SFU professor unearths the ancient fossil plant history of Burnaby Mountain
IMAGE: FIG. 4. REPRODUCTIVE PLANT MACROFOSSILS FROM THE SIMON FRASER UNIVERSITY EXPOSURE. A, PARTIAL TRILOBED FRUITING BRACT OF PALAEOCARYA CF. P. WOLFEI, SIMILAR TO BRACTS OF LIVING ENGELHARDIA. B, FRUIT VALVE OF THE MALVACEOUS CRAIGIA. C, LIQUIDAMBAR FRUIT CLUSTER SHOWING THE WOODY ELONGATED STYLES OF THE EMBEDDED CAPSULES. D, STERILE FLOWER OF HYDRANGEA. E, FLORAL CALYX OF FLORISSANTIA CF. F. SPEIRII. THE SPECIES IS UNCERTAIN BUT BASED ON THE LARGE SIZE OF THE CALYX (DIAMETER = 51 MM), WHICH IS MOST SIMILAR TO F. SPEIRII. ALL SCALES ARE IN MILLIMETERS. view more
CREDIT: SIMON FRASER UNIVERSITY
New research led by Simon Fraser University paleobotanist Rolf Mathewes provides clues about what plants existed in the Burnaby Mountain area (British Columbia, Canada) 40 million years ago during the late Eocene, when the climate was much warmer than it is today. The results of their plant fossil analysis were recently published in the International Journal of Plant Sciences.
Mathewes as an undergraduate, and his supervisor at the time, professor Robert C. Brooke, found and collected plant fossils from a deposit exposed during the construction of the university in the late 1960s. The fossils were kept at SFU but remained locked away in cabinets for many years until Mathewes returned to the collection as a professor. He dedicates the paper to the memory of Brooke, his late supervisor and mentor.
One of the fossils identified by their colleague David Greenwood, from Brandon University, is of a palm leaf fragment. The team also identified a hydrangea flower and the flower of an extinct plant from the same family as the basswood, a tree native to Eastern North America. A microscopic analysis of fossil pollen extracted from the fine shale also reveals the presence of alders, ferns, elms, sweetgum, and many other plants.
“These plant fossils tell us the climate was warm temperate to subtropical because of the presence of palms,” says Mathewes, study lead and SFU professor of paleoecology & palynology. “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.”
Study co-author Tammo Reichgelt (University of Connecticut) used new climate modelling techniques to confirm the warmer conditions.
Although planted palms can be found growing in the Lower Mainland today, Mathewes notes that these plants would not survive here on their own as they did in the distant past.
“Even if they flowered and produced seeds, their young seedlings would never be able to compete with the seedlings of Douglas fir and hemlocks and alders that are our native vegetation and probably would die in the first hard frost of winter,” he says.
He explains that most of Burnaby Mountain is comprised of sandstone and gravel but the fossils are only preserved on shale or mudstone. In the late Eocene, Burnaby Mountain had not yet formed and was a floodplain, like the Fraser River Delta, with ponds and river channels with vegetation growing near sea level.
The plants and trees growing on the floodplain deposited their leaves, flowers and pollen into the fine sediment of a shallow lake or pond. Their fossils formed through a process of being compressed under layers of sediment for millions of years.
One of the fossil leaves clearly displays round feeding marks made by an insect, and Mathewes says there is still much to be discovered, identified and studied from the pollen samples and a second fossil deposit site.
Fig. 7. A, Large leaf of cf. Anacardites franklinensis, a species defined by Wolfe from the Eocene Puget Group. B, One of several leaf fragments of an uncertain Myrtaceae (Syzgoides), based on an entire-margined leaf with a strong midvein and thin, closely spaced eucamptodromous secondaries that connect to an intramarginal vein (arrow). C, Unidentified cordate leaf with actinodromous venation, entire margin, and fimbrial vein visible along lower margin, suggestive of Menispermaceae. D, Insect body fossils have not been found in the Burnaby Mountain sediments, but some examples of insect leaf damage are present, like this unidentified dicot leaf with rounded skeletonized feeding spots. All scales are in millimeters.
Fig. 6. Selected dicot leaves. A, Dryophyllum pugetensis leaf confirming craspedodromous venation, with teeth concentrated in distal portion of lamina, and showing a slight trend to falcate curvature. B, Leaf of Platanus with distinctive platanaceous teeth at leaf tip. C, Basal portion of cf. Acer leaf, with long petiole and basal actinodromous primary venation. D, Leaf of cf. Alnus, craspedodromous with two tooth sizes. Alder pollen is also present. E, Leaf of cf. Rhamnus, with dense apically curving semicraspedodromous secondary veins. This leaf closely matches morphology of extant Rhamnus purshianus but does not show the minute teeth at the leaf edge. All scales are in millimeters.
