The Search for the Most Primitive Conifer Which ancestors of the gymnosperms from the Carboniferous-Permian transition are the most likely candidates for being the first ancestor of all conifers? Which fossil finds exhibit the most primitive features? Which species has the best prerequisites suggesting that all other conifers are derived from it? These questions are some of the most difficult to answer in the history of the evolution of plants. The oldest conifer remains ever found, described as Swillingtonia denticulata were dated in the Moscovian (315 to 307 million years ago) and came from Yorkshire in England. Only microscopic remains were found, but these exhibited Y-shaped, forked tips. Amazingly, this pseudomonopodial growing pattern, in which
branching only took place on one level and one leaf dominated, extending slightly above the other, had existed since the Devonian in plants such as Sawdonia or other zosterophylls, from which all other plants subsequently derived. While the clubmosses, horsetails and the ferns diversified in a short period of time until they
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Perneria thomsonii. 1. Detailed view of a twig with apical, tripinnate sterile leaves and sharp needles in the lower part. 2. Upper part of a twig. 3. A juvenile and an adult leaf, all from Lower Saxony (Coll. Th. Perner).
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Permian: Birth of a New World
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