Fossil Focus: The evolution of tree-kangaroos

Fossil Focus
by Christine Janis1 Ladies and gentlemen, I give you tree-kangaroos. These wonderful animals can, in myriad ways,  demonstrate the power of evolutionary biology and geology in explaining the patterns we see in modern ecosystems. Here, I want to show how palaeontologists can piece together multiple lines of evidence to understand the evolutionary relationships of fossil and living organisms. Introduction First, a little introduction to the tree-kangaroos (genus Dendrolagus). These small, tree-dwelling (‘arboreal’) marsupials live in the rainforests of Australia and New Guinea, and belong to the macropod family of animals, which also includes ground-dwelling kangaroos and wallabies. They grow up to about 80 centimetres long, not including the tail, and mainly eat vegetation (see Fig

Patterns in Palaeontology: Old shapes, new tricks — The study of fossil morphology

Patterns in Palaeontology
by Verity Bennett1 Introduction: The size and shape of an organism is the product of genetics and environment. It is the raw material on which the process of natural selection (survival of particular animals over others) acts, and so is of central interest in studies of the evolution of ancient forms of life for which DNA information is not available. Fossil morphology, or shape, is the basis of most palaeontological studies, be they describing new species or making deductions about the animal’s lifestyle. Phylogenetic studies, those that place species in groups depending on how closely they are related to each other, are based on the presence and absence of particular features. This works on the theory that the more closely related two animals are, the more features they are likely to h

Life as a Palaeontologist: Going solo and making a living out of working with fossils

Life as a Palaeontologist
by Leyla Seyfullah*1 Introduction: In an article on Palaeontology [online] last year, Sarah King explained how undertaking a PhD can help you to launch an academic career in palaeontology. Obtaining that PhD can be a frustrating yet ultimately rewarding experience, but it is only the beginning for many palaeontologists — and it is worth pointing out that a PhD isn't a prerequisite for certain jobs in palaeontology (for example, dealing fossils). Here, I hope to give you a sense of what might happen after the PhD, and how this could lead to a wide range of new challenges and take you down previously unimagined paths. You didn't think that getting a job in palaeontology would be straightforward, did you?! As a PhD (Doctor of Philosophy) student, you are dedicated to working on your doct

Life as a Palaeontologist: Academia, the Internet and Creative Commons

Life as a Palaeontologist
by Ross Mounce*1 Introduction: The results of scientific research can be of interest to experts and non-experts alike. This is perhaps especially true for palaeontology, which captures public interest — but obtaining access to this information is sometimes difficult, even for scientists. Taking a rather different tack from previous Palaeontology [online] articles, I'm going to provide a brief overview of how the Internet has changed and is significantly changing palaeontology and academia in general, helping to open up research for the greater benefit of science and society. Figure 1 — Sir Tim Berners-Lee sends a message at the London 2012 Olympics. When Sir Tim Berners-Lee helped to invent the World Wide Web more than 20 years ago, he did it 'for ever

Patterns in Palaeontology: The first 3 billion years of evolution

Patterns in Palaeontology
by Russell Garwood *1 Introduction: Breathe in. Breathe out. It’s a good bet that you’re currently sitting in front of a computer, reading; I’m going to go ahead and assume that you’re breathing, too. In, and out. You probably weren’t even thinking about breathing until I mentioned it, but all the same, it’s keeping you alive. Oxygen from the air is being transported into the cells of your body, which are using it to create energy. So far, so good. But what you may not realize is that the cellular machinery performing this process so integral to our existence (Fig. 1) has roots buried deep in the geological past. It’s a story that begins before the origin of organized cells, in an ancient, alien world. But if we’re going back that far, we might as well go all the way back, to the very be

Fossil Focus: Marsupial evolution – A limited story?

Fossil Focus
by Verity Bennett*1 Introduction: There are three groups of mammals alive today: the egg-laying monotremes (echidnas and platypuses); the marsupials (those with pouches); and the placentals (those that develop a placenta in the womb and give birth to comparatively developed young). Marsupials and placentals are sister groups, more closely related to each other than to monotremes. Along with their closest fossil ancestors, marsupials belong to the clade metatheria, whereas placentals belong to the clade eutheria. Together, metatheria and eutheria comprise the therian mammals. Marsupials are much less diverse than placental mammals in terms of numbers of different groups, range of lifestyles, range of body shapes and where they live. Why this is the case is still not well understood, and a

Fossil Focus: Pterosaurs

Fossil Focus
by David W. E. Hone*1 Introduction: Pterosaurs are often mistakenly called flying dinosaurs, but they are a distinct, although related, lineage. They are an extinct group of reptiles from the Mesozoic era (251 million to 66 million years ago) and were the first vertebrates to evolve powered flight (Figs 1 and 2). Pterosaurs were first described as early as 1783 and recognized as flying reptiles shortly afterwards, and more than 150 species are now known. Fossil pterosaurs have been found around the world, with every continent yielding specimens. Adult pterosaurs ranged in size from around 1 metre in wingspan to more than 10 metres; the largest species were the biggest flying animals of all time. They occupied the skies for much of the Mesozoic era and had the air to themselves unt...

Patterns in Palaeontology: The Cambrian explosion – Paradoxes and possible worlds

Patterns in Palaeontology
by Jonathan B. Antcliffe1 Introduction: The transition between the Precambrian and the Cambrian period (about 550 million to 500 million years ago) records one of the most important patterns of fossils in all the geological record. Complex animals with a suite of shells, intricate body plans and associated movement traces appeared for the first time, suddenly and unambiguously, in sequences all over the world during this interval. This ‘Cambrian explosion’ remains one of the most controversial areas of research in all of the history of life, and one of the most exciting. Palaeontological data like this is definitive in its support for evolutionary theory, the relative sequence of first appearances in the fossil record over the past several billion years ties very closely with what we wou

Fossil Focus: Using Plant Fossils to Understand Past Climates and Environments

Fossil Focus
by Leyla J. Seyfullah*1 Introduction: Fossils provide us with our only direct record of prehistoric life. Studying them can help us to reconstruct the anatomy, behaviour and evolution of long-extinct organisms. Perhaps less obviously, fossils are also among the most important sources of information for scientists attempting to learn about past (palaeo) climates and environments — a major focus of research in Earth and environmental sciences, motivated in part by concerns over future climate change. Fossil plants (Fig. 1), in particular, can be useful for decoding past climate signals. Most plants are terrestrial (meaning that they live on land). They are generally incapable of moving around, and so are totally dependent on the atmosphere and the soil or rock (substrate) on which they gro

Fossil Focus: Xiphosura

Fossil Focus
by Jason A. Dunlop*1 Introduction: The Xiphosura are commonly known as horseshoe crabs because the front part of their bodies is horseshoe-shaped. They have sometimes been called king crabs, although this name is also used for a group of large true crabs. Despite their various common names, xiphosurans are not crustaceans. Older studies assumed that they were some sort of crab, mostly because they have gills and live in the sea, but careful anatomical studies towards the end of the nineteenth century showed that they are actually more closely related to arachnids. The name Xiphosura means ‘sword tail’ and refers to another obvious feature of these animals: a long, pointed tail spine. Horseshoe crabs — especially earlier fossil ones — also look quite a lot like trilobites. This has led to