#meiolaniidae

[ppaleoartistgallery]

#Paleostream 19/04/2025

here's today's #Paleostream sketches!!!

today we sketched Tullimonstrum (Tully Monster), Ornithosuchus, Xerces blue, and Ninjemys

[arminreindl]

Meiolaniidae

So honestly I'm relatively new to digital painting. I sketched a little here and there, made skeletals, but actual painting I've done very little. But I ended up putting this together for my work on the Wikipedia page for meiolaniid turtles. (Yes the Ninjemys colours are a reference to it being named after the TMNT)

I've rambled a bit about them before, but basically, meiolaniids are weird stem-turtles thought to be outside the two main modern groups we have. They were decently large animals, their shells alone range from 1 meter to 2 meters in length (3 to 6ft I believe?), they were land animals, had some crazy horns and tails that were encased in spiky armored rings and tipped with a tail club. Here some photos with paleontologist Victoria Arbour, a Ninjemys tail club photographed by Serjoscha Evers and a Meiolania tail club illustrated by W.H. Wesley.

They were found throughout almost the whole Cenozoic, with the oldest form dating to the Eocene of South America and the most recent ones living from the Pleistocene to Holocene in Australia and on various South Pacific Islands. They are honestly pretty cool animals and super underrated, which is why I decided to give their wikipedia pages upgrades in the first place. Which also meant doing a bunch of other illustrations (that I was more in tune with) and pulling a bunch of public domain photos and putting them on wikimedia. Here some skeletals and charts I made, open the last pic, it shows multiple different Meiolania species atop each other.

The results were pretty mixed tbh. Some of the most recent forms, Gaffneylania, Warkalania and even Ninjemys had relatively little to write about. But things were more exciting with Niolamia (if you remember my rant about its messed up history). Meiolaniidae itself was just a big summary of all the other stuff, but easily the most extensive was Meiolania itself, which took AGES to research and put togehter. Tho I'm pretty happy with the result. Here's a little side by side, old and new.

[alphynix]

Almost-Living Fossils Month #20 -- Some Very Spiky Turtles

The meiolaniformes were a group of terrestrial turtles that first appeared in the fossil record in the Early Cretaceous, around 125 million years ago. Although they were originally thought to be cryptodirans, more recent studies suggest they weren’t actually quite true turtles at all, instead being close evolutionary cousins to them in a much older and more “primitive” lineage that may go back as far as the Triassic.

They’re known mainly from South America and Oceania, but they may have had a more global distribution during the Cretaceous, with some fossils from the northern continents sometimes being classified as members of the group. However, only the South American meiolaniformes seem to have actually survived through the end-Cretaceous extinction.

The most distinctive meiolaniformes were the heavily armored meiolaniids, which first appeared in Patagonia during the Early Eocene (~48 mya). With large horns on their heads and thorn-like spikes along their long tails, they seem to have convergently evolved to fill the same sort of large-herbivore-tank niche as ankylosaurs and glyptodonts.

They also had fairly large nasal cavities, which might indicate a well-developed sense of smell -- or may have been an adaptation for regulating the heat and moisture content of each breath, similar to the complex noses of ankylosaurs.

The South American meiolaniformes all went extinct around the end of the Eocene (~33 mya), but some meiolaniids had already dispersed across to Australia via Antarctica (before the continents had fully separated, and before Antarctica had frozen over) and they continued to survive there for most of the rest of the Cenozoic. They even went on to spread to various islands around Oceania, suggesting they were able to float and swim like modern giant tortoises.

The largest Australian meiolaniids reached sizes of around 2.5m long (8′2″), making them some of the biggest of all known terrestrial turtles. These giant forms went extinct in the Late Pleistocene, around 50,000 years ago, alongside much of the other Australian megafauna.

A few smaller varieties hung on in smaller islands to the east, with one of the latest-surviving species being Meiolania platyceps on Lord Howe island. It was only about half the size of its biggest Australian relatives -- an example of insular dwarfism -- and lived into the Late Holocene just 3000-2000 years ago.

Meiolania species on other islands seem to have gone extinct after the arrival of humans. But Lord Howe Island appears to have never been inhabited prior to European settlement in the late 1700s, so it’s unclear why this last of the meiolaniformes disappeared.

[Edit: A new study of Meiolania platyceps’ anatomy suggests it may have been more aquatic than previously thought. It might have been something like a giant herbivorous snapping turtle or an armored reptilian hippo, bottom-walking around in coastal lagoons, with its big nasal cavity housing salt glands.]

