Proboscidean cladogram, by Vladimir Nikolov
Showing posts with label Prehistory. Show all posts
Showing posts with label Prehistory. Show all posts
Friday, 27 November 2015
Elephants Of Antiquity
Elephants, members of the group proboscidea, are beloved by everyone; they are big, charismatic, and essential keystone species throughout their native range, even in the places where they are now extinct. Once one of the most widely distributed groups of large herbivorous mammals on the planet, they are now confined to tropical Asia and Africa, and even then just barely in many places. I have mentioned them before when talking about some of the regions which they once inhabited, but never in great detail. That changes now, and in this post I hope to cover pretty much the entire native range of proboscideans on all continents, focusing mostly on those now extinct. Just to clarify briefly what I mean when I say "native", while the term has no true agreed upon meaning, for the sake of this post I will define it as any animal which is currently or would still have been present in an area, if not for human activity. Another fact that must be mentioned is that the terms "proboscidean" and "elephant" do not mean the same. All elephants are proboscideans, but not all proboscideans are elephants. The proboscidean family tree is typically divided into two main groups, the elephants and the mastodons, which split early on in their history. So, with that settled, let us begin with the two places where elephants are still present.
Monday, 9 November 2015
Exploring the natural land cover of Europe
How would Europe have looked if we had never come along? This subject has been covered before, specifically as goes the fauna, but today I will be tackling a different side of this, namely how the landscape itself would have looked. Traditionally imagined as a dense, continent-wide closed canopy forest, this view now seems unlikely, but precisely how it looked is difficult to assess, simply due to our lack of clear evidence. Despite this, enough data is available to give us a general picture of roughly how it may have looked, even if a large amount of educated guesses and inferences are required. The importance of discussing this subject must not be understated, as it is absolutely vital to conservation and habitat restoration. As has been covered here, trying to protect and restore the wrong habitats can have a devastating effect on wildlife, as demonstrated by the stark decline in many species caused by the intensive management of heaths throughout much of the continent. To understand how best to protect species we must first know what their natural habitats were, and in what conditions they once thrived. In this post, I will be covering the continent in general, but again with a stronger focus on western Europe, as this is where most attempted habitat restoration is currently taking place and where data is most plentiful.
Old-growth beech forest in Slovakia, often but mistakenly used as a model for all pristine European habitats
Saturday, 31 October 2015
Lands Pristine: Europe during the Eemian
Previously I have spoken about prehistoric Australia in great length, namely here and here, and recently wrote an in-depth post about ancient California. Pre-Human Europe however has been something of a neglected subject, despite also being the one I have the greatest interest in. I have mentioned details about it in passing, but now is its time in the limelight.
When people think of prehistoric Europe, they typically picture the early Holocene, covered here, but as that post discusses, the pristine European wilderness was already gone by then. No, to see Europe as it would still have looked today if not for our presence, one must go back to the Eemian, also known as the last interglacial. Spanning from 130,000 to 115,000 years ago, it was the last point in time when the climate resembled todays, but the megafauna had not yet died out. All of the modern species we know today already existed, and at a cursory glance it would have looked quite similar, but the Eemian was to modern Europe what present day southern Africa is to its northern counterpart, an unspoilt, pristine version of the latter, in which the now vanished giants were not just present, but dominated the landscape. In this post I will be covering primarily western Europe, as that is the place with which I am most familiar, and we will explore a Europe quite different from what we know today.
When people think of prehistoric Europe, they typically picture the early Holocene, covered here, but as that post discusses, the pristine European wilderness was already gone by then. No, to see Europe as it would still have looked today if not for our presence, one must go back to the Eemian, also known as the last interglacial. Spanning from 130,000 to 115,000 years ago, it was the last point in time when the climate resembled todays, but the megafauna had not yet died out. All of the modern species we know today already existed, and at a cursory glance it would have looked quite similar, but the Eemian was to modern Europe what present day southern Africa is to its northern counterpart, an unspoilt, pristine version of the latter, in which the now vanished giants were not just present, but dominated the landscape. In this post I will be covering primarily western Europe, as that is the place with which I am most familiar, and we will explore a Europe quite different from what we know today.
