Geologic Time

The Earth has existed for about 4.5 billion years old, but animals did not appear until 540 million years ago.  This period is called the Palaeozoic era, and lasted from 540 million years ago until 245 million years.  The next period in the Earth's development started 245 million years ago and lasted until 65 million years ago, at which point about 80 to 90% of all animals were killed, with the main exception being birds.  This was the Mesozoic era.  After it came the Cenozoic era which began about 65 million years ago and is the period we live in now.  During this time mammals diversified into an amazing variety of creatures, of which a large percentage are long since extinct.   Below is a table laying out these periods in the earth's development in greater detail.  They will be used to show the development of the platypus and at which stages its ancestors existed.

Paleozoic era

544 to 245 million years ago

Mesozoic era

245 to 65 million years ago

Cenozoic era

65 million years ago to today


544 to 505 mya


245 to 208 mya


65 to 1.8 mya


505 to 440 mya


208 to 146 mya


1.8 mya to today


440 to 410 mya


146 to 65 mya



410 to 360 mya

mya = million years ago


360 to 286 mya


286 to 245 mya


On the whole, little is known about the ancestry of the platypus.  But a variety of different fossils have been found that seem to show that the platypus had ancestors which had similar attributes.  It has been suggested that the platypus developed as a result of therian mammals (metatherians and eutherians) diverging over 180 million years ago (Connolly et al, 1999).  In addition a fossilised bone analysed by Meng & Wyss (1995) seems to suggest that the monotremes are related to the long extinct multituberculates.

In 1985, the fossil of an opalised lower jawbone with 3 molar teeth (Steropodon Galmani) was found in New South Wales, Australia (Grant, 1989).  It was an early ancestor of the platypus which existed about 110 million years old.  This means that there was a platypus-like animal alive in the Cretaceous period, around the time of the dinosaurs.  It is the oldest mammal fossil that has been found in Australia, so far.

The next possible ancestor of the platypus was discovered in Patagonian sediment that was over 60 million years old (Thwaites, 1991).  It was a fossil tooth that has been dated to about 62 million years old.

South America and Australia used to be joined together.  During the Earth's development, they eventually separated to form their own landmass.  No other fossils have been found in South America that can be linked to the platypus.  There have been no suggestions as to why the platypus continued to evolve in Australia but died out in South America after the two continents separated.

Fossils of other platypus ancestors have been found.  Three of them are Obduron Insignis, Obduron Dicksoni, and Obduron Species A, which were all discovered in Australian sediments.  These animals existed between 15 and 25 million years ago.  It is thought that all of them kept their teeth into adulthood, hence the name Obduron, which means enduring teeth.  These species are different to the present day platypus, because it does not have teeth, only a plate to grind its food.  The Obduron Insignis is the most recent of the three platypus relatives and it is though to have existed about 15 million years ago (Grant, 1989).

Fossils have been found of the present day platypus (Ornithorhynchus Anatinus), with the oldest one dating back to about 100,000 years ago, which is the Quaternary period.   


Fossil evidence has shown that the platypus has ancestral connections to animals that lived in the Cretaceous period.  One question that arises is how did the platypus evolve into the animal it is today.  Two theories have been suggested to explain the way in which the platypus and other monotremes, e.g. echidna, has evolved in relation to two other mammal groups; the marsupials, e.g. kangaroos, and the placentals, which are animals that use a placenta to aid the rearing of their young.

The first (Theory B) is that relatives of the monotremes formed their own evolutionary branch that was distinct from the development of both the marsupials’ and the placentals’ relatives.  This is thought to have occurred over 135 million years ago, at the beginning of the Cretaceous period.  Then at some point between 135 and 65 million years ago, the marsupials and the placentals divided to go their own evolutionary route.

The second theory (Theory A) was first proposed by Gregory (1947), but did not become popular until the 1970s (Hamilton, 1988).  His proposal was that at some point between 135 and 65 million years ago, the monotremes and the marsupials separated from the placentals, causing them to evolve in a different way.  After this the monotremes and marsupials separated from each other.  These two theories are shown in the diagram below

The evidence to support Gregory’s theory is that the reproductive processes of both the marsupials and the monotremes have a remarkable similarity.  The embryos of both groups are at some stage encased in a shell during the gestation period.  In the case of the monotremes this occurs for the whole gestation period, but for marsupials the shell is only present for two thirds of the gestation period.   


