Digging for evidence
University students uncovered fossil cone-bearers and flowering plants.
Students led by professor John Curtis, Department of Biology, traveled to Sentinel Butte, North Dakota in search of fossil plants. Their findings agreed with evidence gathered worldwide that flowering plants were diverse when the last dinosaurs were extinct, about 65 million years ago.
Flowering plants vs. cone-bearers
Flowering plants have dominated cone-bearers for the past 100 million years. Resinous, tough, slow-growing cone-bearers could not defend against beaked dinosaurs and grazing mammals later on. Even today cone-bearers thrive where browsers are few and flowering plants have difficulty in cool, wet or dry climates with short growing seasons and heavy snow loads.
Dinosaurs that stretched tall vs. speedy plants
Stegosaurs and longnecks munched on tall, cone-bearing trees. Over browsing created forest openings where young cone-bearers and protoflowers filled in. Protoflowers may have evolved when mutations allowed leaves to curl around naked cone-bearer seeds forming a shell or pod. Co-evolving with protoflowers, low feeding dinosaurs moved in and cropped off young plants. Protoflowers, possibly faster growing and indigestible to longnecks, overtook slow growing cone-bearers leaving longnecks little to eat. Most longneck sauropods went extinct 135 million years ago.
Flowering plants vs. dinosaurs that browsed low
Emerging 125 million years ago, flowering plants needed protection from low feeding dinosaurs. Natural selection favored fast growing trees which towered over browsers. Low growers survived by producing toxic chemicals and mass producing seeds that grew and matured quickly before being mowed down.
Fossils on exhibit |
|
|---|---|
| Fossil | Comments |
| winged fruit | from a maple like tree |
| palm leaf fragment | looks like a blade of grass but came into existence several million years later |
| Parataxodium | relative of a cone-bearing yew |
| Cyclocarga | walnut family |
| Paleocarpinus | member of the birch family |
| Hamamelis | relative of witch hazel |
| ginkgo | cannot be distinguished from living ginkgo leaves |
| Platananthus | probably related to sycamore |