Fossil Focus: Cinctans

Fossil Focus
by Imran A. Rahman*1 Introduction: The fossil record of early animals — which dates back at least to the Cambrian period, more than 500 million years ago — is packed full of bizarre sea creatures that seem, at first glance, rather different from anything alive today. These include the armoured slug-like Wiwaxia, the spiny worm-like Hallucigenia and Earth’s first big predator, Anomalocaris. Collectively, these fossils were termed “weird wonders” by the evolutionary biologist Stephen Jay Gould; they possess some, but not all, of the characteristics shared by their modern relatives, and so are crucial for understanding the early evolution of animal phyla. This article focuses on a peculiar extinct group of Cambrian weird wonders called the cinctans, which look more like tennis racquets t

Fossil focus: Giraffidae — where we’ve been and where we’re going

Fossil Focus
by Chris Basu1 Giraffes (Giraffa camelopardalis) are charismatic and iconic animals. Together with their closest living relatives, okapis (Okapia johnstonii), they are remnants of an otherwise diverse group of even-toed ungulates - Giraffidae. Giraffids are ruminants (they have a specialized four-chambered stomach), and are related to other ruminant groups such as bovids (including cattle and antelopes), cervids (deer) and antilocaprids (pronghorns).  Ruminants use microbes in their stomachs to ferment and break down vegetation that would otherwise be impossible to digest. The origins of Giraffidae are hazy. DNA analysis confirms that they are a valid group, and that they diverged from other ruminants approximately 25 million years ago. This agrees with what is generally understood f

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

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: Stuck in time — life trapped in amber

Fossil Focus
by Leyla J. Seyfullah*1 and Alexander R. Schmidt1 Introduction: Some of the most extraordinary fossils ever discovered, from insects to plants and feathers, are preserved in amber. Amber is the term for various solidified forms of plant resin that occur in the rock record. It can be found in many different colours, shapes and sizes (Fig. 1). Until the past decade, it was thought to be very rare, but new discoveries have shown that it is more abundant in terms of both geographical coverage and presence through time than was previously thought. Although many amber deposits do not contain fossils, some do. Fossils (also known as inclusions) in amber often have exquisite, three-dimensional preservation, retaining fine surface and structural details, and are frequently preserved at lea...

Patterns in Palaeontology: Palaeogenomics

Patterns in Palaeontology
by Jeffrey R. Thompson*1 Introduction: Palaeontology is truly a science of the twenty-first century. Palaeontologists are no longer concerned only with fossils, but also with topics such as genetics, developmental biology and chemistry — although most of us can’t resist digging around in the dirt from time to time! You are almost as likely to find a palaeontology graduate student in a class on molecular biology as in one on stratigraphy. This is because, in recent years, the integration of fossil, developmental and genetic data has fast become one of the most promising ways to study the patterns and processes of evolution. At this point, it may be helpful to introduce some of the sources of information that palaeontologists use to address large-scale evolutionary questions. Molecular

Fossil focus: Acanthodians

Fossil Focus
by Richard Dearden*1 Introduction: The acanthodians are a mysterious extinct group of fishes, which lived in the waters of the Palaeozoic era (541 million to 252 million years ago). They are characterized by a superficially shark-like coating of tiny scales, and spines in front of their fins (Fig. 1). The acanthodians’ heyday was during the Devonian period, about 419 million to 359 million years ago, but their fossil record stretches back to the Silurian period (around 440 million years ago). One specialized filter-feeding group, the Acanthodiformes, persisted until the end of the Permian period (about 252 million years ago), disappearing in the end-Permian mass extinction. Acanthodian fossils were first described by the eminent Swiss palaeontologist Louis Agassiz during the nineteenth c

Fossil Focus: Seals, sea lions and walruses

Fossil Focus
By Morgan Churchill*1 Introduction Pinnipeds (seals, sea lions and walruses) make up the second most numerous group of marine mammals (behind whales), with 35 species found throughout the world’s oceans and in several freshwater lakes. They are represented by 3 living families: the Phocidae (earless seals; 19 species), found around the globe; the Otariidae (sea lions and fur seals; 15 species), restricted to the North Pacific and Southern Hemisphere; and the Odobenidae (walrus; 1 species), confined to the Arctic. Two additional extinct families are recognized: the Desmatophocidae and the Enaliarctidae of the North Pacific. Pinnipeds show a variety of adaptations for aquatic living, including flippers for moving through water, changes in teeth related to capturing and feeding on slippery

Fossil Focus: Ichthyosaurs

Fossil Focus
By Ryan Marek*1 Introduction A literal translation of ichthyosaur is 'fish lizard', yet ichthyosaurs were neither fish nor members of the lizard family; they were a group of highly successful marine reptiles who lived from the early Triassic period to the late Cretaceous period, around 248 million to 90 million years ago. Ichthyosaurs were among the first diapsids  (a group of animals which have evolved two holes on each side of their skulls, includes birds and all reptiles except turtles) to evolve a thunniform (fish-like) body plan as an adaptation to life in the sea (Fig. 1). They were also the first air-breathing vertebrates to evolve this body plan; the only other group to do so was the whales and dolphins, millions of years later. Most ichthyosaurs after the Triassic had the fish-l

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