Alvonatalia

Alvonatals Temporal range: Late Cretaceous-Holocene 83.173–0 Ma PreЄ Є O S D C P T J K Pg N Possible Early Cretaceous records
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An adult TBD (left), TBD (center), and TBD (right)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Alvonatalia
Subgroups
TBD TBD TBD

Alvonatals are a xenotherian infraclass of the order Alvonatalia. Unlike the three primary infraclasses of Mammalia – placentals (Eutheria), marsupials (Metatheria), and monotremes (Prototheria) – alvonatals are unique in that all extant species of the infraclass hail from off-world rather than originating on Earth. Alvonatals are distinguished by their method of asexual reproduction, where live young are born through a navel cavity which remains sealed between births. Furthermore, sexual dimorphism within alvonatal species is based around community roles rather than utility within the reproductive cycle.

Most alvonatal species give birth to substantially more developed precocial young, which are capable of movement from the moment of birth. As with placentals and marsupials, alvonatals are nourished within the placenta of an apex alvonatal until birth, and are partially-nursed and protected by mesa alvonatals until capable of digesting solid foods on their own. However, the vast majority of alvonatal newborns can see, hear, and move on their own from the moment of birth. Alvonatals represent the overwhelming majority of mammalian lifeforms residing on the planet of TBD, and most of the animal life imported to the other worlds inhabited by TBD are comprised of alvonatals.

The word alvonatal is derived from the Latin words alvus ("belly" or "stomach") and nātus ("born"), referring to the method of birth via the navel cavity.