Saturday, 21 January 2017

Fossilised Hedgehog Ankles?

Many moons ago, back when I was at University (and studying zoology formally, instead of just as a hobby), the great majority of invertebrate-eating, non-flying, placental mammals were placed in a single group, the Insectivores. Even then there was some suspicion that this was a bit of a "wastebasket taxon", a group of animals placed together because it wasn't obvious what else to do with them. Molecular phylogenetics and cladistics were still in their infancy in those days, and, so far as I recall, the latter was never even mentioned.

Since then, things have changed, giving us a better picture of evolutionary relationships overall. Among other things, the number of animals that really belonged in the Insectivora was whittled away, as we discovered where the things we'd thrown into the wastebasket really belonged. The rump of the group, a genuine evolutionary unit that now goes by the less accessible name of "Eulipotyphla", does, however, still contain its most familiar members, animals such as shrews, moles, and hedgehogs.

Part of the problem is that these are relatively unspecialised mammals, in the sense that they remain broadly similar to what we think the first ever placentals looked like. Moles, of course, have adapted to a burrowing underground lifestyle that makes them fairly distinctive, but this is rather less true of their relatives. This also makes things difficult when we're looking at fossils, and we're trying to figure out just how far down the placental family tree any given suspected small insectivorous animal actually is.

Sunday, 15 January 2017

Socially Awkward Mice

Many mammals have complex social lives, in which they have to interact with others of their kind in a multitude of different ways. Even those that predominantly live alone still require some degree of social interaction, especially during the breeding season, or when raising young. But for those that regularly encounter other members of their species, social interaction is particularly important, and its sophistication in primates was likely one of the key factors in the rise of humanity.

In the case of humans, of course, much of our social knowledge is built up as children, learning social rules through observation and experience as well as through more explicit instruction. And, while out ability to use language to impart detailed information is something that's essentially unique to us, the need for a suitable environment to fine tune social behaviour isn't something that just arose out of nowhere. Raising an animal in isolation from others of its species might not be as cruel as trying to do the same to a human child, but that's not to say that it wouldn't have some effect on them.

Sunday, 8 January 2017

Ice Age Survivors in Hungary

Asiatic wild ass
The end of the Ice Ages saw a number of extinctions sweep across the world, particularly the Northern Hemisphere. Those animals that did not die out as the climate suddenly became warmer often moved further north, changing the composition of the local fauna wherever they had previously lived. This was no "mass extinction" of the sort associated with the end of the dinosaurs, but, on a smaller scale, it was nonetheless significant.

However, as we know all too well, it was by no means the last time that animals went extinct, let alone the last time that they have been eliminated from some local area. Many of these later extinctions were, of course, due to human activity, especially as we colonised new continents or discovered new islands.

But not necessarily all of them, since the climate has not, in fact, remained constant since the Ice Ages ended. After the sudden thaw that marks the boundary between the Pleistocene and the current, Holocene, epochs, warming continued, but slowed. It reached a peak somewhere around 4,000 to 5,000 BC, and then began a slow cooling that has continued almost until the present. Even that cooling trend has had its fluctuations and reversals, most notably the Medieval Warm Period of the 10th to 13th centuries AD.

Sunday, 18 December 2016

New Mammal Species 2016

Reticulated giraffes
2016 has, on the whole, been a bit of a rubbish year. Or so the common wisdom has it; one suspects that, for instance, the deaths of some particularly prominent celebrities at the beginning of the year has heightened our perception of those that died later on (relative to any other given year). And it's probably been quite a good year for you if happen to be a Trump supporter, or a fan of Nigel Farage.

But that debate doesn't belong here, instead, as the year draws to a close, it's time to take a survey of the species of mammal that have been newly discovered this year. Or, more accurately, newly named, since what we generally do these days is find some population of a previously known species that turns out not to belong to it, and to be something else instead. There have, as always, been a fair number of them this year, and there's no guarantee that they'll all stand the test of time, and still be considered valid species in, say, 2026.

