When we talk about the ancestors of hippos or rhinos, the extinct mammal which can be relatable is the Toxodon.
Toxodon also called ‘bow tooth’ is considered as the most common large hoofed mammal in South America from the Late Pliocene period to the Late Pleistocene epochs.
They were herbivorous mammals having a barrel-shaped body like a present-day rhino and also the position of nasal openings like a hippopotamus.
They are believed to be a cross between the rhinos and hippos.
The T. platensis was the most common herbivores across South America and lived at the Great American exchange, it is the same place where at present the formation of Isthmus of Panama is created, to join North and South America.
Although they did not have the threat from predator dinosaurs, because they were long extinct, the saber-tooth natural cat species from North America called Smilodon, might have preyed on them.
Also as the Toxodon overlapped the time period with humans, a large factor of their extinction might be due to human hunting. Some of the fossil remains have signs of butchery and arrowheads.
The T. platensis had a large-sized body and head, almost barrel-shaped.
They were a bulky hippo look-alike creature 8 ft 10 in (2.7 m) in length and 4 ft 11 in (1.5 m) in height, making them among the largest mammal in South America in the Pleistocene period.
They had stubby legs, short neck, and dental structure of teeth well adapted for eating tough grass and shrubs just like a modern rhinoceros.
It is also believed that they had a well-developed snout because of the position of their nasal openings and were equipped with a short, elephant-like proboscis at the end of the
To support their bulky and well-developed body with strong muscles and its powerful head, their vertebrae had high apophyses.
On the feet, they had three functional toes similar to the ungulates.
The sloped appearance of their body, was because the hind limbs were longer and raised higher compared to the front limbs and had a stay apparatus, which allowed their knees to be passively locked while standing and supported them to feed for a long time.
It had broader jaws which consisted of bow-shaped teeth and incisors, which is why it is also called ‘bow tooth’.
The dental feature of teeth exhibited enamel hypoplasia as the teeth had no roots and were ever-growing like rodents.
Toxodon were mixed feeders, mostly feeding on a variety classification of small plants, leaves, twigs, and vegetation above ground, feeding in a small group.
They are both an animal that eats grasses, which is a grazer, and also as a browser, an animal that feeds on the foliage of bushes and low-growing small trees.
There is a possibility that it had a prehensile lip, although it is not certain, only considered by researchers.
According to them, the lips could have been used to guide food into the mouth, allowing them to adapt to whatever was available.
Earlier it was believed that Toxodon had a semi-aquatic habitat because they had similar looks as hippopotamus,
but later reports stated that they had primarily terrestrial life, living in grasslands with semi-arid vegetation and shrubs.
They are herbivores and mostly plant-feeders.
Although there is no such evidence of their reproduction, as they belonged to the genus Toxodon and were mammals, we can assume that they gave birth to one young calf.
After the mating, the female species incubates the embryo within itself and gives birth to a young offspring.
Both parents take care of the offspring until it is mature enough to feed and protect itself.