In 1964, two students conducting a hydrological survey stumbled
upon a trail of large fossil footprints 50 metres (165 feet)
offshore from Horton Bluff, Nova Scotia. They were exposed
at extreme low tide when a storm had swept away the overlying
mud. The discoverer, Dr. David Mossman, is now a professor
of Geoscience at Mount Allison University in Sackville, New
Dr. Mossman eventually mapped 27 footprints spanning a distance
of 20 metres (65 feet). Their preservation in Lower Carboniferous
Period rock made them, at the time, the oldest vertebrate
tracks in the fossil record. They remain the oldest vertebrate
fossil trackways ever found in Canada.
Learn more about the science of trackways.
A Mysterious Trackway
Not only was the trackway old, it was of unprecedented size.
Each footprint was 30 cm (1 foot) long and they were spaced
30 cm (1 foot) apart. The tracks are deep with raised edges,
suggesting that the animal was heavy and the mud very soft
when it waddled by approximately 350 million years ago. The
absence of claws and the width of the trackway show it as
having been made by an amphibian.
It is impossible to identify the animal, as no bones of an
amphibian large enough to have made these tracks have ever
been found in Canada. We can only guess its identity.
One candidate is the semiaquatic predator Eryops. This bulky
amphibian grew to be over 2 metres (6 feet) in length. Its
size and powerful jaws made it a formidable predator in water.
On land, however, it lumbered along on short legs and was
itself vulnerable to predation.
It is also possible that the animal that made these large
tracks was a type of extinct amphibian more related to crocodiles
than to living frogs or salamanders. If so, it probably had
fangs and would have been a most feared carnivore in the Carboniferous
Preserving the Fossil Record
Late in the summer of 1979, a team from the Nova Scotia Museum
cast this spectacular trackway in fibreglass to provide a
permanent record. By 1991, roughly half the tracks had vanished
as the beach rock fell prey to the eroding action of the tides.