A review of the evidence for living plesiosaurs
One of the topics I'm most frequently asked about as a plesiosaur specialist is what I make of the Loch Ness Monster. In this review I'll cast a critical eye over the evidence for living plesiosaurs.
Before I delve into the details I should state that I have no agenda. I have no reason to deny or circumvent any evidence for living plesiosaurs. To the contrary, it would be wonderful if plesiosaurs existed today. As a plesiosaur researcher this would provide an opportunity to study a real specimen and answer some of the big questions about plesiosaur biology - the aim of my research is, after all, to understand plesiosaurs. This article will remain objective and will provide a concise, unbiased, and critical review of the evidence for living plesiosaurs.
The fossil record
The youngest plesiosaur fossils come from Late Cretaceous rocks. This leaves a 65 million year gap in the fossil record from the end of the Cretaceous Period to the present day. On this basis plesiosaurs are regarded to have gone extinct 65 million years ago. The discovery of a fossil plesiosaur in Cenozoic rocks would possibly strengthen the case for living plesiosaurs, but none are known. The story of the coelacanth is often presented as a tale of caution for sceptics to take heed, however, the case is not analogous because plesiosaurs are air-breathing reptiles and must surface frequently to inhale. This means they would be unable to stay submerged in the deep ocean as can the coelacanth. While this does not completely rule out the possibility of plesiosaurs surviving to the present day, this significant gap in the fossil record is, at the very least, inconvenient for proponents of the living plesiosaur hypothesis.
Even a good photograph of a clearly plesiosaur-like organism would not provide conclusive proof for the existence of living plesiosaurs. It is just too easy to hoax photographs, and increasingly so with the advent of Photoshop etc. A compelling photograph, or preferably a good series of photographs taken in quick succession, would certainly warrant further investigation. To this day, the most compelling photographs of possible living plesiosaurs have either been admitted or demonstrated as hoaxes (Fig. 1a), confidently identified as known living organisms (usually whales and sharks), or are of such ambiguity or low resolution/quality that they remain insufficient as evidence one way or another (fig 1b). All of the underwater photographs purported to show the Loch Ness monster have either been identified as tree trunks or demonstrated to have been retouched and manipulated (http://www.museumofhoaxes.com/nessiehoaxes.html)
Fig 1a. One of the hoaxed Nessie photographs
Fig 1b. (right) more 'evidence' for living plesiosaurs? (radio controlled plesiosaur)
Video evidence is a step up from photographic evidence, but is thin on the ground. Proponents of living plesiosaurs provide 'the Dinsdale film', taken in 1960, as the most compelling video evidence for a monster in Loch Ness. For example, Bauer (2002a, p.227) states that this footage represents the "strongest objective evidence for Nessies". The film contains a "large hump [which] moves in a curving path, submerging after a time" (Bauer 2002b p. 457). I have not seen the footage so I cannot comment in detail, suffice to say, a moving hump is not robust evidence for a living plesiosaur.
There are plenty of reported sightings of sea monsters (see Huevelmans for a thorough account), but anecdote is the least reliable form of evidence. There are two main problems with sightings;firstly they are untestable and therefore do not provide scientific evidence. Even if the witness is honest, this brings us onto the second problem with sightings: eye witness accounts are notoriously inaccurate. This was demonstrated during the filming of the BBC documentary, 'Search for the Loch Ness monster'. A simple experiment was performed in which a simple stick was raised out of the water of the Loch for a few seconds in view of a group of unsuspecting tourists. They were asked to draw what they saw. A surprisingly large number reconstructed a 'head' on the end of the 'neck'. It seems that we sometimes see what we would like to see. The human brain is fallible, open to misinterpretation, and even the most sceptical observer can be misled.
The best known sonar evidence is of too low resolution to be conclusive. It may simply represent physical artefacts in the water, such as layers of differing temperature (Bauer 1988).
Purported living plesiosaur photographs and sightings often portray or describe animals that do not match the basic body shape present in all known plesiosaurs. For instance, plesiosaurs do not have two humps or diamond shaped paddles, as suggested by Scott and Rines (1975) in their paper 'naming the Loch Ness monster'. Recent studies of plesiosaur neck flexibility and posture have shown that long-necked plesiosaurs could not keep their necks out of the water as described in some sightings. Furthermore, the necks of plesiosaurs were held horizontally straight and rigid, they were not extremely flexible as erroneously described and portrayed in early palaeontological literature and 'historic art' (see below). If the existence of living plesiosaurs is a purely cultural phenomenon then we may predict eyewitness accounts to 'adapt' to new scientific consensus. Proponents of living plesiosaurs sometimes suggest that evolution may explain the discrepancy, and while possible, given the unfounded premise this is clutching at straws.
In an attempt to explain the relative lack of sightings in Loch Ness, Bauer (1988, p.14) informs us "Nessies don't spend much time at the surface" and that "no one, including those who believe in them, should expect to see one". But like whales, dolphins and sea turtles, plesiosaurs have lungs. They are air-breathers so they must surface several times per day to breath. This simple anatomical fact weakens the case for a viable population of living plesiosaurs in any lake in close proximity to human settlements. In the 'dinsdale film' the "last sequence shows a definite paddling action" (Bauer 2002, p. 229). However, plesiosaurs are known not to have paddled. They used predominantly up and down strokes rather than back and forth strokes (e.g. Robinson, 1975 and others) (and see my plesiosaur locomotion page).
