The Lake Dinosaur
Everyone knows about Nessie, the lake monster of legend purported to inhabit Loch Ness, a lake in Scotland with a topography similar to Loughborough Lake. Over the many decades of sightings, various explanations have been put forth regarding the origin of this mysterious lake monster. The most popular, no doubt, is that Nessie is one of the last remaining Plesiosaurus, a lake dinosaur that was presumed extinct over 66 million years ago.
Nessie is not the only lake dinosaur of yore. Canada has its own monsters, most notoriously Ogopogo, a lake dinosaur first sighted by First Nations in Lake Okanagan in the 1900s. Ogopogo went on to prominently feature on a Canadian postage stamp, as its legend continues to live on. One is of course at liberty to think what one may about myths on surviving dinosaurs and lake monsters. However, about 10 years ago, it was established as scientific fact that dinosaurs, indeed, never went extinct. In fact, scores of lake-dwelling dinosaurs inhabit our very Loughborough, many of them living off of its rich spoils of fish. I am speaking of course of the class of dinosaurs known as Avialae, otherwise known as birds.
The Loon is, in fact, a great example of what I call a modern lake dinosaur. Like the Plesiosaurus, the dinosaur ancestors of Loons - Therapods such as the raptors that wreaked havoc in Jurassic Park - were presumed to have gone extinct some 66 million years ago during an asteroid impact that marked the end of the Cretaceous period. However, it has become apparent that not all dinosaurs were equally affected by this cataclysmic event. Some smaller, feathered Therapods managed to escape the ensuing firestorms and subsequent changes in climate by taking to their wings.
In 2005, it was first reported in the journal Science that proteins sequenced in collagens taken from Tyrannosaurus Rex bone fragments - a Therapod - are nearly identical to those in chicken bones. This means T. Rex likely tasted more like chicken than an Alligator does. Like chickens, Therapods were two-legged, laid eggs and likely brooded their nests. Baby Therapods likely wore down feathers to keep themselves warm. Early winged Therapods featured ultra-light hollow bones that kept them aloft. These dinosaurs were most certainly capable of flight, but were likely not as agile as today's more highly evolved dinosaur raptors, like the Bald Eagles on our lake. The flight of early Avialae probably resembled that of a flying squirrel, swiftly gliding from tree to tree to stay out of reach of predators.
Scientific evidence is now so overwhelming, that we must simply accept that birds are the dinosaurs that did not (yet) go extinct. Feathers, in particular, form a strong line of evidence for this hypothesis. Long before Avialae developed flight, dinosaurs wore pennaceous feathers to stay warm and to impress other dinosaurs with a dazzling array of colours. Most feathers mix colours using pigments that absorb light in all wavelengths but a few. But some evolved in a much more spectacular fashion, developing a reflection known as iridescence. These feathers amplify light not unlike a laser, via quantum interference.
You can see this interference effect in a gas spill on the surface of the lake: light waves reflecting off of the bottom of the thin layer have to travel further than light waves reflecting off of the top of the spill. Like tuning a guitar, when light waves combine at the surface they either synchronize and amplify, or cancel each other out. This effect relies on two things: the distance traveled by the light wave and the size of its wavelength, or in other words, the angle and colour of the light. This is why oil slicks and soap bubbles develop the most delightful rainbow patterns, rapidly shifting colour with even the slightest change in perspective.
Robert Hooke was the first to document this kind of colourization in feathers in his 1665 book Micrographia, noting that unlike oil, feathers lose their iridescence when submerged in water. We now know this is because such feathers employ tiny keratin structures that look like wood stacks with small air gaps. Each gap provides an additional reflection that amplifies only a wavelength that fits. Filling the air gaps with water extinguishes those reflections, rendering the feathers without colour entirely. Unlike the layers in a gas spill, the layers in feathers are arranged in two dimensions, such that a change in angle does not dramatically alter the distance that light has to travel. This narrows the rainbow effect to only a minor shift in hue that, if anything, produces a more vibrant display when the feathers are moved.
Blue feathers, in particular, excel in reflecting only a narrow band of colours. This is because when seen from an angle, their iridescence shifts into wavelengths that are too short for the human eye to perceive. One dinosaur on our lake that demonstrates this effect is the entirely unassuming Barn Swallow, which can be found nesting in local barns, or underneath Perth Road bridge in summer. Their backs, in fact, do not appear to radiate at all and cast but a dark blue shimmer. However, this is deceiving, as their peak iridescence lies in the ultraviolet wavelengths. Dinosaurs evolved a fourth colour cone in their retina that allows them to see this spectrum of colours. In their eyes, swallows produce the most spectacular display of violets imaginable. Our lake dinosaurs use these mesmerizing but, to us, invisible reflections to impress their partners. They show off the health of their genes by advertising their nanoscale perfection.
Clearly, we need to accept that there is a lot more to nature than meets our eye. Dinosaurs may not have become extinct just yet, but they rely, as much as any creature, on an intricate web of intangibles. These being invisible does not imply they do not also require our protection. Maintaining the gaps between the planks of an old wooden barn - allowing swallows to enter and breed there - is just as important to the swallow as it preening the gaps that make its feathers shine. By extension, it is only through gaps in our knowledge that we drive these lake dinosaurs back into extinction. If only we could see.
