Among several species of Mursia, Mursia obscura RATHBUN, 1919 from the middle Oligocene of Panama Canal Zone is the oldest and similar to Mursia armata and to Cycloes. Mursia marcusana RATHBUN 1926 has been reported from the upper Oligocene Blakeley formation of Washington. This species has ridges and tubercles on the surface of the carapace similar to those of Mursia armata. Mursia yaquinensis RATHBUN, 1926 from the Oligocene of Yaquina City, Oregon State is similar to Mursia gaudichaudii, which inhabits along the Pacific coast of North America and South America. Mursia takahashii IMAIZUMI, 1952 from the Miocene of Sendai, Japan is also of armata type. Necrocarcinus of the Calappidae has about twenty species. Only one species, Necrocarcinus hannae RATHBUN, 1926 has been known from the Eocene (Tejon of ARNOLD) of California. Necrocarcinus of the Albian evolved to Cenomanocarcinus of the Turonian through the transitional species, Necr. tricarinatus BELL (Cenomanian, England), Necr. texensis RATHBUN (upper Albian, Texas), and Necr. graysonensis RATHBUN (upper Albian, Texas). Necrocarcinus hannae is very similar to Mursia. Mursia takahashii evolved to Mursia armata curtispina which has the widest distribution among the recent species.
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