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Scaldicetus is an extinct genus of highly predatory macroraptorial sperm whale. Although widely used for a number of extinct with primitive dental morphology consisting of Tooth enamel teeth, Scaldicetus as generally recognized appears to be a wastebasket taxon filled with more-or-less unrelated primitive sperm whales.
The name Scaldicetus caretti was coined in 1867 from numerous physeteroid teeth collected in Neogene deposits near Antwerp, BelgiumDu Bus, B.A.L., 1867. Sur quelques Mammifères du Cragd’Anvers. Bulletin de l'Académie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique, 24: 562-577. probably from the early-to-middle Miocene Bercham Formation. However, some of these remains may have been zombie taxon 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, tooth 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,Kohno N, Ray CE. Pliocene walruses from the Yorktown Formation of Virginia and North Carolina, and a systematic revision of the North Atlantic Pliocene walruses. Virginia Museum of Natural History Special Publication. 2008;14: 39–80. but was subsequently made the type specimen of a new genus, Albicetus.
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.
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.
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 tooth enamel coating, about thick. The teeth were moderately curved and were deeply rooted into the skull, implying a strong bite.
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.
Paleoecology
The Deist Formation, judging from the mollusk assemblage, probably represented a shallow sea with volatile , moving , and . Whale remains include a Cetotheriidae baleen whale, the baleen whale Plesiocetus, a Kentriodontidae 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, a Squalus dogfish sharks, the angelshark, a Carcharias, and a Pristiophorus sawshark.
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