Trafalgar Square, 130,000 years ago, by Roman Uchytel
Friday, 30 October 2015
A World In The Tar Pits: California before Humans
California is known for many things; Hollywood, Silicon valley, and more recently unprecedented droughts. What it is less known for however, at least to the general public, is the vast diversity of life that once lived there. Located in California lie the La Brea tar pits, which are, as the name suggests, a group of tar pits, that have been trapping animals for the last 40,000 years, giving us an incredibly detailed view into the paleofauna of the region. Perhaps the best site for late Pleistocene animals in the world, it certainly contains some of the most spectacular creatures. From giant ground sloths and saber toothed cats to mammoths and mastodons, prehistoric California had one of the most diverse megafaunal assemblages in the world, far outmatching that of even Africa, both today and in the Pleistocene. In this post we will be travelling back 11,000 years, shortly after the end of the ice age, and right before the arrival of the first humans.
Paleoenvironment of La Brea, by Charles Knight. The animals in the foreground are the sabertooth Smilodon, Harlan's ground sloth, and the giant vulture Teratornis. In the background can be seen a herd of Columbian mammoths.
Saturday, 17 October 2015
Big cats of Europe - past and present
British big cats, German big cats, Danish big cats, French big cats. Every European country seems to be reporting sightings of mysterious, large, often black cats nowadays. Of course, in the vast majority of cases, these are either hoaxes or misidentification, the fact that melanistic animals are most often reported, despite being far rarer than individuals of normal colouration, should itself be a clue to this reality. Whatever the case. some of these sightings have possibly been of real big cats. In central Europe for instance, lynx are fairly widespread, and to a person unfamiliar with the animal, could quite convincingly appear as a leopard or jaguar. These sightings are less tenable on the British isles, but even in Scotland wildcats are present, if barely, and hybrids between them and domestics are often significantly larger than your average housecat. Barring the occasional zoo or circus escapee however, the only true big cats to be encountered in present day Europe is the aforementioned lynx. But this was not always the case. Today I will be talking about the history of big cats in Europe since the last interglacial, their distribution, diversity, success, and eventual downfall by way of spears and bows.
An Eurasian lynx, the only real big cat left in Europe
Wednesday, 14 October 2015
Frozen in time: The illusion of stable ecological communities and the geological perspective
Evolution as a process is, at its most basic level, relatively easy to understand: Slow adaptation over many generations favoring forms more well suited to their environment. This is of course so overly simplified as to border on flat out inaccuracy, there are so many complicated processes at play in evolution that one could not possibly do them all justice in a brief summary. The point however stands that the general perception of what evolution broadly speaking is can be defined as an endless process of refinement. We tend to perceive the species that exist today as perfectly adapted to their environments, fully capable of persisting and surviving on their own. After all, if this was not the case, how could they even be here in the first place? This mindset is not necessarily wrong at face value, species must be competitive in order in order to persist. The issue here is the lack of perspective. Species and populations that may seem stable and self-sustaining in the short term may actually be in a state of chronic decline over a longer course of time. The lifespan of an individual person is so fleeting compared to the vastness of deep time, that perceiving such declines is essentially impossible without the benefit of hindsight.
When we look at a pristine forest, an un-managed oldgrowth, we see a vast and complex community of plants and animals, each fulfilling its own role in the ecosystem. Trees of varies species tower above us, often forming dense stands, seemingly impenetrable and ageless. Yet this is an illusion. Pollen cores and fossil evidence clearly shows that forests, and all other ecosystems for that matter, are in a state of constant flux, everchanging, but on a timescale too slow for us to perceive. The communities of trees that a person visiting a Himalayan forest today might see would be almost wholly different from that experienced by a person walking through the same area just a few thousand years prior. But this state of constant change is not just an endless reshuffling, many species once common are now gone, and many that we today would consider "staples" of the forests will no longer be here millennia in the future.
