Palaeocast

The Carboniferous period is host to some of the largest arthropods to have ever lived. Giant taxa such as the griffenfly Meganuera and the millipede Arthropleura are almost talismanic and are often depicted in reconstructions of the period. Since many other groups also have giant representatives in the Carboniferous, what is it about this time that allows for arthropods to grow to such large sizes? Arthropods breathe very differently to how we do with many using a series of branching hollow tubes called trachea for gas exchange throughout the body. This tracheal system uses diffusion and advection to exchange oxygen and carbon dioxide from areas of higher concentration to lower concentrations. In 1995, a study in the journal Nature suggested that elevated oxygen concentrations in the Carboniferous (approximately 30%, as opposed to 21% today) allowed for gigantism in arthropods since oxygen could diffuse deeper/further into their larger bodies. A recently published study in the same journal is now casting doubt on that interpretation and in this interview, we are joined by one of the authors, insect physiologist Prof. Jon Harrison from Arizona State University. He introduces us to the tracheal system and its link to the size of insects in the Carboniferous.

Prof. Paul Barrett of the Natural History Museum, London, recently authored A History of Dinosaurs in 50 Fossils. We took this as an opportunity to get an overview of what we really know about dinosaurs and how it's even possible to tell their story with just 50 specimens. In this episode, Paul discusses the history of dinosaur research, the current state of the science and what are still some of the big unknowns.

Today, there is only one living species of rhynchocephalian: the tuatara of Aotearoa/New Zealand. Despite today's paucity of species, this was once a diverse group of reptiles, with a wide range of lifestyles from swimming in the ocean to climbing trees. Once highly abundant around the world, reasons for their decline are still debated and may have had to do with competition from their relatives, the squamates, or changing environments. Rhynchocephalians are related to lizards and snakes within Lepidosauria, but despite their outward appearance, are not lizards themselves and have a number of differences that make them distinct. In this interview, we speak to Dr. Victor Beccari, an expert in rhynchocephalians, and discuss this and more about this fascinating group of reptiles.

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Grassy biomes, including grasslands, savannahs and crops, cover over 40% of all land on Earth. They play a significant role in carbon and silica cycles and have a large impact upon the climate. Grasslands (grass-dominated ecosystems) have shaped the evolution of numerous groups of organisms, most obviously grazing mammals, and can support a huge amount of biodiversity. Humans evolved in the savannas and through domestication of grasses formed agriculture, leading to a modern diet dominated by grasses such as oats, rice, wheat and corn. As anthropogenic climate change threatens large scale uncertainty, it's vital that we understand the controls that govern the success of this fundamentally important group. It is only by studying the evolutionary history of grasses that we might be able to predict how they will fare in future. Joining us in this episode to speak about the challenges of piecing together the evolutionary history of grasses from a relatively poor fossil record is Prof. Caroline Strömberg of the University of Washington.

Determining the origin of teeth in vertebrates is an incredibly significant but notoriously difficult problem within palaeontology. Teeth didn't evolve in the mouths of our ancestors, but are first seen as part of the external skeletons of jawless fish as structures called 'odontodes'. These would later migrate into the mouth with the evolution of jaws, becoming the teeth we have today, but odontodes still remain present in the skin of modern cartilaginous fish, giving them their rough texture. The oldest known odontodes are from the late Cambrian Period and represent the very first evidence for vertebrates in the fossil record. Unfortunately, they are only ever found as part of fragmentary pieces of exoskeleton, however, given that their specific construction is only known in vertebrates, there is little else they could possibly be… Joining us for this episode is Dr Yara Haridy, University of Chicago, who set out to use modern new scanning techniques to better understand the nature of these first teeth and what they tell us about the evolution of vertebrates. What she discovered was unexpected, but also led to better understanding of the purpose of odontodes in the dermal exoskeletons of our ancestors.

Ants are a hugely successful family of eusocial insects with over 14,000 modern species described. They are known from every continent except Antarctica and show a wide range of ecologies. Whilst many of us are familiar with their highly organised social structures and castes, there still remain a lot of public misconceptions about how their societies function. The evolutionary history of ants is equally as impressive, with roughly as many fossil ant species known as there are of dinosaurs! Since their appearance in the Cretaceous, several early lineages of ants (stem ants) have gone extinct. In this episode, we're joined by Dr Christine Sosiak of the Okinawa Institute of Science and Technology as we explore what some of these stem ants were like and ask how the different groups of ants fared over geological time.

An ecosystem can be described as all the interactions that occur between organisms and their physical environment. The processes acting within an ecosystem operate on a wide range of spatial and temporal scales and include both biotic and abiotic factors. Ecosystem engineers are those species that have a significant impact on the availability of resources to other species and can be responsible for the creation, maintenance, modification or destruction of an ecosystem. The introduction, or even removal, of such a species can have profound effects on both physical and biological elements of an ecosystem. Whilst we can recognise the impact of ecosystem engineers in modern systems (e.g. the introduction of an invasive species), we don't fully understand what happens when an entirely new ecosystem engineering behaviour evolves. This has undoubtedly happened numerous times throughout geological time with the Great Oxygenation Event and the Cambrian Substrate Revolution being notable examples. Joining us for this episode is Dr Tom Smith, University of Oxford, who has been using a computational approach to try to model what happens when an ecosystem engineer is introduced into an environment. The open access study is available to read here.

