Sunday 3 March 2024

The Rhinos of Samos

Today, rhinoceroses are rare animals, with three out of the five species on the verge of extinction. Millions of years ago, however, not only were they much more common, but there were many more species, and with greater diversity, than we have today. 

How diverse that was depends on how broadly you interpret the word "rhino" when fitting it to formal scientific classifications. Even if we take the narrowest definition, considering only animals descended from the last common ancestor of the living animals, you can still add over two dozen species to the tally, although obviously, they weren't all alive at the same time. Adding in all the "rhinoceratoids" - anything more closely related to a rhino than to any other living animal - obviously gets you a great many more, although many of them didn't look much like the creatures we'd recognise. 

Sunday 25 February 2024

Antilopine Antelopes: Tommy's Gazelle and Relatives

Thomson's gazelle
You probably don't need to live in Africa to be aware that there are a great many different kinds of antelope. (A couple of years ago I came across an online picture quiz of "can you name these African animals?" Over half of them were antelopes.) It's hard to say which of these are the most familiar to the general public, because quite a few of them probably are, at least in general terms. But one subtype of antelope that people will at least recognise are the gazelles.

Gazelles are smallish, fleet-footed animals; the word comes from the Arabic ḡhazāl, which literally means something like "slim/agile creature". Gazelles are widespread, perhaps surprisingly so, and there are many different species. Of these, the one that may be the most familiar to people outside of Africa is Thomson's gazelle (Eudorcas thomsonii) for the simple reason that it's the one that lives in the Serengeti and therefore gets into a lot of wildlife documentaries. Mostly getting eaten by big cats, to be sure, but it's a start.

Sunday 18 February 2024

Oligocene (Pt 7): Not Quite Camels, Not Quite Pigs

While the ruminants of Oligocene North America would have looked similar to the musk deer of today, some of the other cloven-hoofed mammals inhabiting the continent at the time were more distinctive. Protoceratids no longer survive, but they had already been around for millions of years at the dawn of the Oligocene, and would survive throughout the whole of the following epoch and a little way into the one after that - an impressive record. Despite this, they never seem to have been very common, and the only undoubted Oligocene example is Protoceras, known primarily from Nebraska, Wyoming, and South Dakota.

It remains unclear exactly what protoceratids were, beyond the fact that they were obviously related to other cloven-hoofed animals. Some features suggest that they were closely related to ruminants (as was assumed when they were first discovered in the 19th century) while others indicate a close relationship to camels; it may even be that they are some early branch that doesn't fit well with either. Despite being the animal for which the group is named, Protoceras is not so well known as its later relatives, many of which notable for possessing a third horn on their snouts in addition to those in the place we'd expect to find horns on a goat or antelope. 

Sunday 11 February 2024

A Tiger's Dinner

One of the basic concepts in ecology is that of the food chain; the idea that plants are eaten by herbivores are eaten by small carnivores are eaten by large carnivores. The reality is both more complex - because, for example, omnivores exist - and simpler, because, at least on land, many of the largest carnivores eat large herbivores, not smaller carnivores. Nonetheless, there's still an underlying truth, and it introduces us to concepts such as the apex predator.

An apex predator is essentially a carnivore that has no predators of its own, an animal that sits at the top of its local food chain. Many mammals fit this description, including wolves, big cats, bears, and killer whales. (The last of those, of course, being an example of a large carnivore that does mainly eat smaller carnivores). Outside the world of mammals, one could add eagles, crocodiles, and sharks, among others. Humans could count as another example, given that we obviously don't have regular predators, but this does depend on your exact definition, since we're clearly omnivorous and, in many parts of the world have a nearly or totally herbivorous diet.

Sunday 4 February 2024

Playing Squirrels

Anyone who has owned a cat or dog will know that playing with toys is not something unique to our own species. Indeed, playing in general is a widespread phenomenon among mammals, and less commonly, in other animals, too. (Crocodiles and alligators, to take just one example). It's perhaps not as thoroughly studied as some other aspects of mammalian behaviour, but it has by no means been ignored and can be useful, for instance, to enrich the lives of animals kept in zoos.

In order to study play in animals, however, we first need a clear definition of exactly what it is we're talking about. A common model used today is the one defined by Gordon Burghardt in a 2005 book on the subject, which defines play as a physical activity meeting four key criteria.

Saturday 27 January 2024

No Such Thing as an Antelope

There is no such thing as an antelope.

Or at least that's true in the same sense that there's "no such thing as a fish". Which is to say that, obviously, antelopes exist but they aren't a scientifically definable group of animals. Or that, if they were, that group wouldn't map closely to what the regular English word "antelope" is supposed to mean.

The word entered English during the Rennaissance, and descends, via Latin, from the Greek "ανθολοψ". That first appears in the 4th century (so not old enough to be Ancient Greek, as such) and referred at the time to a mythical beast said to live along the Euphrates that had horns so sharp and serrated that it used them to cut down trees. We don't know why the Byzantine Greeks called it this, but there's not some "lope" that it's "ante" to (nor, to use most other European languages, is it an anti-lope); it's just a coincidence that the word sounds that way. For all we know, they were borrowing a word from some other, older language spoken somewhere out east.

Sunday 21 January 2024

Rise of the One-Toed Horses

The horse family contains, depending on your definition, just seven or eight living species of wild animal. If you count them separately, you can add the two domesticated species to those (that is, the horse and the donkey) but that's it. Moreover, all of these species are so closely related to one another that they can interbreed, albeit usually to produce sterile offspring, and so are traditionally placed into a single genus: Equus.

The genus is noted for its members having just one toe on each foot. The story of how this happened, and the number of toes became reduced, is one of the most frequently repeated in mammalian evolution, although the detail may be more complex than is sometimes presented. The story of how the genus evolved since that point, however, is much less so.