Prehistoric Mammal Discoveries of 2020

The largest known Oligocene whale was
moved into the new genus Ankylorhiza
this year

Well, that year was... different. Fortunately, it didn't stop me posting and, indeed, a cancelled summer break meant that you got one more post than anticipated you lucky people, you. But as 2020 finally passes into the history books where it can bloody well stay, it's time for the end-of-year roundup of paleontological discoveries that didn't make the regular blog. As always, no theme, just a random assortment of journal papers that may, for all I know, be thoroughly contradicted by this time next year. But this is a collection of things that some scientist, somewhere, thinks that they demonstrated in 2020:

Fossil Cats (That Aren't Sabretooths)

Acinonyx pardinensis

The cat family is traditionally divided into two subfamilies: the "purring cats", which are mostly small, and the "roaring cats" which are all medium to large in size. When most people think of fossil species, however, the first ones to pop into their minds are almost certainly the sabretooths, such as Smilodon. These belonged to a third subfamily (and whether they could roar or not depends on fragile bones and soft tissues that haven't survived) that left no modern descendants, dying out towards the end of the Ice Ages.

The sabretooth cats represent an early branch in cat evolution, perhaps splitting off at some point during the Early Miocene, over 20 million years ago. But this means that the cats we are familiar with must have existed - in some form - for equally long, leaving their own fossil history. If you wound back the evolutionary clock on a domestic cat, or even a tiger, you wouldn't find a sabretooth or anything that looked much like one. Exactly what you would find isn't something we can know with certainty, but we do know of a number of fossil species of non-sabretooth cat that at least give us some idea.

The Mammal That Lived Like a Woodpecker

Plesiadapis

The time since the extinction of the non-avian dinosaurs is traditionally divided into seven "epochs". Unsurprisingly, the more recent the epoch, the more familiar the animals that inhabited the Earth at the time. In my current long-running series on the animals of the Miocene (the fourth of these epochs, and also the second-longest) I have been able to talk about a number of mammals that can at least be placed into groups we understand. Horses may have had three toes, elephants may have had four tusks, and so forth, but at least we can tell, without any great difficulty, that they are, in fact, horses and elephants.

As you'd probably expect, this gets harder the further back you go. Firstly, even animals belonging to familiar groups are getting further away from their present-day forms. There comes a point where whales still walked on land, for instance. Secondly, the further we go back, the more animals we find that didn't leave any modern descendants, and, indeed, weren't even closely related to anything that did (Smilodon, for instance, has no living descendants, but it's still pretty obviously a cat). That can sometimes make it harder to say where such animals fit into the mammalian family tree or, perhaps more importantly, how they lived and behaved.