The Aboriginal population had known about the platypus for many centuries.  But it was not until 1797 that the Europeans discovered them.  The first scientific examination and description of the platypus was made by George Shaw.  He gave the platypus the name - Platypus anatinus.  He published his findings in Naturalists Miscellany vol X in 1799.  This is his description:


"The animal exhibited on the preſent plate conſtitutes a new and ſingular genus, which, in the Linnćan arrangement of Quadrapeds, ſhould be placed in the order Bruta, and ſhould ſtand next to the genus Myrmecophaga.

Of all the Mammalia yet known it ſeems the moſt extraordinary in its confirmation; exhibiting the perfect resemblance of the beak of a Duck engrafted on the head of a quadraped.  So accurate in the ſimilitude that, at firſt view, it naturally exhibits the idea of ſome deceptive preparation by artificial means: the very epidermis, proportion, ſerratures, manner of opening, and other particulars of the beak of a ſhoveler, or other broad-billed ſpecies of duck, preſenting themſelves to the view: nor is it without the moſt minute and rigid examination that we can perſuade ourſelves of its being the real beak or ſnout of a quadraped.

The body is depreſſed, and has ſome reſemblance to that of an Otter in miniature: it is covered with a very thick, ſoft, and beaver-like fur, and is of a moderately dark brown above, and of a ſubferuginous white beneath.  The head is flattiſh, and rather ſmall than large: the mouth or ſnout, as before obſerved, ſo exactly reſembles that of ſome broad-billed ſpecies of duck that it might be miſtaken for ſuch: round the baſe is a flat, circular membrane, ſomewhat deeper or wider below than above; viz. below near the fifth of an inch, and above about an eighth.  The tail is flat, furry like the body, rather ſhort, and obtuſe, with an almoſt bifid termination: it is broader at the baſe, and gradually leſſens to the tip, and is about three inches in length: its color is ſimilar to that of the body.  The length of the whole animal from the tip of the beak to that of the tail is thirteen inches: of the beak an inch and half.  The legs are very ſhort, terminating in a broad web, which on the fore-feet extends to a conſiderable diſtance beyond the claws; but on the hind-feet reaches no farther than the roots of the claws.  On the fore-feet are five claws, ſtrait, ſtrong, and ſharp-pointed: the two exterior ones ſomewhat ſhorter than the three middle ones.  On the hind feet are ſix claws, longer and more inclining to a curved form than those of the fore-feet: the exterior tow and claw are conſiderably ſhorter than the four middle ones: the interior or ſixth is ſeated much higher up than the reſt, and reſembles a ſtrong, ſharp ſpur.  All the legs are hairy above, and naked below.  The internal edges of the under mandible, (which is narrower than the upper) are ſerrated or channelled withnumerous ſtriae, as in a duck’s bill.  The noſtrils are ſmall and round, and are ſituated about a quarter of an inch from the tip of the bill, and are about the eighth of an inch distant from each other.  There is no appearance of teeth: the palate is removed, but ſeems to have reſembled that of a duck: the tongue alſo is wanting in the ſpecimen.  The ears are auditory foramina are placed about half an inch beyond the eyes: they appear like a pair of oval holes of the eighth of an inch in diameter; there being no external ear.  On the upper part of the head, on each ſide, a little beyond the beak, are ſituated two ſmalliſh, oval, white ſpots; in the lower part of each of which are imbedded the eyes, or at leaſt the parts allotted to the animal for ſome kind of viſion; for from the thickneſs of the fur and the ſmallneſs of the organs they ſeem to have been but obſcurely calculated for diſtinct viſion, and are probably like those of Moles, and ſome other animals of that tribe; or perhaps even more ſubcutaneous; the whole apparent diameter of the cavity in which they were placed not exceeding the tenth of an inch.

