Sunday, 25 January 2015

What is a Primate?

Brown lemur
In 2012 and 2013, I finished off the year by posting short(ish) responses to questions entered into search engines that had, according to the blogger interface, led people to Synapsida. I didn't do this last year, because the great majority of the questions were ones I had already answered - perhaps an artefact of how many posts there are now at this blog. But somebody did ask "what is the definition of a primate?" and that struck me as something I could expand on at length. So here we are. What is a primate?

The simple, dictionary, definition is "a member of the order Primates". That's obviously a circular, and rather unhelpful, definition, but, then dictionaries aren't the same thing as encyclopaedias. But even it requires picking apart a bit. For a start, note the capital 'P' in the word "Primates". This indicates it's the name of a discrete thing, and not just the plural of the word "primate". It's a Latinate word, like "Rodentia" for the order of rodents or "Proboscidea" for the order of elephants and their extinct kin. Which means that it may not be pronounced the way you think; it has three syllables: Prime-ATE-eez. It literally means "of the first rank", because, you know, anything with us in it has to be of the highest rank. (Hence the title "primate" given to some high-ranking bishops).

Sunday, 18 January 2015

The Smell of Success

One of the noticeable features of mammals, when compared to other vertebrates, is that they tend to have a highly developed sense of smell. Most vertebrates can smell, even if, in the case of fish, it's not quite what we'd think of by that term. Indeed, the sense of smell is pretty poor in most fish (sharks are among the exceptions, hence that blood-in-the-water thing), and it's also rubbish in birds, and not too great in many amphibians. It's rather better in reptiles, but the snakes, which appear at first glance to be really good at it, actually do so by cheating (more on that later).

But, by and large, the sense of smell reaches its apogee with the mammals. It's not just dogs that have a far better sense of smell than you do. It's also mice, deer, cats, and many others besides. The mammalian olfactory system is superbly evolved, and this dates right back to the origin of the class. In short, it's usually far better than anything we've got.

Except... um... we are mammals. So what gives? Why are we humans so useless at something that our fellow milk-giving relatives have perfected? Something that, presumably, has a lot to do with the success of mammals as a class?

Sunday, 11 January 2015

The Dog Family: Wolves, Dogs, and Dingoes

Eurasian wolf
The best known and most familiar of the species in the dog family is surely the grey wolf (Canis lupus). This is not least because it is the one that we happen to have domesticated, and which most of us see just about every day. Even the wild form is so familiar that there are a great many wildlife documentaries and web pages out there that cover the species better than I can in one blog post, and I don't want to go too much over that ground. But nonetheless, for the sake of completeness, at least some sort of overview is needed here.

The term "grey wolf" is the generally accepted one for the species as a whole. While there are other species that are referred to as wolves, this is the one that we generally mean when we say the word "wolf" without qualification. Most other terms, such as "timber wolf", "steppe wolf", and so on, refer either to groups of one or more subspecies, or are simply alternative terms for the same animal. Once being spread throughout almost the entire Northern Hemisphere (albeit to only a limited extent in Africa), it is unsurprising that there are rather a lot of subspecies.

But how many? That's a question of some debate. I have talked before about how difficult it can be, in practice, to separate one species from another; the problem is even worse when you're trying to count subspecies. One scheme, for instance, has as many as 24 subspecies in North America alone, while another, more conservative, scheme recognises just twelve worldwide. There are a great many opinions that lie somewhere in between.

Sunday, 4 January 2015

Claws of the Bear-Dogs

Arctocyon primaevus
Over the four or so years that this blog has been running, I have covered a number of discoveries of or about fossil mammals. These have come from various epochs within, and beyond, the Age of Mammals, and so are a wide range of different ages. But I don't believe that I've ever previously discussed a fossil from the very first epoch of the Age of Mammals, the Paleocene.

This is partly because, being the oldest, it's not an epoch from which very many good quality fossils survive - at least, as compared with later epochs (as opposed to, say, comparably short periods during the Permian). On the other hand, though, it's obviously an important one, because this is the time during which mammals rose to inherit the Earth in the wake of extinction of the dinosaurs. The great diversity of mammals that we see today had much of its origin in the explosive radiation of new forms that first occurred during the Paleocene. Few modern groups are recognisable from this time, but we do see a number of immediate ancestors of those later groups.

Sunday, 14 December 2014

New Mammal Species 2014

Waiomys mamasae
New species of animal are discovered every day. That isn't hyperbole; I mean it literally. I'm not sure of the exact number of new species that were named last year, but it's in the thousands, and likely a five-figure number, at that. This is, you'll note, rather a lot.

The great majority, of course, are insects. "An inordinate fondness for beetles" and all that. Most of the ones that aren't are also invertebrates, typically small things like mites, spiders, or crustaceans. When we do look at vertebrates, most of the new ones are fish, with amphibians and reptiles not far behind. For instance, looking at the new species described in the daily journal Zootaxa (by no means the only source for such things, although it is one of the largest) on Friday 12th December 2014, I count seven beetles, two flies, three crickets, a frog, a salamander, a gecko, and (unusually) a bunting.

In fact, new birds are, if anything, even more rarely described than new mammals. But while while new mammal species are not discovered that often, there are still several each year. So, for this, the last post of 2014, why not look back at some of the mammals that were officially described for the first time this year? This will not be, by any means, a comprehensive survey, just a sampling, and I'm not even counting the various new fossils that have been described, but nonetheless, here we go:

Sunday, 7 December 2014

Struggle of the Marsh Antelopes

All things being equal, herbivores would prefer to live in those areas with the best and most lush vegetation. The reality, of course, is that all things are very rarely equal. There are all sorts of reasons why a herbivore might not wish to live somewhere where they can get the best quality food.

One of those reasons is the presence of predators. If predators also live where the vegetation happens to be best, a herbivore has to strike a balance between the quality of the food and the risk of getting eaten. But a herbivore also has to worry about... other herbivores.

If you eat exactly the same thing as some other animal, and try to do so in the same place, whichever one of you is even marginally better at it is going to, over a sufficiently long period of time, out-compete the other one and drive it to at least local extinction. We see this, for example, in England, where grey squirrels introduced from North America have out-competed the red squirrels native to the island. There are only a few places left in England where you can still see red squirrels, but the foreign grey squirrels are quite common.

Saturday, 29 November 2014

The Dog Family: Canidae

A wolf
The dog family does not have the same variety of different forms and species as does the weasel family. I also suspect that, with the exception of grey wolves, it doesn't get the sort of attention that the big cats do. Yet, of course, even apart from the wolves and their domestic descendants, it includes a number of familiar species, as well as some that are rather more exotic. So, with goats and marmosets out of the way, let's turn to the taxonomic family of man's best friend.

With, perhaps, one or two exceptions, most members of the dog family are instantly recognisable as such. Ignoring the domestic breeds, they typically have muscular bodies, long legs, large, mobile, ears, heads that are broadly triangular in shape, and bushy tails.

Their legs are the shape they are because they're adapted to chasing prey, and most dogs are therefore pretty good at running. They have four toes on each of the hind feet, and, while most of them do have the full set of five on the front feet, the thumb (or "dewclaw") doesn't reach the ground. Their snout is the length and shape it is, partly to get in a large and sensitive nose, and partly to fit in an array of teeth that don't restrict them purely to eating meat.