The thyreophorans, the armored dinosaurs, evolved in the Early Jurassic and soon grew to be the dominant low browsers of the middle Mesozoic evolving into (among other things) the famous stegosaurs in the Middle Jurassic. Stegosaurs went extinct soon after the end of the Jurassic, in the Early Creataceous (but with a possible Late Cretaceous record), but the more heavily armored thyreophorans, the ankylosaurs, survived, and by the end of the Cretaceous, existed in two major groups, the immense, tank-like, club-tailed ankylosaurids, and the somewhat smaller, less well armored nodosaurs. Both groups diversified throughout the Early and middle Cretaceous, with the ankylosaurs ranging across Eurasia and North America, while the nodosaurs spread across the globe. Nodosaur fossils have been found on almost every continent on Earth, a fact that no doubt saved them from the disaster wrought upon their kin.

Fossils indicate that ankylosaurs in general were faring well all the way up to the Eocene (50 million years ago). However, the very latest Cretaceous deposits in North America fail to turn up any evidence of other herbivore group, while revealing abundant hadrosaurs, ceratopsians, and other ornithischians. Apparently, some disaster other than the Chicxulub bolide was responsible for the abrupt extinction of most if not all of the ankylosaurs and nodosaurs in the Northern Hemisphere, except for the nodopotamids. Though recent expeditions indicated that the vast majority of ankylosaurs seemed to die out during the final days of the Eocene epoch in North America, however with fossils of the nodopotamids dating back to the Oligocene and Miocene epoch, this issue is still under a lot of debate even to this very day.

In Asia and South America, they seemed to cling to life, though barely. Over millions of years, all of the Asian ankylosaurs were wiped out in the Miocene epoch by the arrival on new herbivores, the nearly the same fate befell their South American cousins the Pliocene epoch with the invasion of various species from North America when both it and South America were linked up about 3.3 million years ago. The only difference is that less than a handful of ankylosaurs thrive in the America's, however, they have seen much more success in the Australasia region, most notably in Australia which seems to be their main bastion while the majority of their relatives marched into extinction.

As far as Spec's preliminary paleontology has implied, whatever killed the ankylosaurs acted upon both our timelines, and the massive club-tailed beasts are just as extinct here as in our home timeline. However, the nodosaurs, with their global distribution, weathered the storm a little better.

While nodosaurs in Asia and Europe went extinct with their ankylosaur cousins 70 million years ago, they maintained a toe-hold in the Americas. Early South America (and presumably Africa and Antarctica) had an abundance of armored plant-eaters, but while several nodosaur species have been recovered from South American Eocene strata, their numbers dwindle until, some time during Pliocene, they cease altogether. Paleontologists theorize that the spread of grasslands, combined with the South American asteroid impact, and the invasion of neohadrosaurs from the North combined to kill off most of the North American South American nodosaurs, except for the aquatic ones. Today, their vast majority niche has been partially filled by other South American natives, the panzertoitals, giant meiolaniid tortoises with armor plates and spiked tails very much like the nodosaurs' extinct cousins, the ankylosaurids, and the vanguards, armored ornithopods descended from Thescelosaurus. However, in Australia and Caribbean Islands (possibly even main land South America), they still thrive.

In the world of Spec, only three groups of ankylosaurs thrive to this very day:

  • Ausankylosauridae
  • Antilleankylosauridae
  • Nodopotamidae

AUSANKYLOSAURIDAE (Dreadnaughts and pyoros)

The ankylosaurs native to the New World suffered heavy loses through out the Cenozoic, however, they still thrive to this very day as semi-aquatic creatures. On the other hand, another line, an offshoot from somewhere at the base of the ankylosaurian family tree, survived the upheavals of the Cenozoic. Australia, ancient home of the famous Minmi and the recently discovered Kunbarrasaurus, managed to keep its thyreophorans, and it is on this island continent, land of so much strangeness and novelty, that one is still able to see live ankylosaurians.

