British paleontologist Richard Owen is probably best known today for coining the word “dinosaurs” in 1841. However, as trained anatomist and zoologist he studied also mammals, birds and was even interested in sea monsters. For 19th century naturalists like Owen and Charles Lyell, founding father of modern geology, the discovery of large marine reptiles in the fossil record gave some credit to modern sea monster sightings. Especially Lyell argued that animal species don’t go extinct, but can survive in inaccessible regions of the world, like the deep sea. Sea serpent reports were just rare encounters with surviving Mesozoic fish-reptiles like ichthyosaurs, mosasaurs and plesiosaurs.
There seems indeed to exist a link between fossils and monsters, however, not the way Lyell imagined. Statistical ecologist Charles G.M. Paxton and paleontologist Darren Naish published new research showing that the discovery of fossil marine reptiles (in particular plesiosaurs) had a detectable influence on “sea monster” reports. Using an electronic database of 1,688 historical reports of sea monster sightings, ranging from 1801 to 2015, they reconstructed how the popular view of sea and lake monsters changed over time, noting a correlation with the discovery of fossil species.
Reports of sea monsters dating to medieval times until the beginning of the 19th century described many of them as large sea serpents. With the discovery of ichthyosaurs and plesiosaurs around 1810 there was a notable decline in reports where the body was described as serpent or eel-like. Especially after 1850, the classic sea serpent is replaced by the long-necked sea serpent featuring four or more fins and a prominent neck, a feature visible in the skeletons of mosasaurs and especially plesiosaurs. Fossil exhibitions and textbooks with illustrations of extinct animals were quite popular at the time and popularized the erroneous image of swan-necked plesiosaurs. Unlike the discovery of plesiosaurs, the discovery of mosasaurs or ichthyosaurs don’t appear to have had the same influence on what people believe they have spotted in the water.
This trend culminates in the 20th century, like in the case of the famous Loch Ness monster sighting of 1933, explained by contemporary newspapers (and sometimes still today) as a surviving plesiosaur using his long neck to peek out from the murky water, or the Zuiyo-Maru carcass, a decaying basking shark described still in 1977 as displaying four large, reddish fins and a long neck.