Up the Andes and back in time
April 18, 2012 2 Comments
In 1924 Lincoln Ellsworth funded a John’s Hopkins University expedition to the Peruvian Andes and among the items that were brought back was a small collection of Lower Cretaceous plant fossils. They were described by paleobotanist E.W. Berry in 1939 and about two weeks ago I found them in the Smithsonian’s paleobotanical collections. When I find an interesting old collection like this one I like to get a little bit of background information on the people who made it, or in this case who made it possible. Lincoln was the only son of James Ellsworth, who made millions as a banker and owner of coal mines across Ohio, West Virginia and Pennsylvania in the late nineteenth and early twentieth century. As an adult Lincoln ended up living and traveling on a trust set up for him by his father. While working for years to set up an expedition to the North Pole, which finally happened in 1925, Lincoln financially supported the Johns Hopkins University trip to the Peruvian Andes in 1924.
In the 1939 report Berry reported the following taxa collected near Huallanca, Peru: Equisetities sp. Coniopteris peruviana, Cladophlebis browniana, Cladophlebis sp. Ruffordia goepperti, Klukia raciborski, Onychiopsis sp. Weicheselia retculata, Thinnfeldia sp. Sagenopteris cf. paucifolia, Otozamites peruvianus, Pterophyllum sp. Cycadolepis bonnieri, Podozamites sp. Brachyphyllum peruvianum, and Thujites pompeckji
When I read old species names from people like Berry and other early 1900′s american paleobotanists for the first time I pay little attention to the specific epithet (the second part of the species names) for a variety of reasons. Many of those old authors were over-splitters, increasing the number of species based on a few or uninformative characters, or based on geographic location. The generic names tell me what major group (e.g. fern, conifer, etc.) the fossil belongs to, but are often also outdated and require taxonomic revision. This is primarily a collection of ferns, cycads, and conifers. When I found the specimens in the museum’s collection, what struck me about them (and stuck Berry as well) was their familiarity. They were deposited sometime in the early part of the Early Cretaceous (145-125Ma) when South America and Africa were united in a single continent, but separated from North America and Eurasia. Nonetheless, Barry’s Weichselia, Sagenopteris, Cladophlebis, Ruffordia, and Coniopteris peruvianus are all indistinguishable from forms found in Europe and North America that I am familiar with. Others probably fit the same pattern, given that Barry chose to give them familiar generic names.
I said that I was struck by the familiarity of the fossils, but it is important to remember that the early part of the Early Cretaceous was globally warm time and therefore the climate gradient from the equator to the poles would have been less steep that it is today. The kinds of plants and the fine-grained, dark nature of the rock suggest that these plants probably grew in a swampy or wetland habitat, as did their northern counterparts. Under similar temperatures, similar water-availability conditions, and similar soil conditions, finding similar plants is not that surprising. Still, were talking across continents here (final separation from North America was in the Middle-Late Jurassic). With more fossils and a better understanding of the taxa that I am not yet familiar with, I wonder if it is even be possible to tell whether a given collection from the early part of the Early Cretaceous is from South America or North America/Europe based on relatively common leaf fossils alone.
Berry, E.W 1939. The fossil plants from Huallanca, Peru. in Contributions to the paleobotany of middle and South America. Johns Hopkins University Press.