All megafauna, all the time. Generally updated once a day, 10:30 GMT +8
Look everyone! It’s Richard Owen, standing with a reconstructed skeleton of Dinornis novazealandiae, which incidentally isn’t actually the Megafauna of the Day. But COME ON, it’s Richard Owen.
The for real Megafauna of the Day is the above bird’s cousin, endemic to the South Island of New Zealand - Dinornis robustus, possibly the tallest bird ever to have lived!
Dinornis robustus, or the Giant Moa, took its bow from the stage of life much more recently than many animals on this blog - going extinct c. 1500, most likely hunted to extinction by the Māori.
Dinornis robustus reached heights of up to 3.6m tall, which makes it a serious contender for the tallest bird of all time, as I mentioned before. It was also one of the most massive, with mass estimates placing D. robustus' weight between 230 to 278 kilograms.
Sexual dimorphism in the giant moa is so great that for quite some time scientists thought that male and female skeletons came from different species, but more recent analysis of the bones have confirmed that the females - described as Dinornis robustus - were simply much, much larger than their male counterparts. The ‘slender moa,’ Dinornis struthioides, were found to all be males of Dinornis robustus.
Continuing my trend of ridiculously gigantic terrestrial mammalian predators, today’s Megafauna of the day is the colossal Arctodus simus.
As with many of the other famous ice age megafauna, Arctodus simus would surely have met with some of our ancestors - it only became extinct around 11,000 years ago.
This Pleistocene predator belongs to an extinct genus, shared with the smaller and more ancient A. pristinus. Collectively known as the Short Faced Bears, this genus would have coexisted with members of the genus Ursus, to which many extant bears belong.
The giant short faced bear’s diet has been a topic of debate for many years, with evidence to support both carnivorous and omnivorous theories. The initial assumption made by palaeontologists was that A. simus was, like modern bears, a true, opportunistic omnivore, but more recent studies have cast doubt on this assumption, although the exact nature of the beast’s carnivorous nature remains unclear.
Above: Brown Bear (Ursus arctos) skull in comparison with that of Arctodus simus.)
A. simus has something in common with yesterday’s Megafauna of the Day, Andrewsarchus mongolensis, which is that it may be the largest land-based mammalian predator ever to have lived. We have a lot more data (like complete or near complete skeletons from multiple individuals) for A. pristinus than for Andrewsarchus, which means the values we have for its size are more reliable.
A recent study of six A. simus specimens supports that bears weighing 900kg or slightly more were more common than previously thought. Individual bears have been estimated to have reached weights in excess of 950kg - for comparison, the largest Polar Bear on record was around 700kg in weight, and on average these bears stand 1.3m tall at the shoulder. A. simus would have stood 1.67m tall at the shoulder.
These claw marks, found at the Riverbluff Cave, Missouri, USA, were made by Arctodus simus, and measure 20cm (8 inches) across, as high as 4.5m (15 feet) up the cave wall.
TURNS OUT, this is a really interesting beast that I didn’t know much about. So instead of droning on, I’ve included more written sources/further reading (yay!) for anyone who’s interested!
For those of you who hate reading (let’s face it, you probably also hate me…) PICTURES YAY
All kinds of interesting things are happening to this picture, which is cool, whether A. simus was an active predator or not!
[ Sources: Wikipedia | What size were Arctodus simus and Ursus spelaeus (Carnivora: Ursidae)?, Per Christiansen, 1999. | Carnivora Forum entry - absent/limited sources but interesting reading | Yukon Beringa Interpretive Centre - North American Short Faced Bear article | "Short Faced Bear 1" - unknown sources but academic writing style with in-text references makes me feel okay about it | Sisinyak, Nancy. The Biggest Bear… Ever!, Alaska Department of Fish and Game ]
Andrewsarchus mongolensis is today’s super enigmatic Megafauna. Known only from a single gigantic skull and a few fragments of bone, nothing solid is known about this beast, but most estimates based on the length of the skull found - 83cm long and 56cm wide - place Andrewsarchus among the largest terrestrial, mammalian carnivores known, if it was not the largest.
Conservative estimates based on similar predators and Andrewsarchus’ distant relatives place the animals’ body weight around 1,000 kilos, which is thought to be near the limit for land predators, however, unless more remains are found, speculation is all that is possible.
