Saturday, 27 September 2014
But there are five other epochs that precede the Pleistocene within the Age of Mammals, and, compared with most of them, it isn't even very long. Heck, it isn't even 5% of the total. As it happens, though, the epoch that immediately preceded the Ice Ages, the Pliocene, isn't much longer. If we imagine, as we're often invited to, the entire history of the Earth as a single year, the Pliocene is, very roughly, the period between 2 and 7 p.m. on the evening of the 31st December. That's not exactly a large chunk.
On the other hand, on a human scale, the Pliocene is vast; the long autumn that leads from the summer of the Miocene into the freezing cold of the great ice sheets that follow. When I first discussed the Pleistocene, I used the example of a TV documentary that whizzes through the whole of history. In fact, it takes one minute to cover each decade of time. So the entire history of the world since the outbreak of World War I is covered in just the final ten minutes. Your life so far is, I can assume with some confidence, covered in even less time than that.
Sunday, 21 September 2014
Carnivores eating other carnivores is called intraguild predation, which sounds like it ought to have something to do with World of Warcraft, but doesn't. (Unless your characters eat one another, which I'm fairly sure the game doesn't allow). Inevitably, such predation means that the lifestyle of a small carnivore is somewhat different from that large one. It's not just being eaten themselves that they have to worry about, either. There's also the risk of something larger coming along and pinching the dinner that you just spent so much time catching. Which, while we're on the technical terms, is called kleptoparasitism.
Sunday, 14 September 2014
|An earlier fossil|
(The new one still has the jaw attached to the rest of the skull)
Even when we look at prehistoric mammals, it's the big ones that get most of the attention. Mammoths. Prehistoric rhinos. Enormous tank-like armadillos. Giant wombats. Big animals are cool, and there were some pretty large ones in the distant past.
Yet, at any point since their first appearance, small animals will always have been more common than large ones. Lots of small and interesting things doubtless scurried about under the feet of the dinosaurs, and so it was with the Age of Mammals, too. So today I want to look at the recently described fossil of a small mammal, and how it too, can tell us something interesting.
Sunday, 7 September 2014
The tamarins that live here, in the northern Colombian forests, must be descended from some group that crossed the Andes, presumably through some of the lower, shorter, passes near what is now the Venezuelan border, or else along the coast. There are three species here today, all apparently descended from that same original group, and including one of the first of any tamarin species to be formally described, back in 1758. This is the cotton-top tamarin (Saguinus oedipus), and it's at once one of the best known members of the marmoset family, and one of the most threatened.
Sunday, 31 August 2014
|It's changed a bit since...|
On the other hand, there were times when the world was much hotter than today, warm enough that there appear to have been no ice caps at all, even at the poles. During the Age of Mammals - the eon of time since the extinction of the non-avian dinosaurs - the hottest of these was the Eocene Climactic Optimum. This took place a little over 50 million years ago, and it lasted rather a long time, punctuated by short periods of even greater heat. (That's 'short' as in they lasted tens of thousands of years, but not millions).
Sunday, 24 August 2014
Over the last 100 posts, I have added a further 16 living families (plus some fossil ones) to the list of those I've covered, from the reasonably well known, such as armadillos, shrews, and porpoises, to the possibly slightly more obscure, such as tuco-tucos and beaked whales. That, even after four years of the blog, leaves an awful lot of families that I still haven't touched. Many of them are, unsurprisingly, small or obscure families, some of them with just a single living species (the aardvark, say, or the Asiatic linsang). But there's still some obvious gaps. I said in my 100th post that I hadn't covered pigs, for instance, and I still haven't, apart from some fossil species.
Sunday, 17 August 2014
But even when we look at the larger, more charismatic, species there are plenty of holes in our knowledge. This is most likely to be the case where an animal doesn't live in Europe, North America, or Australia, and isn't quite as high in the fame stakes as, say, chimpanzees, elephants, or tigers. Living somewhere it's inherently difficult to get to, like a tropical forest, is also a factor, as is living at sea if you're not valuable to whalers or the like.
Which leaves plenty of opportunity for modern zoologists to do the sort of thing that naturalists used to do in days gone by, and make some pretty basic studies of a particular animal's behaviour while still breaking new ground. Assuming of course, you can go to wherever the animal is and spend a long time there. Which, if it were that easy, would probably have already been done.
The masked palm civet (Paguma larvata) is one such animal. They're not entirely obscure, living in forests from southern China down to Indonesia, and having first been identified as a species back in 1827. They're something like 60 cm (2 feet) long, plus tail, and, in the grand scheme of things, they aren't particularly rare or endangered. Certainly we know a lot about what they look like, where they live, what they eat when they're in captivity, and so on. But actual studies of their wild behaviour, while hardly non-existent, are fairly limited, and typically only of a small number of individuals.