When we conſider the general form of this animal, and particularly its bill and webbed feet, we ſhall readily perceive that it muſt be a reſident in watery ſituations; that it has the habits of digging or burrowing in the banks of rivers, or under ground; and that its food conſiſts of aquatic plants and animals.  This is all that can at preſent be reaſonably gueſſed at: future obſervations made in its native regions, will, it is hoped, afford us more ample information, and will make us fully acquainted with the natural hiſtory of an animal which differs ſo widely from all other quadrapeds, and which verifies in a moſt ſtriking manner the obſervation of Buffon; vizs. that whatever was poſſible for Nature to produce has actually been produced.

On a ſubject ſo extraordinary as the preſent, a degree of ſceptiſm is not only pardonable, but laudable; and I ought perhaps to acknowledge that I almoſt doubt the teſtimony of my own eyes with reſpect to the ſtructure of this animal’s beak; yet muſt confeſs that I can perceive no appearance of any deceptive preparation; and the edges of the rictus, the inſertion, &c. when tried by the teſt of maceration in water, ſo as to render every part completely moveable ſeem perfectly natural; nor can the moſt accurate examination of expert anatomiſts diſcover any deception in this particular.

The Platypus is a native of Auſtralaſia or New Holland, and is at preſent in the poſſeſſion of Mr. Dobson, ſo much diſtinguished by his exquiſite manner of preparing ſpecimens  of vegetable anatomy."

On later pages Shaw adds the following:-

"In the deſcription of the animal called Platypus, in a preceding number of this publication, I obſerved that “, a degree of ſceptiſm is not only pardonable, but laudable; and I ought perhaps to acknowledge that I almoſt doubt the teſtimony of my own eyes with reſpect to the ſtructure of this animal’s beak.”  I therefore recommend to the attention of thoſe who may be equally zealous in the inveſtigation of a point ſo intereſting, the deſcriptions given by Pallas, Guldenſtedt, and Lepechgin of an animal, not indeed very rare in ſome parts of Europe, but which ſeems to have been hitherto but indifferently figured, and, till lately, but very imperfectly described, viz. the Sorex maſchatus Lin.  In this animal, in ſome particulars, an evident approach ſeems to be made to the Platypus; and though the ſtructure of the feet differs as to exact ſimilitude, there is yet a general reſemblance; except that the authros above mentioned repreſent the hind feet as much more widely webbed than the fore; the contrary of which is the caſe in the Platypus: the tail is alſo of a widely different appearance.  It is undeniable however that no animal would ſo well anſwer for an experiment of ingenious deception as the Sorex moſchatus.  Upon the whole this paradoxical quadraped muſt be left to future inveſtigation, and we muſt be content at preſent to remain ignorant of its real nature."

This first sighting of the platypus was made on the banks of a lake near Hawkesbury River, New South Wales.  This platypus find was recorded by Lieutenant-Colonel David Collins in his "Account of the English Colony in New South Wales" p in 1802.  He describes it thus:

"The Kangaroo, the Dog, the Opossum, the Flying Squirrel, the Kangaroo Rat, a spotted Rat, the common Rat, and the large Fox-bat (if entitled to a place in this society), made up the whole catalogue of animals that were known at this time, with the exception which must now be made of an amphibious animal, of the mole species, one of which had been lately found on the banks of a lake near the Hawkesbury.  In size it was considerably larger than the land mole.  The eyes were very small. The forelegs, which were shorter than the hind, were observed, at the feet, to be provided with four claws, and a membrane, or web, that spread considerably beyond them, while the feet of the hind legs were furnished, not only with this membrane or web, but with four long and sharp claws, that protected as much beyond the web, as the web projected beyond the claws of the fore feet.  The tail of this animal was thick, short, and very fat; but the most extraordinary circumstance observed in its structure was, its having, instead of the mouth of an animal, the upper and lower mandibles of a duck.  By these it was enabled to supply itself with food, like that bird, in muddy places, or in the banks of the lakes, in which its webbed feet enabled it to swim, while on shore its long and sharp claws were employed in burrowing; nature thus providing for it in its double or amphibious character.  These little animals had been frequently noticed rising to the surface of the water, and blowing like the turtle." (Fleay 1980, pp.xiii-xiv)

Three years later Thomas Bewick (1805) made one of the first drawings of the platypus, with it he wrote the following description:

"Is found in the fresh water lakes . . . about the size of a small Cat, it chiefly frequents the banks of the lakes; its bill is very similar to that of a Duck, and it probably feeds in muddy places in the same way; its eyes are very small; it has four short legs; the fore legs are shorter than those of the hind, and their webs spread considerably beyond the claws, which enables it to swim with great ease; the hind legs are also webbed, and the claws are long and sharp.  They are frequently seen on the surface of the water, where they blow like a turtle: their tail is thick, short and very fat." (Fleay 1980, p.xiv).

