| Popis: |
The Lower and basal Middle Albian ammonite Subfamily Lyelliceratinae Spath, 1921 is reviewed, and restricted to the genera Tegoceras Hyatt, 1903, Lyelliceras Spath, 1921, and Pseudobrancoceras Kennedy, 2004. An evolutionary origin in Brancoceratinae Spath, 1934 is proposed. The South American taxa from Colombia and Peru referred to Tegoceras, Lyelliceras, Prolyelliceras Spath, 1930b, and its synonym Ralphimlayites Etayo-Serna, 1979, are lyelliceratine homoeomorphs, derived independently from Brancoceratinae. The North African 'Prionotropis' radenaci Pervinquière, 1907 is tentatively referred to Prolyelliceras, while 'Lyelliceras' flandrini Dubourdieu, 1953 is a further lyelliceratine homoeomorph subgenerically or generically distinct from Prolyelliceras. The following are described from KwaZulu: Tegoceras mosense (d'Orbigny, 1841), T. collignoni (Breistroffer, 1953), T. camatteanum (d'Orbigny, 1841), Lyelliceras lyelli (d'Orbigny, 1841), L. pseudolyelli (Parona & Bonarelli, 1897), L. latili sp. nov., and Pseudobrancoceras versicostatum (Michelin, 1838). On the basis of this revision, a sequence of four faunas are recognized, characterized, successively, by the presence of 1: Tegoceras gladiator and Aioloceras, 2: Tegoceras camatteanum;3: Lyelliceras pseudolyelli, and 4: Lyelliceras lyelli, the appearance of the last-named marking the base of the Middle Albian Substage. |
