Wednesday, July 17, 2013

Try Not to Catch the Eye of the T-Rex

Yesterday was one of those perfect days, warm, but not hot. Endless blue sky lifting from the horizon. Ian is off work this week, so I asked if we could go to Drumheller and visit the Royal Tyrrell Museum of Palaeontology. We'd been down when it first opened in 1985, but I was longing for a repeat visit.

So, about 11:30 yesterday morning we were on our way in my little red car, which had never seen a highway, and must have been confused by the lack of a fence of shops on either side of the road. Instead we rode through rolling fields of canola, patched with fields of wheat planted in precise rows your eye could follow as easily as lines stitched on leather. 

We stopped for lunch in Drumheller, whose outskirts sport all the bustle and big box stores and restaurants you see in any Canadian city, but whose older downtown with 1920s buildings was practically deserted. Craft shops, galleries, all the mom 'n pop shops that serve any tourist-centred town. 

The location of the Museum seems to be a secret. A single sign pointing vaguely that way --> was it. You drove down a neighbourhood street lined with houses on the edge of dilapidation, crossed bridges, wandered down an unmarked stretch of deserted road. I was convinced we were lost. Ian had been there several times and was confident that there was a museum at the end of this particular long and winding row. Of course he was right. There finally was a sign: 3.5 kms, 2.5 kms, turn-off ahead! 

They've hidden the thing down in the gully, which unbuilt-in looks like this, which is Horseshoe Canyon on the way to Drum. Glacial run-off and the Red Deer river have carved a deep rift in the land, and it's out of the sides of these pyramids of silt and rock that dinosaur bones erode. 

Inside the museum you step back in time, layer by layer. As we walked through the exhibits Ian remarked how the vertebrates were built to a basic plan, spine, ribcage, limbs, neck and skull, but what an astonishing variety of forms life has taken on that basic plan. 

The Dimetrodons were not dinosaurs but a pelycocsaur, and were probably more closely related to us than to the dinosaurs. They appeared in the late Paleozoic Era, about 280 million years ago, long before the dinosaurs evolved. Dimetrodon died out during in the Permian extinction 245 million years ago. 

Dimetrodon had mammal-like characteristics. They lived mainly in swampy areas. Unlike their fellow non-finned pelycosaurs, they warmed up early after sunrise, and cooled off more efficiently during the heat of the day. This efficient thermoregulation along with their large and powerful jaws gave them the advantage and allowed them to be the dominant carnivore of the era. 

An ancient alligator-like critter named Eryops also lived during the Permian period (roughly 270 million years ago), long before the dinosaurs evolved. It was an amphibian (related to today's frogs, newts and salamanders) and one of the larger animals of the era, about five feet long. Like many of today's frogs it lived in swamps, but unlike today's frogs it had lots of teeth! This meat-eater had a stout body with very wide ribs, a strong spine, four short, strong legs, a short tail, and a wide, elongated skull with many sharp teeth in strong jaws.

From slow and lumbering giants who ate plants and relied on sheer size for protection, to the massive and obviously predatory T-Rex this "zoo" of the long-since vanished is mind-boggling. From lumbering giants whose limbs dwarf today's human, to creatures who you'd find it hard to see without a magnifying glass the evolution of the forms of life on this planet as we know it today are almost incomprehensible. 

The hundreds, if not thousands, of generations it must have taken to produce the exquisitely frilled protective head shield of the Chasmosaurus span a time scale we cannot even begin to wrap our heads around. Natural selection, generation after generation, of animals who survived long enough to breed because they had a protective covering on that most vulnerable of places, the connection between spine and skull. With time the shield became ever larger, ever more imposing. They were big to begin with, rather like an enormous plated rhino, 5-8 m (16-26 feet) long and could weigh 3.5 tons. From finding fossils with preserved skin we know they were covered with bumpy, faceted projections. They laid eggs and raised their young while living in herds, like many larger mammals do today. 

The Stegosaurus was another big creature of the era, with an impressive row of alternating bony plates that ran the length of its spine. It grew up to 8-9 meters (30 feet) long and almost 3 meters tall (9 feet). However its brain was only the size of a walnut so it couldn't have been the brightest bulb in the chandelier. The rear legs were longer and straighter than the front, which sprawled to the sides. As you can see from the skeleton, its skull was long and narrow and was carried close to the ground. The plates were made of a spongy type of bone which was filled with blood vessels, so they may have been used as a sort of temperature regulating mechanism, or they may have been there to attract a mate. (Oh baby! I do like the look of your plates!) The spikes at the end of the tail were probably protective. Stegosaurus may not have been smart but they were strong and getting hit in the head with those spikes would have ruined most predator's day. 

We walked around and compared the pelvis and shallow hip sockets of the big plant eaters to the wash-tub size hip sockets of the predatory T-Rex. The plant eaters barely had hip sockets. It's obvious from the structure of the pelvis, hip and femur that their legs had a limited range of motion forward or backward, and speed would have hardly been possible. On the other hand the T-rex had a pelvis, hips and legs built for running. The femurs were bowed in opposition to the force the enormous muscles of the legs must have exerted on them when they ran. 

I'd never noticed this before but the T-rex has a retractable spur on its back feet, just like the spur on a rooster. If you've ever seen a rooster go after a cat or dog who has gotten into the hen yard, you can visualize how those spurs were used. The rooster doesn't have the advantage of a mouthful of teeth the size of a man's forearm, or forearms to grasp his unfortunate victim, but those spurs can still eviscerate a cat or small dog. Yeech, I don't even want to think of it. 

They say T-rex hunted in packs. I think I'd just have my heart attack and die before they reached me. There were parts of the Museum we didn't see because I have my limits, and some really neat areas were so difficult to photograph that I didn't get pictures. But it was a great day, not just because of the museum, but also because I got to spend several uninterrupted hours with my oldest son. If you get the chance, go see the museum. It's fabulous. It'll make you think. A motto on a pillar as you exit the building says, "The only constant is change."

1 comment:

Anonymous said...

I haven't been to this museum since the late 1980's myself. Such a vista is the badlands.