Sometimes, paleontologists strike proverbial gold and find a segment of dinosaur tissue, including skin, capillaries, and – as revealed in an incredible special publication by the Geological Society of London – even a brain.
A fossil hunter, searching around Sussex in southeastern England almost a decade ago, stumbled across a small brown pebble. After being analyzed by a group of paleontologists, it was dramatically revealed to have been the fossilized soft brain tissue of an Iguanodon, a plant-eating dinosaur that lived around 133 million years ago at the start of the Cretaceous.
Significantly, this is the first ever example of fossilized brain tissue from a dinosaur. Although the original biological tissue itself no longer exists, the immaculate, complex detail of its structures have been incredibly well-preserved by what the researchers have referred to as “mineralized ghosts.”
Detailed CT scans also revealed that the fossilized remnants of strands of blood vessels, collagen networks, capillaries and even the outer layers of neural tissues were also brilliantly preserved by the natural pickling process.
Co-author Dr Alex Liu, a palaeobiologist at the University of Cambridge, told IFLScience that brain tissues “are amongst the least likely tissues we would expect to ever be found in a fossilized terrestrial vertebrate.”
This unfortunate dinosaur appears to have died near a bog or swamp, one containing a soup of highly acidic, oxygen depleted disgustingness. Having taken a tumble into it, its brain was essentially “pickled” by the bacteria-unfriendly mess, and its soft tissue was mineralized before it decayed away.
Turning up around 20 million years after the docile, quadrupedal Stegosaurus and the bird-like, raven-sized Archaeopteryx made their debut, Iguanodons were lumbering, bulky, bipedal beasts that fed off low-lying vegetation and fought off predators with their unusual thumb spikes.
It belonged to the Ornithischians, the group of dinosaurs that did not contain the true ancestral forms of birds. Despite this, Liu notes that this herbivore’s sausage-shaped brain appears to be very bird-like, as well as showing some morphological similarities to that of modern-day crocodiles.
An artist's impression of a species of Iguanodon. David Roland/Shutterstock
Gif in text: A 3D scan of the pebble-sized brain. University of Manchester