Questions for Further Thought
- Study the composite cladogram available in the Virtual Paleobotany Laboratory. Find an example of a grade of organization that has been lumped together as a taxon irrespective of evolutionary relationships. Use material on reserve in the BioSciences Library (start with Kenrick and Crane, 1997) to learn more about this genus. How had overall similarity led us astray in thinking about the plants grouped together in this genus? What characters are synapomorphic for this genus? What characters are pleisomorphic?
- In the introduction to the lab, we write: "From the point of view of a botanist visiting the Silurian or Early Devonian, when these plants lived, the plants grouped together in this lab would represent the monophyletic crown group of embryophytes." This statement is meant to justify grouping paraphyletic lineages together in a single lab. Is this perspective legitimate or are we goofing you? Explain.
- What features of the Rhynie Chert suggest that the plant remains are autochthonous rather than allochthonous?
[Geologic Time Scale]