When we look at a pristine forest, an un-managed oldgrowth, we see a vast and complex community of plants and animals, each fulfilling its own role in the ecosystem. Trees of varies species tower above us, often forming dense stands, seemingly impenetrable and ageless. Yet this is an illusion. Pollen cores and fossil evidence clearly shows that forests, and all other ecosystems for that matter, are in a state of constant flux, everchanging, but on a timescale too slow for us to perceive. The communities of trees that a person visiting a Himalayan forest today might see would be almost wholly different from that experienced by a person walking through the same area just a few thousand years prior. But this state of constant change is not just an endless reshuffling, many species once common are now gone, and many that we today would consider "staples" of the forests will no longer be here millennia in the future.
Saturday, 26 September 2015
Relict lineages and late surviving species
We all know how the story of a species goes; At some point it evolves, arising from a previous ancestor. Maybe it thrives and spreads far and wide, or maybe it remains restricted to a small area, persisting in relatively low numbers. If it does gain a wide distribution, it will probably split into multiple subspecies, and eventually, some of these may themselves evolve into what we would term a new species. Eventually however, animals recognizable as members of the original species will go extinct, descendants or no descendants. They disappear from the world, their role in the ecosystem taken by other creatures, or perhaps left vacant if said niches no longer exist. Whatever the case, they are gone. But the borders between extinction and survival are not as solid as many people think. First off, we have the aforementioned situation in which a parent species gives rise to further descendants. If the wild Grey wolf went extinct, Canis lupus would still persist in the form of the Domestic dog and Dingo, and any descendants that they may have. In this way, species with descendants never really go "extinct" in the technical sense, their lineage is carried on, but the distinct morphology and ecology is still lost. Another form of not-quite extinction is called Functional Extinction, when individuals of a species are still present, but persist at so low numbers that they will never be able to recover, and are doomed to eventually die out. An example of this would be the Thylacine, which while officially extinct by 1933, probably continued to persist in low numbers until at least the 50s. Despite this, the species itself was probably functionally extinct as early as the beginning of the 1930s, and by the time the last captive individual, Benjamin, died, the species had already been doomed to extinction for a while.
The type of not-quite extinction I will be talking about today is the concept of relict lineages, groups which, while long past their glory days, still exist in the form of at least a single species. For me to consider a lineage "relict", it must be represented by only a few species, typically only one, and must be in constant but slow decline. Relict lineages can persist for a relatively long time after the rest of their relatives die out, and these few remaining species are termed "late survivors", but if they continue for too long, say more than 5 million years, they are clearly capable of adapting and diversifying, almost certainly possessing quite a large population, and thus not properly considered "relict". In this post, I will be going over some hypothetical late survivors, how and when they may have lived, and why we don't know about them.
The type of not-quite extinction I will be talking about today is the concept of relict lineages, groups which, while long past their glory days, still exist in the form of at least a single species. For me to consider a lineage "relict", it must be represented by only a few species, typically only one, and must be in constant but slow decline. Relict lineages can persist for a relatively long time after the rest of their relatives die out, and these few remaining species are termed "late survivors", but if they continue for too long, say more than 5 million years, they are clearly capable of adapting and diversifying, almost certainly possessing quite a large population, and thus not properly considered "relict". In this post, I will be going over some hypothetical late survivors, how and when they may have lived, and why we don't know about them.
