First bryozoan fauna from the Eocene–Oligocene transition in Tanzania

<p>Records of Cenozoic tropical bryozoan faunas are sparse, particularly from Africa. Here we describe a previously unknown bryozoan ‘sand fauna’ from a drill core across the Eocene–Oligocene boundary from a hemipelagic clay succession in Tanzania. Although low in diversity, this well-preserved fauna includes four cheilostome species, all new to science: <i>Heteractis tanzaniensis</i> sp. nov., <i>Bragella pseudofedora</i> gen. et sp. nov., <i>Lacrimula kilwaensis</i> sp. nov. and <i>L. crassa</i> sp. nov. The four species vary in mineralogy, with <i>H. tanzaniensis</i> having an entirely aragonitic skeleton, <i>B. pseudofedora</i> being bimineralic and the two species of <i>Lacrimula</i> calcitic. These species have either free-living ‘lunulitiform’ (<i>H. tanzaniensis</i>) or rooted ‘conescharelliniform’ (<i>B. pseudofedora</i>, <i>L. kilwaensis</i> and <i>L. crassa</i>) colonies adapted to life on a soft, unstable seafloor. The peak occurrence of bryozoans in the core coincides with the Eocene–Oligocene Glacial Maximum (EOGM), characterized by global environmental change from a greenhouse to an icehouse world, sea-level fall, cooling of the oceans and changes in water circulation that may have led to enhanced nutrient levels favourable to bryozoans both in Tanzania and elsewhere.</p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:6E49FB4A-EB50-4BCE-9D3D-B139CB5D4C5A" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:6E49FB4A-EB50-4BCE-9D3D-B139CB5D4C5A</a>