[arminreindl]

"Paleontology can be really petty and stupid"

In 1898 Santiago Roth discovered the armored tail of a large turtle in Patagonia, which he showed to British paleontologist A.S. Woodward. Recognizing it as the remains of a meiolaniid, Roth was told to go on an expedition to find more material, which he did. This material, which included an almost fully preserved skull, was initially published on in a brief communication in 1899.

Strangely, also in 1899, Florentino Ameghino published his own communication claiming that his brother Carlos had found the almost fully preserved skull of that same kind of turtle, a meiolaniid he dubbed Niolamia argentina.

It is curious how both Ameghino and Roth seem to have found the exact same material of a meiolaniid in different localities at the same time, but weirder things have happened. Tho it is further pretty weird how Ameghino rushed to get a name out, but didn't bother describing what defined the animal nor designated a holotype. Hell he didn't even illustrate his skull. But lets give him some time.

Two years pass, its 1901 now. Woodward publishes a proper description of Roth's skull, illustrating the animal in detail. Having heard that Ameghino found a remarkably similar fossil, Woodward assigns the Roth skull to the same species as the Ameghino skull. Although he doesn't carry over the genus Niolamia, instead placing the fossils in Miolania (a misspelling of Meiolania, described a few years prior from Australia). Ameghino didn't seem to mind or disagree, tho he still hadn't properly described nor figured his skull.

1938: Ameghino is dead at this point and weirdly, his Niolamia skull is still nowhere to be found. Since his initial description was wholy insufficient, George Gaylord Simpson (yes thats his actual name) decides to declare the Roth skull the type specimen for Niolamia (the neoptype). Meaning that the genus is now defined on this skull rather than the one Ameghino had when coining the name.

Fast forward to 2011. It is now generally accepted that Roth's skull is the fossil that defines what Niolamia is. Of course Ameghino still gets credit, after all he described the first remains, even tho nobody has ever seen those...ever really. Over a 100 years passed and far as anyone could tell, the last person to have seen those bones were Ameghino and his brother, after which they just disappeared. But we still got the Roth skull, and Juliana Sterli and Marcelo de la Fuente could readily redescribe Niolamia based on that.

But Sterli seems to suspect that something very fishy is going on. Remember, Ameghino just happened to find a perfectly preserved skull at the same time as Roth did. Ameghino made sure to get a name out before Woodward got around to fully describe it. Ameghino only vaguely compared the skull to Meiolania, but didn't specify its unique features nor did he actually illustrate his material. So Sterli said out loud what I'm sure many people must have been thinking. "Did Ameghino just make it all up?"

In 2015 Sterli comments on the matter by noting how awfully convenient the whole situation was. Although no concrete evidence exists, Sterli suggests that Ameghino may have found out about Roth's skull, lied about having found a similar one, and named Niolamia not on a fossil he actually had but based on what little he knew about Roth's discovery.

This is just a basic summary of a rabbit hole I recently went into and my god its so frustrating on so many levels. Again we don't have concrete evidence that Ameghino's skull didn't actually exist, but the way the timing lined up and the fact that he was in a feude with Francisco Moreno, which has been likened to an Argentinian Bone War, means that this suggestion isn't that out there. It really doesn't help that his supposed skull was only ever mentioned by him in 1899 and never again. Ameghino never claimed it was destroyed or stolen, hell, far as I could find he even agreed with Woodwards research.

What's also fascinating is that seemingly, for over a hundred years, nothing was written in scientific literature casting doubt over his claim. I'm sure some people must have called bullshit on him in private, but the only resource I could find that actually goes as far as to say "Hey isn't his weird that the Ameghino skull is basically a phantom" came out in 2015. Everything in-between seemed content with just assuming that Ameghino and Roth both had skulls and just never followed up on whatever happened to the former. Then again I could just as much understand if people just didn't want to deal with this nightmare of a backstory.

[arminreindl]

Niolamia is a fascinating turtle. Living during the Eocene (probably), it is one of the earliest known meiolaniids. What makes meiolaniids special is not just that they were sizable land turtles, but two other things 1) The massive horn-like scales, primarily those marked A-C. Niolamia has some of the most impressive ones at that, with the A scale forming an almost ceratopsian-like frill at the back of the head and two large, flattened, side-ways directed horns before said frill. 2) The long tail was armored, covered in bony rings with spikes and in some species even a straight up tail club

The two images above are things I put together for the Wikipedia page of Niolamia. The first shows the growth of the species. The small skull is a juvenile Niolamia, originally described as Crossochelys but synonymized by later researchers. The bigger skull (to scale) is the neotype (or holotype?) of Niolamia. Check out an older post for some history on that. The other is a simple sideview of the skull and lower jaw, nothing too fancy.

