I may as well finish what I started. Inspired by the two recent brontothere articles, Dan Varner and Mike P. Taylor were kind enough to supply the pictures you see here. Both feature Megacerops specimens displayed at the American Museum of Natural History in New York.
This classic photo shows Erwin S. Christman (1885-1921) working on the life-sized Megacerops head that he and William K. Gregory created for what’s now the Lila Acheson Wallace Wing of Mammals and Their Extinct Relatives at the AMNH [we looked briefly at Christman's work on theropod dinosaurs back here]. At the time (c. 1911), this head was labelled as that of Brontotherium platyceras*, a name now included in the synonymy of Megacerops coloradensis (Mihlbachler in Janis et al. 2008). While many M. coloradensis individuals have paired horns that look like blunt, parallel knobs, individuals once labelled as Brontotherium tend to have Y-shaped horns that are flattened from front to back. These are most likely big, old males.
* It started out as Menodus platyceras Scott & Osborn, 1887 and, over the years, was also termed Megacerops platyceras.
Thanks to Henry Osborn’s influential work on the group, brontotheres became intimately associated with the AMNH. In 1929, Osborn published a two-volume, 953 page monograph on the group, proposing numerous new genera and species (Osborn 1929). Christman’s illustrations decorated the work, as did those of Charles Knight and Lindsey Morris Sterling. Osborn’s approach to brontothere taxonomy proved problematic and he’s been criticised for being a ‘hyper-splitter’ (Debus & Debus 2002). Recent revisions have sunk the majority of these alleged taxa. George Simpson, also of the AMNH, was able to say in 1945 that Osborn had clearly been led astray by individual, sexual, ontogenetic and taphonomic variation, and he noted that ‘subjective criteria have seemed to warrant placing every good specimen in a new species’ (Simpson 1945, Wallace 1994).
This incredible skeleton, easily the best known brontothere specimen in the world, is AMNH 518, collected from White River, South Dakota, in 1892. You can gauge its size from the adjacent person, and note that Christman’s ‘Brontotherium‘ head is just making it into shot at the very top. Originally identified as Brontops robustus, AMNH 518 is also now included within Megacerops coloradensis. This specimen is particularly well known because it has an obvious rib trauma on its right hand side – a healed injury that has usually been regarded as resulting from intraspecific combat.
And there we have it, thanks to Dan and Mike for passing on the images. There are, of course, many other neat and striking brontothere images out there: Carl Buell’s paintings and Frederick Blaschke’s Field Museum diorama of 1931, among others, coming to mind. Hat tip to them all, for we must move on…
Refs – -
Debus, A. A. & Debus, D. E. 2002. Dinosaur Memories. iUniverse, Bloomington.
Janis, C. M., Hulbert, R. C. & Mihlbachler, M. C. 2008. Addendum. In Janis, C. M., Gunnell, G. F. & Uhen, M. D. (eds). Evolution of Tertiary Mammals of North America, Volume 2: Small Mammals, Xenarthrans, and Marine Mammals. Cambridge University Press (Cambridge), pp. 645-693.
Osborn, H. F. 1929. The titanotheres of ancient Wyoming, Dakota, and Nebraska (two volumes). United States Geological Survey Monographs 55, 1-953.
Simpson, G. G. 1945. The principles of classification and a classification of mammals. Bulletin of the American Museum of Natural History 85, 1-350.
Wallace, J. 1994. The American Museum of Natural History Book of Dinosaurs and Other Ancient Creatures. Prion, London.