ornithopod – Nix Illustration

Spectember/Spectober 2024 #07: Mole Dino

Today’s spec creature is a combination of a couple of submissions – James P. Quick asked for “a post-K/Pg relict dinosaur from pre-glaciation Antarctica”, and an anonymous asked for “a subterranean (like, say, Talpa or Spalax) burrowing dinosaur”:

At the time of the K/Pg mass extinction some of the small ornithopods that inhabited Late Cretaceous Antarctica had been developing increasingly complex burrowing behavior and a more generalist omnivorous diet than most other ornithischians – and, along with their ability to endure the long dark cold polar winters, this was juuust about enough for them to survive while the rest of their non-avian cohorts vanished.

They were very briefly a fairly successful disaster taxon in the devastated polar forests, but they were quickly displaced by other diversifying survivors and never really got another ecological foothold to regain anything close to the non-avian dinosaurs former glory.

Instead the little ornithopods specialized even further for burrowing, spending more and more of their lives underground to avoid the increasing competition and predation from mammals and birds.

A shaded sketch of a speculative descendant of small ornithopod dinosaurs in Antarctica. It's a fuzzy little mole-like animal with a hoked beak at the tip of its toothy snout, no eyes, a keratinous shield on its head, large shovel-clawed forelimbs, a chunky body, stocky legs, and a fat bristly tail.

Now, well into the Cenozoic at the dawning of the Miocene, Cthonireliqua quicki is the very last representative of the non-avian dinosaurs. Small and stocky and mole-like, just 15cm long (~8″), it has muscular forelimbs with large shovel-like claws, a keratinous shield on its head, and a thick bristly tail where large fat reserves are stored.

Its eyes are almost completely absent, only vestigial remnants present under the skin of its face, and it navigates its extensive burrows using sensitive whisker-like filaments and its keen senses of hearing and smell. Still omnivorous like its ancestors, it feeds on whatever it comes across while tunneling – mainly worms, insects, smaller vertebrates, roots, and tubers.

Unfortunately for Cthonireliqua, and the rest of its Antarctic ecosystem, time is running out. Over the last few million years Antarctica’s climate has been steadily cooling and drying, the continent has become fully isolated, and the Antarctic Circumpolar Current has formed. Glaciation is well underway in the continental interior, and the once-lush forests are shrinking away and being replaced with tundra.

Soon all evidence of these dinosaurs’ existence will be buried under the ice.

Minqaria

For a long time there were no hadrosaurid fossils known from Africa.

This seemed to mainly be due to the limits of the geography of their time. Hadrosaurs evolved and flourished during the late Cretaceous, when Africa was isolated from all the other continents, and they didn’t seem to have ever found their way across the oceanic barriers.

…Until in 2021 a small hadrosaur was discovered in Morocco, a close relative of several European species, showing that some of these dinosaurs did reach northwest Africa just before the end of the Cretaceous – and with no land bridges or nearby island chains to hop along, they must have arrived from Europe via swimming, floating, or rafting directly across several hundred kilometers of deep water.

And now another hadrosaur has just been described from the same time and place.

Minqaria bata lived in Morocco at the very end of the Cretaceous, about 67 million years ago. Only known from a partial skull, its full appearance and body size is unknown, but it probably measured around 3.5m long (~11’6″) – slightly larger than its previously discovered relative, but still very small for a hadrosaur. It might represent a case of insular dwarfism, since at the time Morocco may have been an island isolated from the rest of northwest Africa.

Along with its close relative Ajnabia, and at least one other currently-unnamed larger hadrosaur species, Minqaria seems to be part of a rapid diversification of hadrosaurs following their arrival in Morocco, adapting into new ecological niches in their new habitat where the only other herbivorous dinosaur competition was titanosaurian sauropods, and the only large predators were abelisaurs.

If the K-Pg mass extinction hadn’t happened just a million years later, who knows what sort of weird African hadrosaurs we could have ended up with?

Crystal Palace Field Trip Part 2: Walking With Victorian Dinosaurs

[Previously: the Permian and Triassic]

The next part of the Crystal Palace Dinosaur trail depicts the Jurassic and Cretaceous periods. Most of the featured animals here are actually marine reptiles, but a few dinosaur species do make an appearance towards the end of this section.

A photograph of a Crystal Palace ichthyosaur statue, posed hauled out of the water like a seal or crocodile. It's partially obscured by plant growth, and is in a state of slight disrepair – moss and lichen patches cover its sides, and a plant is growing out of a crack on its back. A moorhen can be seen in the water swimming towards it.

