''Bisonalveus'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of shrew-like

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s that were presumably ground-dwelling and fed on

plants Plants are the eukaryotes that form the kingdom Plantae; they are predominantly photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars f ...

and

insects Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...

. ''Bisonalveus'' fossils have been discovered in the upper

Great Plains The Great Plains is a broad expanse of plain, flatland in North America. The region stretches east of the Rocky Mountains, much of it covered in prairie, steppe, and grassland. They are the western part of the Interior Plains, which include th ...

region of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, including sites in modern-day

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

North Dakota North Dakota ( ) is a U.S. state in the Upper Midwest, named after the indigenous Dakota people, Dakota and Sioux peoples. It is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minneso ...

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

, and

Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...

. The fossils have been dated to 60 million years ago, during the Tiffanian North American Stage of the Palaeocene epoch. ''Bisonalveus'' is the last known genus of the Pentacodontinae sub-family to have arisen, replacing the genus '' Coriphagus'' in the early Tiffanian. ''Bisonalveus'' itself appears to have gone extinct by the middle Tiffanian. ''Bisonalveus'' is represented by two known species: ''B. browni'' (Gazin, 1956) and ''B. holtzmani'' (Gingerich, 1983).

''Bisonalveus browni''

''Bisonalveus browni'' was discovered in 1956 from fossilized jaw fragments (including molars). Later discovered fossils included front teeth and a dagger-like canine tooth with an enameled groove. The canines do not have a corresponding surface on the lower jaw, indicating that they were not used for chewing, but rather for stabbing. That would mean ''Bisonalveus'' was a predator, presumably hunting small insects. The grooves on the canines may have been used for delivering venomous saliva into the prey, which would thereby make ''Bisonalveus'' one of the few known

venomous mammals Venomous mammals are animals of the Class (biology), class Mammalia that produce venom, which they use to kill or disable prey, to defend themselves from predators or Biological specificity#Conspecific, conspecifics or in Agonistic behaviour, agon ...

. Perhaps, like the modern

solenodon Solenodons (from , 'channel' or 'pipe' and , 'tooth') are venomous, nocturnal, burrowing, insectivorous mammals belonging to the family Solenodontidae . The two living solenodon species are the Cuban solenodon (''Atopogale cubana'') and t ...

, ''Bisonalveus'' bit its victims to inject its toxic saliva and buried the immobilized prey in a cache for later consumption. However, because several nonvenomous mammals (such as baboons and other primates) have similar grooves on their teeth, some scientists have questioned whether these grooves truly indicate venom delivery. If ''Bisonalveus'' was a forager, the grooves might have served the purpose of introducing (nonvenomous) saliva for digestive reasons. Alternatively, the grooves might have been useful as they increased the amount of enamel on the canines, thereby strengthening these slender teeth.

''Bisonalveus holtzmani''

''Bisonalveus holtzmani'' is named for Dr. Richard Holtzman, who, in 1978, described the first tooth that was later determined to belong to this species. ''B. holtzmani'' can be distinguished from ''B. browni'' in that it is about 30% larger.

References

{{Taxonbar, from=Q2258423 Cimolestans Paleocene mammals Paleocene genus extinctions Prehistoric mammals of North America Prehistoric mammal genera