You are currently browsing the tag archive for the ‘monotreme’ tag.
Here is a watercolor picture from my the little moleskine sketchbook which I carry around. A pompous, three-legged grandee makes his serene progress through a palace landscape. Around him are fawning moth courtiers and little fairies (as well as a horrified little flatfish who has somehow wound up in the garden’s reflecting pool). Although it is good to poke fun at the airs of aristocrats, my favorite part of the picture are the fluffy pink flying fox in the center and the ancient monotreme. Watercolor is not my finest medium, but maybe if I keep trying to capture fantastical foibles with the set I carry in my bag, I will keep improving…
Ah the magnificent platypus! I told you the other day that there were other mammals on the list of Ferrebeekeeper top ten blog posts and here is one right now…barely. With its duck-like beak, beaver-like physique (& fur), and egg-based reproduction, the lovable monotreme platypus has been capturing hearts and provoking perplexity ever since it was first discovered by European natural scientists.
The platypus (Ornithorhynchus anatinus)
Here at Ferrebeekeeper we concentrated on one of the platypus’ lesser known weird attributes—his scary venomous spur! (I say “he” not to encourage gender stereotypes, but because only the male platypus has venom glands). Of course platypuses are remarkable in so many other ways. Genetic evidence suggests that monotreme lineage dates back to the dawn of the Mesozoic era! These adorable furry egg-laying rapscallions split from early mammalian ancestors back before the ascendancy of the dinosaurs.
Of course it isn’t just zoologists and paleontologists who are fascinated by platypuses, In my former life as a toymaker, I noticed that all sorts of toys and toy retailer names involved platypuses. Not only was there was “The Purple Platypus” a stylish independent toy store, there were also multitudinous platypus plush creatures. A platypus is the hero of the popular animated show “Phineas and Ferb” (ostensibly a lovable family pet, Perry the platypus is actually “Agent P.”, an international special operative working for OWCA—the Organization Without a Cool Acronym). There was even a platypus figure in the extremely rare “Deluxemorphs” toy set of the now defunct Zoomorphs.
Perry the Platypus AKA “Agent P”
So that our top ten list does not become a stale list of links to old (albeit extremely popular) posts, here is a galley of platypus mascots and adorable platypus cartoons.
Some sort of Business Platypus?
A Platypus was one of the mascots of the Australian Olympics!
Look at all of the adorable beaks and flippers! It’s amazing that all mascots aren’t platypuses…
Hey! That’s not a mascot–it’s original Aboriginal art!
The animals and plants of the Oligocene rainforest at Riversleigh (as envisioned by an artist)
Occasionally in the geological past, extraordinary circumstances resulted in the near-perfect preservation of an entire ecosystem. These astonishing fossil beds are known as Lagerstätten (one of the first such finds was in Germany) and they provide one of the best sources of information about life on this planet. A particularly rich Lagerstätten is located in the arid scrubland of Riversleigh in northwest Queensland, Australia: there fossils from the Oligocene and Miocene epochs are preserved in uncompressed limestone (which allows paleontologists to recover 3 dimensional skeletal remains). During the late Oligocene, Riversleigh was a lush and vibrant rainforest filled with an incredible profusion of bizarre life forms. When the Oligocene ended, the region dried into grasslands (and the climate continued to dry out further in subsequent epochs until the present, when the area is a near desert).
The giant carnivorous platypus (Obdurodon tharalkooschild)
All of this is backstory to a remarkable recent discovery. This week paleontologists studying the bats, snakes, and strange tropical marsupials of Riversleigh made an unexpected discovery–a giant hunting platypus twice the size of the living species. This big predator, Obdurodon tharalkooschild, was a formidable meter long (3 foot) creature with sharp teeth for grabbing crayfish, amphibians, aquatic reptiles, and fish. The newly discovered platypus lived in the long-lost rainforests of Queensland. It was a generalist with a much larger diet than the somewhat specialized modern platypus.
No, it wasn’t THAT big…
Monotremes (platypuses & the more recently evolved echidnas) are an extremely ancient branch of mammalian life which date back at least to the Jurassic–and more likely to the Triassic epoch or earlier. Platypuses are believed to have evolved in what is now South America and then spread to Antarctica and finally to Australia. The amazing giant hunting platypus indicates that there were hitherto unexpected branches of platypus evolution. I wonder if Obdurodon tharalkooschild was toxic (like the modern platypus). I also wonder what strange monotreme fossils lie beneath the ancient ice of Antarctica.
Obdurodon--A Miocene Platypus which flourished 15 to 20 million years ago
Ferrebeekeeper has an abiding interest in monotremes including both the poisonous platypus and the enigmatic echidnas (with their advanced frontal cortex). But sadly that is about it as far as it goes for the extant egg-laying mammals: there are only two living families of monotremes (with a scanty total of five species split between them). To learn more about these animals one must turn to paleontology. Unfortunately even in the fossil record, monotremes are extremely rare.