( I really love these diagrams. Bless you, Dinoguy2, if that is your real name.)
[ Sources: Wikipedia | D Palmer, The Marshall Illustrated Encyclopedia od Dinosaurs & PrehistoricAnimals, 1st edn, Marshall Publishing, London, 1999, p. 234 ]
Welcome back, cupcakes! I had a brief intermission in daily life this week, apologies for the lack of Megafauna. Right now I am compiling a gigantic queue, so hopefully this won’t happen again!
CAW CAW MOTHERFUCKERS, today’s Megafauna of the Day is Argentavis magnificens, the largest flying bird known.
Although A. magnificens is known only from partial skeletons, estimates place its wingspan at around 7.3m - only three meters less than the width of a Cessna 152 aircraft. Scientists have also extrapolated the birds weight to about 70 kilograms.
Like other large flighted birds, A. magnificens would have flown mainly by gliding, launching itself from high places and using thermal currents to keep it aloft. The largest
Related to the New World vultures, this Late Miocene bird was probably a scavenger, feeding on the carcasses of the large land mammals of the period. Like so many other megafauna, the massive size of A. magnificens would have made it vulnerable to changes in food supply or climate.
[Sources: D Palmer, The Marshall Illustrated Encyclopedia od Dinosaurs & Prehistoric Animals, 1st edn, Marshall Publishing, London, 1999, p. 179 | BBC News ]
[Image Sources: 1: Malcolm Ellis for D. Palmer, loc. cit. | 2 ]
-familyToday we dip once more into Australian Megafauna, this time showcasing the largest of all known kangaroos,
The largest member of the extinct sub-family Sthenurinae, the Short-faced kangaroos, Procoptodon goliah hails from the Pleistocene epoch - like perhaps every other megafauna so far(?) - and would most likely have had to contend with the fearsome Thylacoleo carnifex, Australia’s apex predator for most of P. goliah's existence. This mighty boomer would have been about two meters tall in a normal upright standing position. While this is a comparable height to a large Red Kangaroo (Macropus rufus), Procoptodon goliah would have been over twice as heavy, reaching up to 200 kg in weight.
Procoptodon goliah was, like other sthenurines, able to reach above its head whilst using its tail to ‘tripod’ itself - no other known kangaroos have this much mobility in their arms. Coupled with the animal’s complex teeth, these features indicate that P. goliah was likely a browser, reaching up with its arms to pull branches down to feed.
(This Procoptodon goliah skeleton was labelled “Thylacoleo carnifex” on the website where I found it. I found this heartily amusing.)
Anyway, note the single toe, and the two long grasping claws on the hands. Also note the extremely short and robust skull - below is the mounted skeleton of Macropus giganteus, the modern Eastern Grey kangaroo. I really wanted to show y’all a Macropus fuliginosus, Western Grey Kangaroo, skeleton, as these are actually found in parkland in outer suburbia less than ten minutes from where I grew up. In fact they’re basically everywhere. But nooo. Five minutes of googling only yielded one identifiable photograph. I’M SORRY.
The differences are stark, despite the differing poses. The modern kangaroo has a long, relatively delicate skull, lacking the massive jaws of Procoptodon goliah. The arms are also shorter and less mobile, lacking gripping claws. The hind legs share many features, differing mainly in the foot - where P. goliah has only one wide toe visible, the Eastern Grey has four. At the end of the single toe, P. goliah had a hoof-like claw, which may have given the animal some extra speed.
While we’re here, it’s worth mentioning that the jumping locomotion of the kangaroo is the most energy efficient mode of land movement in the animal kingdom. Booyah.1
Like it’s un-buddy Thylacoleo, Procoptodon goliah also had interesting teeth. The lower jaws were ankylosed, meaning that the teeth were fused to the bone of the jaw, and the molars of Procoptodon have been described as “ape-like,” and compared to those of Australopithecus boisei (One of our ancestors, for those of you not into your taxonomy).
* Does the art look familiar? Peter Trusler also produced this fucking badass stamp series in 1993 of Australian dinosaurs. Words can’t tell you how much 6 year old me loved those goddamn stamps. Both of these stamp series are resplendent moments in my nation’s proud history of… postage stamps.