The bottom two photos aren't mine but those of Victoria Arbour, but show the weirdness and size nicely. The first image shows Niolamia (right) next to Ninjemys (left). While the second picture shows Ninjemys with as I said Victoria Arbour. Which still gives a good idea of how big these animals heads were.

[arminreindl]

Gaffneylania: Argentinian Horned Turtle

Those familiar with the reptiles of Cenozoic Australia may be familiar with the turtle family known as the Meiolaniidae. A group of stem-turtles that appear deceptively like modern snapping turtles or land tortoises, yet are not especially close to either. To those that know them, Meiolaniids bear some resemblance to ankylosaurs or even ceratopsians, possessing horns that sometimes form frill like structures and having clubbed tails. The two illustrations below are by the always talented Hodari Nundu and were drawn for the articles on New Caledonia and Lord Howe Island by The Extinctions (check them out), featuring Meiolania mackayi and Meiolania platyceps respectively.

While meiolaniids are mostly associated with Australia and the surrounding islands, primarily around the later half of the Neogene and the Quarternary, their lineage starts much earlier and far away. Meiolaniids first appeared in Patagonia some 50 million years ago. Previously one genus was known from there, the frilled Niolamia, until in 2015 Sterli and colleagues described a second Argentinian meiolaniid: Gaffneylania auricularis (Gaffney's Roamer with Ears).

Now on a surface level, Gaffneylania is a wonderfully complete animal. We have parts of the skull, most of the lower jaw, multiple vertebrae of the neck and tail, various shell plates from different specimens and limb bones. In theory great, in practice not so much, as most these elements are sadly very fragmentary and disarticulated. So it takes some creativity to put things together.

Take the horns for example. While we have parts of the skull, we lack the skull roof and most of the upper jaw (safe for a fragment of the maxilla+premaxilla). So we don't have as clear a picture of how the horns and shields of Gaffneylania should look like. We do have a horn, but its broken at the base so we can't tell how it would fit on the skull. Still we can look at it and compare it to others. Now from the front, the horns of Gaffneylania (1st from the left) are broad and flattened, similar to what we see in Niolamia (2nd from the left) yet different in having rounded, not pointed, tips. They also differ clearly from the less flat horns we see in Ninjemys and Meiolania (3rd and 4th respectively). The images below in order are from Sterli et al. 2015, Victoria Arbour, Ghedo and David Morgan-Mar.

In other parts it also generally matches other meiolaniids. The limbs are very robust and short, the lower jaw is short but differs from Meiolania in having two, not three cutting ridges, and further differs in which ridge is the bigger one. The shell tho known mostly from individual fragments does at least show that its outer edge was serrated rather than smooth. The fossil material also includes a series of osteoderms, bone that was embeded into the skin and functioned as armor. These osteoderms came in different sizes and likely covered the forelimbs of Gaffneylania. Below are elements from Gaffneylania compared to Niolamia (reconstruction by Sterli et al. 2011) and to Miolania (Richard Owen 1888).

Anatomically there isn't a whole lot more to break down, as we don't have preserved tail rings that form the tail club in derived neiolaniids (tho that would have been useful in determining relationships). So lets briefly address how it happens that meiolaniids are known from Australia and South America, despite their distance. The short answer is rather simple. Antarctica. Meiolaniiformes were a chiefly Gondwanan group that at one point or another disperesed into Antarctica, at the time not yet a frozen wasteland, and continued to diversify there. From Antarctica, meiolaniids could have traveled to both South America and Australia before the two continents split off entirely. Through this, members of the same family ended up on vastly different continents when climate began to change for the worse, becoming colder and dryer. And that's when the paths diverged. South America didn't move especially much and around the Middle Eocene turtles began to go extinct in Patagonia, unable to deal with the temperatures. Things would have gone similarily in Australia if it wasn't for the fact that the continent was continuously drifting north at the same time, balancing out the climate change with just getting closer to warmer latitudes. But even then, meiolaniids on the mainland suffered the same fate as much of Australia's megafauna while their island relatives might have survived longer, but obviously not until today.

To any paleoartists out there, there has seemingly never been an attempt at reconstructing this animal. Just thought I might mention that. And of course the obligatory Wikipedia page, courtesy of yours truly: Gaffneylania - Wikipedia