Miniature Mediterranean Mammoths

Insular dwarfism is a phenomenon that has occurred many times throughout evolution. What happens is that a population of some large animal becomes trapped on an island, out of contact with its mainland kin., Because the island has a limited size, it also has a limited amount of food on it, and this is a problem for a large animal that needs plenty to eat,

If the island is particularly small, of course, the animals in question are likely to die out, if not immediately, then dwindling over a few generations until they lack the genetic diversity to sustain themselves. On the other hand, if the island is a large one (such as, say, Britain) then there may not be a problem at all, and nothing happens beyond the usual genetic drift between isolated populations. 

Prehistoric Mammal Discoveries 2024

Zalamdalestes

I have reached the end of another year and that means it's time for what has become a tradition on this blog over the last eight years: a look back at some of the discoveries about fossil mammals made in 2024 that didn't make into the regular posts. As usual, this will be a quick whistle-stop tour of mammalian palaeontology, hopefully focusing on some of the more interesting findings. Like any field of science, it has not been standing still.

Large Herbivores

Woolly mammoths (Mammuthus primigenius) are among the best-known of all prehistorical mammals to the general public and, aided by the fact that some lived recently enough to be preserved in permafrost, they are also amongst the best-studied. But there is still more to learn about the details of their lives and habits. A study published this year looked at the detailed isotopic composition of a fossil mammoth that had died about 12,000 BC in Alaska, showing that she was female, and had migrated over 1000 km (600 miles) during her lifetime, having originally been born in the Yukon. The area in which she died was popular with mammoths, but also with humans - she may have died peacefully, but the presence of people where mammoths congregated may not be a coincidence.

Prehistoric Mammal Discoveries 2023

Potamotherium

It's the last post of the year for 2023, and that means it's time once again to take a brief look at discoveries from the last year in the world of fossil mammals that didn't make it into this blog. Because, while dinosaurs are undoubtedly popular, the study of prehistoric mammals is also a major field, aided by that, being (mostly) relatively recent they tend to be more numerous and better preserved. Of course, everyone's heard of woolly mammoths and sabretooth cats but there's plenty more out there and, if I'm going to zip through them at speed today, I'm also going to try and cover as wide a range as possible. So, let's get going...

Prehistoric Mammal Discoveries of 2019

Nehalaennia, an 8 million-year-old rorqual
from the Netherlands, first described this year

As the year - and decade - approach their inevitable conclusion, it's time again to look back at a few palaeontological findings of 2019 that didn't, for whatever reason, make it into the regular Synapsida posts. As always, there is no theme to this list, just a sample of what seemed interesting linked only by when it happened to be published.

Prehistoric Mammal Discoveries of 2017

Albertocetus meffordorum, the post-cranial anatomy of which
was described for the first time this year.

At the end of each year, I do a slightly different post to wrap up the blog for the season. The format of these has changed over the years, and this year, again, it's time to do something slightly different from previous occasions. Not that there haven't been some interesting new species discovered this last year, with, to my mind, the Skywalker gibbon (Hoolock tianxing) being the stand-out example. This was announced early in the year, having been discovered in the Chinese/Myamar border region by a group of researchers who were fans of a certain science fiction franchise ("tianxing" literally translates to "sky-walker" in Standard Chinese), and is likely already endangered.

But this year, instead of discussing just how many new kinds of bat we discovered in the last twelve months, I'm going to note that my posts on fossil mammals tend to be more popular than those on the living sort, and take a look at a partial assortment of scientific papers published on this subject in the last year that, for various reasons, didn't end up in my regular blog posts. So here goes.

Pliocene (Pt 10): Before There Were Zebras

At the dawn of the Pliocene, Africa, like Europe, was a much wetter place than it is today. As a result, it was also much greener, a place of lusher vegetation, and the animals that fed on it. While that likely made little difference to the heart of the Congo jungle and to the more tropical reaches of West Africa, which are about as green as they're going to get, elsewhere the changes would have be obvious to any putative time traveller.

The biggest difference was likely in the north, where the even the very heart of what is now the Sahara Desert was likely covered in arid scrubland - hardly hospitable, but a significant improvement over baking hot dune-fields. By one estimate, moist savannah and open woodland stretched as far north as 21°, covering what are now countries like Chad, Sudan, and Mauritania. Further east, Somalia would also have been covered by woodland, rather than its current dry grasslands, and, at the opposite end of the continent, there may have been small forests in what are now the Namib Desert and the Kalahari.

It didn't last, of course. Around 3 million years ago, as the world fell irrevocably into the long autumn of the late Pliocene, Africa became not only cooler, but drier. And, if the generally cooler climate did not make too much difference to a continent sitting on the equator, the loss of rain certainly did. It's at this time that the Sahara, and the other deserts we are familiar with today, began to form, and the wildlife had to either adapt to that fact, or die. What was good news for voles in Europe, promoting the tougher grasses on which they thrive, was bad news further south, where the grass gave way to open sand.

Pleistocene (Pt 8): Mammoths v. Mastodons

American mastodons

The arrival of the first mammoths in North America was a significant turning point in the development of the local wildlife. It's so important that this date, 1.9 million years ago, marks the beginning of the first of just two 'land mammal stages' that define North American wildlife during the Ice Ages. It used to also mark the beginning of the Pleistocene itself, but for various reasons, that's now been shifted a little further back.

