Forensic archeologists have made an artistic rendition of bipedos aridus, which was the dominant species at the time. They are believed to be the creatures which created all of the plastic deposits vital to our modern economy, which they secreted as a waste product after consuming even more ancient petroleum pollutants.
Their extinction was proven to be a consequence of this, as digestion of complex hydrocarbons had been proven in experiments to produce large amounts of CO2 and methane gas. This of course led to the Great Boiling, and the extinction of over 70% of our planet Hydos’ life at the time.