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Author: Imran Rahman

Patterns in Palaeontology: Environments of the Cambrian explosion

Patterns in Palaeontology: Environments of the Cambrian explosion

Patterns in Palaeontology
by Thomas W. Hearing*1 Introduction: Shimmering curtains of sunlight stream down through the waters of a shallow sea that has been advancing landwards for several million years. This transgression has formed wide areas of shallow continental shelf seas. The sea bed teems with life — some of it familiar, some much less so. The oddities begin on the floor of this tropical sea: a reef built not of corals, but by carbonate-producing microbes and the strange archaeocyathan sponges, alongside creatures that look more conventionally sponge-like but probably aren’t. Streams of seaweed drift on the currents; closer examination reveals small, snail-like shelled molluscs on some of the tendrils. A trilobite scuttles for cover, startled by the flickering shadow passing overhead, and narrowly avoids
Patterns in Palaeontology: Palaeoproteomics

Patterns in Palaeontology: Palaeoproteomics

Patterns in Palaeontology
by Caitlin Colleary*1 Introduction: The fossil record is our only direct window to the history of life on Earth. The ability to find and study the remains of animals, plants and other organisms that lived millions of years ago is extraordinary, and as technology has improved over the past few decades, scientists have realized that fossils contain more information about the stories of extinct life forms than even Charles Darwin could have imagined. Biomolecules (such as DNA, proteins and lipids) that make up modern animals contain information about how their bodies work (physiology — that is, physical and chemical functions), relationships to other animals and their evolutionary histories. With the advances in analytical tools such as high-resolution mass spectroscopy, the study of biomol
Fossil Focus: The Ediacaran Biota

Fossil Focus: The Ediacaran Biota

Fossil Focus
by Frances S. Dunn*1 and Alex G. Liu2 Introduction: The Ediacaran period, from 635 million to 541 million years ago, was a time of immense geological and evolutionary change. It witnessed the transition out of an ice-house climate, the break-up of one supercontinent (Rodinia) and the assembly of another (Gondwana), a major meteorite impact (the Acraman event) and unprecedented shifts in global ocean chemistry that included a significant rise in oxygen concentrations (Fig. 1A). Rocks from the Ediacaran also record the appearance of a diverse (species-rich) group of large, morphologically complex lifeforms: the Ediacaran biota. These organisms were globally abundant from about 571 million to 541 million years ago. To our modern eyes, many Ediacaran fossils look strange and unfamiliar, and
Fossil Focus: Acritarchs

Fossil Focus: Acritarchs

Fossil Focus
by Heda Agić*1 Introduction: The acritarchs are a major, long-ranging and successful group of small, capsule-like, organically preserved fossils, which are present in the rock record of most of Earth’s history, dating back 1.8 billion year, or perhaps even as many as 3.4 billion years (Fig. 1). They include mostly single-celled microfossils ranging from a few micrometres (one-millionth of a metre) to one millimetre in size, and each is made up of a sac of organic tissue (vesicle). They are most commonly round, and can be either smooth or covered in spines (Fig. 2). Acritarchs are found in rock deposits that were once marine and terrestrial aquatic environments, and have been described from localities on all continents, as well as from all time periods from the Proterozoic eon (starting 2
Education and Outreach: Dinosaurs in the movies

Education and Outreach: Dinosaurs in the movies

Education and Outreach
by Szymon Górnicki*1 Introduction: Dinosaurs fit perfectly into the role of movie monsters: many were enormous, or had distinctive characteristics such as spikes, horns, claws and big teeth. The fact that they aren’t found in the modern world (except for birds) excites the imagination, and films represent some of the few opportunities to see them as they may have looked when they were alive. It’s not surprising that the history of movies featuring dinosaurs goes back more than 100 years. The cinematographic rise of the dinosaurs: The first moving picture featuring dinosaurs was Prehistoric Peeps (1905), an adaptation of a cartoon with the same name. The film launched the popular trend of showing primitive humans and non-avian dinosaurs living alongside one another, even though the foss
Patterns in Palaeontology: A story of vision

Patterns in Palaeontology: A story of vision

Patterns in Palaeontology
by James Fleming*1 Introduction: Photoreception, the ability to perceive light, is a sense shared by many living organisms on Earth. However, only some can take the step beyond merely detecting light levels, and generate an image. Humans are among the animals that have image-forming vision, and are able to see in colour in the day (polychromatic diurnal vision) and in black and white at night (monochromatic nocturnal vision) — the shades of colour that we pick up on an evening out trigger our diurnal receptors at very low levels. However, this is not the only way in which animals can see the world around them. Some species, such as whales and dolphins, can see only monochromatically no matter the time of day, while others see in colour no matter how dark it gets! The elephant hawk-mot

Fossil Focus: Mesozoic crocodyliforms

Fossil Focus
by Jonathan P. Tennant*1 Introduction: Crocodilians are truly iconic creatures, and throughout history have inspired stories of dragons and soul-devouring gods. Modern crocodilians are the crocodiles, alligators, caimans and gharials, all part of the crown group Crocodylia (Fig. 1). There are only 23 recognized species alive today, and of these 10 are considered to be endangered, according to the IUCN red list, due to ongoing environmental disruption and human activity. This relative lack of modern diversity stands out in stark contrast to that of their close relatives, the dinosaurs, whose modern descendants, the birds, have about 10,000 species around today! It isn’t obvious from looking at modern birds and crocodiles that they share a common ancestor. For instance, when was the last t

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: 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