Sunday, 12 July 2020

He Said, She Said

One of the most distinctive behavioural features of the human species is our ability to communicate. So far as we know, no other animal can convey even remotely as much information as we can by speech alone, never mind the advantages that writing brings. But we didn't come out of nowhere, and other mammals can also communicate vocally, something that may have particular relevance to the development of our own species when we look at other primates.

A number of primate species are highly vocal, such as gibbons or the aptly named howler monkeys. Another example, which may be less obvious. is the common marmoset (Callithrix jacchus). This is a species I've talked about before, a small monkey native to South America with a number of unusual biological and anatomical adaptations related to its reproduction and diet. (Unusual for primates in general that is, not compared with other marmosets). But it is behaviourally interesting as well.

Sunday, 5 July 2020

Small Cats: Lynxes of North America

Canada lynx
For much of the 20th century, it was thought that there were only two species of lynx, one of which lived right across the high latitudes of the Northern Hemisphere, from Portugal to Newfoundland, by way of Siberia and Alaska. That began to be questioned towards the end of the century, and, since about 2005, it's been pretty much universal to consider this widespread animal to actually comprise three different species. Two of those live in Eurasia, with the other one found only in North America.

This, of course, is the Canada lynx (Lynx canadensis); the alternative form of 'Canadian lynx' is also used in some formal sources, but only seems about half as popular. It lives across virtually the whole of Canada south of the tundra but, despite the name, is also found in part of the US. Alaska is the most obvious example here, but Canada lynx can also be found south of the border in the Cascade and Rocky Mountains, around Lake Superior, and in much of Maine. Between 1999 and 2006, a number of Canada lynx were also re-introduced to Colorado, where they had been locally extinct since at least the 1970s; so far, they seem to be doing well enough.

Sunday, 28 June 2020

What's the Closest Living Relative of Whales?

(For the TLDR crowd; just read the last paragraph).

It's been known for a long time that, at the highest level, mammals can be divided into three evolutionary groups based on their method of giving birth: marsupials, the egg-laying monotremes, and the placental mammals. That last group contains around 95% of all living mammal species, including everything from wolves to dolphins and moose to monkeys.

Given that wide variety, it's less obvious how we should divide up the placental mammals into smaller groups that genuinely reflect their evolutionary relationships. It's obvious that, say, cheetahs are members of the cat family and, at a slightly higher level, it's unsurprising that, for example, the dog and bear families are reasonably close relatives of one another. But once you get much higher than that, it becomes less so.

Sunday, 21 June 2020

Giant Wolverines of South Africa

Modern wolverine
Africa is the world's second-largest continent, containing about 20% of Earth's total land area. Despite this, it's probably fair to say that its the least palaeontologically explored continent - with the obvious exception of Antarctica. But this is not to say that there aren't several very good fossil sites in Africa, many of which have contributed significantly to our knowledge of animal evolution.

The most famous of these sites are those connected with the evolution of our own species, but there are a number of sites that have yielded, for example, significant dinosaur fossils. When it comes to mammals other than humans (and whatever else was living alongside them), Kenya and South Africa have proved particularly rich sources - although, of course, there are others.

Sunday, 14 June 2020

Small Cats: Lynxes of Europe and Asia

Eurasian lynx
Once we get away from the "big cats" as traditionally thought of (lions, tigers, leopards, cheetahs, and so on) the majority of wild cat species are at least broadly in the size range of the domestic animal. However, there are a few cats that are decidedly medium-sized on this particular scale, of which the best known in the Northern Hemisphere are probably the lynxes.

Lynxes are readily identifiable animals, and the word "lynx" itself dates back to at least the Ancient Greeks. They were also one of the original seven species of cat identified by Linnaeus in 1758 when he created the modern system for scientific naming of animals. As early as 1792, they were split off from the other cats into a subgenus of their own, now considered a full genus. This was in Robert Kerr's translation of Linnaeus' original work into English, by which point, at least four different species of lynx had been scientifically named and described (including one by Kerr himself, in the book in question).

Sunday, 7 June 2020

Miocene (Pt 20): Unicorn-Pigs and the First Hippos

Prodeinotherium
Pigs seem to have been another example of animals crossing over from Asia when that continent collided with Africa around 17 million years ago. The oldest fossil pigs in Africa date from about that time and are represented by Kenyasus from Kenya and Nguruwe from Namibia and South Africa. These were relatively small, short-snouted pigs with a primitive appearance similar to that seen in their presumed Asian ancestors.

Because of these primitive features, determining exactly where they fit in the pig family tree isn't a simple matter, but they are often placed with a group called the kubanochoerines. Assuming this is correct (and it's far from settled) they must have evolved fairly rapidly into much larger and more distinctive animals. The best-known member of the group is the giant "unicorn-pig" Kubanochoerus, which lived in China during the Late Miocene. This was an exceptionally large, long-legged animal, perhaps standing 120 cm (4 feet) high at the shoulder and - even more dramatically - sporting a long pointed horn that projected from the centre of its forehead.

Saturday, 30 May 2020

Chorus of the Dolphins

It's well-known that cetaceans - dolphins, porpoises, and whales - make calls to communicate with one another, in addition to the sonar pings used to navigate. The complexity of these calls varies significantly between species, although even sperm whales, for example, producing little more than a regular pattern of clicks, while humpback whales produce what appear to be sophisticated 'songs'.

Among the most studied of such calls are those of bottlenose dolphins (Tursiops spp.) which are the type most commonly seen in aquaria, making them relatively easy to observe. Having said which, it was only in 1998 that scientists confirmed that there was more than one species of bottlenose, leading to some confusion as to which one lived where and, by extension, which one any given prior study referred to. And, as I blogged about when the announcement was made back in 2011, we now know of a third one as well.