Based on genetic evidence, biologists believe that the first monotremes made their advent in the history of life about 220 million years ago during the Triassic era; however the earliest known fossil monotreme so far discovered was a fossil jaw from the early Cretacious era about 120 million years ago. The bones belonged to Steropodon galmani, which seems to have been a beaked swimmer about 50 cm (20 inches) long which lived in Australia. Steropodon was apparently a giant among Cretacious mammals–most of which seem to have been shrew-sized (so as to better avoid attention from their contemporaries, the dinosaurs). Reconstructions of Steropodon all seem to resemble the platypus, and most paleantologists would probably concede that it was a sort of platypus—as apparently were other Mesozoic fossil monotremes such as Kollikodon and Teinolophos (platypuses and these platypus-like forbears are called the Ornithorhynchida). During the Cretaceous era, the land which is now Australia was in the South Polar regions of the world (approximately where Antarctica is today). Although temperatures were much warmer during the Cretaceous, monotremes must still have been able to deal with terrible cold: it is believed that the extremely efficient temperature control and the deep hibernation mechanism which these animals continue to display first evolved during that time.
An artist's reconstruction of Steropodon
The only monotreme fossil which was not found in Australia was from another platypus-like creature named Monotrematus sudamericanum. The creature’s remains were found in a Patagonian rock formation from the Paleocene era (the era just after the fall of the dinosaurs). Monotremes probably flourished across South America and Antarctica, as well as on Australia, but evidence is still scarce. There are most likely many interesting monotreme fossils throughout Antarctica, but, for some reason, paleontologists have not yet discovered them. Additionally, unlike the marsupials (which still quietly flourish throughout South America), the poor monotremes were wiped out on that continent.
Another artist's vision of Steropodon galmani--Notice how peeved the poor creature looks!
Last week I wrote about the Eocene era and the great proliferation of mammalian types which took place during that warm and fecund time. Although most families of mammals alive today first appeared on the scene during the Eocene, obviously the monotremes were already incredibly ancient. The Eocene does however seem to have been significant time for the monotreme order: the aquatic platypuses were apparently the ancestral monotremes, and echidnas (the Tachyglossidae) probably split off from them during the Eocene. Unfortunately we have no Eocene monotreme fossils so this conclusion is based on genetic evidence and on the suffusion of Miocene monotremes which include representatives of both Ornithorhynchida and Tachyglossidae. Some of these latter creatures are spectacular, like Zaglossus hacketti the giant echidna from the Pleistocene which was about the size of a ram! As Australia dried up so did the monotremes and now there is only one species of platypus left…
The Giant Echidna (Zaglossus hacketti) which lived until 20,000 years ago...
Well, that’s a cursory history of the monotremes based on what we know. I wish I could tell you more but unfortunately there is no fossil evidence concerning the first half of the order. Sometimes I like to imagine the first monotremes—which were probably clunky, furry platypus-looking characters with an extra hint of iguana thrown in. These creatures fished in the alien rivers of the Triassic world in a time when dinosaurs and pterosaurs were also still evolving.
Poison is very common in the animal kingdom (and throughout the other kingdoms of life) both as a means of defense and as a weapon for hunting, however only a tiny handful of mammals are poisonous. A few shrews have mildly venomous bites. The European mole has a toxin in its saliva which can send earthworms into a coma (allowing it to store them in the larder for later). The Solenodon, a strange burrowing nocturnal insectivore is perhaps most toxic among the mammals–with one glaring exception. At the beginning of the month we wrote about the clever echidna–a monotreme with unusual brain physiology. The echidna’s closest relative, and the world’s only other remaining monotreme, the duck-billed platypus is the planet’s most poisonous mammal by far. Not only do platypuses have bills, lay eggs, and utilize electrical sensory apparatus to hunt, but the male has a moveable poisonous spur on his hind legs which is attached to a venom-producing crural gland. Only the male platypus is capable of producing a toxic peptide cocktail and injecting it through his spurs. Female platypuses (and all echidnas) have rudimentary spurs which drop off and lack functioning crural glands. Platypus venom causes pain and hyperalgesia—which means an increased sensitivity to pain–so you shouldn’t cuddle male platypuses no matter how adorable their funny little bills may look to you.
The crural glands...and the spur!
The Stanford neuroblog (from whom I borrowed the attached image of a platypuses’ poisonous organs and appendages), notes the similarity of platypus venoms with reptile venoms, “One evolutionary curiosity: the defensin-like peptides found within the platypus venom are also found within reptile venom. However, genetic analysis in 2008 revealed that the platypus peptides evolved independently from the reptile peptides, although both were derived from the same gene family.” Its curious to think of how our ties with reptile forbears are manifested in the curious and endearing (and poisonous!) platypus.
Eek! Get down...he's got a platypus!
