Windows to the past: plant fossils give insight into ancient Burnaby climate

Burnaby Mountain towers in our city’s horizon; a constant, watchful presence and a natural monument to the ancient history of our region.

But what was there before the mountain?

A new paper out of Simon Fraser University looks into the mysteries of what existed in Burnaby 40 million years ago, in the late Eocene period and long before humanity.

The paper, penned by Rolf W. Mathewes, David R. Greenwood, and Tammo Reichgelt and published in the International Journal of Plant Sciences, analyzed fossils found in the Burnaby Mountain area.

Now a paleobotany professor at SFU, Mathewes himself found the fossils when he was a student at the university in the 1960s, along with his now deceased supervisor Robert C. Brooke.

The pair found the fossil samples when ongoing construction at the university exposed a section of the mountain’s sandstone bedrock that included finer sandstones, mudstones, and shale. However, it wasn’t until Matthewes returned to SFU as a professor himself that the fossils were properly analyzed.

The fossils help to paint a picture of a very different region than the one we know today. Burnaby Mountain didn’t yet exist in the late Eocene, and was instead a sea-level floodplain with ponds and river systems leaving behind silty deposits in their wakes.

Underneath those sediments were leaves, flowers, and pollen from native plants in the area—plants like palm trees that wouldn’t survive in the area today.

“These plant fossils tell us the climate was warm temperate to subtropical because of the presence of palms,” Mathewes said in a press release.

“If you wanted an analogue for what the climate was like compared to today, the conditions would be similar to the East Coast of the United States somewhere around Wilmington, North Carolina, where palms are still native today.”

Meanwhile, fossil pollen found at the site shows the presence of many other plant species like alders, ferns, elms, and sweetgum.

And the samples have much more insight to offer—Mathewes and his co-authors wrote that the megafossils found at Burnaby Mountain include rare reproductive organs like flowers, seeds, and fruit, which are particularly important in finding what a fossil’s nearest living relative would be.

There are also a number of other microfossils that the team has yet to analyze—and one of the fossil leaves found show round feeding marks made by an insect.

Mathewes dedicated the paper, published in the March/April issue of the journal, to his late supervisor and professor with whom he first found the fossil samples.