Found in the fossil record between the Jurassic and the middle Miocene, Notosuchia was a highly diverse and strange group of crocodylomorphs, most notable for their terrestrial lifestyle. Joining us for today's episode is Dr Yohan Pochat-Cottilloux from the Laboratoire de Géologie de Lyon, who specialises in the study of crocodylomorphs. Together, we will explore the wide range of scientific methodologies that have so far been used to study the lives of these strange reptiles and discuss how they may have looked and behaved.

In 12 years of podcasting, we have never actually taken the time to address the fundamentals of our field. Such questions could include: what is palaeontology, what is a fossil, how does one become a palaeontologist, and why is palaeontology important? For what should have been our very first episode, we've invited Prof. Roy Plotnick, University of Illinois Chicago, to help us outline everything you need to know about the field of palaeontology. Roy has had a long and varied palaeontological career, he maintains a blog all about the field, and he is author of the book Explorers of Deep Time.

The Middle Jurassic is incredibly important to our understanding of pterosaur evolution; however, the remarkable rarity and incompleteness of Middle Jurassic pterosaurs has long hampered scientific understanding of the lineage. Joining us this episode on the other side of the microphone is one of Palaeocast's own team members, Dr Liz Martin Silverstone, a Technical Specialist at the University of Bristol who has recently described Ceoptera evansae, a darwinopteran pterosaur from the Isle of Skye. Together, we explore the new specimen, how it fits in to the group, and the insights it can give us in to pterosaur evolution.

LOOP 8.4: LOOP Showrunner Dan Tapster returns to give a retrospective on the series and its production. We look at went well and address criticisms; is it possible to keep everyone happy? We finish this series by discussing the show's take-home messages and Dan's hopes for Life On Our Planet's legacy. Life On Our Planet (LOOP) is a new 8-part series created for Netflix by Silverback Films and Amblin Television. This Steven Spielberg produced series, narrated by Morgan Freeman, is hugely ambitious in its scope, telling the story of life throughout the whole Phanerozoic Eon. Ancient organisms and environments are painstakingly recreated by the supremely talented Industrial Light and Magic, whilst modern natural history scenes add vital context to the story. This show has been worked on for six years, during which time countless papers were read and around 150 different palaeontologists contributed their time and knowledge. The whole production had culture of letting the scientific rese arch dictate scenes, resulting in one of the most accurate on-screen representations of prehistoric life there has ever been. And how do we know all this? Well, our very own team members Tom Fletcher and Dave Marshall have been embedded within the LOOP team since day one! We are therefore in a totally unique position to reveal to you the work that went into this series, from both the production and research side of things. In this unofficial series, we've been granted exclusive access to many of the people responsible for creating LOOP, we explore what it takes to create a palaeontological documentary and we delve deeper into the science with some of the show's academic advisors. Each day, we will be releasing batches of interviews, each relating to a specific episode of LOOP. Image courtesy and copyright of Netflix.

LOOP 8.2: Prof. Danielle Schreve, Royal Holloway University of London, joins us to cover the last 2 million years of Earth's history. We explore the periodicity of glacials and interglacials and the control Earth's orbit around the sun has on climate. She then places the Holocene's megafaunal extinctions and major palaeobiogeograpical events within this climatic context. We finally look at the impact of human radiation on the world and the lessons we can learn from this time. Life On Our Planet (LOOP) is a new 8-part series created for Netflix by Silverback Films and Amblin Television. This Steven Spielberg produced series, narrated by Morgan Freeman, is hugely ambitious in its scope, telling the story of life throughout the whole Phanerozoic Eon. Ancient organisms and environments are painstakingly recreated by the supremely talented Industrial Light and Magic, whilst modern natural history scenes add vital context to the story. This show has been worked on for six years, during which time countless papers were read and around 150 different palaeontologists contributed their time and knowledge. The whole production had culture of letting the scientific rese arch dictate scenes, resulting in one of the most accurate on-screen representations of prehistoric life there has ever been. And how do we know all this? Well, our very own team members Tom Fletcher and Dave Marshall have been embedded within the LOOP team since day one! We are therefore in a totally unique position to reveal to you the work that went into this series, from both the production and research side of things. In this unofficial series, we've been granted exclusive access to many of the people responsible for creating LOOP, we explore what it takes to create a palaeontological documentary and we delve deeper into the science with some of the show's academic advisors. Each day, we will be releasing batches of interviews, each relating to a specific episode of LOOP. Image courtesy and copyright of Netflix.