Scaldicetus

Scaldicetus is an extinct genus of highly predatory macroraptorial sperm whale. Although widely used for a number of extinct physeterids with primitive dental morphology consisting of enameled teeth, "Scaldicetus" as generally recognized appears to be a wastebasket taxon filled with more-or-less unrelated primitive sperm whales.
Taxonomy.
"Scaldicetus" is known from the Miocene to Pleistocene deposits of Western Europe, the U.S. (California, Florida, Maryland, Virginia), Baja Peninsula, Peru, New South Wales, and Japan. However, "Scaldicetus" is probably a grade taxon, and fossil teeth assigned to it (largely due to the lack of distinguishing characteristics in fossil teeth alone) probably represent more-or-less unrelated sperm whales united by their primitive characteristics rather than actual ancestry. Consequently, this would inflate the genus's distribution.
The name "Scaldicetus caretti" was coined in 1867 from numerous sperm whale teeth collected in Neogene deposits near Antwerp, Belgium probably from the early-to-middle Miocene Bercham Formation. However, some of these remains may have been reworked and redeposited into younger rocks. More remains also near Antwerp from the Diest Formation date to the Tortonian (late Miocene).
Synonyms of "Scaldicetus" include "Palaeodelphis", "Homocetus", and "Eucetus". The genus "Physodon" described by French paleontologist Paul Gervais in 1872 was previously considered a synonym, but it was declared a "nomen dubium" in 2006.
"Scaldicetus" is sometimes classified into the dubious subfamily Hoplocetinae along with "Diaphorocetus", "Idiorophus", and "Hoplocetus" based on the presence of large, robust, enamel-coated teeth. The macroraptorial sperm whales "Livyatan", "Zygophyseter", "Brygmophyseter", and "Acrophyseter" potentially also belong to this subfamily.
""Ontocetus" oxymycterus", described from the middle Miocene (Langhian) of Santa Barbara, California, was assigned to "Scaldicetus" in 2008, but was subsequently made the type of a new genus, "Albicetus".
Tooth anatomy.
Unlike the modern sperm whale which only has teeth on the bottom jaw, "Scaldicetus" had teeth in both jaws. The lectotype for "S. caretti" had at least 45 teeth in total in its mouth in life. Like other macroraptorial sperm whales but unlike the modern sperm whale, the teeth were covered in a thick enamel coating, about thick. The teeth were moderately curved and were deeply rooted into the skull, implying a strong bite.
Like in other sperm whales, tooth dimensions vary widely; for the lectotype: the total length of the tooth root (the part of the tooth beneath the gum line) is between and the maximum total length of the entire tooth is . Like in other macroraptorial sperm whales, tooth size increased from the back of the jaw to the front. The maximum diameter of the crown (the part of the tooth that is visible and erupts from the gum line) ranges from , and diameter was greatest midway up the tooth.
Paleobiology.
The teeth of the lectotype of "S. caretti" exhibit vertical root fractures which were probably brought on by chewing hard food or repetitive application of excessive force while chewing or biting. It is likely these injuries were sustained while biting a fairly large vertebrate, such as various marine mammals as other macroraptorial sperm whales are suspected of hunting.
However, the killer whale–which preys on large marine mammals–is not known to exhibit these fractures, though this may be because killer whale teeth are more resistant to shock, having a smaller pulp cavity and, thus, a thicker tooth. Further, terrestrial carnivores that chew through bone display these fractures, and those that prey on larger prey have larger tooth roots. Like in the killer whale, "Scaldicetus" may have mashed its food in smaller pieces to ease swallowing, which would have increased the risk of hitting bone which would cause such fractures.
Like other macroraptorial sperm whales, "Scaldicetus" probably occupied the same niche as the killer whale.
Paleoecology.
The Deist Formation, judging from the mollusk assemblage, probably represented a shallow sea with volatile ocean currents, moving sand bars, and megaripples. Whale remains include a cetotheriid baleen whale, the baleen whale "Plesiocetus", a kentriodontid dolphin, and the beaked whale "Ziphirostrum". Shark remains were not very common; those found belong to the extinct broad-toothed mako (the ancestor of the great white shark), the extinct mako shark "Isurus desori", a "Squalus" dogfish, the angelshark, a sand tiger shark, and a "Pristiophorus" sawshark.