A review of fossil Bursidae and their use for phylogeny calibration Author Sanders, Malcolm T. Author Merle, Didier Author Puillandre, Nicolas text Geodiversitas 2019 2019-03-08 41 5 247 265 journal article 10.5252/geodiversitas2019v41a5 1dd366f3-9e6d-4dcf-a082-408a0ea91bc4 1638-9395 3699932 urn:lsid:zoobank.org:pub:33E8EF32-4BE4-4992-9917-8611CA0AD579 Genus Olssonia n. gen. urn:lsid:zoobank.org:act: 9BB6F0C9-71ED-4F96-BAE8-3BA325B57714 TYPE SPECIES. — Bursa chira Olsson, 1930 . DERIVATIO NOMINIS. — Dedicated to the American palaeontologist A. A. Olsson. SPECIES INCLUDED. — Olssonia chira ( Olsson, 1930 ) n. comb. , O. yasila ( Olsson, 1930 ) n. comb. DISTRIBUTION. — Olssonia n. gen. is a genus restricted to the Eocene to early Miocene of Peru . DIAGNOSIS. — Shell biconic, dorsoventrally compressed, shortspired, with 7 primary cords on the convex part of the whorl, all but P1 evenly reduced in variceal and intervariceal intervals of each whorl (P1 hardly more expressed than other cords); posterior siphonal canal short; varices strictly aligned; prominent columellar callus. COMPARISONS. — Olssonia n. gen. resembles Marsupina but possesses a lesser number of primary cords on the convex part of the whorl ( 7 in Olssonia n. gen. , 8 in Marsupina ). It resembles Aspa but has a much more prominent columellar callus, it is much more granulose, and it has a more sharply defined shoulder and a wider spire angle. Olssonia n. gen. resemble Bufonaria ( Fig. 3B ), with the same straight anterior siphonal canal, but lacks a spine or blade on the posterior siphonal canal ( Fig. 3B ; white arrow). REMARKS The representatives of this genus are the oldest confirmed Bursidae ; as such they can be used to calibrate the node Bursidae .