monotreme

American  

[mon-uh-treem] / ˈmɒn əˌtrim /

noun

1. any animal of the Monotremata, the most primitive order of mammals, characterized by certain birdlike and reptilian features, as hatching young from eggs, and having a single opening for the digestive, urinary, and genital organs, comprising only the duckbill and the echidnas of Australia and New Guinea.

---

monotreme British  

/ ˈmɒnəʊˌtriːm, ˌmɒnəʊˈtriːmətəs /

noun

1. any mammal of the primitive order Monotremata, of Australia and New Guinea: egg-laying toothless animals with a single opening (cloaca) for the passage of eggs or sperm, faeces, and urine. The group contains only the echidnas and the platypus

---

monotreme Scientific  

/ mŏn′ə-trēm′ /

1. Any of various mammals of the order Monotremata. Monotremes are the most primitive type of living mammal. They lay eggs and have a single opening (cloaca) for reproduction and elimination of wastes. The females have no teats but provide milk directly through the skin to their young. The only living monotremes are the duck-billed platypus, found in Australia and New Guinea, and the echidnas, found in New Guinea. Monotremes may have evolved already in the Jurassic Period, but the precise nature of their relationship to marsupials and placental mammals is disputed.

---

Other Word Forms

• monotrematous adjective

Etymology

Origin of monotreme

1825–35; < French monotrème < New Latin monotrema, assumed singular of Monotremata, neuter plural of monotrematus monotrematous

Example Sentences

Fossilised pieces of the animal's jaw bone were found in opal fields in northern New South Wales, alongside evidence of several other ancient and now extinct monotreme species.

From BBC • May 27, 2024

Recorded by science only once in 1961, Attenborough's long-beaked echidna is a monotreme: an evolutionarily distinct group of egg-laying mammals that includes the platypus.

From Science Daily • Nov. 9, 2023

Besides the duck-billed platypus, echidnas are the only other surviving monotreme: an ancient type of mammal that lays eggs.

From Slate • Jan. 28, 2023

Resembling a pug-size hedgehog with the schnoz of an anteater, they are one of only five living species of monotreme, that rare mammal that lays eggs.

From Science Magazine • Jan. 17, 2023

Moreover, it requires a large amount of material to form a mammalian egg, such as that of the monotreme.

From The Whence and the Whither of Man A Brief History of His Origin and Development through Conformity to Environment; Being the Morse Lectures of 1895 by Tyler, John Mason