Sunday, 12 January 2020

Voyage of the Kinkajous

For much of the time since the extinction of the dinosaurs, South America was an island continent. Developing in isolation, the mammals living there developed a number of unusual forms not seen elsewhere. Around 2.8 million years ago, however, South America became joined to its northern counterpart via the Isthmus of Panama. Northern animals flooded south, and relatively few headed in the opposite direction. As a result, unlike Australia, which remains an island continent today, the mammalian fauna of South America includes many animals at least broadly familiar from elsewhere.

Among the first mammal families to make the crossing was that of the raccoons. Although this had first appeared in Asia, living species are now found only in the Americas (ignoring some recent man-made introductions) with most of them found in tropical habitats. In fact, they reached South America almost ridiculously early, something we know because we have a fossil example that's around 7 million years old... at least 4 million years before the land crossing we'd expect them to have used had formed.

Sunday, 5 January 2020

Digging in a Winter Wonderland

Humans have a somewhat ambivalent attitude to snow, greeting it either with joy and wonder or with concern and frustration, in large part depending on how old you happen to be. It decorates Christmas cards, covers the countryside in pristine white, and provides plentiful opportunities for play. On the other hand, it makes travel difficult, and may even interrupt deliveries of food, making our lives awkward. (Plus, if you're in a city, it may not stay white for very long).

If heavy snow makes it difficult for us to get around and obtain sustenance, the same obviously goes for animals that live in the relevant parts of the world. Different species have different strategies for how to cope with its arrival. Some hibernate, while others avoid the problem by migrating somewhere else for the winter, but there are, of course, a number of species that simply have to put up with it. Those that live particularly far north may even have to do so for over half the year, and the difficulty of doing this is probably at least part of the reason why relatively few species do.

Sunday, 15 December 2019

Prehistoric Mammal Discoveries of 2019

Nehalaennia, an 8 million-year-old rorqual
from the Netherlands, first described this year
As the year - and decade - approach their inevitable conclusion, it's time again to look back at a few palaeontological findings of 2019 that didn't, for whatever reason, make it into the regular Synapsida posts. As always, there is no theme to this list, just a sample of what seemed interesting linked only by when it happened to be published.

Sunday, 8 December 2019

Small British Mammals: Moles

If hedgehogs are generally welcome in suburban gardens, there's one native British animal that generally isn't, and, like the hedgehog (and shrews) it belongs to a group of insect-eating mammals technically called the Euliptophyla. This, of course, is the European mole (Talpa europaea), sometimes called the "common mole" if we even need to distinguish it from other kinds of mole at all.

As the name implies, European moles are essentially unique to Europe. They are found throughout much of the continent, from northern Spain, Italy, and the central Balkans in the south to southern Sweden and Finland in the north. They are not found in southern Russia, but do reach just beyond the boundary with Asia in the northeast. While they are not native to Ireland, they are found on a number of smaller islands off the coasts of England, Scotland, and Denmark.

Sunday, 1 December 2019

Miocene (Pt 17): A Diversity of Dogs

Eucyon
As North America dried out in the Late Miocene, and slowly transitioned towards the deserts and open grasslands that became dominant across the central parts of the continent, it wasn't just the herbivores that were forced to adapt. Carnivores may not have been affected so directly, but, if their food source was changing, they had to do so too.

There were two particularly significant changes among the North American mammalian carnivores that took place around this time. One was the extinction of the bear-dogs, a group with a long history on the continent that was, by this time, typified by relatively large animals that would have looked more like bears than dogs (although they were neither). Over in Europe and Asia, the bear-dogs survived for rather longer, although even there they struggled...  but in North America, the changes were too extreme for them to cope with, and they died out as the Late Miocene dawned.

Sunday, 24 November 2019

Small British Mammals: Hedgehogs

There can be few British mammals more distinctive and well-loved than the hedgehog. Indeed, a 2016 poll found that it is, by a substantial margin, Britain's favourite mammal. (For what it's worth, and by a similar margin, the robin is apparently our favourite bird).

The animal that Brits simply call "the hedgehog" is more accurately the European hedgehog (Erinaceus europaeus), and it's found through pretty much the entirety of western Europe. In fact, across much of the continent, the eastern border of its occurrence is very roughly where the old Iron Curtain used to be. That's a simplification, of course, and aside from some border regions of former 'Eastern Bloc' countries, they are also found quite extensively in the Czech Republic, Estonia and parts of north-west Russia. They are also common on several larger islands, including Ireland, Corsica, Sardinia, and Sicily, and, in more recent times, they have been introduced to the Azores.

Sunday, 17 November 2019

Don't Sleep with Your Sister

Conservation of mammals (or other animals) isn't simply a matter of providing enough suitable habitat for them to live in. One other consideration is that that habitat should not be overly fragmented - and this can be a problem as we build roads or other transport networks that cross otherwise wild terrain. The problem with fragmented habitats is that, even if there is enough space and food to support a small population of the animal in question, that population cannot reach and interact with other populations. And this leads to inbreeding.

We have known that inbreeding is a bad thing in animals since... well, probably at least since we started domesticating livestock. In our own species, there's a natural revulsion against incest, something that's reflected in moral teachings that go back at least as far as the Old Testament, and similar codes in other cultures. Animals too, avoid inbreeding when they can, perhaps finding the scent marks left by genetically similar individuals to be unpleasant.