Squalodon

The extinct whales called Squalodon have tusk-like front teeth and molars which have the outline of a leaf with a coarsely "serrated" edge.

More Science From an Easy Chair 1888

The cetaceans or whales are widely different from all other mammals but the tertiary Zeuglodon and Squalodon, which have been placed by some naturalists in an order by themselves, are considered by Professor Huxley to be undoubtedly cetaceans, “and to constitute connecting links with the aquatic carnivora.

XI. On the Geological Succession of Organic Beings. On the Affinities of Extinct Species to Each Other, and to Living Forms 1909

These river Dolphins naturally come after the extinct Phocodontia or seal-toothed whales, and bear considerable resemblance in the dentition to the extinct genus Squalodon.

Natural History of the Mammalia of India and Ceylon Robert Armitage Sterndale 1870