Sunday, 17 September 2023

We're Up All Day to Get Lucky

One of the key characteristics that's often listed for the behaviour of a mammal species is what time of day it tends to be active. There are four basic options here, of which the most obvious are diurnality and nocturnality. The others are crepuscularity if it's most active around dawn and dusk but not in between, and cathemerality if it really doesn't care - often because it lives underground. But, either way, it's natural to assume that this behaviour is relatively fixed in an animal; either it's nocturnal or it isn't.

In reality, however, it turns out that this can have a lot to do with the circumstances. And, in the modern world, those circumstances are most likely to be shaped by... what else, but humans? 

The issue, of course, is that humans are for the most part diurnal. Which isn't much of a problem for animals that are naturally nocturnal, but can be if they, too, would prefer to be active during the daylight hours. What we see time and time again across the world, and across different mammal species, is that where humans are most likely to encounter wild animals, those animals shift their behaviour towards nocturnality to avoid the stress of meeting us too often.

Sunday, 10 September 2023

Skunks of the World: Spotted Skunks

Eastern spotted skunk
At least outside of the Americas, the most familiar species of skunk is the striped sort and, as I mentioned last time, even scientifically speaking, this is the animal that defines the skunk family. It's perhaps surprising then, to note that, despite it also being very widespread and highly visible, it wasn't the first species of skunk to be named.

That honour goes to the spotted skunk, which appeared in the earliest recognised list of scientific animal names in 1758. This isn't to say that nobody knew at the time what a striped skunk was, merely that the naturalists of the day had yet to identify them as something distinct from the spotted sort, and it was the latter that happened to be described first - the striped skunk followed less than twenty years later, in 1776. Before they were given their own genus, both species were originally placed in Viverra, which comes from the Latin word for "ferret" but seems to have been used for any small, slender mammalian carnivore that didn't fit elsewhere (not including, ironically, the ferrets). 

Sunday, 3 September 2023

Oligocene (Pt 4): Time of the Giants

The Grande Coupure saw many new animals pouring across from Asia into Europe. Whether or not the tapirs were among them is not immediately obvious. The oldest tapir that we know of is a fossil discovered in Germany and dated to the early Oligocene, not long after the Coupure. Named Protapirus, we know that it, or its very close relatives were found not only in Asia, but also North America, by the second half of the epoch and managed to survive, with relatively little change, into the Early Miocene that followed, dying out about 20 million years ago. 

At first glance, since the oldest fossil is German, it appears that tapirs originated in Europe and then spread east, and it's purely a coincidence that they happened to do so after the Coupure - which, after all, was a time of climatic change. The problem is, there wasn't anything remotely tapir-like living in Europe before the Coupure, but there were plenty of potential ancestors elsewhere. So it's perhaps more likely that the first true tapirs were Asian, and we simply haven't found their fossils yet. Even so, we can at least say that Protapirus, and its later relative Paratapirus (which never seems to have left Europe) really were tapirs, rather than some close relative. A key feature here is that, unlike their earlier relatives, they already had the modifications to the nasal bones that suggest the presence of the short trunk that modern tapirs have, although it was probably less prominent than in current species.