Fun Xenotarsosaurus Facts For Kids

Christian Mba
Oct 20, 2022 By Christian Mba
Originally Published on Sep 25, 2021
Edited by Luca Demetriou
Fact-checked by Kidadl Team
The Xenotarsosaurus facts are an interesting way to unearth million-year-old secrets about these reptiles
Age: 3-18
Read time: 5.5 Min

The Xenotarsosaurus is a type of theropod dinosaur that belonged to the clade of Saurischia and the family of Abelisauridae. It was discovered in 1980 by Juan Carlos Sciutto, a geologist in the Chubut province of Argentina. Later, paleontologist José Fernando Bonaparte recovered some more bones, and in 1986, Jorge Rodriguez, Olga Giménez, and Graciela Bochatey confirmed the fossils and categorized their genus and species as Xenotarsosaurus bonapartei.

The scientific name of these dinosaurs means 'strange tarsus lizard' because of their unique fused ankle structure. This species is speculated to have been the prime predator of its region and fed on Drusilasaura, a titanosaur, and Secerosaurus, a hadrosaurid. In addition, some studies have shown that members of Abelisauridae were slow-growing compared to other theropods and took at least 20 years to reach maturation.

The fossil representation proved they were theropod bones and consisted of a right hind limb with the tibia, femur, fibula, and ankle astragalocalcaneum along with the anterior dorsal vertebrae. The fossil site was located in the Bajo Barreal Formation, and the Xenotarsosaurus is believed to have lived during the Cenomanian–Turonian period of the late cretaceous epoch.

If you enjoy reading about fossilized beasts, take a look at the T-Rex and the Dilophosaurus.

Xenotarsosaurus Interesting Facts

How do you pronounce 'Xenotarsosaurus'?

The word Xenotarsosaurus is pronounced as Zee-noe-tar-so-sore-us.

What type of dinosaur was a Xenotarsosaurus?

The Xenotarsosaurus is a theropod dinosaur species.

In which geological period did the Xenotarsosaurus roam the earth?

These dinosaurs are estimated to have lived between the Cenomanian to Turonian CSI geological timescale of the Late Cretaceous epoch.

When did the Xenotarsosaurus become extinct?

Although the exact period of their extinction is unknown, theropods are estimated to have gone extinct about 65 million years ago.

Where did a Xenotarsosaurus live?

The Xenotarsosaurus dinosaur is said to have lived in South America because the fossil was discovered in the Bajo Barreal Formation of the Golfo San Jorge Basin of Chubut province and Santa Cruz in Argentina.

What was a Xenotarsosaurus' habitat?

Due to the lack of excavation findings related to these dinosaurs, it isn't easy to narrow down on their exact habitat. However, it is known that during the cretaceous period, the climate was much warmer than the present day.

Who did a Xenotarsosaurus live with?

There is a lack of evidence about the living behavior of the Xenotarsosaurus. However, it has been suggested that some theropods lived in raised their young in cooperative packs and would socialize in several ways which are not clearly known.

How long did a Xenotarsosaurus live?

The lifespan of the Xenotarsosaurus has not been studied, but evidence suggests that several theropods had a lifespan of around 10-20 years.

How did they reproduce?

Although the exact form of reproduction among the Xenotarsosaurus is unknown, there have been some speculations about the reproductive cycle of most theropods. Firstly, fossils of theropods have proven that some of them showed sexual dimorphism, and their specific feature used for sexual display are on their heads, such as the two horns above the eyes of the Xenotarsosaurus. Based on the fossil discoveries as well as the behavior and anatomy of the existing relatives of dinosaurs, such as large crocodiles like the Saltwater Crocodile and birds, it is known that these reptiles were oviparous, i.e., egg-laying. It is also speculated that later theropods had similar sex organs as birds, and their eggs were fertilized internally. The unearthing of nest and egg fossils confirm that theropods laid hard-shelled eggs, and some nests have shown clutch sizes of up to 40 eggs. Medium-sized dinosaur species followed a pattern of laying their eggs in tight clusters instead of spreading out. Theropod eggs are elongated and around 5-21 in (12.7-53.3 cm) long, depending on the species. Apart from the above, information about parental care and brooding behavior is almost impossible to find out.

Xenotarsosaurus Fun Facts

What did a Xenotarsosaurus look like?

All of what is known about the Xenotarsosaurus is related to the fossil specimen found in Bajo Barreal Formation in Argentina. These comprise the right hind leg bones, including the ankle astragalocalcaneum, femur, fibula, and tibia, and two anterior dorsal vertebrae. Since they belong to Abelisauridae, they would have had two horns above their eyes with forelimbs tinier than those of the T-Rex and a knobbly back.

