The Arthur Grant Sighting - Evidence of living plesiosaurs?

CLAIM: In 1934, veterinarian student Arthur Grant reported an encounter with the Loch Ness monster and gave a description that exactly matched a plesiosaur. (Hovind, 2003, 1:21:11)

RESPONSE: Arthur Grant, a veterinary student, was riding his motorcycle by Loch Ness around one in the morning on January 5th 1934 when he nearly collided with a dark animal in the road in front of him.

Illustration of the alleged sighting of Loch Ness monster by Arthur Grant in January 1934. (c. Wikimedia)

"I was almost on it...when a small head on a long neck turned in my direction, and the object, taking fright, made two great bounds, crossed the road and plunged into the lake." (Time, 1950)

Grant sketched a creature with a small, eel-like head at the end of a long neck, a bulky torso, four visible limbs described as flippers or webbed toes, and a 5- to 6-foot-long tail.

Sketch of the Arthur Grant alleged Loch Ness monster sighting in January 1934. (c. Wikimedia)

Crucially, the animal was already on land and able to move quickly enough to avoid being struck by the motorcycle. Whatever creature Grant may have seen, his sketch and narrative demand a reptile that can both leave the water and support its weight on shore - abilities that plesiosaurs did not possess.

In plesiosaurs, all four limbs were composed of stiff, paddle-like hydrofoils. The elbow and knee joints were locked; the long bones could only move up and down in a limited arc to allow for underwater "flight". The shoulder and pelvic girdles were fused into broad bone plates, and their ilium (the weight-bearing bone in land reptiles and mammals) had shrunk to a vestigial rod that no longer braced the spine, leaving no skeletal mechanism for supporting the body on land. (Witton, 2019) While some rare, smaller genera may have been able to "flop" along shallow shores, their movement would have been clumsy and inefficient, since plesiosaurs both gave birth and hunted in the water and had no ecological drive to attempt making it onto land - as paleontologist Mark Witton (2019) summarizes:

"Any notion that plesiosaurs were capable of hauling themselves onto land is not only unnecessary in light of what we know of their reproductive biology, but also contradicts much of what we understand about the functional morphology of semi-aquatic animals. Their four-flipped construction looks a little more terrestrially-capable than the body of a whale or ichthyosaur, but I suspect an accidentally beached plesiosaurian would be in just as much trouble as these more classically-shaped marine forms. History shows that we can make beached plesiosaurians look half convincing in art, but it's a hollow victory: the science is not on our side."

Further, Grant drew large, forward facing eyes on the very top of an "eel-like" head - features useful for an amphibious predator scanning above water. Plesiosaurs, by contrast, had laterally placed eyes and rigid, thicker necks that remained mostly straight, not flexible and bent upward like a swan or periscope. (Strauss, 2019)

The primary anatomical requirements for Grant's creature - load-bearing limbs, flexible joints, erect neck posture - directly contradict what we know about plesiosaur biology. Arthur Grant may have seen some kind of marine organism that winter night in 1934, but based on his descriptions and sketches of the creature, it likely was not a living plesiosaur, and as such, should not be used by young-Earth advocates as evidence of the coexistence of humans and dinosaurs.

REFERENCES AND FURTHER READING

Strauss, B. (2019, January 31) Plesiosaurs and Pliosaurs - The Sea Serpents. ThoughtCo.

Time (November 20, 1950) Foreign News: Monster Rally. 

Witton, M. (2019, January 25) Plesiosaurs on the rocks: the terrestrial capabilities of four-flippered marine reptiles. Mark P. Witton's Blog.