An Ultimate Guide to Arsinoitherium: Arsinoe’s Beast

Leave a comment / / Updated on: 24th September 2023

NameArsinoitherium DietHerbivorous 
Name Meaning“Fears nothing”Height1.8 meters (5.9 feet)
PronunciationAre-sin-oh-ee-thee-ree-umLength3.5 meters (11.5 feet)
EraCenozoic – TertiaryWeight2.5 metric tons (2.75 short tons)
ClassificationMammalia, Embrithopoda, ArsinoitheriidaeLocationAfrica

Arsinoitherium Mammal Pictures

Arsinoitherium in white background
Arsinoitherium in white background | Warpaintcobra via iStock

The Arsinoitherium

Gage Beasley's Arsinoitherium Soft Stuffed Plush Toy
Gage Beasley’s Arsinoitherium Soft Stuffed Plush Toy

Having been named in honor of Arsinoe I, the queen of Egypt, the Arsinoitherium is now a renowned prehistoric paenungulate mammal.

The Arsinoitherium lived in prehistoric Africa approximately 36-27 million years ago, from the Late Eocene until the Early Oligocene.

Arsinoe’s beast is a quadrupedal rhino-like herbivore that is, in fact, closely related to elephants and sirenians, not rhinos. 

The Arsinoitherium likely lived in tropical rainforests and swampy environments. 

Some scientists even argue it was a swamp dweller that occasionally walked on land to feed.

By far the most remarkable characteristic of the genus is the pair of large horns above the nose, accompanied by another pair of smaller knob-like ones above the eyes.

If we’ve aroused your interest, keep reading to discover more!

Gage Beasley's Prehistoric Shirt Collection
Gage Beasley’s Prehistoric Shirt Collection
Gage Beasley's Prehistoric Plush Collection
Gage Beasley’s Prehistoric Plush Collection

Physical Characteristics

Arsinoitherium was a herbivorous rhinoceros-like mammal that lived in Africa in the Early Oligocene Period
Arsinoitherium was a herbivorous rhinoceros-like mammal that lived in Africa in the Early Oligocene Period | CoreyFord via iStock

Arsinoitherium was a rhinoceros-like mammal. It was heavily built and featured two pairs of horns – the larger ones projected forward and upward, while the smaller ones were located over the orbits.

Unlike rhinoceros horns, which consist of keratin, Arsinoitherium horns are bony structures riding from the skull. 

However, scientists assume that the bones may have been covered by a layer of keratin.

This mammal’s neck was short yet thick. The forelimbs were shorter than the hind limbs, but all four were massive, elephant-like. The forelimbs may have also been slightly bent outward.

These mammals were quite large and heavy. They likely measured approximately 3.5 meters (11.5 feet) long and 1.8 meters (5.9 feet) tall at the shoulder and weighed 2.5 metric tons (2.75 short tons).

Arsinoitherium mammals are often compared to white rhinos in terms of size, although the extant species is slightly larger. 

It measures 3.4–4 meters (11.2–13.1 feet) long, 1.6-1.86 meters (5.2–6.1 feet) tall at the shoulder, and weighs up to 4.5 metric tons (5 short tons).

Since the genus consists of several Arsinoitherium species, it’s worth mentioning that they may have differed in size. 

For example, it is known that Arsinoitherium zitteli was smaller than Arsinoitherium andrewsi and Arsinoitherium giganteum

Arsinoitherium horns
Arsinoitherium horns | CoreyFord via iStock

The form of their horns may also have been different depending on the species.

At first glance, you’ll tend to argue that the Arsinoitherium looks like a white rhino. That was our first thought too!

However, the most obvious thing that sets the two apart is the limb structure, which, as mentioned, is columnar, elephant-like.

Some hip and skull characteristics are also more similar to elephants than rhinos. 

Additionally, white rhinos have only two horns made of solid keratin and an additional noticeable hump on the back of their necks.

Habitat and Distribution

The Arsinoitherium existed from the Late Eocene until the Early Oligocene, approximately 36-27 million years ago. 

These mammals were inhabitants of North Africa and likely lived in tropical rainforests and mangrove swamps.

The earliest and best-known specimens have been unearthed from the Jebel Qatrani Formation in Faiyum, Egypt, and Chilga, Ethiopia. 

Other fossils were recovered from Oman, Tunisia, Libya, Angola, and Kenya.

These territories likely featured tropical rainforests, mangrove swamps, marshes, and rivers that emptied into the Tethys Sea.

Forest Habitat | TonyFeder via iStock

Scientists argue that the Jebel Qatrani Formation probably had slow-moving freshwater habitats filled with aquatic vegetation. 