Xenotarsosaurus has very short forelimbs
*We've been unable to source an image of Xenotarsosaurus and have used an image of Aucasaurus instead. If you are able to provide us with a royalty-free image of Xenotarsosaurus, we would be happy to credit you. Please contact us at

How many bones did a Xenotarsosaurus have?

The number of bones in the body of Xenotarsosaurus dinosaurs is unknown because only the right hind leg bones, including the ankle astragalocalcaneum, femur, fibula, and tibia, and two anterior dorsal vertebrae of their bodies have been discovered.

How did they communicate?

It is almost impossible to derive the communication patterns of the Xenotarsosaurus due to the lack of research and fossil findings.

How big was a Xenotarsosaurus?

This dinosaur species was around 18-20 ft (5.48-6.09 m) long and 22 ft (6.7 m) tall. This means that they were almost as tall as the Giraffe but slightly shorter than the male Blue Whale.

How fast could a Xenotarsosaurus move?

The exact speed at which these theropods could move has not been discovered. However, based on calculations of feet size and footfalls of several medium-sized theropods, it can be concluded that they moved at a speed of 26.84 mph (43.2 kph).

How much did a Xenotarsosaurus weigh?

Based on scientific calculations, the weight of the Xenotarsosaurus may range between 948-1,654 lb (430-750 kg), which is less than that of a mature Pacific Walrus.

What were the male and female names of the species?

The male and female of these dinosaurs do not have separate names. It has one name, Xenotarsosaurus, which means 'strange tarsus lizard.'

What would you call a baby Xenotarsosaurus?

The young dinosaurs can be called nestlings or hatchlings, and theropods can also be called chicks.

What did they eat?

The diet of this species is carnivorous, and some observations suggest that they used to feed on Drusilasaura, a titanosaur, and Secerosaurus, a hadrosaurid.

How aggressive were they?

Considering these dinosaurs we the prime predators of the region they were found, they would have been quite aggressive when capturing their prey.

Did you know...

The Xenotarsosaurus, which means strange tarsus lizard, received this because of the unique fusion of two of its ankle bones, a feature quite unusual for theropods.

Is the Xenotarsosaurus the same as the Carnotaurus?

Although both these theropod species belonged to Abelisauridae and were found in South America, they are not entirely similar and belong to a separate genus. The Carnotaurus is a large theropod, while the Xenotarsosaurus is a medium-sized one.

What is the largest Abelisaurid?

The Ekrixinatosaurus is estimated to have been the largest member of Abelisauridae with a striking length of up to 29.5-32.8 ft (9-10 m).

Here at Kidadl, we have carefully created lots of interesting family-friendly dinosaur facts for everyone to discover! For more relatable content, check out these Dwarf Crocodile facts and Water Dragon facts pages.

You can even occupy yourself at home by coloring in one of our free printable Xenotarsosaurus coloring pages.

Xenotarsosaurus Facts

What Did They Prey On?


what Type of Animal were they?


Average Litter Size?


What Did They Look Like?

Medium-sized theropod with small arms like the T-Rex, with a large knobbly back and two horns above its eyes

How Much Did They Weigh?

948-1,654 lb (430-750 kg)

Skin Type


How Long Were They?

18-20 ft (5.48-6.09 m)

How Tall Were They?

22 ft (6.7 m)









Scientific Name

Xenotarsosaurus bonapartei

What Were Their Main Threats?

Natural disaster

What Habitat Did They Live In?

The terrestrial environment in the Cenomanian to Turonian timescale of the Late Cretaceous epoch

Where Did They Live?

South America in the Bajo Barreal Formation of the Golfo San Jorge Basin in the Chubut province and Santa Cruz, Argentina
We Want Your Photos!
We Want Your Photos!

We Want Your Photos!

Do you have a photo you are happy to share that would improve this article?
Email your photos

More for You

See All

Written by Christian Mba

Bachelor of Science specializing in Computer Science

Christian Mba picture

Christian MbaBachelor of Science specializing in Computer Science

Christian Mba is an experienced blogger and content writer with over a decade of experience. He holds a Bachelor of Science degree in Computer Science from Nigeria and has a keen interest in Python programming. Along with his writing and blogging expertise, he is also an SEO specialist with more than six years of experience. Chris, as he is commonly known, has a passion for music and enjoys playing the piano.

Read full bio >