An international team of paleontologists from the United States, China, Japan, Russia and Mongolia, have discovered a new extinct species of plant from the Early Cretaceous (~100–125 million years before present) that appears to be distantly related to living Ginkgo biloba. The new fossils, named Umaltolepis mongoliensis, were collected from ancient peat deposits at the Tevshiin Govi lignite mine in the steppes of central Mongolia. They are very abundant, superbly preserved, and include fossil leaves and shoots as well as peculiar seed-bearing capsules. The field work in Mongolia began in 2011 and is ongoing.
“To understand the diversity of plants around us, we need to understand their evolutionary history. Having a clearer picture of what the world was like 100 million years ago helps us protect plants and biodiversity today. Finding something like this does not happen very often,” said Dr. Patrick Herendeen, Chicago Botanic Garden senior scientist.
Fossils of Umaltolepis have been known for some time, but until now, poor preservation made them difficult to understand. It has taken the scientists three years to understand this fossil plant. The stems and leaves are similar to the ginkgo tree, but the seeds, and especially the structures they are borne in, are unlike any other known plant, living or extinct.
The seed-bearing structures are not at all like the living ginkgo tree. Ginkgo has large seeds with a fleshy (and stinky) outer covering, but seeds of Umaltolepis are small and winged. As they developed, Umaltolepis seeds were protected inside a tough, resinous, umbrella-like outer covering, which was almost completely closed and only later opened from below to release the seeds.
The key to determining how Umaltolepis is related to other seed plants lies in understanding how its strange seed-bearing capsules compare with the seed-bearing structures in other extinct plants. While they are not closely similar to those of any other living or extinct plant, preliminary comparisons point to the seed-bearing structures of two other groups of extinct plants that have also been suggested to be part of the Ginkgo lineage. These comparisons and the unique features of Umaltolepis emphasize the extent to which Ginkgo biloba is the last living member of a group of plants that was much more diverse and important in the past.
Other fossils collected from the Tevshiin Govi lignite mine include several additional kinds of seed plants, some related to modern pines and spruces. Others are early members of the family that today includes the swamp cypress and redwoods. Also present in the ancient swamp forests of central Mongolia are a variety of extinct plants that are thought to be early conifers, but that have no clear living relatives. Dinosaurs from the Cretaceous of Mongolia have been known since the time of the famous explorer and paleontologist Roy Chapman Andrews (1884-1960), but the plants that supported those extinct animals are only now coming into sharper focus.
This research was supported by a grant from the National Science Foundation. The team included:
· Patrick S. Herendeen and Fabiany Herrera, Chicago Botanic Garden, Glencoe, Illinois
· Gongle Shi, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China
· Niiden Ichinnorov, Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
· Masamichi Takahashi, Niigata University, Niigata, Japan
· Eugenia V. Bugdaeva, Institute of Biology and Soil Science, Far East Branch, Russian Academy of Sciences, Vladivostok, Russia
· Peter R. Crane, School of Forestry and Environmental Studies, Yale University, New Haven, CT & Oak Spring Garden Foundation, Upperville, Virginia.