A real specimen of a living plesiosaur, or a recently deceased plesiosaur, would provide sufficient scientific evidence. Although no living specimens have been reported discovered, many corpses have been claimed to be plesiosaurs. The most famous example is the carcass of a large rotting animal caught by Japanese fishermen in 1977 and declared to be the remains of a plesiosaur. There are numerous lines of evidence that discredit this claim and confirm that it was a rotting basking shark (Kuban, 1996). Nevertheless, it is quite easy to see why an untrained eye might interpret this as a plesiosaur (Fig. 2). Perhaps the most convincing piece of the anatomy is what appears to be a small skull on a long neck (Fig. 3). However, when compared to the chondrocranium (braincase) of a basking shark (Fig. 4) it is clear that the similarity with a plesiosaur is only minimally superficial. The large jaws of the filter-feeding shark have rotted away to give the impression of a small head (the chondrocranium), and the flesh between the head and fins has rotted away to give the appearance of a longish neck.
To clinch the deal, biochemical analysis of samples taken from the specimen have also confirmed its shark identity. The same reasoning applies to all of the other carcasses washed up on shorelines around the world. Corpses are washed up all the time, in various states of decay. It is telling that only the most decomposed ones are considered to be plesiosaurs. It is also interesting to note that no plesiosaur carcasses have ever been washed up on the banks of Lock Ness. A block of five plesiosaur vertebrae were reported from the banks of Loch Ness in 2003, but although nobody has publicly taken responsibility, the specimen was clearly planted as a hoax or publicity stunt, or left there by accident: the vertebrae were not recent bones, but fossilised remains preserved in a rock type that originated many miles away from Loch Ness. (see: http://news.nationalgeographic.com/news/2003/07/0729_030729_lochness.html)
An illustration claimed to be recent aboriginal art depicts a plesiosaur, but it cannot be demonstrated as authentic (Fig 5). The typical medium of aboriginal art is rock but the plesiosaur art is not. The artwork also bears striking similarity with existing modern artwork and shares the same anatomical errors - the necks of plesiosaurs are now known to have been held-straight and rigid, they were not extremely flexible as depicted. Even if the artwork was genuine, it is perfectly possible that the illustration is based on fossil evidence as plesiosaur fossil remains are known from Australia.
There is no scientific evidence supporting the existence of plesiosaurs living today. There is a lack of compelling photographic evidence and a lack of demonstrable plesiosaur corpses or living specimens.
In addition, there are other lines of reasoning why plesiosaurs do not exist today:
The relatively low number of sightings.
The fact that the first sightings coincide with the first discoveries of plesiosaurs.
Unfortunately, living plesiosaurs almost certainly do not exist today.
Epilogue - so why do people still believe in living-plesiosaurs?
This is an important question because while it is all well and good discrediting 'evidence', not all belief is based on evidence. There are three possible reasons for this. The first and most widespread reason is that 'monster fans' may want to believe in living plesiosaurs because it is such a cool prospect (it really is!). Maybe they cherry pick data, maybe they just haven't heard the above arguments, or maybe they just don't care for evidence either way?
The second reason applies to those who have dedicated much of their time investigating 'living plesiosaurs' and may have developed faith in the idea. In a personal article by Bauer, he describes his involvement searching for Nessie and reveals a touching emotional tie with his subject matter. He claimed that photographic proof was "no longer important to me...No such proof could add to the gifts that had already come to me through the mediation of Nessie". While proof may not be important to Bauer, it is important to me.
The third and potentially dangerous agenda is creationism and anti-evolution propaganda. Given that all of the evidence indicates plesiosaurs are extinct and that the youngest plesiosaur specimens in the fossil record date to 65 million years ago, it is easy to understand how a creationist might perceive the existence of living plesiosaurs as evidence against evolution and for a young earth. In reality, the discovery of living plesiosaurs would not threaten evolutionary biologists. Organisms may evolve at extremely slow rates, as has already been well documented in numerous other organisms, where is is known as stasis. Creationists may also believe that the discovery of living plesiosaurs would cause geologists to rethink the age of the earth, but the distribution of fossils throughout the rock record has no impact on the absolute dates of the rocks. Unfortunately, not everyone understands, wants to understand, or accepts, the robust science in support of evolution and the age of the earth. For these people, the propaganda for living plesiosaurs must seem quite convincing, and I hope they find this article for at least a little perspective.
I would like to thank Phillip O'Donnell for reminding me to write this article and Henry Bauer for making much of his published work freely available online. Thanks also to Nizar Ibrahim for comments, and everyone at cryptozoology.com who commented on this article. Cheers guys!
- Bauer, H. H. 1988. Loch Ness Odyssey, Snowy Egret, 51, 8--15
- Bauer, H. H. 2002a. The case for the loch ness 'monster': the scientific evidence. Journal of Scientific Exploration, 16, 225-246.
- Bauer, H. H. 2002b. Common knowledge about the Loch Ness Monster. Journal of Scientific Exploration, 16, 455-477.
- Robinson, J, A. 1975. The locomotion of plesiosaurs. N. Jb. Geol. Paläont. Abh. 149, 286-332.
- Scott P. and Rines R. 1975. Naming the Loch Ness monster. Nature 258, 466-468.
- Kuban, G. J. 1997. Sea-monster or shark? An analysis of a supposed plesiosaur carcass Netted in 1977. Reports of the National Center for Science Education 17, 16-28.
Update: Comments and responses
There have been a couple of responses to this article. A fundamentalist Christian with a 'young-earth' perspective wrote a short rebuttal. I would have responded but I have already addressed all of his points. Simply put, his views are based an faith and form a case study for the third agenda for believing in living plesiosaurs, as outlined in the 'epilogue' section above. I will, however, comment on one of the figures because I thought it demonstrated a lack of critical thinking in this case:
The modified photo and part of the caption from the rebuttal
"...It has features similar to the Mosasaur."
The source image:
Of course, there is a very obvious continuation of the spine past the 'mouth'. I have indicated this feature with an arrow.