Palaeocast

Gavialoids are a superfamily of crocodilians with distinctive elongated snouts specialised for the capture of fish. Today, the family is represented by just two species: the gharial, Gavialis gangeticus, and the false gharial, Tomistoma schlegelii. Despite their current low diversity and limited geographical range, the fossil record of gavialoids contains significantly more taxa with fossils discovered on nearly every continent.
In this episode, we speak to Dr Paul Burke, Swedish Museum of Natural History, who has been working on the placement of a particularly problematic species from the Eocene of Egypt within the gavialoid tree. 'Tomistoma' cairense was originally described in 1927, so what could modern imaging techniques tell us about its anatomy almost a century on? We look at how redescriptions of old fossils can allow new family trees to be drawn and what we can learn about the evolution of gavialoids through time.

The Cambrian Explosion is one of the most significant events in evolutionary history. Classically, it describes the sudden appearance of complex fossils (including all major animal groups) at the beginning of the Cambrian Period. Before then it was thought that only relatively simple single-celled or multicellular life existed. We now understand this event to be a lot more nuanced, recognising many of the geological biases at play and having discovered complex fossils in the earlier Ediacaran Period. Many researchers therefore consider the term 'Cambrian Radiation' to be a better representation of the event.
Whether an explosion or a radiation, determining the events of the Ediacaran and Early Cambrian and their causes is a constant area of palaeontological research. Numerous drivers behind this event have been hypothesised ranging from oxygen availability and nutrient cycling to an arms race between predators and prey. It is likely that no single factor will be identified as an underlying cause, but the relative extent to which each contributed to the event will be debated for many years to come.
In this interview, we are joined by Dr Julien Kimmig, Staatliches Museum für Naturkunde Karlsruhe, Germany, who recently authored a study on the coprolites of the Early Cambrian, the evolution of guts, and the influence the 'Cambrain Fecal Revolution' may have had on the wider Cambrian Radiation.

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.

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 relies upon the process of diffusion where oxygen and carbon dioxide will be exchanged 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.