CREDIT
Simon Fraser University
JOURNAL
International Journal of Plant Sciences
ARTICLE TITLE
Plant Megafossils, Palynomorphs, and Paleoenvironment from the Late Middle to Late Eocene Burnaby Mountain Flora, Huntingdon Formation, British Columbia, Canada
Oldest bat skeletons ever found
described from Wyoming fossils
52-million-year-old fossils support idea that bats diversified rapidly on multiple continents during the Eocene
Peer-Reviewed PublicationIMAGE: A PHOTO OF ONE OF THE TWO NEWLY DESCRIBED BAT SKELETONS REPRESENTING ICARONYCTERIS GUNNELLI. THIS SPECIMEN, THE HOLOTYPE, IS NOW IN THE AMERICAN MUSEUM OF NATURAL HISTORY’S RESEARCH COLLECTIONS. view more
CREDIT: MICK ELLISON/©AMNH
Scientists have described a new species of bat based on the oldest bat skeletons ever recovered. The study on the extinct bat, which lived in Wyoming about 52 million years ago, supports the idea that bats diversified rapidly on multiple continents during this time. Led by researchers at the American Museum of Natural History and Naturalis Biodiversity Center in the Netherlands, the study is published today in the journal PLOS ONE.
There are more than 1,460 living species of bats found in nearly every part of the world, with the exception of the polar regions and a few remote islands. In the Green River Formation of Wyoming—a remarkable fossil deposit from the early Eocene—scientists have uncovered over 30 bat fossils in the last 60 years, but until now they were all thought represent the same two species.
“Eocene bats have been known from the Green River Formation since the 1960s. But interestingly, most specimens that have come out of that formation were identified as representing a single species, Icaronycteris index, up until about 20 years ago, when a second bat species belonging to another genus was discovered,” said study co-author Nancy Simmons, curator-in-charge of the Museum’s Department of Mammalogy, who helped describe that second species in 2008. “I always suspected that there must be even more species there.”
In recent years, scientists from the Naturalis Biodiversity Center started looking closely at Icaronycteris index by collecting measurements and other data from museum specimens.
“Paleontologists have collected so many bats that have been identified as Icaronycteris index, and we wondered if there were actually multiple species among these specimens,” said Tim Rietbergen, an evolutionary biologist at Naturalis. “Then we learned about a new skeleton that diverted our attention.”
The exceptionally well-preserved skeleton was collected by a private collector in 2017 and purchased by the Museum. When researchers compared the fossil to Rietbergen’s expansive dataset, it clearly stood out as a new species. A second fossil skeleton discovered in the same quarry in 1994 and in the collections of the Royal Ontario Museum was also identified as this new species. The researchers gave these fossils the species name Icaronycteris gunnelli in honor of Gregg Gunnell, a Duke University paleontologist who died in 2017 and made extensive contributions to the understanding of fossil bats and evolution.
Although there are fossil bat teeth from Asia that are slightly older, the two I. gunnelli fossils represent the oldest bat skeletons ever found.
“The Fossil Lake deposits of the Green River Formation are simply amazing because the conditions that created the paper-thin limestone layers also preserved nearly everything that settled to the lake’s bottom,” said Arvid Aase, park manager and curator at the Fossil Butte National Monument, in Wyoming. “One of these bat specimens was found lower in the section than all other bats, making this species older than any of the other bat species recovered from this deposit."
While the I. gunnelli skeletons are the oldest bat fossils from this site, they are not the most primitive, supporting the idea that Green River bats evolved separately from other Eocene bats around the world.
“This is a step forward in understanding what happened in terms of evolution and diversity back in the early days of bats,” Simmons said.
ABOUT THE AMERICAN MUSEUM OF NATURAL HISTORY (AMNH)
The American Museum of Natural History, founded in 1869 to advance research in science and education, is one of the world’s preeminent scientific, educational, and cultural institutions. The Museum encompasses more than 40 permanent exhibition halls, galleries for temporary exhibitions, the Rose Center for Earth and Space including the Hayden Planetarium, and the Richard Gilder Center for Science, Education, and Innovation, opening May 4. The Museum’s scientists draw on a world-class permanent collection of more than 34 million specimens and artifacts, some of which are billions of years old, and on one of the largest natural history libraries in the world. Through its Richard Gilder Graduate School, the Museum offers two of the only free-standing, degree-granting programs of their kind at any museum in the U.S.: the Ph.D. program in Comparative Biology and the Master of Arts in Teaching (MAT) Earth Science residency program, whose graduates make up approximately half of New York City’s certified Earth Science teachers. Visit amnh.org for more information.
JOURNAL
PLoS ONE
ARTICLE TITLE
The oldest known bat skeletons and their implications for Eocene chiropteran diversification
ARTICLE PUBLICATION DATE
12-Apr-2023
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