Poked by a pinecone...blame dinosaurs
3/2/11
Anyone who has ever had to pick up pinecones and was violently poked in the process knows what a painful experience it can be. Instead of cursing to the heavens, you should blame dinosaurs for the pulsing pain in your hands or feet (I honestly don't even want to think about the excruciating experience of running barefoot and unwittingly stepping on a rogue pinecone).
While most modern conifers produce two distinct types of cones - slender male cones that house pollen, and bulky female cones which house seeds - most ancient cones were about the same size and shape. To answer why this situation might have arisen, Dr. Andrew Leslie of Yale University scoured the world's herbariums (like any good paleobotanist would) in search of fossilized cones. He measured the widths of 70 well-preserved specimens and compared them with the 200 or so living species of conifer. Unsurprisingly, his original observation stood up - female cones have indeed increased in size. But why?
To figure this out a number of factors had to be considered. First was what actually increased in size. Leslie found that it was actually the scales, which are used primarily for protective purposes, that increased dramatically in size. Second was when the shift in size happened. Interestingly, the shift seemed to begin right around the Jurassic period (199-145mya) when many of the largest herbivores (Diplodocus and Barapasaurus) walked the Earth. The long necks of these dinosaur species would have allowed them to graze much higher up on trees than an others before them, in turn putting female cones at risk.
While the pattern of the timing and physiologies of the cones are very striking, Leslie feels as though we shouldn't be so quick to discount small mammal and bird species that may have been inhabiting the upper canopies of these trees. The relatively poor recording of these species in the fossil record makes it a bit more difficult to figure out exactly what was going on in the trees themselves, but hopefully one day we will be able to figure this out!
While most modern conifers produce two distinct types of cones - slender male cones that house pollen, and bulky female cones which house seeds - most ancient cones were about the same size and shape. To answer why this situation might have arisen, Dr. Andrew Leslie of Yale University scoured the world's herbariums (like any good paleobotanist would) in search of fossilized cones. He measured the widths of 70 well-preserved specimens and compared them with the 200 or so living species of conifer. Unsurprisingly, his original observation stood up - female cones have indeed increased in size. But why?
To figure this out a number of factors had to be considered. First was what actually increased in size. Leslie found that it was actually the scales, which are used primarily for protective purposes, that increased dramatically in size. Second was when the shift in size happened. Interestingly, the shift seemed to begin right around the Jurassic period (199-145mya) when many of the largest herbivores (Diplodocus and Barapasaurus) walked the Earth. The long necks of these dinosaur species would have allowed them to graze much higher up on trees than an others before them, in turn putting female cones at risk.
While the pattern of the timing and physiologies of the cones are very striking, Leslie feels as though we shouldn't be so quick to discount small mammal and bird species that may have been inhabiting the upper canopies of these trees. The relatively poor recording of these species in the fossil record makes it a bit more difficult to figure out exactly what was going on in the trees themselves, but hopefully one day we will be able to figure this out!
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