Although there are supposed to be three Jurassic ichthyosaur statues here, only the big Temnodontosaurus platyodon could really be seen at the time of my visit. The two smaller Ichthyosaurus communis and Leptonectes tenuirostris were almost entirely hidden by the dense plant growth on the island.

Two photographs of the Crystal Palace ichthyosaurs. On the left the island is clear of foliage and all three can be seen; and on the right is the current overgrown state. — Ichthyosaurs when fully visible vs currently obscured
Left side image by Nick Richards (CC BY SA 2.0)

Two photographs of the large Crystal Palace ichthyosaur, showing closer views of the eye, flipper, and tail fin. Int he background a second ichthyosaur can be seen through the foliage. A moorhen is pecking around near the flipper. — *Head, flipper, and tail details of the Temnodontosaurus. A second ichthyosaur is just barely visible in the background.*

Ichthyosaurs were already known from some very complete and well-preserved fossils in the 1850s, so a lot of the anatomy here still holds up fairly well even 170 years later. They even have an attempt at a tail fin despite no impressions of such a structure having been discovered yet! Some details are still noticeably wrong compared to modern knowledge, though, such as the unusual amount of shrinkwrapping on the sclerotic rings of the eyes and the bones of the flippers.

An illustration comparing the Crystal Palace depiction of an ichthyosaur with a modern interpretation. The retro version has long toothy jaws, very large eyes, a seal-like body, four scaly-looking flippers, and a small eel-like fin on its tail. The modern version is a much more dolphin-like animal with smaller eyes, smooth triangular flippers, a dorsal fin, and a vertical crescent-shaped tail fin.

Spectember 2022 #01: Arboreal Ornithopod

Despite some minor delays, it’s time once again for #Spectember – when I dive back into the big pile of speculative evolution concepts that you all submitted to me in 2020, and try to get through a few more of the backlog.

(…There’s still over 50 of them left. This is going to take a while.)

So today’s concept comes from an anonymous submitter, who requested an arboreal ornithopod dinosaur:

Retro vs Modern #12: Edmontosaurus annectens

Hadrosaurs were first discovered during the 1850s in North America, with the eponymous Hadrosaurus being both one of the most complete dinosaurs known at the time and also the first dinosaur skeleton to ever be mounted and displayed.

Like many other dinosaurs of the time hadrosaurs were initially reconstructed as bipedal with an upright kangaroo-like pose. Early in the history of their study their wide flat “duckbill” snouts were thought to indicate they were semi-aquatic, and they were frequently portrayed swimming and wading while feeding on soft water plants.

While elaborately bony-crested hadrosaurs like Parasaurolophus have become some of the most famous and recognizable members of the group, the species that’s gone through the most radical changes in our understanding in recent years is probably Edmontosaurus annectens.

1890s-1960s

Edmontosaurus has had an especially messy taxonomic history with various specimens spending decades under many different names, commonly being labelled as Anatosaurus and Trachodon for much of the 20^th century. For the sake of avoiding a lot of confusion I’m just going to keep referring to it here as “Edmontosaurus”, even though the naming issues weren’t properly sorted out until the 1990s.

The earliest specimen of what we know call Edmontosaurus was discovered in the 1890s, and the first to actually bear the genus name was the closely related species Edmontosaurus regalis discovered in the 1910s. For many decades it was mostly reconstructed in the then-typical “tripod” posture and seen as being highly aquatic, with an exceptionally well-preserved “dinosaur mummy” specimen being used to support that view – skin impressions around its hands were interpreted as paddle-like webbing used to swim.

The mummy also showed fairly thin and delicate skin, with a pattern of many tiny scales dotted with clusters of larger scales, and what appeared to be a fleshy skin frill running along Edmontosaurus’ neck and back.

2020s

The idea of amphibious hadrosaurs was finally challenged in the mid-1960s, at the start of the Dinosaur Renaissance, with details of their anatomy, possible stomach contents, and the environments that their fossils had been preserved in all being used to help reinterpret them as fully terrestrial herbivores that walked on four legs and ran on two. The discovery of Maiasaura nesting colonies in the late 1970s also revealed a lot of new information about the life history of these dinosaurs, and helped to popularize the image of them as social animals living in herds and caring for their young.

