Two very different animals found fossilised in the same burrow, its always fun for palaeontologists to try and figure out how these unusual finds came about. This is also a great example of how useful scanning technology (e.g. synchrotron) has been for palaeontology. We can now see detailed structures that are trapped within rock, eradicating the potential for damage to fossils.
No one had any idea that the bonus fossil was there until University of the Witwatersrand paleontologist Vincent Fernandez and colleagues had the contents of the burrow scanned