premolars and lacks accessory denticles. P2 is the largest upper tooth and the first in the upper row with large accessory denticles. Like the more posterior premolars, it is buccolingually compressed and double-rooted. It has a dominant central protocone flanked by denticles that decrease in size mesially and distally, resulting in a tooth with a triangular profile. P3 is similar to but slightly smaller than P2, except that it has a projection on the lingual side which is the remnant of a third root. In P4, smaller than P2–3, the larger distal root is formed by the fusion of two roots. The upper molars extend onto the zygomatic arch and are considerably smaller than their neighbouring premolars. Like P4, their distal root is wider than the mesial and formed by the fusion of two roots. The profiles of the molars are more rounded than those of the premolars. Similar to the upper incisors, the lower incisors are simple conical teeth curved distally and aligned with the cheek teeth. I1, the smallest tooth, is sitting on the anteriormost portion of the dentary, with its alveolus left open towards the mandibular symphysis and located as close to the alveolus of I2 as it can. I2, I3, and C1 are very similar, considerably larger than I1. The lower premolars are double-rooted, buccolingually compressed teeth, except the deciduous P1 which is single-rooted. P3 is the second largest cheek tooth, P4 the largest; both are very similar, dominated by the central cusp. In the lower molars the accessory denticles on the mesial edges are replaced by a deep groove called the reentrant groove. The apical cusp is the primitive protoconid. M2 and M3 are morphologically very similar. M3 is sitting high on the ascending mandibular ramus. Paleoecology Dorudon calves may have fallen prey to hungry Basilosaurus, as shown by unhealed bite marks on the skulls of some juvenile Dorudon. See also Evolution of cetaceans References Notes Sources Haines, Tim & Chambers, Paul. (2006) The Complete Guide to Prehistoric Life. Canada: Firefly Books Ltd. External links BBC Wildfacts: Dorudon Eocene mammals of Africa Basilosauridae Eocene mammals of North America Prehistoric cetacean genera Fossil taxa described in 1845