Additionally, they compare the habitat of this formation to that observed in today’s Central Africa.

If there were rivers, they may have been filled with reeds (grass-like plants), papyrus (an aquatic flowering plant), and floating plants, like water lilies (rhizomatous aquatic herb) and Salvinia floating ferns.

It has also been suggested that the territory experienced a natural phenomenon called the monsoon, a seasonal reversing wind causing changes in precipitation.

Behavior and Diet

Arsinoitherium was a herbivorous rhinoceros-like mammal
Arsinoitherium was a herbivorous rhinoceros-like mammal | CoreyFOrd via iStock

Based on the form of its muzzle, the Arsinoitherium is thought to have been a browser rather than a grazer. 

Supposedly, it fed on low bushes and relied either on a prehensile tongue or a flexible upper lip to grasp the food. 

The high mobility of its head, which could move up and down with no restrictions, likely aided in feeding.

Due to the massiveness of its limbs, the Arsinoitherium likely could not move fast. 

Some sources even argue that considering the physiology of its limbs, the Arsinoitherium may have been a semiaquatic mammal.

Swamp habitat | bombuscreative via iStock

Instead of living in forested habitats, there’s a high possibility it preferred swampy territories. 

As such, it may have been a swamp dweller that emerged to forage on land, which probably took a long time, considering how slow the Arsinoitherium was.

Nevertheless, not all scientists agree with this theory. Some are convinced the Arsinoitherium was fully terrestrial. 

Unfortunately, as much as we’d like to advise that statement X is true, this will remain a mystery until future findings and studies confirm otherwise.

Life Cycle

Life restoration of A. zitteli
Life restoration of A. zitteli | Mauricio Antón via Wikipedia CC BY 4.0

Some sources mention that Arsinoitherium individuals may have been sexually dimorphic.

Male horns were triangular in section and larger. Their inner and posterior parts were flattened, and the outer side was rounded.

Female horns, on the other hand, were much smaller and erect. Additionally, the tips were irregularly ossified and rounded anteriorly.

Young Arsinoitherium had rounded tips that were likely of a remarkable fibrous or spongy texture, which indicates continuous growth.

Horns of the extinct Arsinoitherium
Horns of the extinct Arsinoitherium | NaturalWorldLover via Nature Rules Fandom

The horns may have played a role in sexual selection and courtship displays.

The reproductive behavior and ontogeny of Arsinoitherium are poorly known. 

Although multiple specimens, including juveniles, were discovered, few studies focused on outlining the reproductive behavior and growth stages particularly.

However, considering that the Arsinoitherium was a mammal, we can assume that males had a penis and testes, while females had a vagina, paired oviducts, 1-2 uteri, and 1-2 cervices.

Arsinoitherium walking in the river
Arsinoitherium walking in the river | Lythronax via Walking with Fandom

Most modern mammals are viviparous, meaning that the mother gives birth to live young, although some reproduce by laying eggs.

It is believed that all viviparous mammals are classified under the Theria subclass. 

Since Arsinoitherium is also a member of this group, we can assume it was viviparous as well.

The gestation period may have been quite long, and the young were probably relatively developed at birth. 

Females probably had mammary glands, which produced milk that the babies fed on.

Evolution and History

Arsinoitherium showing its big horns
Arsinoitherium showing its big horns | Hammerheadsharkbb via Nature Rules Fandom

The Arsinoitherium is part of the Placentalia infraclass under the mammalian clade Eutheria

These animals are called true placental mammals and likely originated from the Eutherians of the Middle Jurassic. 

At the time, Eutherians were small creatures adapted for an arboreal lifestyle.

True placentals, however, originate from the Late Cretaceous. Protungulatum may be one of the earliest true placental ungulates, while Purgatorius is often considered a stem-primate. 

Further down the taxonomic tree, the Arsinoitherium is found in the Paenungulata clade under the Afrotheria superorder. 

This makes it closely related to proboscideans, which include prehistoric elephant-like mammals and modern mammals.

Gage Beasley Prehistoric's Arsinoitherium Concept
Gage Beasley Prehistoric’s Arsinoitherium Concept

Alongside sirenians, the Arsinoitherium and elephants are grouped as Tethytheria because they are thought to have had common aquatic or semi-aquatic ancestors that inhabited the shore of the Tethys Sea. 

As such, the semiaquatic lifestyle of the Arsinoitherium cannot be fully ruled out.

However, since nothing comes easy in studying our world’s prehistory, some studies indicate that there’s something wrong with the classification of Arsinoitherium

Could it be that it was wrongly classified as both a paenungulate and an afrotherian? It remains unknown, but this classification has not been altered yet.

