Year: 2013

Life as a palaeontologist: Palaeontology for dummies, Part 1

Life as a Palaeontologist
by Russell Garwood *1 pa·lae·on·tol·o·gy / pa·le·on·tol·o·gy noun /ˌpælɪɒnˈtɒlədʒi/ or /ˌpeɪlɪɒnˈtɒlədʒi/ — The scientific study of prehistoric life. Introduction Palaeontology. If you’re reading this, it is likely that you’ve already encountered this particular corner of the scientific world, and know what it involves. If not, welcome: I think palaeontology is awesome and I hope that by the end of this article, you will too. Either way, it never hurts to define terms. As the above definition says, palaeontology is the study of prehistoric life. The discipline is actually rather wide ranging, with many sub-disciplines, but it is fair to say that most forms encompass the study of fossils or their traces. This study allows us to better understand extinct organisms’ biology, evolutionary

Fossil Focus: Heterostraci

Fossil Focus
by Joseph N. Keating*1 Introduction: The Heterostraci (which means ‘different shield’) make up an extinct group of jawless fish that lived during the early to middle Palaeozoic era, approximately 440 million to 359 million years ago. They were exceptionally diverse, with over 300 species currently described from marine and freshwater sediments of North America, Europe and Siberia­­­. Heterostracans are characterized by their external armour of distinct plates, which are composed mainly of bone and dentine (a hard-tissue component of teeth in vertebrates). Most heterostracans can be classified into two major groups, the cyathaspids and the pteraspids, which differ with respect to the structure, number and arrangement of their armoured plates. Heterostracan fossils are rarely found as comp

Patterns in palaeontology: An introduction to ancient DNA

Patterns in Palaeontology
By Peter D. Heintzman*1 Introduction: Deoxyribonucleic acid, or DNA for short, is the magical molecule that encodes instructions on how to build organisms, and has been doing so successfully for at least the past 2.5 billion years. Although its function has remained constant throughout this time, the instructions themselves have been slowly modified and upgraded to cope with the changing demands of organisms and the environments in which they live. A modification to DNA is called a mutation, and it is through mutations that we are able to track how organisms have changed, or evolved, through time. In all multicellular organisms, there are two major types of DNA: mitochondrial (mtDNA) and nuclear (nuDNA) (Fig. 1). These have different histories and can therefore tell us different thing...

Fossil Focus: Encephalized bipedal apes

Fossil Focus
by Holly M. Dunsworth Humans would not have evolved if the ancestors of the African great apes had not. The ape fossil record begins 23 million years ago with the earliest putative apes, including Morotopithecus and Proconsul (Figure 1), from sites in East Africa, followed by many others throughout Africa, Europe and Asia. Although this record is fairly rich, it has done no better than DNA-based estimates at helping researchers to determine how living apes are related. Genetic studies estimate that gorillas split off from other apes about 9 million to 8 million years ago, and that the ancestors of bonobos and chimpanzees began evolving separately from the ancestors of humans 7 million to 6 million years ago. Comparative anatomy, physiology, behaviour and genetics provide enough e...

Patterns in Palaeontology: Why the thunder lizard was really the deceptive lizard.

Patterns in Palaeontology
by Chloe Marquart1 When I tell the average stranger that I'm a palaeontologist, the first question that I'm inevitably asked is: "Like Ross from Friends?" The second is: "Have you named any dinosaurs?" The naming of fossils is actually a very small part of the work that palaeontologists do, but it often garners the most attention from the press and public. It can be difficult for people to understand how scientists can suddenly decide that a well-known, often iconic name has never 'existed' - in a scientific sense, at least. Many grown adults still mourn the loss of their beloved Brontosaurus (more on him later), and in the past few years, campaigns were begun to ‘Save Triceratops’ when it was declared that this dinosaur and Torosaurus might be the same animal (Fig. 2). Although

Patterns in Palaeontology: Exceptional Preservation of Fossils in Concretions

Patterns in Palaeontology
by Victoria McCoy*1 Introduction: Have you ever seen a geode — a boring-looking ball-shaped rock that, when split open, reveals a remarkable crystalline interior? For most people, the first reaction to the dazzling crystal interior is to marvel at its beauty. But for some — and perhaps you fall into this group, since you are reading this article — the second and more important reaction is to wonder how it got that way. The people who ask this question understand that the beauty of nature is far greater when we understand it deeply and see it more fully; in short, they are scientists at heart. If you are a scientist at heart, I have very good news for you. There is something out there that is like a geode, but perhaps even more interesting, at least to fossil lovers: the curious rocks

Patterns in Palaeontology: Development in the Fossil Record

Patterns in Palaeontology
By Jo Wolfe*1 Introduction: Development, the process by which a single egg cell transforms into a complex adult organism, has fascinated biologists for more than 200 years. In the mid-nineteenth century, before and during the time when Charles Darwin was uncovering the principles of natural selection, a number of biologists who wondered what caused evolutionary relationships among organisms looked to development for answers. The German zoologist Ernst Haeckel popularized the phrase “Ontogeny recapitulates phylogeny” — where ontogeny is an organism’s development and phylogeny is its evolutionary relationships. You may have seen a version of his famous diagram in biology textbooks (Fig. 1). Haeckel suggested that, during each successive stage of development, an animal would pass through a

Fossil Focus: Trilobites

Fossil Focus
by Mark Bell*1 Introduction: Trilobites make up one of the most fascinating and diverse groups in the fossil record. Over the course of their long history — which dates back to near the beginning of the Cambrian period, around 520 million years ago — they have inhabited a wide range of marine environments, from reefs to abyssal depths. In addition, trilobites have evolved several different life strategies, from burrowing to swimming; these are reflected in their varied appearances, or morphologies (Fig. 1). Several species, famously those from the Devonian period of Morocco (about 420 million to 360 million years ago), developed a rich array of protective spines, which has made them a popular choice among fossil collectors and dealers.   The earliest scientific report of a

Patterns in Palaeontology: Who’s there and who’s missing?

Patterns in Palaeontology
by Simon Darroch*1 Introduction: Sitting in the sweltering heat of southern Japan, I’m faced with a conundrum. The limestone cliff in front of me preserves the boundary between the Permian and Triassic periods, a point in time around 250 million years ago that witnessed the greatest mass extinction of the Phanerozoic eon. I’m collecting rock and fossil samples from around this boundary to study how the make-up of fossil communities changed in response to this extinction event: this is palaeoecology. The boundary itself couldn’t be easier to spot — the lower (and older) part of the cliff is composed of a pale white-yellow limestone packed full of fossils of shelled marine invertebrates including brachiopods, bivalves and gastropods, as well as microscopic sea-floor-dwelling (benthic) crea

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