The Short-Beaked Echidna (Source: M McKelvey/P Rismiller/)
Last year featured an in-depth examination of Echidna, the terrifying “mother of monsters” from Greek mythology. To start this year on a glorious high note, here is an essay concerning the actual echidnas (Tachyglossidae), a family of mammals from Australia and New Guinea. The echidnas were much wronged when explorers named them after a hellish demigoddess. Although I have never met—or even seen—a living echidna, they are one of my favorite creatures for many reasons. Combining a gentle temperament with fascinatingly alien intelligence, the echidna is a delightful animal whose taxonomical oddity reveals the strange paths of fate which life takes over great expanses of time.
Along with the charismatic platypus, the echidna is the last of the egg-laying monotremes. Monotremes are a very different sort of mammal than the other two major divisions of mammals, the eutheria and the metatheria. The teeming eutheria (familiar mammals like shrews, manatees, picas, goats, and humans) nourish their fetal young by means of a placenta. The ancient metatheria (marsupials) sustain their developing young in a special pouch. The monotremes predate both groups and give evidence of mammals’ origins. Genetic studies suggest that the monotremes originated from some reptile-like ancestor about 220 million years ago. The long and tangled family history of the mammals and their antecedents will have to wait for another post–suffice to say that monotremes have been here for an extraordinarily long time. The surviving monotremes, however, are not primitive atavists, but extraordinarily advanced descendants of those ancient progenitor mammals. They have evolved and survived in varying fashions over the long eons. Over those millions and millions of years, the echidna developed a very interesting brain.
Echidnas have the largest neocortex relative to bodymass of any creature. The neocortex (which Hercule Poirot always creepily referred to as “the little grey cells”) is involved in higher brain functions such as spacial cognition, logic, and problem solving. This special tool has taken the echidna far: like humans, and unlike almost all other creatures, echidnas live in very diverse habitats. Actually it is the short-beaked echidna (Tachyglossus aculeatus) which lives in different habitats—the other two extant species live in tropical New Guinea and are little known to science. Although all three species seem to share most traits, I am really writing solely about Tachyglossus aculeatus which ranges from the hot dry desert scrub, to the tropical rainforest, to the coast, to the cold snows of the Australian Alps (where they can lower their body temperature a few degrees above freezing and hibernate). Echidnas live on termites and ants, omnipresent social insects which are evolutionary winners in their own right. Echidnas dig up these insects with powerful razor claws and gobble them down using a long sticky tongue which zips in and out of a toothless tube-like mouth. Echidnas are not known to fight each other or other animals. In the great evolutionary battle they are pacifists (provided you are not an ant or termite) and if approached aggressively they will curl into a ball and trust their sharp spine-like hairs to keep them safe. They are also phenomenal burrowers and can quickly tunnel down through anything other than solid stone.
An orphaned puggle being handraised.
Because of their cleverness, relatively little is known about echidnas. They are difficult to capture since they disdain baits and can figure out most traps. Similarly, in zoos, echidnas have proven extremely gifted at escape. Their mating habits are largely mysterious to us but seem to involve non-confrontational competition. The female echidna is followed for an extended period of time by a train of interested males. In response to an unknown signal, the male echidnas begin frantically digging, trying to nudge one another out of the way. Just how the victor emerges from this competition is unknown, but one the female has chosen, the other males walk away with no obvious rancor. After laying her egg, the female immediately rolls it into a pouch-like fold on her abdomen. Once the puggle has hatched, the mother echidna solicitously tends it for seven months, after which it roams off free and solitary.
Echidnas have an extra sense, electoreceptivity, but for them it is much weaker than it is in their close cousins the platypuses. It has also been noted that echidnas vibrate. Water placed near captive echidnas shows distinct ripples in the surface. Perhaps they vocalize on frequencies beneath the range of human hearing (as do elephants). Speaking of captivity, Echidnas have survived for up to 30 years in zoos even though it is a difficult environment for the blithesome free-roaming animals. It is believed they live twice that long in the wild—but, again, nobody really knows.
Agh! Get away from there! I though you had a large neocortex!
Likewise nobody knows the echidnas’ total population numbers or how healthy the species is. What is known is that, sadly, even the intelligent and peaceful echidnas are running into problems in the modern world. Like other good-hearted pedestrians, echidnas are often killed by careless drivers. Echidnas face increasing habitat destruction from human houses, farms, and roads. Likewise they must deal with new predators, the dingos, which have discovered that urinating on balled-up echidnas will cause the latter to uncurl for a moment in stunned disgust (giving the ruthless dogs a chance to rip into their guts).
I wonder what echidnas think of us. They know of our traps, our radio-tracking devices, and they know how to avoid aborigine hunters. They are becoming wise to our deadly cars and to the dirty tricks of dingos. Still they remain curious about people and will sometimes come out of the wilderness in groups to examine our suburbs and cities before melting back into the wild. Humankind took a long while to understand that echidnas are not dim-witted reptilian pincushions but rather clever and highly developed generalists. Do they generously think the same of us, or do they put humankind from their mind as something foul when they head back to the ancient, open outback?
ferrebeekeeper 