Published on June 16th, 2021 | by David Marshall


Episode 126: Beasts Before Us

In this episode, we talk to our very own Dr Elsa Panciroli about her new book Beasts Before Us. In it, she tells the untold story of mammalian evolution, tracing the origin of synapsids back to the Carboniferous. You’ll be taken to fossil sites around the world to meet some of these pioneering animals and some of the palaeontologists that discovered them.

For this interview, we’ll give you an overview of the early evolution of synapsids and dispel many of the misconceptions about what our ancestors were really like.

We’ve got a couple of copies of the book to give away, so look out on our social media channels for details of the competition! For everyone else, Beasts Before Us is available to buy online and in all good book shops.

Dr Elsa Panciroli standing over the fossil of the largest mammal known from the time of dinosaurs, Repenomamus giganticus, at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP). As well as being large, species of Repenomamus have been discovered with the bones of baby dinosaurs in their stomach, showing that mammals were not only much bigger at this time than previously thought, but that their interactions with dinosaurs were more varied than once assumed.
A simplified synapsid family tree from Elsa’s book, Beasts Before Us: The Untold Story of Mammal Origins and Evolution. Most people assume the story of mammals only begins with the extinction of the non-bird dinosaurs 66 million years ago, but the book tells the less well-known part of their evolution, from their origins in the Carboniferous to the founding of modern mammal groups by the end of the Mesozoic. Illustration by Marc Dando.
The platypus, Ornithorhynchus anatinus, provides unique insights into the evolution of modern mammals. It is one of the only surviving monotremes (alongside echidnas), the only mammals that still lay eggs. This skeleton is in the collections of the University of Edinburgh’s Zoology Department.
Platypus, Teleosaurus, Dimorphodon, from Nebula to Man by Henry R. Knipe (1905). In the 19th Century, monotremes such as the platypus were thought to be at the bottom of a hierarchy of mammals. Marsupials were considered more advanced, and placental mammals (especially humans) were at the top. It was thought monotremes and marsupials lived alongside the dinosaurs – resulting in images like these, in which Mesozoic reptiles preyed on ‘primitive’ mammals. We now know all of these mammals are relatively recent, although their ancestors co-existed with the dinosaurs. Courtesy of Biodiversity Heritage Library.
Perhaps the most famous early Permian synapsid is Dimetrodon, pictured here in a work by artist April Neander, who illustrated the chapters in Beasts Before Us. Often mistakenly lumped in with dinosaurs, Dimetrodon is actually an early relative of ours. Discussions about the purpose of its back sail are outlined in the book, but it was probably used for display rather than thermoregulation.
The skull of the therapsid Lycaenops (foreground), an ancient mammal- relative from the Permian of South Africa. Therapsids were once called ‘mammal-like reptiles’, but the term is now defunct because we now know mammals did not evolve from reptiles – the reptile and mammal lineages split very early in the evolution of tetrapods (in the Carboniferous). Therapsids were incredibly successful and diverse in the Permian, and included massive predators, bulky herbivores, burrowers, and even climbing species.
Docofossor brachydactylus, the ‘Jurassic mole’, was a mammaliaform that lived in the Late Jurassic in China. Its discovery is one of many that have transformed our understanding of mammals in the time of dinosaurs. Animals like Docofossor have highly specialised adaptations for diverse ecologies, in this case having wide shovel-shaped paws for a subterranean lifestyle. Other spectacular mammal fossils include opossum-like climbers, gliders, and otter-like swimmers. Credit Zhe-Xi Luo/University of Chicago.
Eomaia scansoria is thought to be the oldest known eutherian, the group which includes placental mammals. Its name means ‘dawn mother’. It was discovered in China in rocks from the Early Cretaceous. This tells us that the ancestors of placentals and marsupials had already diverged at this time – although they remained a small part of the ecosystem until much later. Credit Zhe-Xi Luo/University of Chicago.
From left to right, Zofia Kielan-Jaworowska, Zorikht, Teresa Maryańska and Gunzhid at Altan Ula camp, Mongolia. Elsa’s book includes details of the incredible life and work of mammal palaeontologists, including Zofia Kielan-Jaworowska (1925-2015), a world-leading mammal researcher who led joint Polish-Mongolian fossil-collecting expeditions and trained many of todays’ top scientists in the field. Credit Institute of Palaeobiology, Poland.

Tags: , , , , , ,

Back to Top ↑