My survey is, therefore, inevitably biased, with a just a semi-random sample of some of the species announcements I happen to have come across. Most of them are going to be small animals, since they're easier to overlook in the first place, but there are a couple of quite large ones. And, by "large", I don't mean just "wolf-sized", either.

Sunday, 11 December 2016

Bovines: Prehistoric Bison and Buffalo

Steppe bison, from a cave in Altamira, Spain
In the course of this series I have described 22 species of bovine. Whether that number accurately reflects the number of species alive today depends, in part, on what you consider to be a species - not least whether or not long-term domestication is a sufficiently dramatic thing to constitute the creation a new species. But that's the number I came up with, and it's worth noting that no less than seven of these species - almost a third - are currently considered "endangered", and at high risk of extinction. Indeed, the kouprey may well already be extinct, while the species to which domestic cattle belong is extinct in the wild.

(On that last note, incidentally, I received a note after posting on the subject reminding me of the Chillingham Cattle of Northumberland. These are sometimes claimed to be aurochs, or genuinely wild cattle, but this has no foundation, and, while they have been living wild for centuries, they are actually feral animals, likely descended from escaped medieval stock).

At any rate, there have been many other species of bovine that have gone extinct over the millions of years since their first appearance, in most cases for reasons that have nothing to do with humans. So, albeit with a focus on the genuinely cow-like ones, rather than the spiral-horned antelopes and their kin, today I'm going to look at some of them.

Sunday, 4 December 2016

The Alluring Scent of Bat Pee

Southern long-nosed bat
As I've mentioned many times before, scent is an important mode of communication for many mammals. A great many species possess scent glands of some kind or another, often located on the face or in the ano-genital region. In addition to their variable location, these can be of varying levels of size and complexity, arguably reaching heir apogee in the well-developed glands of animals like musk deer or the defensive sprays of skunks and zorillas. Apart from those that spend their entire lives in the water, some sort of scent producing structures seem to be present in just about all kinds of mammal; even humans have modified sweat glands in the armpits and groin that secrete something different from the normal odour-free sweat produced elsewhere on the body.

Having said that, humans can't really be considered to have scent glands in the sense that some other animals do, and our sense of smell is pretty rubbish compared with most non-primate mammals. We do not, as a general rule, communicate by wafting our smelly armpits at one another. But many other mammals do something that isn't quite so far from that, and in a variety of different ways.

Bats are no exception to this general rule. Many bat species have scent glands, often located on the throat or the upper part of the chest, and they can leave scent marks behind to communicate with others of their kind - often signalling something like sexual availability. By no means all bats have fully formed scent glands, but that doesn't mean that the others don't use scent in some way.

Saturday, 26 November 2016

Bovines: Blue Bulls and the Smallest Bovine

Male nilgai
The bovine subfamily can be divided into two main evolutionary branches. One consists of the truly cow-like bovines, including such things as bison, buffalo, and yak, alongside the regular domestic animal. The other are the "spiral horned antelopes", African species that, despite being more closely related to cows than (say) gazelles, nonetheless have a generally antelope-like body form. But there are two living species that fit into neither of these branches. They are relatively closely related to one another, and so form a third, much smaller, evolutionary branch (usually given the taxonomic rank of "tribe"). Although generally considered "antelopes", both species are native to Asia, unlike their spiral-horned kin.

The larger, and likely better-known, of the two is the nilgai (Boselaphus tragocamelus). Standing 120 to 140 cm (4' to 4'7") at the shoulder, although they are considered antelopes, there is a somewhat cow-like appearance to them, albeit with a much narrower head. Indeed, the scientific name reflects their somewhat odd form, since it literally translates as "cow-deer goat-camel" (in fairness, the two halves of the name were coined separately, and not used together for over 60 years afterwards). They are found throughout India, and in some neighbouring regions of Pakistan and Nepal. They have also been introduced into South Africa, Italy, Mexico, and Texas; while the Italian population died out in the 1940s, and the South African ones remain confined to their ranches, some of those in North America managed to escape, and can still be found wild in those areas today.