It was six years ago that local geologist Kevin Sharman, then working for Teck, discovered a series of imprints left behind by what turns out to be an ancestor of a modern crocodile while working on site at Quintette.
The tracks have been dated back to about 100 million years ago, and are now the headliners in a recently published article in the international journal Cretaceous Research.
According to Charles Helm, who is currently working on his PhD at the Department of Geoscience, Faculty of Science, at Nelson Mandela University in South Africa, these are some of the finest swim traces of crocodiles ever discovered. There are well over 100 tracks, almost all of which are crocodilian. Partial trackways with complete hand and footprints are visible.
“Tumbler Ridge has become known as a BC hotspot for dinosaurs, based on the string of trackway and skeletal discoveries that have been reported over the past two decades,” says Helm. “But it can be easy to forget that dinosaurs were just one group of track makers that inhabited the region’s Cretaceous marshes and swamps. Crocodylians form another such group, but have received less attention.”
The slabs discovered by Sharman are starting to change that. But what to do with the series of slabs, located well off the road in the mine? The first thing to do was to preserve the imprints. The partially buried slabs were excavated, to fully expose the fossils, then latex molds of the tracks were made. Hundreds of digital photographs were taken to create high-fidelity 3D computer models. Latex was applied in many layers over the next few weeks, and staff recovered the moulds to create replicas of the track-bearing surfaces for the museum’s Dinosaur Discovery Gallery.
Once the tracks were preserved digitally, the work began to recover the actual physical rocks, which weighed in at about 5000 kg apiece. To assist with the recovery, Teck Resources built a 200-metre access road to get the equipment to the site to recover the fossils, which were safely recovered and moved to the museum.
“The real heroes of this story are Teck and LaPrairie, who helped recover the fossils. I can’t think of anywhere else in the world there is such a great relationship between industry and science,” says Helm. “Building a road so they could get in and recover the fossils? It’s way beyond what is expected.”
“Teck is extremely proud of the collaborative relationships that have been established between our steelmaking coal operations and the paleontological research community,” said Ray Proulx, Senior Coordinator of Community and Aboriginal Affairs for Teck in Northeastern B.C. at the time. “We are happy to have facilitated the identification and study of this significant find, which will help shed light on another chapter in our planet’s history.”
The tracks have been part of the museum exhibit since they were discovered, but for the last few years, they have sat unanalyzed, until recently, when Helm was able to recruit Martin Lockley of the University of Colorado (whom Helm has worked with on swim traces he discovered in South Africa). Lockley was the lead author of the publication, while Guy Plint, a Geologist from the University of Western Ontario was the second author. Helm and Sharman are also listed as co-authors.
“Martin has a replica of the trackway in Colorado,” says Helm. “He was able to compares our trackways with others he has collected from around the Western USA, including Colorado. They are all from roughly same time period, and he was able to compare and analyze the tracks.”
According to the research, it appears the crocodiles were swimming in a tidal channel on a low-lying coastal plain, and scratching the muddy bottom with their claws, creating ‘swim traces’. The traces are from the Cretaceous Period and are approximately 112 million years old. They were found in Gates Formation rocks.
In places there is evidence that they also dragged their tails. It is possible to estimate the length of the crocodiles from the distance between the toes in the swim, and it appears that they were about a metre in length.
The paper compares the local crocodile swim traces with those from a similar time period from the western USA.
While the Tumbler Ridge area and the Tumbler Ridge UNESCO Global Geopark are well known for dinosaurs, there is something special about crocodiles. They did not become extinct at the end of the Cretaceous, but have ‘survivor status’, and are still with us today with a recognizably similar body plan.
“As an added bonus, most of my research work is in Pleistocene sediments on the Cape south coast of South Africa,” says Helm. “Because of the Tumbler Ridge discoveries, I was able to spot the tell-tale signs of probable swim traces, the first of their kind ever reported from Africa. Description of these sites was published in the South African Journal of Science. Those ones are only about 100,000 years old, so a very different time scale, but the pattern was the same.”
Helm says the discovery never would have been made without people like Sharman knowing what to look for. “These weren’t obvious tracks, so hats off to Kevin for realizing that there was something that looked weird and should be investigated? We need that mindset of being open to new ideas.”
Helm says that there will be more papers based on these tracks and possibly other related discoveries. “This one sets the stage for more exciting releases in the future.”
Trent is the publisher of Tumbler RidgeLines.