Wednesday, 23 September 2015
The early Holocene of Europe - from 11,000 to 6000 BP
The Quaternary extinction is a much talked about subject today, as it is both fascinating in the context of prehistory, and simultaneously important in modern conservation. Typically defined as the rapid decline in global biodiversity during the late Pleistocene up until present, it is sometimes referred to as the sixth mass extinction in earth's history, the previous one wiping out the non-avian dinosaurs 66 million years ago. Personally, I dislike the term Quaternary extinction. The event mostly occurred within the last 50,000 years, making the term "Quaternary" odd, since the Pliocene and majority of the Pleistocene was not involved. Some have also referred to it as the Pleistocene extinction, which is equally incorrect, as it has continued up until the present. I prefer the term "Anthropogenic extinction", and have used it previously, as I believe it is more apt. It ignores the timeframe in which it has occurred, instead describing the primary causal factor, humans.
While it is true that the most dramatic of the Anthropogenic extinctions occurred either during the late Pleistocene or around the industrial revolution, in this post I will be focusing on a very different, but in some ways even more significant period, the early Holocene. The early Holocene is special in that it represents a relatively brief span of time, approximately 5000 years, in which environmental conditions were similar to today, yet direct human influence on the landscape was not. Instead, the most major human influences during the early Holocene were the same as those during the Pleistocene - hunting. While many of the most important megafauna were already gone by the time the Holocene began, several were not, and for just a few thousand years, we got a glimpse of something similar to what the world may have looked like had humans not existed.
While it is true that the most dramatic of the Anthropogenic extinctions occurred either during the late Pleistocene or around the industrial revolution, in this post I will be focusing on a very different, but in some ways even more significant period, the early Holocene. The early Holocene is special in that it represents a relatively brief span of time, approximately 5000 years, in which environmental conditions were similar to today, yet direct human influence on the landscape was not. Instead, the most major human influences during the early Holocene were the same as those during the Pleistocene - hunting. While many of the most important megafauna were already gone by the time the Holocene began, several were not, and for just a few thousand years, we got a glimpse of something similar to what the world may have looked like had humans not existed.
Saturday, 29 August 2015
Lizard Kings: The giant Monitors of prehistoric Australasia
Today, the Komodo dragon is quite a well known animal. As the largest lizard in the world, it carries a prestigious title, and it is indeed an impressive creature. The Komodo dragon is however only one part of a greater puzzle, that being the giant Monitor lizards that once dominated much of Australasia. Not much is known of these enigmatic animals, but the bits and pieces we do have seem to reveal what was previously a widespread and successful group, now mostly extinct.
The most famous of the giant Monitors is obviously Megalania, a huge lizard that inhabited southern Australia up until the arrival of humans, when it was wiped out in the Anthropogenic-extinction. Known only from fairly incomplete remains, despite being a very recent animal, Megalania has been the subject of much debate, chiefly over its size. Original estimates from when it was first discovered placed it at 7 meters in length, what that would have made it a truly enormous animal, but in 2002, Zoologist Stephen Wroe found it to be a great deal smaller, at only 4.5 meters in length. This was again changed in 2009, when Wroe himself along with other researchers upsized it to 5.5 meters. In truth, we have no idea how large Megalania really was, since we do not know of its proportions. Ralph Molnar said in 2004 that if it's proportions were like those of a Komodo dragon, it would have been 7 meters long, while if they were similar to a Lace monitor, it would be upwards of 8.
The most famous of the giant Monitors is obviously Megalania, a huge lizard that inhabited southern Australia up until the arrival of humans, when it was wiped out in the Anthropogenic-extinction. Known only from fairly incomplete remains, despite being a very recent animal, Megalania has been the subject of much debate, chiefly over its size. Original estimates from when it was first discovered placed it at 7 meters in length, what that would have made it a truly enormous animal, but in 2002, Zoologist Stephen Wroe found it to be a great deal smaller, at only 4.5 meters in length. This was again changed in 2009, when Wroe himself along with other researchers upsized it to 5.5 meters. In truth, we have no idea how large Megalania really was, since we do not know of its proportions. Ralph Molnar said in 2004 that if it's proportions were like those of a Komodo dragon, it would have been 7 meters long, while if they were similar to a Lace monitor, it would be upwards of 8.
Varanus priscus, by Vlad Konstantinov
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