Ankalagon saurognathus

Ankalagon saurognathus Temporal range: Early Paleocene
Ankalagon saurognathus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	†Mesonychia
Family:	†Mesonychidae
Genus:	†Ankalagon Van Valen, 1980
Species:	†A. saurognathus
Binomial name
†Ankalagon saurognathus (Wortman, in Matthew, 1897)
Synonyms
Dissacus saurognathus

Ankalagon saurognathus is an extinct carnivorous mammal of the family Mesonychidae, endemic to North America during the Paleocene epoch (63.3—60.2 mya), existing for approximately 3.1 million years.^[1]

Known from the Paleocene of New Mexico, Ankalagon is the largest mesonychid known from the Paleocene of North America, and it provides the best evidence for sexual dimorphism in mesonychids.^[2]

Description

The main feature that distinguishes A. saurognathus from the ancestral Dissacus species is its size: Ankalagon grew to be as large as a bear,^[3] as compared to the coyote or jackal-sized species of Dissacus. In fact, the only North American mesonychids that surpassed Ankalagon in size were the larger species of the Early Eocene genus, Pachyaena, such as P. gigantea and P. ossifraga, which, too, grew to the size of bears.^[3]

Evidence of sexual dimorphism comes from the fact that some jawbones were larger, and had more massive molar teeth better suited to crushing bones than other jawbones, suggesting that the males crushed bones.^[2]

Ecology

The strong jaws, sharp, hooked canines and triangular molars that form a shearing edge typical of other mesonychids suggest that A. saurognathus was a hypercarnivorous apex predator. The massive molars of the males suggest that the males were also scavengers that ate bones.

Etymology

The generic name refers to the dragon Ancalagon, who was mentioned in The Silmarillion by J.R.R. Tolkien. In The Silmarillion, Ancalagon was described as being one of the more powerful servants of the malevolent being, Morgoth, having been bred to be the fiercest, mightiest, and largest dragon in all of Middle Earth. According to Tolkien, "Ancalagon" translates from Sindarin as being anc 'jaw', alag 'impetuous'.^[4]

Leigh Van Valen studied the New Mexico mesonychid Dissacus saurognathus and eventually came to the conclusion that D. saurognathus differed enough from the sympatric D. navajovius, and from other members of the genus to merit its own genus. Van Valen intended to erect the genus "Ancalagon," but found that it was already occupied by a Middle Cambrian priapulid described by Simon Conway Morris, Ancalagon minor, a possible free-living ancestor of the parasitic acanthocephalids.^[5]

The species name, "saurognathus," translates as "lizard jaw."

References