From the 1990s onwards new discoveries of additional “mummies” of both Edmontosaurus and other hadrosaurs have given us even more insights into the soft parts of their anatomy. Their necks and tails were much more thickly muscled and chunky than their skeletons alone suggest, the frill may have had a sort of rectangular segmented appearance, and the webbing on their forelimbs was actually more of a “mitten” that bound their hands into fleshy weight-bearing pads. And instead of a broad “duckbill” they actually had large hooked beaks covering their snouts, giving then more of a horse-like head shape.

We now know Edmontosaurus lived during the very end of the Cretaceous, about 73-66 million years ago, with the older part of that time range represented by Edmontosaurus regalis in Western Canada and the younger part represented by Edmontosaurus annectens in Western Canada and the Western and West North Central United States. It was one of the largest known hadrosaurs with most adult specimens around 9-12m long (~30-39′), but some of the very largest known partial remains suggest the existence of rare enormous “super-adults” that were about 15m long (49′).

Edmontosaurus was probably a grazing animal primarily eating tough low-growing foliage like horsetails, cropping off mouthfuls with its beak and then grinding them up with batteries of hundreds of teeth in the back of its jaws using a unique complex chewing motion.

Its skin had a complex texture of varying scale shapes and sizes across its body, and one mummified specimen of Edmontosaurus regalis shows a raised bumpy pattern of large scale clusters on its neck and a fleshy crest on the top of its head. It’s currently unclear if these were sexually dimorphic features and we don’t know if Edmontosaurus annectens actually had them too, but I’ve speculatively included them in this reconstruction anyway.

And despite being one of the most intensely-studied and completely known non-avian dinosaurs in the world, Edmontosaurus is somehow still continuing to surprise us. Parts of the mummy specimen nicknamed “Dakota” are still being carefully prepared, and in late 2019 the North Dakota Geological Survey teased an unexpected discovery – a large single hoof-like nail on the front of its hand, unlike anything ever seen before on a dinosaur, and suggesting that Edmontosaurus may have been much more specialized for purely quadrupedal movement than previously thought.

Official details on the “hoof” still haven’t been published yet, but whenever it happens it’ll be exciting to find out just what’s actually going on there.

Retro vs Modern #02: Iguanodon bernissartensis

Named just a year after Megalosaurus, in 1825, Iguanodon has remained a fairly iconic dinosaur ever since.

Discovered in a different region of Southeast England, its fossilized teeth were soon recognized as being similar to those of modern iguanas – but much much larger. Partial skeletal remains were initially reconstructed as belonging to a gigantic herbivorous lizard, with what was thought to be a horn placed on the tip of its nose.

1850s

The Victorian Crystal Palace statues of Iguanodon depicts a more bulky reptile with a nose horn, a toothless beak at at the front of its jaws, scaly skin, thick upright legs and hoof-like claws. Much like the Megalosaurus of the time it’s really not nearly so bad of a reconstruction as it’s often accused of being, showing a surprisingly naturalistic and almost mammal-like interpretation of these animals compared to later portrayals.

Technically the particular “Iguanodon” species at Crystal Palace has more recently been renamed Mantellisaurus atherfieldensis, but it was considered to be Iguanodon at the time so it’s included here anyway.

1880s-1960s

A massive discovery of the remains of nearly 40 Iguanodon individuals in a coal mine in Bernissart, Belgium, revealed the full anatomy of these dinosaurs for the first time. Much more well-preserved and complete than the patchy English material, these larger Iguanodon bernissartensis eventually became the official type species for the whole genus – a standard used to help determine whether similar-looking fossils are Iguanodon or not.

The Bernissart specimens were restored as bipedal animals in an upright kangaroo-like pose, with their tails dragging behind them acting like a tripod to prop them up. What had previously been the single “horn” was finally realized to instead be a thumb spike on each hand, interpreted as a defensive weapon against predators.

This image of Iguanodon persisted for decades, with a giraffe-like long prehensile tongue sometimes also depicted (including a particularly bizarre interpretation of it sticking out through a hole in the lower jaw!).

2020s

The Dinosaur Renaissance in the late 20^th century corrected Iguanodon‘s posture to hold its body horizontally, and it was eventually recognized as being capable of both bipedal and quadrupedal movement. Juveniles were found to have walked more on their hindlimbs, while adults spent more time on all fours but were still capable of running bipedally when they needed to.

