Small flying reptile makes big paleontological impact
Size of Hornby fossil challenges beliefs about pterosaurs
The discovery of fossil remains on Hornby Island of a cat-sized pterosaur, a prehistoric flying reptile, is turning some ideas in paleontology on their heads.
Sandy McLachlan, 29, now taking a master’s program in paleontology at the University of Victoria, made the discovery in December 2008.
McLachlan said paleontologists have been surprised by the size of the creature.
It was small compared with most other known pterosaurs of the late Cretaceous Period, by which time some had evolved as big as modern giraffes.
“It’s been thought pterosaurs started small and evolved to get bigger and bigger,” he said.
“It was thought as they got larger they became less adept in the environment, clumsier, heavier.
“So they just got outpaced by the smaller and more versatile birds” already on the scene by the late Cretaceous (about 77 million years ago).
But the Hornby pterosaur was about the size of a large bird (albeit with a wingspan of about 1.5 metres). It was living and competing in the same environmental niches as birds, which could also fly but are unrelated as species.
It also indicates there were more pterosaur species than had been believed.
So now, the scientific mystery becomes: Why did they go extinct, while birds survived?
The Hornby pterosaur specimen is being kept at the Royal B.C. Museum, where McLachlan works as a research associate.
His principal area of interest is marine animals, mollusks, ammonites and microscopic animals found in plankton, a new area of paleontology.
McLachlan has been an amateur fossil collector since 1998. Even as an amateur, he decided it made sense to concentrate on one area and build up a varied knowledge of the prehistoric fauna through time.
McLachlan chose Hornby because it has proven to be one of the richest fossil sites in the area.
When he found the pterosaur, he was looking specifically for “concretions.”
These are roughly spherical nodules formed by chemical processes, linked to the decomposition of animal organic material. They can appear as distinct lumps in the surrounding sedimentary rock that contain fossils.
When McLachlan found the nodule bearing the pterosaur fossil, he could see what turned out to be a wing bone sticking out. He could also tell it was hollow, so he knew it was from either pterosaur or bird.
He cleaned up the nodule as best he could, but didn’t want to risk destroying the fossil by cracking it open with a hammer and chisel.
McLachlan reached out to other experts in B.C., who extracted the tiny fossilized bones using fine air chisels. They identified it as pterosaur.
It was also determined that the animal was an adult, based on the fusing of the bones in tailbone. This meant the creature was not the small, immature offspring of something large.
From there, the specimen made its way to the University of Southampton in the U.K. and to Elizabeth Martin-Silverstone, the world’s leading expert on pterosaurs.
Martin-Silverstone published a Royal Society scientific paper on the find in July.
The animal has not been given a scientific name because the specimens were too fragmentary.