Stagodontidae is an extinct family of

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...

metatherian

mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur o ...

that inhabited

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

and

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

during the

late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

, and possibly to the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...

Description

Currently, the family includes four genera, '' Eodelphis'', '' Didelphodon'', '' Fumodelphodon'' and '' Hoodootherium'', which together include some seven different species. In addition, the

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in ...

species '' Pariadens kirklandi'' might be a member of the family. Carneiro and Oliveira (2017) considered the species '' Eobrasilia coutoi'' from the early

(

Itaboraian The Itaboraian ( pt, Itaboraiense) age is a period within the Early Eocene geologic time (53.0–50.0 Ma) epoch of the Paleogene, used more specifically with South American land mammal ages (SALMA). It follows the Riochican and precedes the Cas ...

) of

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

to be a stagodontid; if confirmed it would make it the only known

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configu ...

and the only known

n member of the family. Stagodontids were some of the largest known Cretaceous mammals, ranging from in mass. One of the most unusual features of stagodontids are their robust, bulbous premolars, which are thought to have been used to crush

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...

mollusks Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

, a diet that apparently evolved independently at least twice within this clade. Postcranial remains suggest that stagodontids may have been semi-aquatic. The most well described forms are found in

Laramidia Laramidia was an island continent that existed during the Late Cretaceous period (99.6–66 Ma), when the Western Interior Seaway split the continent of North America in two. In the Mesozoic era, Laramidia was an island land mass separated from A ...

, but they are also present on Appalachian and

n sites, further leading credence to their aquatic habits. Cretaceous fossils were also found in

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

, suggesting a pan-Laurasian distribution for Cretaceous metatherians. The evolution of ''Didelphodon'' and other large stagodontids (as well as large

deltatheroidean Deltatheroida is an extinct group of basal metatherians that were distantly related to modern marsupials. The majority of known members of the group lived in the Cretaceous; one species, '' Gurbanodelta kara'', is known from the late Paleocene ( ...

s like ''

Nanocuris ''Nanocuris'' is an extinct genus of Deltatheridiidae from the Cretaceous of Canada (Saskatchewan) and United States ( Wyoming - Lance Formation).R. C. Fox, C. S. Scott, and H. N. Bryant. 2007. A new, unusual therian mammal from the Upper Creta ...

'') occurs after the local extinction of eutriconodont mammals, suggesting passive or direct ecological replacement. They are considered rare in any given fauna they appear in, probably due to their specialised habits.

Classification

Stagodontids were once thought to be closely related to the

Sparassodonta Sparassodonta (from Greek to tear, rend; and , gen. , ' tooth) is an extinct order of carnivorous metatherian mammals native to South America, related to modern marsupials. They were once considered to be true marsupials, but are now t ...

, but later studies suggest they belong to a more ancient branch of the metatherian family tree, possibly closely related to pediomyids, being in particular closest to '' Pariadens'', which forms the immediate outgroup to Stagodontidae. With the possible exception of ''Eobrasilia'' (see above), stagodontids are last known from the

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the inte ...

, and are thought to have gone extinct in the K-T Extinction. * Family Stagodontidae ** Genus '' Didelphodon'' *** ''Didelphodon coyi'' *** ''Didelphodon padanicus'' *** ''Didelphodon vorax'' ** Genus '' Eodelphis'' *** ''Eodelphis browni'' *** ''Eodelphis cutleri'' ** Genus '' Fumodelphodon'' *** ''Fumodelphodon pulveris'' ** Genus '' Hoodootherium'' *** ''Hoodootherium praeceps''

References

{{- Metatheria Late Cretaceous mammals of North America Prehistoric mammal families Turonian first appearances Late Cretaceous extinctions