Palaeontologica Polonica 47, 4, 667-672 (2002)
evolutionary changes of the Early Cretaceous (Valanginian) marine gastropod
Rissoina (Buvignieria) sp. from W¹wa³ (central Poland) show a pattern
typical of the Ancient Lake Concept. Its morphology is stable during period of
unstable conditions and starts to change gradually when the environment
becomes stable. The linear character of the evolutionary changes of Rissoina
sp. and lack of evolution among co-occuring gastropods suggests that the rate
of evolution was controlled by intrinsic factors, not the environment.