In the early 1900s George Matthew became a pioneer in the identification and scientific classification of fossil footprints. Palaeontologists call this area of research vertebrate ichnology, in Matthew’s case the study of footprints made by amphibians and reptiles more than 300 million years ago. Matthew lived in Saint John, and while he made his living working at the Customs House he was also a geologist and palaeontologist, and a member of the Natural History Society of New Brunswick. As it happened however almost all the fossil footprints Matthew studied were from Nova Scotia. Fossil footprints from New Brunswick were rare. One exception was a fossil from Saint John, the subject of a story for another time.
So in the 1970s when fossil footprints were discovered at Lepreau Falls Provincial Park west of Saint John it was exciting for palaeontologists. Footprint trackways were discovered in October 1974, during a University of New Brunswick, Department of Geology student field trip. Preliminary identification was followed by a description in the Canadian Journal of Earth Sciences in 1978 by William Sarjeant and Peter Stringer. Plaster casts were made of the trackways because the fossils could not be extracted without quarrying that would have damaged the tracks, and they were located in a Provincial Park. Today New Brunswick’s Heritage Conservation Act enforced in 2010 would require a permit to collect the fossil or to alter the fossil site.
Not all fossils need to be collected and the decision made in 1974 to leave the fossil in place was a good one. The plaster cast was placed in the New Brunswick Museum palaeontology collection where it now resides as number NBMG 3044. A second trackway was discovered in October 1977 adjacent to the first and another plaster cast was sent to the New Brunswick Museum as NBMG 3047.
When Sarjeant and Stringer identified the two fossil footprint trackways as Isocampe lepreauense and Rhynchosauroides franconicus, all the geological evidence at the time indicated the rocks were from the Triassic Period of geologic time, about 240 million years old. The fossils were eroded but based on comparison with footprint fossils of the same age elsewhere the two scientists believed the footprints were made by ancient reptiles.
The age of rocks at Lepreau Falls remained a puzzle for many decades after but further geological mapping by the geologists working for the New Brunswick government finally resolved the age of the rocks and now consider them to be much older. The sediments making up these rocks were deposited in rivers about 325 million years ago during the Mississippian Period. The revised age of the rocks made it necessary to re-think the fossil footprints described earlier. Almost 40 years later a team of palaeontologists and geologists re-examined the fossils and the rocks they were found in. Matt Stimson, Randall Miller, Spencer Lucas, Adrian Park, and Steven Hinds published a scientific paper resulting from the new study in 2016 in the journal Atlantic Geology. We now believe the footprints were made by ancient amphibians, not reptiles. Instead of two different kinds of animals leaving their footprint tracks the research study concluded that all the footprints were made by the same kind of animal, just walking in a different fashion. Think of you and some friends walking, running or hopping along a beach, all humans, but leaving different footprint impressions. After 40 years the fossils at Lepreau Falls are little more worn down than when they were first discovered. What made the new study possible was that Sarjeant and Stringer placed their original fossil casts in a museum collection where they could continue to be studied. They followed good scientific practice.
And what did Stimson and his colleagues decide the fossil should now be called. A comparison with other Mississippian age footprints revealed they best matched fossils found at other sites of the same age that had been given the name Matthewichnus, to honour the pioneering work of 19th century New Brunswick palaeontologist George Matthew, a happy coincidence.