The mammoths in question arrived from Asia, crossing over the Bering land bridge, the recurring appearance and disappearance of which greatly influenced North American wildlife during this time. They were southern mammoths (Mammuthus meridionalis), the dominant species of mammoth in Asia at the time, but they quickly evolved into a home-grown American animal: the Columbian mammoth (Mammuthus columbi).

It used to be thought that, even ignoring any late-surviving southern mammoths, there were at least two different species of mammoth living in North America in the early to mid Pleistocene. We're now pretty confident that they're all just examples of Columbian mammoth. Nonetheless, you will often see references to the "Imperial mammoth" (Mammuthus imperator). Perhaps the biggest elephant that has ever lived - they were about thirteen feet tall at the shoulder - these were probably just really big Columbian mammoths. Not that that's anything to sneeze at, mind you.

Pleistocene (Pt 7): Meanwhile, Across the Atlantic...

Columbian mammoth
(It's likely that the real animal was hairier than the one in
this reconstruction, but it shows the tusks effectively)

Over the last five parts of this series I have described the history of Pleistocene Europe, describing some of the ways that the animal life of the continent changed over those thousands of millennia, and looking at a few particular animals in more detail. But one doesn't need a degree in zoology to notice that today, the wildlife of North America, for example, is different to that of Europe. North America has coyotes, raccoons, cougars, armadillos, and pronghorn antelope, to name just a few animals that are simply absent in Europe. (Or, in the case of raccoons, were absent until somebody made the mistake of releasing some of the furry nuisances in 1930s Germany).

It's hardly surprising that that continent also had different wildlife during the Pleistocene. One notable difference, for instance, is that we humans weren't there. Obviously, neither Columbus nor Leif Ericsson were genuinely the first person to discover America. But even whichever long-lost group of Native Americans was actually the first to discover the great western continent, they did so long, long, after the first Europeans discovered Europe. While Europe had at least some species of human inhabiting it for about two-thirds of the Pleistocene, nobody reached America until the epoch was all but over.

Pleistocene (Pt 4): Time of the Woolly Mammoths

The second-to-last Ice Age ended around 0.13 million years ago, a full 95% of the way through the Pleistocene. As I've described in Part 3, it was just one of a series of Ice Ages stretching back nearly two million years, and separated by relatively warm 'interglacials'. For much of this time, European wildlife had had a distinctly 'African' flavour, with lions, hyenas, hippos, and elephants, among others, inhabiting the continent alongside the ancestors of more familiar European animals.

Such animals prospered during the warmer gaps between the Ice Ages, and this, the last full interglacial, was no exception. The phrase 'hippos in the Thames' is often used when talking about this time, and its perfectly accurate. The climate of the day was, if anything, slightly warmer than it is now, with the ice retreating far into the Arctic. All that melting ice had to go somewhere, of course, and the sites of modern day coastal cities such as Amsterdam and Copenhagen would have been underwater. On land, much of the northern continent was covered by dense oak forests, a green wilderness yet to be cleared to make way for farmland or towns.

Pleistocene (Pt 3): Ice Ages and Interglacials

Life-size reconstruction of a steppe mammoth
(compared with a 3-year old human)

When the Pleistocene began, Europe's climate was much the same as it is today, and the general shape of the continent would also have been instantly recognisable from space. The animals however, were different, many of them being ones we would now associate with Africa - rhinos, elephants, hyenas, and cheetahs, among others. In part 2, I described how that began to change 1.8 million years ago (which, incidentally, was once defined as the beginning of the Pleistocene - see part 1 for why that changed).

This was a time of cooler weather, as the Ice Ages began to dawn. Forests retreated in the face of advancing tundra, and musk oxen, bison, and (strangely) European hippos began to make their appearance. The cold snap was prolonged, and, so far as we can tell, the fauna of Europe remained relatively stable for the next 600,000 years. That's still a very long time - if we go back to my analogy where we get just one minute to watch the events of a decade, with the whole of written history thereby spread out into a nine hour spectacular, this phase of European history would last a full six weeks.

1.2 million years ago, half way through the Pleistocene, the climate changed again, and mammals (and other animals) were forced to adapt. However, the change wasn't towards yet colder weather, but back towards a warmer, more pleasant climate. The forests grew back, with all their dense undergrowth in attendance, and the harsh steppe-lands retreated into the north. As had been the case at the dawn of the Pleistocene, European weather would have been much as it is now.

Pleistocene (Pt 2): Europe at the Dawn of the Ice Ages

Pachycrocuta brevirostris, a European hyena

The Pleistocene is the time of the Ice Ages, when great ice sheets rolled across much of the northern hemisphere. Nothing much lived on the ice sheets themselves, just as there is very little today in the heart of Greenland. But, as we've seen, not only were their wide bands of tundra and pine forest reaching across much of today's 'western' world (and, of course, a fair chunk of the Orient), but the ice ages weren't continuous; there were many warm gaps between them.

The mammals of the Pleistocene include what are surely the most familiar fossil mammals to most people, the ones we generally think of when we think of 'after the dinosaurs'. For this was the time of the mammoths and sabretooths. They're familiar to us because, aside from the tiny sliver of warm weather we currently live in, the Pleistocene is the most recent, and therefore the best preserved and the most easily analysed, of all the epochs of the Age of Mammals. It's been the setting for a number of films, books, and TV series - to name just two, the Ice Age cartoons, and the Earth's Children series.

Yet, when we think seriously about Pleistocene animals, there are a couple of important points to bear in mind.