The first platypus specimens reached Britain in 1798.  Some of them were skins, others were stuffed, but they were all thought to be fakes.  This was because the Chinese were selling "mermaids" to the visiting sailors.  These "mermaids" were created from the mummified bodies of monkeys that were cleverly attached to the tails of fish by the local taxidermists.  At a later date some specimens, which had been preserved in spirit, were sent to Britain.  This made it easier for the scientists to believe in the existence of such an animal, and it gave them the opportunity to begin to examine its anatomy and physiology.

Everard Jones was one of the first people to dissect a platypus and he published a paper in 1802 to this effect (Barrett, 1944).  He ruled out any possibility that it was a fake and ensured that it was without doubt a member of the animal kingdom, but he did not resolve the mammal, reptile, and other creature paradox.

There had been rumours before, especially from the indigenous population, that the platypus laid eggs, but as usual there was a lot of scepticism about this strange animal.  The first sighting of such an event was observed at Woods Point, Victoria in 1864 where a captive platypus laid two eggs.  However, it took another 20 years before W.H.Caldwell (1884; Barrett, 1944) proved the egg-laying ability of the platypus beyond all scientific doubt.  It had taken almost a century for the scientists to decide that the monotremes (platypus & echidnas) were mammals, but were a separate group within this class.   


The platypus has been called a variety of different names.  The aborigines called it mallangong, boondaburra and tambreet.  With the arrival of the Europeans the platypus was given other names such as duckbill, watermole, duckmole and platypus.  In 1799, George Shaw was the first to attempt to name it scientifically, when he called it Platypus Anatinus, which means flat-footed and bird-like.  The platypus is not actually flat-footed but it could seen as being so, because its webbed feet make it look flat-footed.

 The German anatomist Blumenbach later changed the name to Ornithorhynchus Paradoxus (a paradox of an animal with a bird-like mouth), because it was found that a beetle had all ready been given the name platypus (Barrett, 1944).  The next change in the platypus’ name was to Ornithorhynchus Anatinus, which means duck-like animal with a bird-like mouth.  However, the name platypus was the one preferred by most people, which is why it has remained.   


In the 1800s, the platypus was hunted for its fur.  Due to their size it would take many pelts to make anything useful, e.g. a full-length coat requires over 70.  This had a devastating affect on the platypus population, to such an extent that the Government introduced laws to protect them and conservation programmes to increase their numbers.   


Barrett, C., 1944. The Platypus. Robertson & Mullens: Melbourne.

Bewick, T., 1805. A General History of Quadrupeds. 4th edition. Newcastle-upon-Tyne.

Collins, D., 1798. An Account of the English Colony in New South Wales. 2 vols. Cadell & Davies: London.

Connolly, J.H., Canfield, P.J., McClure, S.J, & Whittington, R.J., 1999. Histological and immunohistological investigation of lymphoid tissue in the platypus (Ornithorhynchus Anatinus). Journal of Anatomy. 195. pp.161-171.

Fleay, D., 1980. Paradoxical Platypus: Hobnobbing with duckbills. The Jacaranda Press: Milton, Queensland.

Grant, T., 1989. The Platypus. A Unique Mammal. New South Wales: New South Wales University Press.

Hamilton, G., 1988. The Platypus. Australian Geographic. 12, pp.50-67

Meng, J., & Wyss, A.R., 1995. Monotreme affinities and low-frequency hearing suggested by multituberculate ear. Nature. 377, pp.141-144.

Thwaites, T., 1991. Duck-billed Platypus had a South-American cousin. New Scientist. 131(1783), p.13.


If anyone has any additional information that I could use, please e-mail it to me.