Today’s Megafauna of the Day is Megaloceros giganteus!
This mighty beast of the Pleistocene ranks among the largest deer ever to have lived, and certainly shared turf with our ancestors - the most recent remains are a mere 7,700 years old.
While M.giganteus is often called the “Irish Elk,” it was neither closely related to modern Elk nor exclusively Irish. It stood around 2.1 metres tall at the shoulder, and was similar in size to Alces alces gigas, the Alaskan moose. Mass calculations suppose that M. giganteus was probably of comparable weight to the Alaskan moose as well - from 540 to 700kg.
These magnificent antlers, the largest of any known member of theCervidae family, could weigh up to an astonishing 40kg and span up to 3.65m from tip to tip. It has often been speculated that the immense size of the giant deer’s antlers contributed to its extinction - but more thorough studies into both Megaloceros giganteus’ habitat and expected antler to body size suggest that this is an unlikely hypothesis.
[Sources: Wikipedia 1 2 3, The Marshall Illustrated Encyclopedia of Dinosaurs & Prehistoric Animals, Dr Douglas Palmer (yes it’s not a proper bibliography what do you expect This Is Tumblr)]
Fridays are one of the best day of the week, and so here is my favourite animal of all time -
T.carnifex has held a special place in my heart ever since I was a wee lass, listening compulsively to my Dinosaur Songs cassette tape. On this cassette, my favourite song was called “Rip it Up," and starred our dear Thylacoleo, here. It was this song, actually, that introduced me to awesome extinct animals that weren’t dinosaurs. If I ever find a digital version, you can be sure it will find its way here.
Thylacoleo carnifex is the final product of the Thylacoleo genus, and also the largest. T. carnifex it is smaller than most megafauna you will find on this blog, standing only around 75cm tall at the shoulder and measuring about 150cm from nose to tail, with an average mass of 130 kilos, making it comparable in size to the modern Panthera leo. This is because the Australian continent has generally smaller animals than the other continents, we get our own definition of Megafauna :
species with body mass estimates of greater than 30 kilograms, or equal to or greater than 30% greater body mass than their closest living relatives.
Deal with it, nerds.
T. carnifex is the largest known mammalian predator to have existed on the Australian continent, however, and is one of the largest marsupial predators known, outclassed in size only by Thylacosmilus and Borhyaena. But not in fuckin’ fabulosity.
Before we get into the gritty scientific details, let’s linger for a moment on taxonomy. Thylacoleo carnifex has one of the coolest sounding scientific names, and a deliciously deadly translation - Pouched Lion Executioner. A bit more badass than Smilodon fatalis' “Deadly Knife Tooth.”
One of the fascinating things about T.carnifex is its unique, highly specialised dentition. Unlike many carnivores, T. carnifex developed killing incisors and carnassials, rather than the more standard killing canines. As can clearly be seen in the above photo, T. carnifex's gigantic cheek teeth resemble nothing so much as bolt-cutters.
Noteworthy front teeth are one of the major defining factors for the order Diprotodontia, which T. carnifex shares with kangaroos, wallabies, possums, and many other marsupials. Diprotodon, a huge animal which probably found itself on T.carnifex's menu, is also (perhaps obviously) from this order. The thylacoleonids are the only known group from within this order to have been primarily carnivorous.
T.carnifex's lower incisors are much more pointed than those of other Diprotodonts, although the incisors aren't what we came to see. The carnassial premolars - the aforementioned bolt-cutters - are highly unique. While most predators use this group of teeth to tear off chunks of flesh from pre-dispatched prey, it is theorised that these were T.carnifex's primary killing tool. These carnassials are also the largest known in any animal. Take that, Smilodon.
The journal article “Bite club: comparative bite force in big biting mammals and the prediction of predatory behaviour in fossil taxa," finds that Thylacoleo carnifex, with one other extinct marsupial lion, had the highest estimated bite force adjusted for body mass of any mammal, living or dead.1 The paper also goes on to hypothesise that this great bite force quotient defines T. carnifex as a large-prey hunter, highly specialised and ill-suited to smaller prey, a common problem in extinct megafauna. For reference, a 100 kg T. carnifex would have had a similar biting force to a 250 kg African lion.2
So how would this super - efficient bite be administered? Probably something like this. The incisors would stab the prey and break the skin, while the carnassials sever the windpipe, spinal cord or major blood vessels , arteries and veins - depending on where the killing bite was placed. In this way, T. carnifex could kill large prey in under a minute, compared to the modern lion’s technique of asphyxiation, which can take up to 15 minutes on large prey, exposing the predator to a number of dangers.