The Ausankylosaurids are clearly related to Minmi in that they share this odd creatures mosaic of features, fitting into none of the recognized thyreophoran group. The skull has the cranial armor configuration of a scelidosaur, the overall proportions of a nodosaur and the hornlets of an ankylosaurid. An ausankylosaur's dorsal (and ventral) armor (numerous rows of small spines/scutes set in a chainmail of tiny scutes that extends across the belly) is quite unlike any Laurasian ankylosaurian. Paleontologists usually place Minmi alone as a basal member of Ankylosauria, but in Spec, with several Minmi-like species surviving, and no other ankylosaurs of any kind, biologists have erected the new family Ausankylosauridae to accommodate these animals.

Australia's ausankylosaur fossil record is poor, but it seems that the descendants of, Minmi, stayed fairly conservative throughout most of their evolution, present in Australia's primal forests as low-level browsers much like their Cretaceous ancestors. With the drying of Australia and the ascent of the euclasaurs, however, these creatures must have begun to die out, and only a few dwarf species of this old, forest-dwelling group remains on the island of Papua. The tropical low-browsing niche has since been left to the pig-like psittacosuids, much smaller than the ausankylosaurians, and so better able to cope with the recent environmental stresses.

The descendants of Minmi did not entirely fade into the background, however, one group, the dreadnaughts, managed to adapt to Australia's increasing aridity, and still survive today. Also called 'ankies', dreadnaughts are some of the largest of Australia's herbivores, the largest species often surpassing 2 tons. Dreadnaughts live in Australia's bracken meadows and dry sclerophyll forests, utilizing their ankylosaur cutting teeth and chewing jaws to eat a variety of spiny and (to other herbivores) extremely unappetizing herbage, including the poisonous bracken, young Eucalyptus, and thorncrown bushes. Enormous and specialized, the dreadnaughts are truly some of the most impressive of Australia's dinosaur fauna. Recently, a new species of ankylosaur was found in New Caledonia. As of now, it is estimated that less than a dozen species of ankylosaur are left in the world, or this area to be more specific.

Pyoro (Pyoro pyoron)


Pyoro, Pyoro pyoron (Papua)

Diminutive, ill-tempered, and loud, the pyoro (Pyoro pyoron) is one of the last of the small ausankylosaurs, the single of species of its genus, and endemic to the island of Papua. These round-bodied little creatures trundle like oversized beetles through Papuan jungle's understory, eating fungi, small plants, roots and bulbs, and bark. Pyoros are not at all shy or skittish, and their blue and white hides show up well against the backdrop of the forest, a fact which has lead biologists to wonder how these little creatures avoid predators. Poison has been proposed as a means of predator deterrent, and if this theory is true, it would be the only known instance of such a substance used by an ornithischian dinosaur. Analysis of pyoro muscle has revealed no toxic compounds, but an as yet untested theory proposed by some workers suggests the presence of a toxin-secreting bacterium that infests the pyoros' skin. This theory would explain the elaborate cleaning ceremonies employed by the pyoros, as well as their seeming invulnerability to predation.

Great Aussie Ankie (Dreadnaughtis maximus)


Great Aussie Ankie, Dreadnaughtius maximus (Australia)

The great aussie ankie, or great dreadnaught (Dreadnaughtis maximus), is second only to the great euclasaur in size. It exists in disjunct eastern and western populations whose habitats range from semiarid scrub to the wet coastal woodlands. They are unfussy eaters and are one of the few dinosaurs that will gladly feed on poisonous bracken ferns.

But when Australia finally broke off and drifted north to the equator, combined with a dryer environment (thanks to the ice ages) and the arrival of grass killing off much of the population, the ecosystem turned from a tundra-forest, to a desert-like "out-back". Luckily, ankylosaurs had already adapted a effective strategy commonly used to survive long winters without plant-material, this is because, despite being known as a family of herbivores, ankylosaurs would occasionally eat rotting wood filled with maggots and beetle-grubs, providing them with the vital proteins.

Yoshi (Yoshisaurus miyamotoi)

Around the size of a Indian Megahorn, the yoshi is easily the largest land animal in Spec New Caledonia. The origins of this ankylosaur were a mystery until the discovery of ankylosaur fossils in Aotearoa dating back to the latest part of the Cretaceous. Apparently, the ancestors of the yoshi once inhabited both New Caledonia and New Zealand when the two landmasses were connected. When the two fragments of Gondwana broke apart in the Oligocene, the ancestors of the yoshi thrived in New Caledonia, their Aotearoan cousins died off as a result of volcanic activity and changes in sea level. Yoshis are similar to Pyoros in shape, with red hornlets littering their bodies from neck to tail.

