What do you think of when someone mentions the Jurassic or Cretaceous ages? Most likely you will immediately think of dinosaurs and other large reptiles such as pterosaurs. Maybe you think of the movie Jurassic Park and the dinosaurs and lush vegetation. These periods are also known as the Age of the Reptiles and aptly so since many layers of the fossil record are loaded with animal bones that belong almost solely to reptiles of some variety. In marine sediments hundreds of sea reptiles (ichthyosaurs and plesiosaurs) have been found around the world and in terrestrial rocks dinosaurs and pterosaurs (flying reptiles) are found to the near exclusion of any other vertebrates.
In addition to their bones, fossils of plants found in the same layers of rock revealed strange coniferous (pine-like) trees along with many cycads and tree ferns but no flowering plant trees at all! No oaks, maples, sycamores, etc.. have been found in these rocks. More significantly so far no flowering plant tree remains have been found in the fossilized feces (coprolites) of those massive plant-eating dinosaurs of the Jurassic (see article: Dino Doo Doo (Coprolites) and the Genesis Flood). Some small flowering plants may have lived at this time but they clearly did not make up any significant part of the flora.
Whether you imagine these scenes from a book or a movie, a significant source of our views of the Age of the Reptiles traces itself back to the early 1800s and a woman who from childhood was fascinated with fossils. Mary Anning (1799-1846) by the age of 12 had already discovered in rocks of the English countryside fossils that she would later describe as a plesiosaur. She spent more than 30 years collecting and describing fossils mostly in rock of Jurassic age. Anning along with William Buckland, who was well aware and an admirer of Mary’s work and described the first true dinosaur, and Cuvier who described and wrote about dinosaurs were instrumental in developing a picture of life in the Jurassic. It eventually lead to Cuvier’s specific proposal that there had been an “age of reptiles.” This was a time when reptiles would have been the dominant animal in all places on earth versus the mammals that we have today. Like the discovery of deep time itself over the previous century this idea of earth’s changing biota over time presented a serious challenge to established views of creation.
Below is a watercolor painted in 1830 showing a scene from the Jurassic time period resulting from the fossils that Mary Anning had discovered and described. This is an amazing scene considering that we have made so many new discoveries since that time and yet the basic reptiles shown here are the main ones we recognize today.
In many ways Cuvier’s proposal based on the work of Anning and Buckland and others capped off a 100 years of work that had developed the idea of “deep time” or the great age of the Earth. The fossil record was now increasingly seen as showing that not only was the earth very old but the fossils recorded time since the distant past show us life was very different from what we see today. This idea of changes in earth’s biota over time was yet another significant challenge to scriptural (Mosaic) geologists of the day and set the stage for even bigger challenges to follow.
It was this recognition of the great changes of life from past to present hat paved the way for Darwin and others to explore how those changes might have occurred. Before Darwin it wasn’t hard to see that organisms had changed or at least been replaced with different organisms throughout the history of the earth but what was the mechanism for that change? Darwin provided a possible mechanism with his theory of “natural selection.” Darwin is often given credit coming up with the idea of evolution but the idea that organisms were different in the past than the present was not novel to Darwin. Rather Darwin was responding to what had already become a well established idea in his time.