Wednesday, May 27, 2026

THE ECHIDNA FROM “DOWN UNDER”

The primitive mammal echidna (also known as the spiny anteater) is a quill-covered monotreme (i.e., a type of ancient marsupial). The echidna, along with the platypus, are the only egg-laying mammals living today. 

Figure 1. Two views (front and left side) of the extant echidna Trachyglossus sp(an 1863 public domain image).            


Kingdom Animalia

Phylum Chordata

Class Mammalia

Clades (two of them)

Order Monotremata

Family Trachyglossidae

Genus Tachyglossus

Type Species T. aculaeatus  


There are two living genera: Tachyglossus lives in Australia and New Guinea and Zaglossus, which lives only in New Guinea. The former has no known fossil species, but Zaglossus has two fossil species (known only from New Guinea).


The echidna is a quill-covered monotreme-type of ancient marsupial and is an egg-laying mammal. Echidnas are closely related to another egg-laying mammal, namely the duck-billed platypus. These are the only groups of living mammals that lay eggs.


Echidnas do not have a poison spur. They also have no teeth. Although they are unable to bite or chew, they use their long sticky tongues to catch termites. Echidnas are powerful diggers! They do not have a venous spur.


The fossil record of echidnas is poorly constrained, but they apparently evolved from the duck-billed playpus sometime between 112 and 19 million years ago (middle Cretaceous to early Miocene).



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