Faded Genes: The 7 Most Primitive Living Mammals

Solenodon

Faded Genes: The 7 Most Primitive Living Mammals(image via: belgianchocolate)

Solenodons (fam. Solenodontidae) are the poster kids for the “living fossil” designation, having barely changed over the past 75-odd million years. Resembling large shrews with scaly, hairless tails, solenodons are found today in Cuba and on the Caribbean island of Hispaniola. When threatened, solenodons exude an unpleasant odor that reminds many of goats… LOTS of goats.

Faded Genes: The 7 Most Primitive Living Mammals(image via: Biodiversity Heritage Library)

If their unsavory appearance isn’t enough reason to avoid getting in a solenodon’s face, these primitive mammals are also venomous. Study of the creatures venom, excreted by modified salivary glands and transmitted via biting, show that is has similarities to snake venom. Solenodons are also unique in that they have a ball joint at the internal base of their long snout, which allows it a surprising degree of flexibility when hunting its primarily insect and earthworm prey.

Yapok

Faded Genes: The 7 Most Primitive Living Mammals(image via: akhenatenator)

The Yapok (Chironectes minimus) or Water Opossum is the only aquatic marsupial – platypuses are monotremes, remember. Their prime habitats border freshwater streams and lakes from southern Mexico down through central and South America to northern Uruguay. Yapoks have webbed feet, but only on their hind legs – their front paws are clawed and web-free. The IUCN classifies the Yapok as being of Least Concern but eventually human pressure for land development and by the fur industry may change that rating.

Faded Genes: The 7 Most Primitive Living Mammals(image via: Biodiversity Heritage Library)

Yapoks have pouches but the female is able to strongly close her pouch to protect offspring inside. Males have pouches as well, though they are less watertight and are used to enclose the males’ genitalia when swimming. The extinct Tasmanian Tiger, or Thylacine, was the only other marsupial in which both sexes were equipped with pouches.