Let's learn about a whole lot of mustelids, including some otters, weasels, and their relations and ancestors! Thanks to Jacob for the suggestion!

Further reading:

Weasels in Stone: Mustelid Evolution

With voices joined in chorus, giant otter families create a distinct sound signature

Further watching/listening:

Video of giant river otters making noise

Giant river otters:

The least weasel is possibly the most cute:

This mink would like to keep its fur for itself please and thank you:

The Patagonian weasel:

The greater grison looks like a badger and a honey badger:

The fisher:

The Chinese ferret badger has a long nose compared to most mustelids:

Show transcript:

Welcome to Strange Animals Podcast. I’m your host, Kate Shaw.

This week we’ll learn about some mustelids, better known as weasels and their close relations! Thanks to Jacob for this week’s suggestion.

The weasel is a member of the family Mustelidae. Members of the family are called mustelids, which includes wolverines and badgers, which we talked about in episode 62, otters, which we talked about in episode 37, and ferrets, which we talked about in episode 150. Most mustelids have short legs and long, slender, flexible bodies, although badgers are an exception since they’re broad-bodied. This body shape allows a mustelid to enter the burrows of other animals and kill them, because mustelids are carnivores.

But not all animals that look like weasels and ferrets are actually mustelids. The mongoose, for instance, is not a mustelid.

The study of how mustelids evolved and spread throughout much of the world is a pretty hot topic these days, which makes it confusing to summarize since so much new knowledge keeps shaking up what we know. But I’ll do my best.

The first mustelids evolved around 30 million years ago in what is now Eurasia, and spread to North America much later and eventually into South America. The oldest mustelid fossils found in North America are a group of animals called oligobunines. I read that word as oligobunnies every single time, but they didn’t look like bunnies. They probably looked like wolverines, which are related to badgers but look more like miniature bears with longer tails, but they probably spent more time underground than wolverines do.

At least one oligobunid might have grown as big as a black bear, at least a small bear. Megalictis was probably an ambush predator and lived around 21 million years ago in what is now the upper Midwest of North America. It had teeth meant for crushing bones. Another oligobunid, Zodiolestes, is one we talked about briefly in episode 103, about trace fossils. The first fossil Zodiolestes was found in a corkscrew-shaped Palaeocastor burrow, presumably because it got stuck in the burrow while it was hunting, but Zodiolestes was also adapted to dig. The oligobunids went extinct around 10 million years ago, possibly outcompeted by a new wave of modern mustelids that evolved in Asia and spread into North America.

One mustelid, Ekorus ekakeran, lived about six million years ago in what is now Africa, with fossils found in Kenya. But it didn’t look like any other mustelid. It had long legs, for one thing. It stood almost two feet tall at the shoulder, or 60 cm, and was built more like a leopard than a mustelid. It would have been a much faster runner than other mustelids as a result, although it was probably an ambush predator. Researchers think it was eventually outcompeted by big cats when they evolved as the forests changed into grasslands.

The biggest mustelid that ever lived, as far as we know, is Enhydriodon, a type of gigantic otter. It lived in Africa around 4 million years ago and may have been the size of a small bear, even bigger and heavier than Megalictis. We only have a single fossil of Enhydriodon, though, a skull, so scientists can only estimate the animal’s size compared to what we know about extinct and ...