I just finished reading the chapter about the Loch Ness Monster in the skeptical cryptozoology book Abominable Science! by Daniel Loxton and Donald R. Prothero. I will review it here.
Overall, the chapter makes a decent analysis of several of the evidence marshaled to support the existence of the Loch Ness cryptid, including the Surgeon's Photo taken by Dr. Robert Kenneth Wilson, who was really a gynaecologist, rather than a surgeon, but, hey, I guess most people don't think of the Loch Ness Monster, but something else entirely, when they hear the phrase "Gynaecologist's Photo". I agree with the chapter's conclusions that the Surgeon's Photo is likely to be a hoax, although I am still open to the possibility that it shows either a bird or an otter, as well as the same conclusion with regard to the Stuart Photo. I should note that when I first set eyes on both of these pictures as a child, they looked off to me, in some way. I suppose my intuition wasn't too far off the mark.
I also found the connection drawn between King Kong and the sighting by the Spicers enlightening, and I am inclined to think that this is quite a plausible suggestion. I think it is quite plausible that the release of the movie King Kong created an atmosphere during the time of the Great Depression which made prospective witnesses more likely to interpret sightings of common animals and disturbances of water in the loch in the light of the film, causing it to morph into a sauropod- or plesiosaur-like entity. I might opine here that the Spicer sighting could have been a group of otters seen crossing the road, which they interpreted as a sauropod-like beast since they might have been driving home groggily after seeing the movie.
These are the good parts of this chapter, in my opinion. Overall, I found the analysis of evidence, such as photos and videos, to be mostly rational and cogent, with one exception. The digital enhancement of the Rines flipper photograph was emphasized, and the original, unenhanced version was shown next to the enhanced version, in an attempt to show how a plesiosaur-like flipper was detectable in the enhanced version, but not in the unenhanced version. However, with me, this juxtaposition of the images had the exact opposite effect as that which was intended. Indeed, I could still clearly make out the shape of a flipper, even in the original, unenhanced version, and it is much too clear to me, I think, to be a case of pareidolia on my part.
But when it came to the evaluation of the plesiosaur hypothesis and the possible entry of prospective Nessies into the loch from the ocean, I was left somewhat disappointed. I did not find the argument put forth against a plesiosaur identity being a possible one for a prospective unknown creature in Loch Ness convincing. This is because the argument overlooked key fossil finds and paleontological studies, overlooked possibilities for plesiosaur behavior and physiology which seem plausible in light of those of relatives known to be extant, and flatly contradicted other portions of the same chapter on the issue of entry into Loch Ness from the sea.
It is stated that "They [plesiosaurs] were tropical animals, unsuited for the cold waters of the loch—and most plesiosaurs were marine animals, unsuited for freshwater in general". Yet a study published three years prior to this book found evidence that plesiosaurs likely were in possession of endothermy, colloquially referred to as "warm-bloodedness". And the claim that plesiosaurs were "tropical animals" is just false. Indeed, plesiosaur fossils have been found in several Upper Cretaceous formations in Antarctica. And while it is true that Antarctica in the Upper Cretaceous was warmer than it is today, it still had a climate not too dissimilar to Southern South America today, as one article covering an Antarctic plesiosaur fossil find noted. Considering the southern tip of South America, Tierra del Fuego, lies at a latitude that is more southerly than Loch Ness is northerly, I doubt that a plesiosaur adapted to the cold climate of Late Cretaceous Antarctic waters would have much difficulty adapting to the cold climate of Holocene Loch Ness waters.
And plesiosaur fossils have also been found in regions indicative of them having lived in a freshwater environment. Indeed, considering that numerous modern species which spend some or much of their life in marine environments, ranging from seals to cetaceans to Bull sharks to both saltwater crocodiles (Crocodylus porosus) and American crocodiles (Crocodylus acutus), have been known to inhabit freshwater environments, as well as saltwater environments, it seems rather dogmatic to me to state that plesiosaurs could not have done the same.
It is also stated that "Finally, plesiosaurs were air breathers. Any plesiosaurs in Loch Ness could be photographed several times an hour, each time they surfaced to breathe." This argument is stating that, as plesiosaurs were air-breathers, they would be regularly seen far more often breaking the surface of the water to take a breathe, rendering it unlikely that they would be able to remain inconspicuous for long in a lake such as Loch Ness. However, the idea has been previously brought forth that plesiosaurs might have evolved snorkel-like appendages on their heads that they might protrude above the surface of the water to take a breathe, which would not be as conspicuous. And while it is argued that such snorkels would, nevertheless, still be detected, another option awaits in the wings. And that is the aquatic cutaneous diffusion method of respiration.
