This is a repository copy of The relationship between Neogene dinoflagellate cysts and global climate dynamics.

A group of mainly Cretaceous areoligeracean dinoflagellate cyst genera, which we call the "Cyclonephelium group", has proved difficult to classify. The group comprises Aptea,

15The Jurassic to Neogene (Miocene) dinoflagellate cyst genus Sentusidinium has a relatively 16 simple overall morphology. This genus, together with Batiacasphaera, Kallosphaeridium and 17 Pentafidia, comprises the Sentusidinium complex. This is distinct from the superficially similar 18 laterally asymmetrical and subspheroidal/lenticular Cyclonephelium complex. complex is clearly polyphyletic, and all three genera are in the order Gonyaulacales. However, 45Batiacasphaera and Pentafidia can not be confidently assigned to a family, whereas 46Kallosphaeridium and Sentusidinium are both in the family Gonyaulacaceae. The number of 47 species within the complex has been reduced to xxx to yyy; furthermore, all infraspecific taxa 48 have been eliminated. Introduction 54Many species of acavate, subspheroidal to lenticular, sexiform gonyaulacalean dinoflagellate 55 cysts (Fensome et al. 1993) with broadly apical archaeopyles, low-relief ornamentation and 56 generally no or very weak development of parasutures have been described from the Mesozoic 57 and Cenozoic. These can be divided into two groups, the Cyclonephelium complex and the 58Sentusidinium complex. The Sentusidinium complex is characterised by laterally symmetrical 59 cysts that belong to the family Gonyaulacaceae; this complex, which is the focus of the present 60 study, comprises the genera Barbatacysta, Batiacasphaera, Escharisphaeridia, 61 3 Kallosphaeridium, Pentafidia, Pilosidinium and Sentusidinium. The Cyclonephelium complex 62 consists typically of laterally asymmetrical, subspheroidal to lenticular cysts that belong to the 63 family Areoligeraceae; this complex is the focus of a separate ongoing study and includes the 64 genera Aptea, Canningia, Canninginopsis, Cerbia, Circulodinium, Cyclonephelium, 65 Senoniasphaera and Tenua. The genera Prolixosphaeridium, Bourkidinium and 66 Tanyosphaeridium are similar to Sentusidinium in having process-bearing cysts with apical 67 archaeopyles. However, all three genera have markedly elongate cyst bodies and generally 68 longer, nontabular processes. Consequently, we do not consider them in this paper. A brief history of the Sentusidinium complex 77The first genus to be described in the Sentusidinium complex was Kallosphaeridium, which was 78 established by de Coninck (1969) and emended by Jan du Chêne et al. (1985a). 79Kallosphaeridium comprises proximate cysts with a five-plate archaeopyle that can be 80 interpreted as apical (5A) or combination (4A1I); the operculum is attached ventrally. Drugg 81 (1970, p. 813) proposed Batiacasphaera for proximate cysts with "rod-shaped elements, either 82 separate or arranged to form a reticulum", and with an apical archaeopyle. This genus was later 83 emended by Morgan (1975) and Dörhöfer and Davies (1980) (see section 3). Sentusidinium was 84 erected by Sarjeant and Stover (1978) to contain proximate to proximochorate cysts with an 85 apical archaeopyle and bearing low-relief ornamentation. Psilate forms with apical archaeopyles, 86 in...