LAMNIFORM FAMILY INCERTAE SEDIS (I)
The extinct genus Archaeolamna was established for taxa earlier places amongst the Odontaspids, though perhaps has greater similarities with the Otodontids, and has also been placed with the Cretoxyrhinids (illustrating how poorly resolved Lamniform taxonomy can be).
The tearing teeth of Archaeolamna are medium sized, with a tall and slender main cusp, broad and well-developed accessory cusps, and pointed root halves separated by a broad, open basal notch. They differ from Cretalamna in lacking the distinctive square root halves, and from Dwardius in possessing a continually narrow lingual neck, and a more distally narrow main cusp. They lack the deep nutritive cleft and basal wrinkles to the crown that are commonly seen in Odontaspids, and also have broader accessory cusps than that group.
1). (A) Archaeolamna sp. - Labial view of an isolated tooth exhibiting forked root halves and broad accessory cusps (x6.0, Grey Chalk (channel lag deposit in West Melbury Marly Chalk), Southerham, near Lewes, Randell Collection RR1821); (B) Archaeolamna kopingensis (?) - Labial view of a lateral tooth (inclined main cusp) (x10.1, Grey Chalk, Samphire Hoe, near Dover, Joe Shimmin collection, image used by kind permission).