at the end of a neck perhaps ten to fifteen feet long and far end, and leading into a body the size of an overturned rowboat, much larger of a body size than would ordinarily go with a mammal with a head of such a size. And the standard reconstructions made up from the sightings do allow for what the sightings describe. Heuvelman's Longneck modifies the general consensus of reports only in that it leaves the tail off (the tail is commonly reported in about 10% of the cases. In Heuvelmans' reconstruction, he easily discounts the 10% in favour of a very few reports which seem to specify that the creature under observation had no tail.These reports ordinarily do not really specify so long a neck or so small a head)
The mane is reported on some larger individuals but in the majority of "maned" reports, the animal is not verifiably of the type we are discussing. In some cases, such as the Corinthian SS illustrated by Heuvelmans, it is unmistakeably the same sort of creature. Oudemans states that it is most often noticed as an irregular (jagged) outline on the larger individuals, and it is most often the same colour as the rest of the animal. The maned males also have the more distinctive colouration: brown, reddish brown and in a minority of cases, greenish brown. The texture of this "Mane or fin" is classically compared to the leaves of kelp, and ordinarily it is a "Mane" of the upstanding type rather than the flowing type. All reports of scales or spikes as well as hair or bristles refer ONLY to the mane: some witnesses have inapprpriately assumed the whole body must be covered with the same material, be it hair or scales. The body is generally smooth and bare in most other parts, and it is sometimes roughter but only along the spine where the mane is.Oudemans also notes that it runs the whole length of the neck and midline of the back: it seems this also continues down the top of the tail in some observations. In Northern latitudes, maned individuals are seen most often in the spring continuing on into early summer and least often in the autumn; a few reports seen in winter seem to indicate maneless individuals out of the larger reports which otherwise agree with the maned type!.
Roy Mackal compared this continuous crenelated fleshy mid-dorsal fin which enhances the male's vertical profile and makes it seem larger to the breeding array of some newts; and upon some consideration, it might actually be analogous to the newt's backfin in breeding array in that it seasonally grows longer/higher and more jaggedly obvious: it is also probably important that it also goes with the individuals with the richest colouration. Since this organ seems to be somewhat keratinized (and the fleshy members of it are sometimes compared to rolls of cotton batting, coconut fibers and even wood shavings), seasonal, but also that it often seems patchy and missing along parts of the length in some individuals but-this is important-missing from different sections of the neck or back in different individuals and on different occasions, I believe the material serves as a harmless means for males to engage in ritual mating contests without doing each other serious injury. Essentially, agression would be displaced into hair-pulling contests. Tending to confirm this observation is the fact that reports of "Whiskers" such as in the Corinthian case are obviously showing the same mane material but lying crosswise in the creature's mouth, exactly as if a male had just pulled a mouthful of material off of another male's mane but not at all in the position the "whiskers" naturally would be if they WERE whiskers, and some reports feature a male "Merhorse" behaving agressively toward humans in a small boat and spitting such pieces of a rival's mane out of its mouth while doing so!
to give the poor seal any practical advantage whatsoever, and it makes both swimming in the water and walking n the land both more difficult.
Reconstruction of a Sea-serpent theory by Rev JG Wood made by Oudemans in his book The Great Sea Serpent. Oudemans DIDN'T go for this idea at all and thought it was laughably unbalanced and awkward. He opted for his long-tailed long-necked seal version instead.
From Lord Geekington's discussion on the flexibility of Plesiosaurian necks:
Maybe having an unusually flexible neck in the vertical plane is useful for living in shallow near shore marine, brackish and freshwater environments - the juvenile in question was from marine deposits. Also problematic is that freshwater plesiosaurs in Australia were apparently subjected to cold to near-freezing conditions according to Kear (2006) - I couldn't imagine a 28 inch juvenile managing that.[like many living animals, they probably had young in spring and summer to give the young a window of advanyage during the warmer months-DD] Freshwater plesiosaurs are potentially very interesting, they've been found worldwide from the early mid-Jurassic to the Late Cretaceous by the way, and I'd be curious about any morphological adaptations.
Back to plesiosaur necks, how flexible are they anyways? The genesis of this post was a paper by Zammit et al. (2008) which rigorously examined just that in the elasmosaur Aphrosaurus. The authors created life-sized 2D models of the vertebrae in dorsal and lateral view and used the minimum and maximum amount of intervertebral cartilage to create a possible range (Zammit et al. 2008). Models were also made of a boid, snake-necked turtle and sea lion for comparison - these tended to produce slight underestimates (Zammit et al. 2008). It turns out that Aphrosaurus could bend its neck 87–155° in the dorsal plane - far from the 360°+ needed for a swan-like posture - and motion in the ventral plane (75–177°) and lateral plane (94–176°) appears to have been greater (Zammit et al. 2008). The authors mention an unpublished master's thesis which showed a similar pattern from Cryptoclidus and Muraenosaurus (both cryptoclidids) and noted that the vertebral centra in those genera had concave articular faces and rounded lateral margins, imply more vertebral movement (Zammit et al. 2008). Exact figures were not given, but the vertebral count (~40) was lower so the cryptoclidid necks are not necessarily more flexible overall.
Zammit et al. mention that cervical zygapophyses are inclined more posteriorly so the back of the neck has increased vertical flexibility at the expense of lateral flexibility; the amount of flexibility also decreases going towards the posterior end of the neck. Previous papers (which I can't access) mention a "tongue in groove" structure also in the posterior part of the neck may be analagous to zygantrum–zygosphene articulations in snakes, which reduce torsion (Zammit et al. 2008, Moon 1999). Elasmosaurs seem to lack a mid-neck increase in flexibility that appears to have been present in cryptoclidids (Zammit et al. 2008). As far as function, Zammit et al. conclude that a strait held neck combined with lateral and/or ventral movement to capture prey is plausible but arching and slight s-curves appear possible as well; these are consistent with models of elasmosaurs as benthic grazers, ambush predators, and active predators using snake/turtle-like strikes.
Fossil showing flexibility inherant in the Plesiosaur's neck
|As Tyler Stone points out, not all surviving Plesiosaurs need be Longnecks|
And there are a number of reports which sound like smaller shorter-necked forms