Opossums: Order Didelphimorphia

Animals in the order Didelphimorphia are known as didelphimorphs, the opossums.  These American marsupials are a diverse group, including only one family but over 60 species. Most occupy Central and South America, but one species, Didelphis virginiana, occurs through most of the continental United States.

Origin of the name

The name opossum comes from the native american indian name (Alogonquin actually). The name was adapted to english during colonial times. Possum is a common abreviation of the name, although technically it represents a different group of australian marsupials. 

How many opossums are there?

Many websites list only 60 species of opossums. However, the most recent taxonomic overview lists 110. See classification below for a full list.

Physical Characteristics

All opossums are found in only one family within this order and thus, share a few key characters. 

Teeth: Opossums have a full set of teeth. Scientists give them a dental formula, which looks something like this (). That means they have five upper and four lower incisors on each side of the jaw, one canine, three premolars, and four molars.

Feet: Opossums are flat footed, which means they put their entire foot on the ground as they walk. They have a unique print that is easily distingushed in the field. 

What do Opossums Eat?

Opossums eat just about anything. They're considered omnivores, meaning you can find them munching on everything from berries to grub and anything in your dumpster. They're often found scavenging on roads, hence the large number that end up as roadkill. 

Where do Opossums Live? 

Opossums in the order Didelphimorphia are known as new world opossums. They are only found in north and south america. Most are found in south and central america. Only the virginia opossum has made it into the US and Canada.

Reproduction 

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Classification

The following taxonomy was compiled from Wilson and Reeder's Mammals of the World (2006).

Subfamily Caluromynae 

Genus Caluromys

• Caluromys philander - Bare-tailed Woolly Opossum
• Caluromys derbianus - Derby's Wooly Opossum
• Caluromys lanatus - Brown-eared Woolly Opossum

Genus Caluromysiops

• Caluromysiops irrupta - Black-shouldered Opossum

Genus Glironia

• Glironia venusta - Bushy-tailed Opossum

Subfamily Didelphinae

Genus Chironectes

• Chironectes minimus - Water Opossum (semi-aquatic) (Mexico to Argentina)

Genus Didelphis

• Didelphis albiventris - 
• Didelphis aurita -
• Didelphis imperfecta -
• Didelphis marsupialis -
• Didelphis pernigra -
• Didelphis virginiana - Virginia Opossum

Genus Gracilinanus

• Gracilinanus aceramarcae - 
• Gracilinanus agilis -
• Gracilinanus agricolai -
• Gracilinanus dryas -
• Gracilinanus emiliae -
• Gracilinanus formosus -
• Gracilinanus ignitus -
• Gracilinanus marica -
• Gracilinanus microtarsus - 

Genus Hyladelphys

• Hyladelphys kalinowskii - 

Genus Lestodelphys

• Lestodelphys halli - 

Genus Lutreolina

• Lutreolina crassicaudata -  

Genus Marmosa

• Marmosa andersoni - 
• Marmosa lepida - 
• Marmosa mexicana -
• Marmosa murina -
• Marmosa quichua -
• Marmosa robinsoni -
• Marmosa rubra -
• Marmosa tyleriana -
• Marmosa xerophila - 

Genus Marmosops

• Marmosops bishopi - 
• Marmosops cracens -
• Marmosops dorothea -
• Marmosops fuscatus -
• Marmosops handleyi -
• Marmosops impavidus -
• Marmosops incanus -
• Marmosops invictus -
• Marmosops juninensis -
• Marmosops neblina -
• Marmosops noctivagus -
• Marmosops parvidens -
• Marmosops paulensis -
• Marmosops pinheiroi - 

Genus Metachirus

• Metachirus nudicaudatus - 

Genus Micoureus

• Microureus alstoni -
• Microureus constantiae -
• Microureus demerarae -
• Microureus paraguayanus -
• Microureus phaeus -
• Microureus regina -      

Genus Monodelphis

• Monodelphis adusta -
• Monodelphis americana -
• Monodelphis brevicaudata -
• Monodelphis dimidiata -
• Monodelphis domestica -
• Monodelphis emiliae -
• Monodelphis glirina -
• Monodelphis iheringi -
• Monodelphis kunsi -
• Monodelphis maraxina -
• Monodelphis osgoodi -
• Monodelphis palliolata -
• Monodelphis rubida -
• Monodelphis scalops -
• Monodelphis sorex -
• Monodelphis theresa -
• Monodelphis umbristriata -
• Monodelphis unistriata -

Genus Philander

• Philander andersoni - 
• Philander frenatus -
• Philander mcilhennyi -
• Philander opossum -

Genus Thylamys

• Thylamys cinderella -
• Thylamys elegans -
• Thylamys karimii -
• Thylamys macrurus -
• Thylamys pallidior -
• Thylamys pusillus -
• Thylamys sponsorius -
• Thylamys tatei -
• Thylamys velutinus -
• Thylamys venustus -

Genus Tlacuatzin 

• Tlacuatzin canescens - 

Experts in Didelphids

• Robert S. Voss - American Museum of Natural History (voss(at)amnh.org)
• Sharon A. Jansa - University of Minnesota / Jansa Lab (jansa003(at)umn.edu)