Victims or Voluntary Swimmers?
Sometimes it takes a youngster to come up with an interesting question. The occasion was a lecture on dinosaurs, presented in Edmonton’s Provincial Museum on December 11, 1990. Following the main address by Dr. Philip Currie of the Royal Tyrrell Museum, an excited group of boy scouts was asking most of the questions. “Is it fun to look for fossils?” “How many dinosaurs has Dr. Currie found?” “What is the biggest fossil found in Alberta?” … Dr. Currie patiently fielded all the queries. Then one young boy asked “Did dinosaurs swim?” As Dr. Currie answered the question, it became evident that this really was an interesting topic.
Dr. Currie remarked that little is actually known about dinosaur habits. There are some tantalizing hints however concerning ankylosaurs or armoured dinosaurs. These remarkable animals were built something like tanks. Their hides were decorated and weighed down by row upon row of bony knobs and spikes. In Alberta, the vast majority of articulated ankylosaur skeletons are found upside down. They lie on their back with feet projecting upward. Most experts, Dr. Currie included, suspect that these animals foolishly ventured into water over their heads. Unfortunately, as their bodies were top heavy, these animals tipped over, sank and drowned.
One wonders if the ankylosaurs voluntarily entered deep water, or if a flash flood overtook the victims. Evidence of similar sad events are widely dispersed. In an interview with an Edmonton Journal staff writer (January 23, 1989), palaeontologist Dr. Dale Russell reported finding an armoured dinosaur, called a stegosaur, upside down in China’s Gobi Desert. Also Dr. Robert Bakker in his 1986 book The Dinosaur Heresies (William Morrow and Company, Inc. New York) discussed several occurrences of armour-plated nodosaurs (ankylosaurs) found upside down in marine sediments. He asks the rhetorical question whether these dinosaurs foolishly went swimming or whether their carcasses were merely washed out to sea. He concludes: “The problem of oceangoing nodosaurs is especially perplexing because the Como carcass, upside down at the bottom of the Benton Sea, is not an isolated instance. Nodosaur carcasses lying on their backs cropped up in marine beds in Kansas in 1909 and several times since in similar sedimentary circumstances.” (p. 40)
Reprinted from Dialogue volume 22 #1 February 1995
Update: The above article demonstrates the relevance of a dinosaur fossil discovery in Ft. McMurray in 2011.
Some of the most famous armoured dinosaurs are the stegosaurs. Every young person knows about Stegosaurus and how funny they looked! The ankylosaurs are also armoured dinosaurs. Their four legs are much shorter than those of the stegosaurs. These animals were covered in heavy bony plates so that they seem built like tanks. They were big too, averaging about 6-8 m (20-26 ft) long. One book on The Great Dinosaurs by Alberta’s dinosaur expert Philip Currie and Zdenek Spinar says about the ankylosaurs: “Because of the great weight of their armour, they would have had great difficulty in swimming because they would have a tendency to roll over onto their backs and sink.” (1994 p. 126) This statement applies not only to the ankylosaur armoured dinosaurs but also to the nodosaur armoured dinosaurs which were a bit smaller than the ankylosaurs.
Good fossil remains of armoured dinosaurs are rare, so it was an exciting day when a new nodosaur fossil was discovered near Fort McMurray, Alberta in 2011 in the Suncor Millenium oilsands mine. More amazing however was the condition of the dinosaur remains. There was a fully three-dimensional body with the exterior skin, armour, and spikes preserved as they would have been in life. Even more amazing, its stomach contents were preserved. It seems that this animal preferred ferns. Have you ever heard of such an amazing fossil? No? Neither had anyone else!!
Scientists from the Royal Tyrrell Museum were very surprised to discover that this newly discovered specimen was a land dwelling dinosaur and not a sea dwelling reptile like a plesiosaur. No land animal had ever previously been discovered in the oilsands. Many people wondered how this heavy, long animal (18 ft) ended upside down in sediments typical of the ocean.
As with many other armoured dinosaur fossils, it seems that this creature was overtaken by rushing waters that tipped him over and carried him far away. Eventually the animal sank to the bottom of the water into soft sediments which perfectly protected its three-dimensional shape. Soon buried by other sediments, the whole thing hardened into a most unusual perfectly preserved fossil. This creature Borealopelta markmitchelli is a dramatic testimony to the power of unique flood waters to sweep away and bury heavy dinosaurs. Truly Alberta is a wonderful place to reflect on the impact of a unique worldwide flood.
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