Whether plesiosaurs were entirely air-breathers, or whether they respired through water, is not something that can be directly ascertained from the fossil evidence at hand. It is, in fact, entirely plausible that plesiosaurs could have been able to supplement their oxygen intake by aquatic cutaneous diffusion of oxygen -- i.e., absorbing molecules of oxygen directly from the water through their skin. Indeed, some turtles are known to respire in this way nowadays, and it is worth noting that, additionally, all humans once respired in this manner, as well, in utero, prior to their birth. If plesiosaurs were able to respire in such a manner, it would render them far more adapted to an aquatic lifestyle and ecological niche. Indeed, considering that extant turtles, which are less aquatic than plesiosaurs probably were (there is evidence that plesiosaurs were viviparous, giving birth at sea, constituting evidence that they were supremely adapted to a nearly completely aquatic existence), have evolved this ability, it would be surprising if plesiosaurs did not, likewise, do the same. A plesiosaur respiring through water via cutaneous diffusion of oxygen would not have a pressing or urgent need to routinely come to the surface to breathe air, meaning that it could conceivably remain hidden in a freshwater lake for a long stretch of time.
When discussing possible entry of the unidentified animals into Loch Ness from the ocean, it is stated, as well, that "The rivers and canals that flow into Loch Ness can be confidently ruled out as commuter routes for large monsters, broken up by shipping locks, or some combination." While it is true that, past a certain upper limit on size, an oceangoing creature would encounter considerable difficulty in navigating these pathways to the loch, it is worth noting that it is a confirmed fact that animals as substantially-sized as seals and porpoises have managed to do so. Indeed, it strikes me as rather perplexing that the author(s) spent so much of the rest of the chapter emphasizing the fact that these known marine animals have been known to make their way into Loch Ness previously with the purpose of using their presence in the loch to explain Nessie sightings. So why the double standard here? If porpoises and seals can swim into Loch Ness from the Moray Firth through the River Ness or the Caledonian Canal, why not putative Nessies, as well?
The statement about "large monsters" not being able to enter the loch is a red herring, as it is by no means a prerequisite that the creatures must already be large at the time that they enter the loch. The creatures could have made their way into the loch from the ocean when they were juveniles, perhaps no larger than salmon, or even smaller, and remained in the loch until they grew larger, rendering them trapped in the loch.
Indeed, this allows me to segue into another issue brought up in this chapter, that of the need to maintain a breeding population of creatures in the loch for eons. It is asserted that, to have a population large enough to breed, it would necessarily follow that there would not be enough food in the loch to sustain them, and the population would be too large for them to be able to remain hidden.
However, it is entirely possible that, rather than a breeding population of creatures having been extant in Loch Ness since the end of the Pleistocene, occasional vagrants have navigated their way into the loch from the ocean, and remained trapped there for a generation or two, before dying out. This would have the additional advantage of explaining why sightings seem to pique in some years in comparison with others. This hypothesis has come to be referred to as the 'Rogue Nessie' hypothesis, and it is covered delightfully well by writer Kurt Burchfiel in this article for StrangeMag magazine: http://www.strangemag.com/roguenessie.html
Finally, it is stated repeatedly that there were no sightings of a strange, unidentified creature in the same vein as Nessie at Loch Ness prior to the 1930s in the decimal Gregorian calendar. Yet this, too, is demonstrably false. Indeed, a newspaper report from the 19th century of the decimal Gregorian calendar reporting on a sighting of what seemed to the locals to be an anomalous large fish in Loch Ness stated that the locals had been inclined to think of the existence of such a besst in the loch as a reality for years, indicating that there was already a tradition of reported sightings of strange creatures in Loch Ness by this time.
And, even if it were true that Nessie sightings made their debut in the 1930s, this would not be a big deal, as, with the Rogue Nessie hypothesis, which postulates that Nessie is an oceangoing creature which occasionally swims into the loch from the open ocean, it is entirely plausible that a small population of these creatures could have entered the loch for the first time in the 1930s.
Overall, the chapter on Nessie, the Loch Ness Monster, the fourth chapter of Abominable Science!, contributes a decent analysis of much of the evidence purported to support this alleged cryptid, while having some deficiencies in the theoretical realms, in particular, when it comes to the arguments presented against a plesiosaur identity for Nessie and those presented against the creatures being able to remain undiscovered in Loch Ness.
The truth is that the palaeontological evidence from peer-reviewed scientific journals is, at worst, indifferent to the question of whether or not a plesiosaur identity is plausible for lake monsters in general, and the Rogue Nessie hypothesis shows that the objections with regard to population size and detectability can be surmounted by certain scenarios, the plausibility of which has been borne out by documented cases of marine animals making the switch to freshwater habitats.
It is worth noting at this juncture that all of the evidence and reasoning presented here applies to most reported lake cryptids, such as Champ of Lake Champlain, Ogopogo of Lake Okanagan, Storsjoodjuret or Storsie of Lake Storsjon, Selma of Lake Seljordsvatnet or Lake Seljord, Nahuelito of Lake Nahuel Huapi, etc.
Endothermy in Plesiosaurs: