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Sunday, 1 December 2013

Zuiyo Maru Addendum and Rebuttal

Rebuttal of Zuiyo Maru Carcass from "Lake Monsters" Facebook Page: 

Sea-monster or Shark?

 A decayed carcass accidentally netted by a Japanese trawler near New Zealand in 1977 has often been claimed by creationists and others to be a likely plesiosaur or prehistoric "sea-monster." Plesiosaurs were a group of long-necked, predatory marine reptiles with four paddle-like limbs, thought to have gone extinct with the dinosaurs about 65 million years ago. However, several lines of evidence, including lab results from tissue samples taken from the carcass before it was discarded, strongly point to the specimen being a shark, and most likely a basking shark. This should not be surprising, since basking sharks are known to decompose into "pseudoplesiosaur" forms, and their carcasses have been mistaken for "sea-monsters" many times in the past. Unfortunately, the results of scientific studies on the carcass data received less media attention than the early sensational reports, allowing widespread misconceptions about this case to continue circulating. Therefore, a thorough review of its history and the pertinent evidence is warranted.On April 25, 1977, a fishing vessel named the Zuiyo-maru of the Taiyo Fishery Company Ltd. was trawling for mackerel about 30 miles east of Christchurch, New Zealand, when a large animal carcass became entangled in its nets at a depth of about 300 meters (almost 1000 feet). As the massive creature, weighing about 4000 pounds, was drawn toward the ship and then hoisted above the deck, assistant production manager Michihiko Yano announced to the captain (Akira Tanaka), "It's a rotten whale!" However, as Yano got a better look at the creature, he became less sure. About 17 other crew members also saw the carcass, some of whom speculated that it might be a giant turtle with the shell peeled off. However, no one on board could say for sure what it was (Aldrich 1977; Koster 1977). Despite the possible scientific significance of the find, the captain and crew agreed that the foul-smelling corpse should be thrown overboard to avoid spoiling the fish catch. However, as the slimy carcass was being maneuvered over the ship in preparation for disposal, it slipped from its ropes and fell suddenly onto the deck. This allowed the 39 year old Yano, a graduate of Yamaguchi Oceanological high school, to examine the creature more closely. Although he was still unable to identify the animal, Yano felt it was definitely unusual, prompting him to take a set of measurements, along with five photographs using a camera borrowed from a shipmate. The total length of the carcass measured 10 meters (about 33 feet). Yano also removed 42 pieces of "horny fiber" from an anterior fin, in hopes of aiding future identification efforts. The creature was then released over the side and sank back into its watery grave. All of this took place within about an hour (Koster 1977). About two months later Yano made a sketch of the carcass, which unfortunately conflicts with some of his own measurements, photographs, and statements When Yano returned to Japan on a different boat on June 10th, 1977, he promptly had his photos developed in the fishery's darkroom. Company executives were fascinated with the photos, some of which did appear to show an unusual animal with a long neck and small head. Local scientists were asked to look over the photos, and remarked that they had never seen anything like it (Koster 1977). Some speculated that it might be some kind of prehistoric creature such as a plesiosaur.

On July 20, 1977, as excitement and speculation about the find began to spread, officials from the fish company held a press conference to publicly announce their mysterious discovery. Although scientific analysis of the tissue samples and other data had not yet been completed, company representatives played up the sea-monster angle. The same day several Japanese newspapers published sensational front-page accounts of the find, soon followed by many other radio and television stories throughout Japan (Sasaki 1978). Although some Japanese scientists remained cautious, others encouraged the plesiosaur idea. Professor Yoshinori Imaizumi, director of animal research at Tokyo National Science Museum, was quoted in the Asahi Shimbun newspaper as saying, "It's not a fish, whale, or any other mammal... It's a reptile, and the sketch looks very like a plesiosaur. This is a precious and important discover for human beings. It seems to show these animals are not extinct after all." (Koster 1977). Tokio Shikama of the Yokohama National University also supported the monster theme, stating, "It has to be a plesiosaurus. These creatures must still roam the seas off New Zealand feeding on fish." Meanwhile, American and European scientists interviewed about carcass mystery generally downplayed the sea-monster theory, as reported by a number of newspapers and wire services (Denver Post, 7/21/77; Washington Post, 7/22/77; Boston Globe, 7/22/77); New York Times, 7-24-77; UPI, 7/24/77; New Scientist 7-28-77). Paleontologist Bob Schaeffer at the American Museum in New York noted that every ten years or so a carcass is claimed to be a "dinosaur" but always turns out to be a basking shark or adolescent whale. Alwyne Wheeler of the British Museum of Natural History, agreed that the body was probably a shark. Explaining that sharks tend to decompose in an unusual manner (addressed further below), Wheeler added, "Greater experts than the Japanese fishermen have been foiled by the similarity of shark remains to a plesiosaur" Other western scientists offered their own interpretations; Zoologist Alan Fraser-Brunner, aquarium curator at the Edinburgh Zoo in Scotland, suggested the body was a dead sea lion (Koster 1977), despite the creature's immense size. Carl Hubbs, of the Scripps Institute of Oceanography in Jolla, California, felt it was "probably a small rotten that most of the flesh was sloughed off" George Zug, curator of reptiles and amphibians at the Smithsonian Institute, proposed that the creature was a decayed leatherback turtle (Aldrich 1977).

The divergence among early scientific opinions in this case might be partly due to the fact that many biologists and zoologists are used to working with complete, fresh specimens rather than badly decomposed carcasses (or worse, photos of such), in which both external and internal organs can be quite different from their appearance in living animals (Obata and Tomoda, p 46).

On July 25 1977, Taiyo Fish Company issued a preliminary report on biochemical tests (using ion-exchange chromatography) on the tissue samples. The report stated that the horny fiber sampled from the carcass was "similar in nature to the fin rays a group of living animals." The "living animals" referred to were sharks; however, the report failed to state this plainly, leading to further confusion by the Japanese media (Sasaki 1978) and the continued spread of monster mania. Toy manufacturers began gearing up to make wind-up models of the beast, while the company which made Yano's borrowed camera developed a whole advertising campaign around his "sea-monster" photos. Dozens of fishing vessels from Japan, Russia, and Korea were reportedly streaming toward New Zealand in hopes of resnagging the hastily discarded creature. Bubbling with excitement, one Japanese citizen confided that he thought sea-monsters were imaginary creatures but "danced when I read in the newspaper that it was still alive!" (Koster 1977). The Japanese government even issued a new postage stamp (Figure 3) featuring a picture of a plesiosaur. Not since Godzilla had a monster so overtaken Japan. The carcass controversy continued to make appearances in the popular press in America, but with less sensationalism. On July 26, 1977 The New York Times reported that professor Fujio Yasuda, who initially promoted the carcass resembled a plesiosaur, acknowledged that initial chromatography tests showed a profile of amino acids closely resemembling a control sample from a blue shark. An August 1, 1977 Newsweek article briefly discussed the "South Pacific Monster" without taking sides. A few months later a more detailed article by John Koster (1977) appeared in Oceans magazine. This account evidently the basis for many subsequent reports, many of which embellished or oversimplified various aspects of the story. Koster mentioned the preliminary tissue results and comments by western scientists supporting the shark interpretation, but also quoted Yano and others suggesting that the issue was not yet settled. Koster himself suggested that the small size of the creature's head, well-defined spinal column, and the lack of dorsal fin, did not fit the shark identification.

Soon news of the controversial carcass also came to the attention of some strict creationists, who suggested that the "likely plesiosaur" supported their young-earth position (Swanson 1978; Taylor 1984; Peterson 1988). After all, they seemed to imply, if a creature supposedly extinct for millions of years can turn up in a fishing net, how can we trust anything geologists tell us? Several lines of evidence strongly indicate that the Zuiyo-maru carcass was a large shark, and most likely a basking shark, rather than a plesiosaur. Those giving the opposite impression have done so by telling only part of the story, or mischaracterizing portions of the evidence. To help set the record straight, such authors should correct any misleading statements of the past on this issue, and refrain from any further suggestions that the carcass was a likely plesiosaur.

Sea Monster carcasses are most often the rotting carcasses of whales,pilot whales,killer whales,basking sharks,turtles and so on in most cases  .There is a huge difference between the so-called sea serpent carcasses,and this hypothetical photograph.

Thanksgiving Zuiyo Maru Addendum

This is the text of Scott Mardis' artricle: My computer has difficulty processing his illustrations (Jay Cooney has already gone ahead and published the full version)

Above: (left) Anthony Buccola‟s sketch of the mutilated basking shark washed ashore at Parker‟s Cove, Nova Scotia, Sept. 14, 2002, (right) a stuffed turkey – duh! "If Parkie was indeed a basking shark, this would be confirmed by it‟s DNA. Professor Herman and Dr Don Stewart from Acadia University obtained a tissue sample from Parkie, from which they extracted some DNA and carried out PCR (Polymerase Chain Reaction) analysis using some basking-shark-specific DNA primers, „bscythF2‟ and „bscytbR1‟. Primer Primer DNA Sequence



The primers had been developed by a UK laboratory to help check for basking shark products and derivatives in commercial products, because of concerns of a worldwide decline in basking shark numbers. These primers have been shown to have a high specificity for basking shark DNA as they need to stand up to legal scrutiny. The primers are based on Cetorhinus maximus(basking shark) cytochrome b (cytb) gene, a mitochondrial gene which encodes mitochondrial protein. According to the strategy, if the PCR results proved to be negative, this would mean that Parkie was not a basking shark, and further analysis would need to be carried out to try to identify what type of creature it was.According to Herman: „When tested, the samples were consistently and unequivocally positive. The DNA amplified very strongly, indicating a match with Basking Shark. There is now little doubt in my mind, based on the DNA evidence, that Parkie was indeed a Basking Shark.‟"- Jerlström, P. and de Roos, H., "Parkie; a new „pseudoplesiosaur‟ washed up on the Nova Scotia coast", TJ 19(2):109–118, 2005. This is a continuation of the Halloween blog on the controversial Zuiyo Maru carcass. If you have any confusion over the matters discussed herein, please refer back to the first installment. The great majority of the evidence concerning the Zuiyo Maru carcass strongly suggests that it was simply a mutilated specimen of a known animal, the basking shark (Cetorhinus maximus), resembling many other such carcasses that have been positively identified in the past and since the discovery of the Zuiyo Maru carcass in 1977. However, enough doubt about that claimed identity for the Zuiyo Maru carcass was expressed by enough qualified biologists (paleobiologists Yoshinori Imaizuni, Tokio Shikama, Leigh Van Valen, Ikuo

Obata and Yoshio Tomoda and ichthyologist Fujio Yasuda) that we may be excused for exploring the remote possibility that it was in fact an unknown or undiscovered animal, perhaps even a reptile resembling in some aspects the presumed extinct plesiosaurs. One thing that is glaringly obvious is that many assertions made by the primary investigators from 1978 that apparently discounted the reptile idea and strengthened the shark argument were in error. Even if you are totally convinced by the available evidence that the Zuiyo Maru carcass could have been nothing other than a basking shark, the comparative studies done in this essay should have been done in 1978 in an effort to be more rigorous to discount the alternative theories and they serve to better illuminate the continuing debate. Circumstantial evidence suggests to many that some unknown animal may exist that vaguely resembles the Zuiyo Maru carcass in general morphology and that this hypothetical animal may be responsible for some of the less-ambiguous anecdotal accounts of "sea monsters", "sea serpents" and "lake monsters". If such an animal really exists and the real possibility is there that we may someday discover it‟s mortal remains, the comparative studies is this essay may serve to better prepare us for a critical analysis of such evidence should it appear one day in the future. "The V-shaped folds along the vertebral column and near the pectoral girdle were identified as myocommata by Omura, Mochizuki, and Kamiya 1978, (p 56-57). Myocommata are composed of strong connective tissues between myomeres, and are found in sharks but not reptiles."- Kuban, Glen, 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(3):1628). OH, REALLY? "Tetrapod musculature-In the living urodeles (the newts and salamanders) of the class Amphibia, the axial muscles are most important for propulsion. The limbs of urodeles are quite weak and tend to be carried forward passively with the undulations of the body. As the primary propulsive force is provided by the muscles of the trunk, urodeles retain large axial muscles. The axial muscles are still segmented, separated by myocommata, although the myomeres run vertically and without the elaborate folding seen in jawed fishes."- (from a website on tetrapod axial musculature, lost the web address unfortunately.) "The abdominal skeleton of lizards is composed of inscriptional ribs, which are endochondral elements that originate within the myocommata of the abdominal musculature (Etheridge, 1965)."- Torres-Carvajal, O. 2004, "The abdominal skeleton of tropidurid lizards (Squamata: Tropiduridae)", Herpetologica 60:75-83, pg. 75. "The apparently similar xiphisternal bars in Tapinurus are associated with the myocommata of the m. pectoralis major, which is not the case in Leiocephalus "-Darrel R. Frost and Richard Etheridge, "A Phylogenetic Analysis and Taxonomy of Iguanian Lizards (Reptilia: Squamata)", The University of Kansas Museum of Natural History, Miscellaneous Publication No. 81, September 28, 1989, pg. 7.

Comparing the apparent myocommata of the Zuiyo Maru carcass with the diagrams above, it is only evident that myocommata muscle divisions seem to exist in some form in the trunk muscles but I can see no evidence of the zig-zag folding diagnostic of bony fish/shark myocommata.

Above: (left) Necturus maculosus salamander displaying myocommata in abdominal musculature, (right) myocommata- like structures visible in the trunk muscles of the Zuiyo Maru carcass.

Above: (left) dorsal view of a skinned monitor lizard, (right) two views of the Zuiyo Maru carcass.

Above: (left) a skinned alligator carcass, (right) two views of the Zuiyo Maru carcass. (Note: I have not yet found positive evidence as to whether crocodilians possess myocommata, but I have found no negative evidence either. There is certainly some resemblance between the appearance of the back of the skinned alligator and the Zuiyo Maru carcass.) Mosasaurs, generally thought to be lizards, almost certainly had myocommata. Ichthyosaurs and plesiosaurs? Who ####ing knows?

A plesiosaur-like sea monster with a dorsal fin that was not a dead, mutilated basking shark? Check! Allegedly, all that was visible above the water of the Valhalla animal was the head, neck and weird dorsal fin. Was there anything to suggest that it had a large body and flippers? The Times (London), June 20, 1906, pg. 12b- R.T. Gould, "The Loch Ness Monster and Others", 1934, pg. 221-

The Valhalla incident of 1905 has generally been hailed as the gold standard for "sea monster" evidence, observations by two trained naturalists through binoculars at a range of 100 yards. Given debatable evidence of an animal carcass with similar anatomical features found some 72 years later, how can we simply ignore the parallels? How did this information elude the investigators in 1978? I suggest that the parameters of the control data used in 1978 were so funneled toward the chondrichthian idea that alternative hypotheses were not effectively explored. Perhaps this essay may remedy that and is justified for that purpose, regardless of the most parsimonious interpretations of the Zuiyo Maru evidence. Alternative explanations for the Valhalla observations? Marine authority Richard Ellis suggested in 1994 that the Valhalla animal may have been a giant squid (Architeuthis

dux) swimming at the surface, with a tentacle mistaken for a long neck and head and a portion of the giant squid’s tail mistaken for a dorsal fin (see illustration below). Skeptical responses to this idea have suggested that the flaccid musculature of the invertebrate squid out of the water would be unable to hold up a tentacle long enough to convincingly portray this appearance. "The final sighting that is mentioned as a possible squid sighting is that seen from the Earl of Crawford’s yacht Valhalla in 1905. Here we have several accounts of an encounter with a serpent by two naturalists, E.G.B. Meade-Waldo and M.J. Nicoll. Again the description is not obviously reconcilable with a squid (apart from being long and thin)

which has to be placed sideways (with the mantle fin uppermost) in the water to match the description. Again it seems doubtful that a squid would not have been recognized especially by two zoologists even though they were at a distance."- Charles G.M. Paxton, "The dangers of over-rationalization, or giant squids are red herrings", Skeptical Intelligencer, Vol. 6, 2003, pp. 19-28. Others (Cameron McCormick? Jay Michael Cooney? If my recollection is wrong, my apologies to both parties) have suggested the Valhalla animal might have been a seal or sea-lion in the act of thermo-regulating (getting rid of excess body heat) by sticking it’s flipper in the air while swimming, with the flipper being mistaken for a dorsal fin (see below). I personally don’t find this explanation convincing for

the Valhalla sighting, as the Valhalla dorsal fin (as drawn and described) bears little resemblance in shape to a pinniped pectoral appendage, but you might think otherwise. A somewhat similar "sea serpent" sighting, the Vondel "sea serpent" of 1907, might be easily explained this way, though. A third sea serpent with a plesiosaur-like head and neck and shark-like dorsal fin reported was the Saint-Francois-Xavier monster of 1925.

The legendary and infamous Dale Drinnon has speculated that this (and perhaps the Vondel serpent as well) may have been relict plesiosaurs thermo-regulating in a manner similar to that of the pinnipeds described above. The thermal physiology of the fossil plesiosaurs is currently unknown but some evidence has emerged in recent years to suggest they may have been partially- warm blooded in the manner of leatherback turtles or fully homeothermic like a marine mammal. (See "Regulation of Body Temperature by Some Mesozoic Marine Reptiles", Aurélien Bernard et al. Science 328,2010,pp.1379-1382, "EARLY CRETACEOUS HIGH LATITUDE MARINE REPTILE ASSEMBLAGES FROM SOUTHERN AUSTRALIA", Benjamin P. Kear et al., Paludicola 5(4), June 2006, pp.200-205, Liebe, L. & Hurum, J.H."Gross internal structure and microstructure of plesiosaur limb bones from the Late Jurassic, central Spitsbergen", Norwegian Journal of Geology, Vol. 92, 2012, pp. 285-309 and Kihle, J., Hurum, J.H. & Liebe, L., "Preliminary results on liquid petroleum occurring as fluid inclusions in intracellular mineral precipitates in the vertebrae of Pliosaurus funkei", Norwegian Journal of Geology, Vol. 92, 2012, pp. 341-352).

What about the demented idea of a plesiosaur with a dorsal fin, like the fanciful painting below? Vertebrate paleontologist Darren Naish said to me once, regarding this idea, that it was extremely unlikely that plesiosaurs would have possessed a dorsal fin, as this would have inhibited body roll in the water. Presumably, this has to do with the locomotor morphology generally assumed for plesiosaurs, that of propulsion by underwater flight from the four flippers, as opposed to tail propulsion like ichthyosaurs, many of which did possess prominent dorsal fins. There is very good evidence that many, if not all, plesiosaurs did possess a caudal fin. "The holotype of the large plesiosaurian

Rhomaleosaurus zetlandicus from the Toarcian (Lower Jurassic) of England comprises an almost complete skeleton, including the caudal vertebral series. The osteology of the tail is described and two morphological characteristics are interpreted as evidence for a caudal fin in Rhomaleosaurus: 1. A distinct node consisting of two relatively anteroposteriorly shortened vertebrae; and 2. Laterally compressed terminal caudal centra. This inference is based on osteological correlates derived from other marine reptile groups that possessed a vertically oriented bilobed dermal tail fin in life (ichthyosaurs, thalattosuchian crocodylomorphs, and mosasaurs). This corroborates evidence from other plesiosaurian taxa and suggests that a caudal fin may have been widespread among plesiosaurians, with implications for locomotion and behavior. Plesiosaurians are sometimes portrayed with a vertically oriented caudal fin on the end of the tail (e.g. Dames, 1895; Woodward, 1896; Zarnik, 1925; Newman and Tarlo, 1967). This trend may have been initiated when Richard Owen noted the terminal caudal vertebrae in a Lower Jurassic plesiosaurian (Archaeonectrus rostratus) were compressed and ‘probably supported some development of the terminal dermal expanse’ (Owen, 1865, p. 26). The only known soft-tissue evidence for a caudal fin in a plesiosaur was described in the holotype of Seeleyosaurus guilelmiimperatoris (MB R.1992; Dames, 1895), for which a black carbonaceous silhouette was identified at the tip of the tail. This taxon was subsequently restored with a large diamond-shaped caudal fin at the tip of the tail (Dames, 1895; Zarnik, 1925). This specimen has

since been covered with paint, obscuring any preserved soft tissue, so this evidence cannot currently be verified. Later depictions of plesiosaurians with a caudal fin have been based on this single piece of soft tissue evidence. For example, ‘Plesiosaurus’ macrocephalus has been portrayed with a diamond shaped dermal tail fin (Woodward, 1896), and Tarlo (1957) speculated on the presence of a tail fin in

pliosaurs, including a triangular fin in a reconstruction

of the pliosaurid Liopleurodon (Newman and Tarlo,1967). The presence of a tail fin has potential implications for plesiosaurian behaviour in terms of swimming speed, manuverability and stability in the water column. Plesiosaurians propelled themselves through the water using four large wing-like flippers (Robinson, 1975; Frey and Riess, 1982; Godfrey, 1984; Riess and Frey, 1991; Lingham-Soliar, 2000; Carpenter et al., 2010). The evolutionary history of most other marine reptiles (and fully aquatic vertebrates in general) is dominated by a convergent trend towards axial locomotion, culminating in the tail-based

propulsive system in ichthyosaurs, mosasaurs and

thalattosuchian crocodylomorphs. A distinct lunate

caudal fin evolved independently in each of these groups (Lindgren et al., 2010). Turtles adopted a paraxial locomotory repertoire, however, they are constrained by their carapace and plastron, and a requirement for the females to move on land to lay eggs, whereas plesiosaurs and their ancestors gave birth to live young in the water and were fully aquatic (Cheng et al., 2004; O’Keefe and Chiappe, 2011). The evolution of paraxial locomotion in plesiosaurs may be the direct result of evolutionary constraints

developed in the ancestors of plesiosaurs (Storrs, 1993), but may also represent a solution to the problem of Carrier’s

Contraint (Cowen, 1996). However, the primitive diapsid ancestors of sauropterygians and the most basal members of the clade (pachypleurosaurs) swam using lateral undulations of the body and tail (Storrs, 1993), so there was a considerable behavioural shift from an axial to paraxial locomotory repertoire between basal sauropterygians and derived plesiosaurs. The paraxial condition in plesiosaurians is therefore unique among diapsid marine reptiles (Massare, 1988) and represents a deviation from the typical convergent trend towards tail-propelled (oscillatory) swimming seen in the majority of fully-aquatic vertebrates. Furthermore, the presence of two pairs of limbs for use in propulsive locomotion (but see Lingham-Soliar, 2000) is another unique adaptation among aquatic vertebrates. Given

these adaptations for paraxial propulsion it is unlikely that the caudal fin, where present, was used as a propulsive organ. Instead, it may have been used to increase efficiency of the tail as rudder (Buckland, 1837), providing additional manuverability and stability during locomotion (Robinson, 1975). Wilhelm and O’Keefe (2010) suggested that rounded edges on the articular centrum facets in the proximal caudal

vertebrae of a possible Pantosaurus skeleton (USNM 536965) may have increased lateral flexibility of the

proximal tail and allowed it to play a role in locomotion. Experimental analysis will be required to determine the true function of the plesiosaur tail, and the exact outline of the dermal tail fin in different plesiosaurian clades remains

speculative pending the discovery of specimens with preserved soft tissues."- Adam S. Smith, "MORPHOLOGY OF THE CAUDAL VERTEBRAE IN RHOMALEOSAURUS ZETLANDICUS AND A REVIEW OF THE EVIDENCE FOR A TAIL FIN IN PLESIOSAURIA", Paludicola 9(3):144-158 October 2013-10-03 Figure 1 from Smith 2013

Skeleton of Seelyosaurus guillelmiimperatoris (from Dames 1895) showing probable tail fin impression. Close-up of probable tail fin impression of Seelyosaurus guillelmiimperatoris (from Dames 1895).

Hypothetical restoration of the caudal fin of Seelyosaurus guillelmiimperatoris (from Dames 1895). Another hypothetical restoration of the caudal fin of Seelyosaurus guillelmiimperatoris by Samuel Williston.

Liopleurodon ferox with hypothetical caudal fin restoration (from Newman and Tarlo 1967).

Hypothetical reconstruction of the caudal fin of Cryptocleidus oxoniensis (from Wilhelm 2010).

Amphibious plesiosaur with hypothetical caudal fin (unidentified source). "The ability of plesiosaurs to move on land is another point of contention. The mechanics of their skeletons imply a completely aquatic existence: the limb girdles are only weakly connected to the axial skeleton and this would inhibit the transfer of force from limb strokes into movement on land. However, small plesiosaurs may have been relatively unaffected by these constraints and might have used their powerful limb downstrokes to propel themselves forward in short ‘hops’."- Adam Stuart Smith, Fossils Explained 54: Plesiosaurs, Geology Today 24(2) (2008), pp.71-75

The plesiosaur Cryptocleidus oxoniensis on land from the BBC’s Walking With Dinosaurs, (Copyright Dave Martill and Darren Naish 2000). So, if we infer that Cryptocleidus might have been amphibious (re Smith, Naish and Martill) and yet may have possessed a caudal fin with no large ventral lobe (re Wilhelm), the anatomy of such a caudal fin might not have been an impediment to limited amphibious behavior. And, interestingly enough, Wilhelm has also suggested that the proposed tail fin of Cryptocleidus may have played an active role in propulsion in conjunction with the flippers. "Evidence from two exceptionally well preserved caudal skeletons of the cryptocleidoid plesiosaurs Cryptoclidus eurymerus and Muraenosaurus leedsi demonstrates that these taxa most likely had a tail fin. Features of the distal tail including an increase in the height of the neural spines, long and wide distal ends for articulation with cartilage, a change in neural spine direction, and lateral compression all allow some inference of shape in the plesiosaur fin. In addition, similarities observed between cetaceans, scombroid fishes, and lamnid sharks indicate regions of enhanced flexibility that allow the tail fin to be moved

independently of the tail. These data strongly suggest that the tail was involved, along with the limbs, in active thrust production during plesiosaur locomotion." - Benjamin C. Wilhelm 2010, "NOVEL ANATOMY OF CRYPTOCLIDID PLESIOSAURS WITH COMMENTS ON AXIAL LOCOMOTION." (A Thesis submitted to the Graduate College of Marshall University In partial fulfillment of The requirements for the degree of Master of Science In Biological Science). Metriorhynchid sea crocodilians (shown above), contemporaries of the plesiosaurs and ichthyosaurs from the middle Jurassic to early Cretaceous, also possessed fish-like caudal fins. They had flippers and unarmored skin also.

What may be significant about the metriorhynchids is that while plesiosaurs, ichthyosaurs and mosasaurs have all been shown to have given live birth to their young in the sea, all living crocodilians lay eggs on land and there is no evidence of live birth for any of the fossil crocodilians (though it may simply have not been found yet).Thus, metriorhynchids may have possessed fish-like caudal fins and yet been obligately amphibious, as well. It has also been confirmed that mosasaurs had fish-like caudal fins but the general consensus is that mosasaurs were not amphibious (see Johan Lindgren et. al, "Soft tissue preservation in a fossil marine lizard with a bilobed tail fin", Nature, 4, 10 September 2013, above figure).

The only marine reptiles that have been generally accepted to have possessed dorsal fins are the advanced thunnosaurian ichthyosaurs, based on skin impressions of such dorsal fins (below). As shown in the images below, these animals also possessed the most fish-like caudal fins of any known marine reptile.

Though the configuration of the dorsal fin and caudal fin of advanced thunnosaurian ichthyosaurs is somewhat analogous to similar structures in sharks and bony fishes, there are deep structural differences (see image below).

(Top) Thunnosaurian ichthyosaur, (center) Great White shark, (bottom) Swordfish. The dorsal fin of ichthyosaurs was supported by no skeletal structures, only connective tissue, while the dorsal fin of sharks and bony fishes is supported by radial elements and fin rays and is connected to the spine. The upper lobe of the tail fin in ichthyosaurs had no skeletal supports, only connective tissue, and the terminal caudal vertebrae bent downward into the lower lobe of the caudal fin. In sharks, the terminal caudal vertebrae bend upward into the upper lobe of the caudal fin and there are no skeletal supports in the lower caudal lobe, only connective tissue. The structure of caudal fin anatomy in bony fishes appears similar to that of sharks, though there appear to be radial elements in the

lower lobe of the caudal fin. The bending of the terminal caudal vertebrae into the lower lobe of the tail fin seems to be the convergent condition seen in all the fossil marine reptiles with caudal fins so far discovered (see image below). Above image (clockwise from upper left): shark caudal fin, ichthyosaur caudal fin, hypothesized plesiosaur caudal fin, metriorhynchid caudal fin, mosasaur caudal fin. The first ichthyosaurs discovered in 1811 and shortly afterward did not preserve the outlines of the dorsal and caudal fins and were initially reconstructed without these features.

"Regarding the reconstruction of ichthyosaurs, probably the most significant symbolic moment in the pageant of scientific advancement staged for the public occurred in 1854 at Sydenham, on the southern outskirts of London, where the Crystal Palace had been relocated from its original

site in Hyde Park following the Great Exhibition that it had housed. The ichthyosaurs at Sydenham had moved away from the image of a monstrous crocodile, since they do not resemble crocodiles as do some early reconstructions. Incomplete and misinterpreted evidence, however, led to mistakes. For example, they are depicted as having crawled from the water upon their paddles, whereas they were not amphibious—a notion apparently still prevalent in 1865 when Dickens playfully referred to the ichthyosaur’s evolution toward terrestrial living. Also, the features known as sclerotic rings, circles of bone around the eye, were depicted as exposed, but in fact they were embedded in the eyes themselves, apparently to help them withstand water pressure. Most importantly, they lack fleshy features not known until late in the century when fossils from the Holzmaden deposits in Germany revealed the outline of complete bodies. Presented with this new evidence, scientists recognized that most of the ichthyosaurs they had been studying had dorsal fins and vertical, fish-like tails, making them resemble dolphins more than ever and establishing them as a textbook case of convergent evolution in which different species independently assume similar forms in response to similar environmental conditions. Richard Owen, however, deserves credit for his recognition that the tails of the ichthyosaurs he studied were not simply pointed like those of crocodiles, although most nineteenth-century visual representations, judging from Martin Rudwick’s examples in Scenes from Deep Time, presented them that way. Early specimens consistently

showed the same abrupt downward turn in the tail portion of the spine, and Owen concluded it must have resulted from force exerted by a vertical tail. Therefore under his influence the Sydenham ichthyosaurs feature tails ending in vertical spade-shaped configurations, since he understandably had failed to realize that the downward bend had in fact supported the lower fluke of a forked tail. Although the earliest discovered specimens, dating from the Jurassic, were dolphin or fish shaped, not all ichthyosaurs, especially the early ones, fit that description. For example, early species are now known to have had the pointed lizard-like tails incorrectly assigned, in most

nineteenth-century reconstructions, to the later porpoise-shaped Jurassic specimens that were the first discovered and only late in the century recognized as having dorsal

fins and forked tails. Based upon a remarkable fossil that shows the details of soft tissue, a recent discovery indicates that later ichthyosaurs had skins containing collagen fibers, like those of sharks, which made their bodies rigid and slick to assist in high-speed swimming, evidence that it most likely fed in deep waters by chasing down prey at speeds perhaps up to twenty-five miles per hour.."- John Glendening, "The World-Renowned Ichthyosaurus: A Nineteenth-Century Problematic and It’s Representations", Journal of Literature and Science Volume 2, No. 1 (2009), pp. 23-47.

Above: Sydenham ichthyosaur model with no dorsal fin and hypothetical spade-shaped tail. Above: Reconstruction of Cymbospondylus sp., a more basal ichthyosaurian relative to thunnosaurs that did not possess

a dorsal fin and heterocercal caudal fin. In what is perhaps a textbook example of the term "mission creep", what, pray tell, has all this got to do with the Zuiyo Maru carcass? Plesiosaurs, due to their great differences in anatomy and assumed locomotor morphology relative to the thunnosaurian ichthyosaurs, are thought to have been highly unlikely to have possessed dorsal fins. Thus, the apparent presence of a dorsal fin on the Zuiyo Maru carcass was taken as strong evidence for the "mutilated basking shark" hypothesis as opposed to the "plesiosaur-like reptile" hypothesis. However, the presence of a dorsal fin on thunnosaurian ichthyosaurs was unknown for around 80 years until the first skin impressions of ichthyosaur dorsal fins were discover in Holzmaden, Germany. The only skin impressions of plesiosaurs thus far discovered are partial impressions around some flippers (Hydrorion brachypterygius, Seelyosaurus guillelmiimperatoris and the "Collard plesiosaur") and the tail fin of one specimen of Seelyosaurus guillelmiimperatoris. Though it appears unlikely, based on predictions from current knowledge, that plesiosaurs had dorsal fins, we do not know for sure as the soft anatomy of the back of plesiosaurs has not yet been found preserved. Add to this the context of an alleged sighting by two professional biologists of a living plesiosaur-like creature with a dorsal fin in the 20th century. And, to confuse matters even further, some minority opinion in the past has suggested the Australian thunnosaurian ichthyosaur Platypterygius australis may have used some form of pectoral fin propulsion to augment

caudal propulsion, due to it’s robust pectoral flippers and associated muscle attachments. After an exhaustive comparative study with marine animals that used pectoral, pelvic and caudal propulsion, though most anatomical features of Platypterygius australis strongly pointed to it being a caudal propulsor, use of the forelimbs and hindlimbs for low speed propulsion could not be ruled out (see Maria Zammit and Rachel M. Norris 2011, "An assessment of locomotory capabilities in the Australian Early Cretaceous ichthyosaur Platypterygius australis based on functional comparisons with extant marine mammal analogues" in The Australian Cretaceous ichthyosaur Platypterygius australis : understanding it’s taxonomy, morphology and palaeobiology by Maria Zammit, doctoral thesis, University of Adelaide, pp. 41-73). And Platypterygius australis is consistently portrayed with a dorsal fin (see below). Why beat a dead basking shark to death? Wake up from your tryptophan-induced coma and smell the coffee! Consider this also: DeBlois 2013 reconstructed the soft

anatomy outlines of the pectoral and pelvic flippers of the plesiosauroid plesiosaur Hydrorion brachypterygius using hydrodynamic principles in conjunction with geometry. DeBlois’ models predicted very different morphology for the pectoral and pelvic flippers of the same individual plesiosaur, with the pectoral flippers having a much larger fleshy trailing edge than the pelvic flippers. This might be an indication of different function between the front and hind flippers. Wilhelm 2010 reconstructed his hypothesized tail fin for a similar type of plesiosauroid plesiosaur, Cryptocleidus oxoniensis, as having a large, fleshy trailing edge, somewhat analogous to DeBlois’ pectoral flippers for Hydrorion brachypterygius. Taking Deblois’ flipper models and Wilhelm’s tail fin and grafting them onto the typical skeleton of a moderately long necked plesiosauroid plesiosaur, one can suggest that perhaps the anatomical similarities of the pectoral flippers and the tail fin imply a similar function (hydrofoils for propulsion), while the disparity of the pectoral flippers may imply a different function for them (rudders for steering).

