Author: Russell Garwood

Fossil Focus – Marrellomorph arthropods

Fossil Focus
by David Legg*1 Introduction: The Palaeozoic era was a time of incredible biological diversification, which saw the origins and establishment of most modern animal body plans and phyla, particularly during the Cambrian explosion, an event which lasted for about 20 million years during the early Cambrian Period (starting about 542 million years ago), and the subsequent Great Ordovician biodiversification event. During this time, there was a lot of ‘evolutionary experimentation’, with many ancient communities dominated by alien-looking creatures unlike any of their modern counterparts. One such peculiar group is the marrellomorph arthropods, roughly 11 species known exclusively from the lower Cambrian (starting about 542 million years ago) to the lower Devonian period (ending about 393 mil...

Fossil Focus: Ammonoids

Fossil Focus
by Kenneth De Baets1, René Hoffmann2, Jocelyn A. Sessa3 and Christian Klug4. Introduction: Ammonoids (Ammonoidea) are an extinct group of marine invertebrates with an external shell. They were cephalopods, and hence closely related to modern cuttlefish, squid, octopuses and the pearly nautilus. In a non-scientific context, they are commonly called ammonites, but that term really includes only Jurassic and Cretaceous forms in its stricter scientific sense. The Ammonoidea as a whole lived from the Early Devonian to the earliest Palaeogene period, covering a timespan of about 350 million years. Normally, only their shells, also called conchs, or their internal moulds are found in the fossil record. Conchs from adult ammonoids range from about 5 millimetres to 2 metres in diameter. Due to...

Perspectives: 2015 in Palaeontology

Perspectives
by the Palaeontology [online] team Introduction: We’re now into our sixth volume — and calendar year — at Palaeontology [online]. Over the years, we have introduced a lot of fossil groups, concepts from palaeontology and overviews of different parts of our field. An intention when we started was also to provide the occasional overview of happenings in the world of palaeontology: to reflect new developments and highlight some current ideas. To that end, we have chosen to start 2016 by looking back over the past year, and forward into the next. In this article, members of the Palaeontology [online] team have chosen their favourite papers from 2015, and indicated what they hope to be up to over the next 12 months. So without further ado, here is team Palaeontology [online]! Imran Rahman: ...

Fossil Focus: The place of small shelly fossils in the Cambrian explosion, and the origin of Animals

Fossil Focus
by Aodhan Butler *1 Introduction: Darwin, the Cambrian explosion and the origin of animals. The small shelly fossils (or SSFs) of the early Cambrian period (approximately 541 million to 509 million years ago) could in many ways be described as the world’s worst jigsaw puzzle. This article will attempt to give a brief tour of the significance, history and biology of this humble yet potentially hugely important group of fossil organisms and how they may help in answering fundamental questions about how and when the major groups of animals evolved on Earth. A palaeontological mystery… “To the question why we do not find rich fossiliferous deposits belonging to these assumed earliest periods prior to the Cambrian system, I can give no satisfactory answer.” Charles Darwin, On the Origin of ...

Fossil Focus: Cambrian arthropods

Fossil Focus
by David A. Legg*1 Introduction: The arthropods make up a major and highly successful group of animals that includes insects and their kin (hexapods); arachnids and their kin (chelicerates); millipedes and centipedes (myriapods); crabs, lobsters, shrimp and their relatives (crustaceans); and the extinct trilobites. In fact, arthropods are the most diverse, abundant and ubiquitous animal phylum. Members of the group outnumber those of all other phyla on Earth, both in terms of species, with more than 1,200,000 currently described (and a potential 10,000,000 remaining to be described), and in terms of abundance. For example, if you gathered all the world’s Arctic krill in one place, it has been estimated that they would weigh 500 million tonnes! Arthropods are found in all oceans and on al...

Fossil Focus: Annelids

Fossil Focus
by Luke Parry*1 Introduction: Annelids, whose name comes from the Latin meaning ‘little ring’, make up a phylum of invertebrates with a unique segmented body plan. They are important components of terrestrial and marine ecosystems, and form one of the most diverse invertebrate groups, including as many as 15,000 described species (Fig. 1). Their closest living relatives are the molluscs, brachiopods and nemerteans (proboscis worms). Annelids can broadly be split into two groups, the polychaetes and clitellates. These groups share many features, such as segmented bodies and paired bundles of bristles made of chitin, called chaetae or setae. The most familiar annelids are the clitellates — the earthworms, leeches and their relatives — which have become adapted to a terrestrial lifestyle...

Fossil Focus: Porpoises

Fossil Focus
by Rachel A. Racicot*1 Introduction Porpoises are among the smallest of modern whales, but they are one of the most amazing groups. They use specialized high-frequency hearing and sound production, and they have one of the best fossil records of any marine mammal. Thanks to modern imaging technology, we have been able to learn about how porpoises are able to sense their environment through echolocation and how they evolved. I will be telling you a bit about a particularly interesting porpoise from the fossil record, Semirostrum ceruttii (‘Cerutti’s half-nose’), and using it as an example of how CT scans help scientists to explore ancient and modern anatomy. What are porpoises? People sometimes use ‘porpoise’ interchangeably with ‘dolphin’, but scientists use the term to refer to a dist...

Fossil Focus: Diagnosing Dinosaurs

Fossil Focus
by Jennifer Anné*1 Introduction Palaeopathology is the study of the disease and repair of ancient life — most commonly in bone. First coined for the study of diseases in Egyptian mummies, the term was adopted to cover fossil material in 1917 by the first dinosaur doctor, Roy L. Moodie, but has become popular only in recent decades. It is surprising that the study of palaeopathology in the fossil record took so long to catch on in palaeontology. Part of the problem lies with difficulty in getting hold of specimens or accessing the techniques and equipment needed for sensitive analysis. But even if all those problems have been overcome, diagnosing a fossil pathology beyond a vague description brings its own challenges. Difficulties with diagnosing Palaeopathologies may be fairly easy for...

Life as a Palaeontologist: Palaeontology for dummies, Part 2

Life as a Palaeontologist
by Russell Garwood*1  Introduction In Palaeontology for Dummies, Part 1, we looked at modern palaeontology as a discipline, including the broad range of specialisms in the field. I hope it convinced you that palaeontology is an exciting and ever-expanding subject. Here, in the second part, we will focus on the birth and historical development of palaeontology, which has at times been highly controversial. We’ll first consider how humans and fossils interacted before science was formalized, then we will move on to the birth of palaeontology during the Enlightenment era in the seventeenth and eighteenth centuries. We will cover the field’s expansion and rapid development during the nineteenth century, and finish with a few of the most notable findings trends in the past century. For sake...

Patterns In Palaeontology: Trends of body-size evolution in the fossil record – a growing field

Patterns in Palaeontology
by Mark A. Bell*1 Introduction: The body size of an animal is often considered the most important part of its biology. Large body size brings many advantages, which can include better ability to capture prey, success in evading predators, intelligence, longevity and reproductive success; it also makes a greater range of resources available. A larger animal has a lower surface area to volume ratio than a smaller animal, which results in less heat loss to the surroundings, allowing it to remain warmer for longer in a cold environment. However, one major disadvantage is that larger organisms are, in general, more specialized, and can require more food for example. This can put species at higher risk of extinction caused by rapid environmental change. Since the work of nineteenth-century ...