Megacerops was a Brontohere, which means “thunder beast”. This family contained the largest land animals during the Eocene epoch. Though they possessed large bony protrusions on their snouts, they were not closely related to the rhinoceros they resembled.
Much of what was previously believed about Megacerops and brontothere behavior has been recently re-evaluated. It was once surmised that males would use their horns to headbutt each other much like modern day bighorn sheep. However, this is unlikely due to the spongy nature of the horn bone being unable to sustain such impact. They are now thought to have engaged more in pushing or wrestling behavior with their horns, and broken rib bones on some specimens seem to indicate that they may have attacked each other from the side.
Brontotheres mainly ate soft plants, and may have gone extinct after such vegetation became harder to find within their range.
History of Discovery
The first major study of brontotheres was undertaken by Henry Fairfield Osborn in the 1920s, and he produced almost a thousand pages of material regarding these animals that is now known to be largely inaccurate. However, the two volumes he published were so immense that no one was willing to tackle the subject again until the late 20th century.
It is now known that much of Osborn’s ideas were incorrect, and that he greatly exaggerated the amount of diversity within the family. The genera Brontotherium, Titanotherium, Brontops, Allops, Menops, Menodus, Symborodon, and Diploclonus are now all believed to belong to a single genus, Megacerops. Osborn’s ideas regarding the evolution of brontotheres is also not correct. He believed their evolutionary path was a direct straight line from one species to the next; thanks to research undertaken by Bryn Mader (1989) and Matthew Mihlbachler (2008) it is now known that the brontothere family tree was not linear at all but had many branches and offshoots.
The Princeton Field Guide to Prehistoric Mammals, Donald R. Prothero, 2017.