(We will return to the flippers/ fins of the Zuiyo Maru carcass and the question as to whether there were phalanges in the flippers/ fins later in this series.) It should be pointed out that not everyone was in agreement that the supposed dorsal fin of the Zuiyo Maru carcass was one, in fact.

Note: Michihiko Yano interpreted A and B in the image above as one pectoral appendage as opposed to a dorsal fin lying on top of a pectoral fin. Others rightly came to the conclusion that this fin was too close to the spinal column to be a pectoral appendage.

John Goertzen ("New Zuiyo maru cryptid observations: strong indications it was a marine tetrapod", CRSQ

38(1):19–29, 2001) proposed that the Zuiyo Maru carcass did not have a dorsal fin but small, rudder-like fins above the pectoral appendages on both sides of the body, a feature wholly without precedent among secondarily aquatic tetrapods (see figures below).

While his argument might make sense regarding a fin overlaying the right pectoral appendage, his arguments regarding a fin overlaying the left pectoral appendage are ambiguous at best. Below are models overlaying Goertzen’s concepts of these upper fins over the skeleton of the plesiosaur Cryptocleidus oxoniensis.

Again, there are no precedents for paired bilateral dorsal structures like these in any fossil or living secondarily aquatic tetrapod and I suspect constraints in tetrapod Hox genes would inhibit the development of such structures.

Above image (clockwise from upper left): the dorsal fin of the Zuiyo Maru carcass, drawing interpreting the dorsal fin of the Zuiyo Maru carcass, the mutilated dorsal fin of the Parker’s Cove, Nova Scotia basking shark 2002, an unmutilated basking shark dorsal fin, the skin impressions of the dorsal fin of a thunnosaurian ichthyosaur and drawing of the supposed dorsal fin of the Valhalla animal 1905. Just because the mutilated Zuiyo Maru dorsal fin was not the same shape as what was described for the Valhalla animal does not mean it could not have been shaped that way in an unmutilated state. Even if the Zuiyo Maru carcass was a mutilated basking shark, it would appear the base of the dorsal fin had become detached from the spinal column. Have there ever been reports of a dorsal fin on that other alleged pseudoplesiosaurian entity, the Loch Ness Monster? In one highly controversial report, the Alistair

Dallas sighting of 1936 (see sketches below). Here is a summary of investigator Mike Dash’s take on the Dallas sighting:"One of these was the well-known Scottish landscape artist Alastair Dallas. My investigation of

the case revealed that Dallas had actually claimed his own close-up sighting of the LNM in 1936: he saw ‘the monster’ hauled out of the water, sucking weed from rocks on the shore (and, in one version of the tale, was so close to it that he was able to throw his sandwiches at it). Being an artist, Dallas had a sketch book with him, and he quickly drew several views of the unlikely-looking creature. Years later, in 1974, he was approached by an LNM researcher named Alan Wilkens. Actually, Dallas wouldn’t speak to Wilkens direct, but he agreed to talk to a representative named Tom Skinner, who was head of biology at Annan Academy. Dallas couldn’t find his sketch at first, so he drew it again from memory. Later, he did discover the original (so he said, though as I noted in my talk, he could equally well have drawn it from scratch in 1974), had it lithographed, and gave a copy to Wilkens, who gave it to the Loch Ness Phenomena Investigation Bureau, and it can be found in their archives in the Loch Ness Exhibition Centre in Drumnadrochit. Wilkens gave me a copy of the other, rougher, sketch. So far as I know, I’m the only person who has now has a copy of the latter, so I’m sure it is a good idea to archive both online.

What all this shows is anybody’s guess. I am just a historian, not a scientist, but the creature as sketched by Dallas seems to have evolved some pretty specialized features, and even I can see that its appearance is – to put it mildly – odd, and that the idea of a 20ft long monster capable of subsisting in Loch Ness by sucking weed off rocks is rather implausible." (from Tetrapod Zoology comment thread, Oct. 4, 2009.)

Dallas’ "monster" is described as having TWO dorsal fins! Dallas’ "monster" is among the outliers of atypical Nessie sightings and is suspect if for no other reason than that. Not a whole lot we can do with it, I’m afraid. At any rate, below is a comparison of the Dallas monster (from a painting at Deviant Art, didn’t get the artist’s name but fantastic work) with the Zuiyo Maru carcass and the Nessie gargoyle head photo. Beyond the Dallas sighting, there is the sighting of a Nessie hump with a dorsal crest made by a Richard A. Meiklem on Aug. 5, 1933. Below is a sketch of the alleged appearance of Meiklem’s hump, observed through binoculars.

The Amazon River Dolphin (Inia geoffrensis) has a dorsal crest along the back somewhat resembling this, sort of a theoretical precursor to a dorsal fin


1 comment:

  1. One aspect of this story which recommends basking sharks as the owners of the washed up carcasses is that people engaged in the basking shark fishery were only interested in the livers, and would sometimes remove the livers at sea, or in shallow waters, and then abandon the rest of the fish. see pages 87 onwards. This article refers specifically to the Scottish fishery practices, but it is not unreasonable to suggest it was applied elsewhere too.


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