Aside from these hornlets, Yoshis are practically defenseless, not needing to be well defended due to the absence of large predators on the island, minus the exception of the Dingodile (which is about the size of a fox) and the Dudu, which shows no interest in preying on the slow moving creature . Because it has no enemies, the Yoshi is a gentle and slow-moving beast, allowing spexplorers to get an insight into it's behavior without worrying about being attacked. Spending most of their time feeding on low-growing plants, Yoshis travel in pairs or groups consisting of siblings or mothers and offspring. Females lay up to 8 baseball sized eggs, which she keeps a close eye on.

NODOPOTAMIDAE (Nodopotamids and Manateers)

Despite suffering heavy losses from multiple changes and competition from the vanguards and the neohadrosaurids, some species of nodosaurs which thrived in the Americas, well outside of Australia and Papua that is, by becoming semiaquatic.

Semi-aqauatic ankylosaurs (clade Nodopotamidae) are herbivores that live in the rivers, bayous, and coastal waters of the New World. In convergence with the Old World potamoceratopsids and duckgongs, nodopotamines are rotund and heavily-built, with relatively short legs and large heads, with eyes and nostrils placed far up so that they protrude from the water.

Fossil evidence indicates that the nodopotamids evolved from the few remaining species of nodosaurs, most notably from Denversaurus, and possibly Struthiosaurus, however this issue is still under debate, when their stock around the end of the Eocene, and then spread slowly across southern North America as their terrestrial cousins declined.  The first fossils of Nodopotamimids start to appear some time between the Oligocene and Miocene epoch. Some three million years ago, during the Great Faunal Interchange between the two Americas in the Pliocene, nodopotamimids spread across the western coastline of South America and infiltrated the rivers of that continent, including the famous Amazon River. When the Pleistocene Ice Age arrived, it killed off a good amount of nodopotamimids that lived in the Northern regions in the New World. However, the Nodopotamimids who lived in warmer climates, most notably the ones in Southeastern North America and South America managed to survive the ordeal.

All nodopotamids are docile plant eaters with powerful beaks, small, peglike teeth, and an armor of bone scutes protecting their backs.  Their chief predators are the crocodilians, mosasaurs and larger theropods which inhabit the land.

Gilded Nodopotamus (Nodopotamus aureus)

The gilded nodopotamus (Nodopotamus aureus) is the smallest of the nodopotamids, a denizen of the lakes and rivers of western and southern North America.  Like other nodopotamids, this two-meter herbivore feeds primarily on aquatic plants, cropping riperine vegitation or scraping algae off rocks with its flattened beak. 


Gilded Nodopotamus, Nodopotamus aureus (Western and Southern North America)

The gilded nodopotamus is not only unusual in its size, but also its habits, which are far more terrestrial than most of its kin.  While these nodopotami do spend much of their time in the water, they are also quite fleet-footed, with proportionally long and powerful legs to support them on land.  Gilded nodopotami are often seen out of water and grazing off soft plants in forests, especially during winter, when the lakes and rivers have started to freeze.

Louisiana Nodopotamus (Nodopotamus louisiensis)


Louisiana Nodopotamus, Nodopotamus louisiensis (Southeastern North America, mostly in Louisiana)

A new species of nodopotamus, the Louisiana Nodopotamus (Nodopotamus louisiensis) was found in the swamps of Louisiana. While spending most of its time in water, it will go up on dry land if the aquatic plants in the area aren't as abundant as the should be or to escape the preadtory alligators that lurk in the dark brackish waters of the Louisiana Swamps.

Their appearance is very similar to the likes of the gilded nodopotamus, the only major difference being the skin color, being a mixture of green and black, most likely an adaptation to camouflage itself from the other predators who live in the bayou areas. Also their tail seems to be more long and slender, possibly for better movement through the thick swamps.

