Prehistoric Mammal Discoveries 2022

New reconstruction of the sabretooth cat
Homotherium, showing that the teeth
would not have been as visible as popularly
supposed

2022 approaches its conclusion and I have to say that, while far from perfect, it was an improvement on the previous two years. There were a couple of weeks without posts this year, one for positive reasons, and one less so, but overall it has been good. Next year, you can look forward to something other than monkeys in my "family" series of posts and also to the conclusion of the long-running Miocene series, which should be as early as February. Until then, here is the now-traditional year-end look back at the paleontological discoveries that didn't quite make it into the blog.

Large Herbivores

Probably the most distinctive thing about deer is that the males have antlers; branching bony head ornaments that are shed and regrown each year. This naturally raises the question of how this evolved, since no other animal has quite the same thing. Acteocemas was an Early Miocene deer, but despite living very early in the group's evolutionary history, it already had antlers that split into two near the tip - which the horns of animals such as cows and true antelopes never do. A Spanish fossil of the antlers described earlier this year showed that it was already shed and regrown, but microscopic analysis indicated that it appeared to have been present for over a year, suggesting longer a more irregular pattern of shedding that must have changed to the seasonal pattern we are familiar with more recently, perhaps in the Middle Miocene.

Leaf-Eating Monkeys: Leading by a Nose

Proboscis monkey (male)

Perhaps the most distinctive and well-known of all the colobine monkeys is the proboscis monkey (Nasalis larvatus). Sufficiently distinctive that it's hard to confuse it with anything else, it was first described as a species all the way back in 1787 by botanist Friedrich von Wurmb, then working for the Dutch East India Company, and given its own genus in 1812.

Indeed, it is strange enough that, during the 20th century, it was assumed to represent a very early side-branch in colobine evolution, existing outside all the other groups in the subfamily. That wasn't just because of its odd appearance, but also because it had two extra pairs of chromosomes to every other colobine monkey. But it turns out that that's a false signal and that, not only are proboscis monkeys a relatively recent branch within the subfamily, their closest relatives include the snub-nosed monkeys whose noses are noted for being extraordinarily short.