by Emma Dunne*1
Life on Earth is incredibly diverse. More than 1.7 million species have already been described and estimates suggest that there could be as many as 9 million in total. But exactly how this rich biodiversity has developed over the last 542 million years since the Cambrian remains the subject of debate amongst palaeontologists. Did biodiversity increase steadily from one geological period to the next, or did it wax and wane without any overall direction? These questions are crucial in a modern context: today, we are flooded with urgent reports on the state of biodiversity worldwide, with many scientists stating that we are in the middle of a biodiversity crisis driven by human impact, leading to what is being called the sixth mass extinction. To understand and
by Jennifer E. Bauer*1
The ancient seas of the Palaeozoic era (541 million to 252 million years ago) teemed with unusual creatures that would be almost unrecognizable to us today. Although these animals look very peculiar, they often have living relatives that we are more familiar with. Consider echinoderms, such as sea stars and sea urchins: these marine animals can be recognized easily by scientists and the general public alike due to their distinctive five-fold symmetry and often vibrant colours. However, the Palaeozoic fossil record of echinoderms includes a wide range of forms that are radically different from living species. Indeed, there are only 5 major living groups of echinoderms, but about 20 extinct groups known only from the Palaeozoic. This means that the foss
by Thomas Clements*1
What are coleoids?
The coleoid cephalopods (Fig. 1), squids, cuttlefish and octopuses2, are an extremely diverse group of molluscs that inhabits every ocean on the planet. Ranging from the tiny but highly venomous blue-ringed octopus (Hapalochlaena) to the largest invertebrates on the planet, the giant and colossal squids (Architeuthis and Mesonychoteuthis respectively), coleoids are the dominant cephalopods in modern oceans. For humans, they are a vital dietary and economic resource and have an important role in our culture. Cephalopods have intrigued and been revered by humans from ancient times and, more recently, during the nineteenth and twentieth centuries, they became part of pop-culture. Stories of gargantuan poulpes attacking the submarine ‘Nautilus’ in Jule
by Mark T. Young*1, Sven Sachs2 & Pascal Abel3
To most people, crocodilians are large-bodied carnivores that have been unchanged since the age of the dinosaurs. However, during their 230 million-year history, modern crocodilians and their extinct relatives evolved a stunning diversity of body plans, with many looking very different from those alive today (crocodiles, alligators, caimans and gharials).
The first crocodylomorphs (the term used for living crocs and various fossil groups) are known from the Late Triassic Period, approximately 235 million to 237 million years ago. These animals lived on land and looked much more like a greyhound than a crocodile, with long legs and a skull that was deep like that of a meat-eating dinosaur, rather than flattened like that
by Andrew Cuff*1
One of the biggest challenges palaeontologists face is how to reconstruct whole animals from their fossils. Most fossil remains are just bones, so how do we go from the bones to the soft tissues? For extinct species, we make deductions by looking at their nearest living relatives. This process is called the extant phylogenetic bracket (EPB).
A good example of using the EPB is in reconstructing dinosaurs. Dinosaurs are alive today as their descendants, birds, but the non-avian dinosaurs we all know and love from Jurassic Park look very different from modern birds. Dinosaurs also have other living relatives: the crocodilians. Along with the dinosaurs and some other extinct groups, these are part of a group called the archosaurs (which means ‘ruling reptile
by Amelia Penny*1
Introduction and background
The ability to build and maintain a skeleton is one of the major innovations in the history of life. During the Cambrian explosion, which began around 540 million years ago, diverse animal (metazoan) skeletons appeared suddenly in the fossil record. This is also when we first see evidence for predation, the ability to move around and most of the animal body plans we would recognize today. The ability to grow a resistant skeleton was a major factor in the evolutionary arms races of the Phanerozoic eon — the time since the Cambrian explosion — and it made possible the dizzying variety of shells, bones and teeth scattered throughout the Phanerozoic fossil record. But the origin of skeletons has a much deeper root, in the Proterozoic eon (2,500 m
by Janet Burke*1
Introduction and background:
Although the microscopic creatures called planktonic foraminifera are still around today, most people have not heard of them. They don’t come to mind when the words "palaeontologist" or "fossil" are mentioned. They don’t have scales or claws, or big sharp teeth. They don’t even have mouths. If you were to visit the lab I work in, you wouldn’t see the specimens, just a row of compound microscopes and funny metal trays, slides and boxes of glass vials a little bigger than a pinky finger. If you look closer at those vials, each one contains hundreds upon hundreds of fossils, and each of those fossils has a story to tell. Etched into the nooks of its chambers and the very molecules of its calcite are facts about the ocean at a brief moment in tim
by The Palaeontology [online] editorial board*1
Every now and then at Palaeontology [online], we like to take a look at the world of palaeontology and reflect on what is happening in the field. Contrary to stereotypes, we believe that palaeontology and associated disciplines represent a fast-moving and exciting area of science. To highlight this, the members of the editorial board have each chosen a favourite paper from 2017. Picking just one paper was difficult for all of us, and it means that we have highlighted just five articles out of the many hundreds published in the past 12 months. Nevertheless, we hope that our choices reflect the breadth and depth of palaeobiological research in the twenty-first century. The papers include incredibly small and ancient invertebrates...
by Aodhán O'Gogain*1
Introduction and background
During the Pennsylvanian subperiod (roughly 318 million to 299 million years ago), lush tropical rainforests covered much of what is now North America and Europe, but were then near Earth’s Equator. These tropical forests were teeming with animals, from 2-metre-long millipedes that scurried along among the roots to fish with fangs 10 centimetres in length that inhabited the associated rivers and estuaries. Living among these giants was a diverse group of small (less than 1 metre) vertebrates that resembled newts, lizards and snakes. These were the Lepospondyli, a sub-class of tetrapods that are characterized by having hourglass-shaped centrums, the central parts of their vertebrae. They had elongated, small bodies and short limbs, with one
by Lukáš Laibl*1
Trilobites are an iconic group of ancient animals, with a fossil record that dates back more than 500 million years and consists of some 17,000 species. These extinct arthropods are characterized by a hard, mineralized exoskeleton, which greatly enhances their chances of being preserved as fossils. The exoskeleton is thought to have been mineralised soon after they hatched from eggs, and so we can find various growth stages of trilobites in the fossil record, including individuals less than half a millimetre long. That makes it possible to study the entire post-embryonic development (that is, the development after they hatch from the egg) of numerous species. This is important because work on the development of ancient organisms provides data crucial for ou