Florida Manateer (Natatorpelta trichechidamimus)

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Florida Manateer, Natatorpelta trichechidamimus (Coastal waters and rivers along the Southern and Southeastern North America)

The Florida manateer (Natatorpelta trichechidamimus) is most commonly found in the salt-water estuaries of Florida. During the night, the manateer paddle into the deep ocean presumably to feed on the nutrient-rich kelp and surface feeding jellyfish. They stabilize themselves on the surface by inflating and deflating their lungs, which helps them stay afloat. Towards the morning, they swim back to shore since this is the time when the oceanic predators come out to hunt. Since their armor plating old covers their dorsal regions, the Manateer's underside is quite vulnerable to attack.

The manateer is a very social dinosaur, frequently traveling in pods of 4-12 individuals. It has been discovered that they engage in grooming behaviors, ridding each other of algae by scraping it off with their sharp beaks. Manateers mate for life. Females walk onto river deltas and sandbanks to lay their eggs, and are very defensive of their young.

Like many aquatic dinosaurs, the manateer is often followed by an armada of fish, some parasitic, some valuable, and still others seeking protection. On a side note, when this creature was first discovered, it was named "Archeopelta trichechidamimus". However, with the discovery of the real-life carnivorus archosauriform back in 2011, a more fitting name has been chosen, "Natatorpelta" meaning "swimming shield".

Amazon River Nodopotamus (Bryodorsus amazoniensis)


Amazon River Nodopotamus, Bryodorsus amazoniensis (South America)

The Amazon River, a body of water that runs down the eastern side of the Andes Mountains, through the widest part of South America, and into the Pacific Ocean, is a vast and energy-rich habitat, fully capable of supporting a diversity of large herbivores.  By far the most common of these aquatic and semi-aquatic grazers are the Amazon river nodopotamus (Bryodorsus amazoniensis), growing up to lengths of 4 meters long, somewhat larger than the gilded nodopotamus. The locals in the area tell of more species of Bryodorsus in the area, but this has yet to be confirmed.


When the mantarxs were first discovered living in the greater Antilles, the initial belief of spexsplorers was they had found yet another branch of the vanguard family tree. However, examination of cranial morphology, along with genetic testing which suggested they diverged from other spec Ornithischians in the Early Jurassic, quickly corroborated that bona-fide Ankylosaurs had been found, alive and kicking (well, more like trampling) on Spec.

Given the lack of any Cenezoic fossil record for the islands, along with the unspecialized skeletons of mantarxs, their ancestry is still subject to some debate. Some hypothesize the group are the descendants of basal Nodosaurs of Eastern North America, unknown in the fossil record but presumably closely related to European forms like Struthiosaurus and Eomantarx termieri, who presumably either swam via Florida, or walked across the Late Cretaceous land bridge. Others hypothesize they are the descendants of migrants coming the other way, from South America, although this is complicated by Cenozoic Ankylosaurs being known so fragmentarily that they may have been Nodosaurs themselves. Genetic studies are, of course, useless. We will simply have to wait for better fossils to turn up for a better answer.

Cuban Mantarx (Mantarx cubae)

At 200kg, the Cuban Mantarx is the largest of the four Mantarx species, as well as the largest land animal in the forests of Cuba. These round-bodied little creatures trundle like oversized beetles through the jungle's understory, eating fungi, small plants, roots and bulbs, and bark.

Outside of the Ogoun preying upon young, the Cuban Mantarx has little to fear from predators. Because of this, it shows interesting adaptations in terms of armor growth. After hatching, its bony scutes quickly grow to fill the dorsal surface of its body. But after about one year of age the scutes stop growing in number and size. Instead, the bare skin between the scutes begins expanding. At the same time, their coloration changes from a drab grey-green to a brilliant blue and white. At this point, a well-fed Cuban Mantarx generally weighs at least 30kg, and has little to fear from any island predator.

The three other Mantarx species are found in Hispaniola, Jamaica, and Puerto Rico. While the first is fairly close in size to the Cuban species, the latter two are far smaller - typically not exceeding 50 kg. Given Mantarx's dispersal across all of the greater Antilles, they are obviously a group with excellent swimming habits, which makes their insular distribution somewhat puzzling. Perhaps, they have grown so perfectly adapted from the splendid isolation of the Caribbean islands that the occasional gravid female who finds herself on Florida's shores simply cannot cope with millions of years of further predator-prey coevolution.

Works Cited

Tree of Life:Nodosauridae

- Daniel Bensen and Brian Choo

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