giganotosaurus.

## Dinosaur Field Guide Description

Giganotosaurus (\*giant southern lizard") is currently the largest known meat-eating dinosaur ever. For many years Tyrannosaurus held that record (although bits and pieces of Carcharodontosaurus and Spinosaurus showed that they were as large as any individual T. rex). Then, in 1995, paleontologists Rodolfo Coria and Leonardo Salgado reported the discovery of a new meat-eater bigger than any tyrant dinosaur. They named
this dinosaur Giganotosaurus, Bone for bone, it was larger than the largest skeleton of T. rex ever found! The skull alone was 6 feet (1.8 m) long! What's more, a lower jaw-bone was later found from an individual even bigger than the first one with a skull perhaps 6.5 feet (2 m) long. Clearly, Giganotosaurus was a gigantic dinosaur. When Giganotosaurus was alive, the most common plant-eaters in South America were the titanosaur sauropods. While a single Giganotosaurus could kill a young titanosaur, it would take many Giganotosaurus to bring down a giant adult. At present, there is no evidence that Giganotosaurus hunted in groups, but a recent discovery from slightly younger rocks shows that the as-yet-unnamed descendant of Giganotosaurus may have Lived in packs.

### Fun Facts

A cast of the skeleton of Giganotosaurus is on display at the Academy of Natural Sciences in Philadelphia, and another will be put on display at the Fernbank Museum in Atlanta in the near future.

### Trivia

Giganotosaurus might be the dinosaur whose name is most often misspelled and/or mispronounced. People often call it Gigantosaurus (with only one'"*"') instead of the proper Giganotosaurus, with two. The name Gigantosaurus was actually given to bits and pieces of a British long-necked sauropod dinosaur back in 1869,*

## Links

https://web.archive.org/web/20040805055242fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_gigan.html

## References

* https://www.nature.com/articles/377224a0
* https://www.npr.org/2015/06/14/414286692/bankrolling-a-dinosaur-dig-and-unearthing-a-giant-the-giganotosaurus
* https://www.tandfonline.com/doi/abs/10.1080/02724634.1994.10011592
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* https://www.researchgate.net/publication/40662857\_New\_specimen\_of\_Giganotosaurus\_carolinii\_Coria\_Salgado\_1995\_supports\_it\_as\_the\_largest\_theropod\_ever\_found
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* https://www.tandfonline.com/doi/full/10.1080/14772019.2011.630927
* https://www.skeletaldrawing.com/home/mass-estimates-north-vs-south-redux772013
* https://ui.adsabs.harvard.edu/abs/2005NW.....92..226N/abstract
* https://web.archive.org/web/20160930130941/http://news.nationalgeographic.com/news/2006/04/0417\_060417\_large\_dino.html
* https://www.app.pan.pl/article/item/app46-193.html
* https://www.investigacionyciencia.es/revistas/investigacion-y-ciencia/termes-prehistricos-atrapados-en-mbar-215/dinosaurios-carnvoros-de-sudamrica-6530
* https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0157793https://www.pure.ed.ac.uk/ws/files/8232966/PDF\_BrusatteSereno2008AllosauroidPhylogeny.pdf
* https://anatomypubs.onlinelibrary.wiley.com/doi/full/10.1002/ar.24602?af=R
* https://www.thecodontia.com/theropods
* https://twitter.com/DanPalaeon1/status/1552415964565622784/photo/1
* https://www.thecodontia.com/blog/i-was-wrong-about-giganotosaurus-not-clickbait