But that’s not all! Thylacoleo carnifex was also possessed of semi-opposable thumbs on its forelegs, equipped with large retractable claws, unique to this species among marsupials. Its forelimbs were also thought to be heavily muscled and powerful, not developed to be particularly good at running (although it was probably still faster than us ponderous humans), but more for grasping. In tandem to this, Thylacoleo's tail bones feature chevrons, allowing it to tripod itself as modern kangaroos are known to do. Meaning it could have reared up, freeing those deadly arms for grasping.
This rather intimidating biological resume has lead scientists prominent in their fields to label Thylacoleo carnifex the most specialised mammalian carnivore of all time.3
As if this weren’t enough, one of the other reasons that I love Thylacoleo carnifex so much is that incredibly well preserved, non-mineralised remains have been found in three caves near to the Nullarbor Plain in Western Australia, my home state. You can read about the amazing 2002 expedition and discoveries here. The photo below shows one of the Thylacoleo skeletons found in the caves - carbon dating reveals that despite appearances it is between 500,000 and 780,000 years old.
Oh, and since Thylacoleo carnifex only died out about 30,000 years ago, Australia’s Indigenous people must have run into this monster more than once. There’s even rock art depicting T. carnifex - clearly showing developed forelimbs with paws which are different to what has been seen in cave art of Thylacines, a blunt head with prominently pointed ears, and stripes similar to those found on Thylacine, although extending higher up the back. This piece of art was found in the Kalumburu region of the Kimberley, in Western Australia.
As a parting statement, I feel it’s more than appropriate to include this quote from Richard Owen, one of the earliest describing the animal:
”[Thylacoleo carnifex is] one of the fellest and most destructive of predatory beasts.”
[Image Sources: Top Art by H. Kyoht Luterman, my favourite Paleo artist | IMG. 2 by Olga Kobrina | IMG. 3 Wikipedia | IMG. 4 WA Museum | IMG. 5 UNSW Science | IMG. 6 WA Museum | IMG. 7 & 8 Antiquity Project Gallery K. Akerman & T. Willing |
(MOST posts won’t be this long. I just really, really love Thylacoleo carnifex, if you can’t tell.)
Thursday, 11 April’s Megafauna is the largest member of the genus Smilodon…
S. populator existed mostly in tandem with the much more famous S. fatalis, towards the end of the Great Ice Age, from 1 million to ten thousand years ago, making it the most recent member of the genus by about 600,000 years.
S. populator was found mostly in the South of the American continent, in contrast to S. fatalis' northern habitat, and it was a larger, more massive animal than its cousin. It would also have looked less like the great cats of our time, with a heavily sloping back - probably similar in appearance to the unrelated modern hyena.
It may have been the largest known felid, estimated to have weighed from 220 to 400kg, possibly more. It was 1.4m high at the shoulder and 2.6m long from tip to tail, with sabre teeth up to 30cm long.
S. populator had extremely robust limbs, designed more for power than for running. Coupled with the iconic sabre teeth, it is likely that these animals had an extremely specialised hunting style well suited to large prey animals, but less effective on smaller, more agile prey. This inflexibility is likely to have contributed to the eventual downfall of the genus.
Unfortunately, due to the much greater popularity of S.fatalis, it’s difficult to source reliable reconstructions of S.populator online. Hopefully I’ll be able to scan some of my dino-books before this goes online.
Paraceratherium, the Megafauna of the Day for the 10th of April, is the largest land mammal known to have existed.
The largest confirmed individual specimen is estimated to have stood 4.8 meters tall at the shoulder and measured 8m from nose to rump. It is thought to have weighed 18 tons.
Paraceratherium comes from the extinct family Hyracodontidae. During the Oligocene epoch, this family was native to Asia and Eurasia.