Skull cast
Arsinoitherium in Teylers Museum | bertknot via Wikipedia CC BY-SA 2.0

The first Arsinoitherium fossils were discovered in 1901 in the Jebel Qatrani Formation in Faiyum, Egypt. 

The specimen was named Arsinoitherium zitteli a year later, in honor of Queen Arsinoe I of Egypt and Karl Alfred Ritter von Zittel, a renowned German paleontologist.

Other fossil discoveries followed, of which the most iconic is the 2003 discovery in Chilga, Ethiopia, that led to the naming of Arsinoitherium giganteum.

Interactions with Other Species

The Eocene gave rise to numerous orders of animals, some of which survived until the present time. 

Arsinoitherium with his new-born
Arsinoitherium with his new-born | Disneysaurus via Dino Fandom

Three-toed horses, camels, deer, rhinos, peccaries, bears, dogs, and others. But which ones lived alongside the Arsinoitherium in Africa?

While we cannot fully confirm which animals the Arsinoitherium crossed paths with, since this depends on each individual’s location and period of existence, we can focus on the creatures discovered in the Jebel Qatrani Formation and assume that there was a certain degree of interaction between them.

Here are some animals that lived in the formation:

  • Primates like Aegyptopithecus, Parapithecus, and Afrotarsius
  • Proboscideans like Moeritherium and Phiomia
  • Ptolemaiids like Cleopatrodon and Qarunavus
  • Hyaenodonts like Apterodon, Flactodon, and Metapterodon
  • Hyracoids like Antilohyrax, Geniohyus, and Megalohyrax
  • Anthracotheres like Bothriogenys
  • Reptiles like Albertwoodemys and Eogavialis.
  • Marsupials like Paratherium
  • Rodents like Phiocricetomys

Birds from the Accipitridae and Pandionidae families were also present. 

Another remarkable extinct bird discovered in the Jebel Qatrani Formation is the Palaeoephippiorhynchus, a large stork closely related to the extant Saddle-billed stork.

The habitat was also home to numerous fish species. If the Arsinoitherium were semi-aquatic, it may have stumbled upon one or two fish under the water!

Artist sketch of Arsinitherium
Artist sketch of Arsinitherium | Dinoboy13 via Dinopedia

It remains unknown whether the Arsinoitherium had any predators, but considering its size, it’s unlikely. 

Instead, there may have been a certain degree of competition for food, as the territory was home to multiple herbivores.

Cultural Significance

The discovery of Arsinoitherium fossils carries a piece of the paleontological puzzle that, in the end, shows us a bigger picture of our world’s prehistoric environments and the life they supported.

However, upon assessing how many studies are concerned with dinosaurs, pterosaurs, and other creatures alike, we can conclude that many prehistoric mammals, including Arsinoitherium and others that lived in Africa, remained in the shadows. 

Cast of an Arsinoitherium zitteli skeleton
Cast of an Arsinoitherium zitteli skeleton | Aramgutang via Wikipedia CC BY 2.5

We can only hope that future research and findings will shed light on other aspects of their lives.

The same is true for the creature’s appearance in media productions and books. 

While the Arsinoitherium is described in various prehistoric wildlife handbooks, few movies and video games feature it as a character.

However, if you want to spot it in motion, we recommend checking out Paleoworld, Chased by Sea Monsters, and Jurassic Park Builder.


The Arsinoitherium was an inhabitant of prehistoric Africa, having lived in Ethiopia, Egypt, Libya, Tunisia, Oman, and possibly Kenya and Angola.

This prehistoric creature is most renowned for its large size and two distinctive pairs of horns.

Contrary to popular belief, this paenungulate mammal has nothing in common with rhinos in terms of evolution. Instead, they are more closely related to elephants.

This may confuse wildlife enthusiasts since, at first glance, the Arsinoitherium resembles a rhino, not an elephant, but certain characteristics can help understand the difference.

For example, its legs were columnar, just like those of an elephant. Additionally, its horns had a bony structure, while rhino horns are made of keratin.

Although the Arsinoitherium appearance is relatively well-studied, its behavior, lifestyle, and reproductive behavior call for further research. 

Hopefully, breakthrough findings will bring to light more jaw-dropping facts!


How did the Arsinoitherium go extinct?

It is believed that the Arsinoitherium went extinct after our planet experienced severe climatic changes that, in turn, led to habitat disruption. 

This caused a major loss of forested environments, which served as homes for the Arsinoitherium


Leave a Reply

Scroll to Top
%d bloggers like this: