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Curator’s Choice
Form and Function:
A Tribute to Adolf Seilacher
Rudists as Bivalvian Dinosaurs
Bournonia bournoni d'Orbigny
Late Cretaceous, France
YPM.6920
| Rudists are extraordinary clams from the Mesozoic that showed pronounced adaptations. Modern clams generally have 2 equal-sized shells (valves) held together by a flexible ligament. The 2 valves of rudists, in contrast, are dramatically different in size and shape. Most rudist families either lost or greatly reduced the ligament through the course of evolution. Like modern corals, rudists probably had symbiotic photosynthetic algae, which helped create ideal conditions for skeletal growth. |