We now have fossils of Iguanodon from across much of Europe during the Early Cretaceous, about 126-122 million years ago. Our modern view of this animal is a heavily built ornithopod that grew to around 9m long (~30′), with a horse-like head, a large keratinous beak at the front of its jaws, chewing teeth further back, and cheeks covering the sides of its mouth. Its chunky forelimbs each had a large thumb spike, hoof-like claws, and a prehensile grasping pinky finger, while its powerful hindlimbs ended in three-toed vaguely bird-like feet.

Soft tissue preservation discovered in related hadrosaurs suggests it probably also had a very bulky body with a thick heavily muscled neck and tail, and possibly an ornamental “frill” running along its back. Skin impressions show a covering of numerous tiny pebbly scales, generally too small to have been visible from a distance.

Aquilarhinus

Aquilarhinus palimentus here was an early hadrosaurid dinosaur known from the Late Cretaceous of Texas, USA, living about 80 million years ago. Around 5m long (16″5″), it had a prominent humped nose that seems to have been an evolutionary prelude to the larger and much more elaborate crests found in later hadrosaurs.

It also had an unusually wide and shovel-like beak, unlike any other known hadrosaur, which was probably a specialization for a different diet than its relatives. Since it lived along coastal marshlands it may have used its broad jaws to scoop up large mouthfuls of soft vegetation – or, much like the “shovel-tusker” proboscideans that were once thought to have a similar lifestyle, it may actually have been doing something else entirely with that beak.

Weird Heads Month #21: Honking Hadrosaurs

The ceratopsians and pachycephalosaurs weren’t the only ornithischian dinosaurs to do weird things with their skulls.

The hadrosaurs are commonly referred to as “duck-bills” (despite how their beaks weren’t actually duck-like at all), and are famous for the elaborate crests seen on some of the group’s members, with shapes ranging from lobes to helmets to hatchets to spikes – and even some of the apparently crestless species are now known to have sported fleshy combs instead of the bony structures seen in their relatives.

But by far the most recognizable of the crested hadrosaurs is Parasaurolophus walkeri, with its long curved backwards-pointing tubular crest.

This particular species was mid-sized for the genus, growing up to around 10m long (32’10”) and is known from Western North America during the Late Cretaceous, about 76-73 million years ago.

Its crest was intermediate in size and shape between the other two known species. The larger Parasaurolophus tubicen had a longer and slightly straighter crest, while the smaller Parasaurolophus cyrtocristatus had a shorter more strongly curved one. Juveniles developed these crests as they matured, starting off with much smaller bumps on their snouts that gradually grew backwards and upwards.

Some hadrosaur crests were purely for visual display, but in the lambeosaurine lineage that Parasaurolophus belonged to they also incorporated complex looping nasal passages that were probably used as resonating chambers, allowing each species to make a unique-sounding loud bellowing call to communicate with each other.

There are also rumors of a currently-undescribed specimen of Parasaurolpphus that has preserved soft tissue around its crest, possibly a keratinous covering or skin flaps that made it appear even larger and more flamboyant in life than the underlying bone. So I’ve given this reconstruction a speculative structure like that, along with hoof-like claws on its hands similar to those recently revealed for Edmontosaurus.

Island Weirdness #07 – Telmatosaurus transsylvanicus

The hadrosauroid dinosaur Telmatosaurus was another resident of Hațeg Island, and while it wasn’t quite as small or specialized as its cousin Tethyshadros it was still dwarfed compared to their other relatives, only growing to about 5m long (16’4″).

It was also the first dinosaur fossil found with a specific type of non-cancerous tumor known as an ameloblastoma on its lower jaw – a surprising discovery, since ameloblastomas were previously only known to occur in mammals and a single snake species. Various other types of abnormal tissue growth have been identified in other hadrosauroids and hadrosaurs, however, suggesting that this particular lineage of dinosaurs may have been unusually susceptible to developing tumors.

Island Weirdness #06 – Zalmoxes robustus

Hațeg Island was home to quite a few unique species right at the end of the Cretaceous, so we’ll be focusing on it for a few more days.

Zalmoxes robusutus was a member of the rhabdodontids, a group of herbivorous ornithopod dinosaurs related to well-known names like Iguanodon, Tenontosaurus, and the hadrosaurs.

It had a chunkier build than its closest relatives, with a deep skull, a large beak, and a rotund body. Like other rhabdodontids it would have had powerful jaw muscles and ridged cheek teeth specialized for scissoring, adaptations for cutting up particularly tough plant matter.

It was also quite small, about 2.4m long (7’10”), although since the largest known fossils represent subadults this may not have been its full size. A second species in the same genus (Zalmoxes shqiperorum) lived on the same island and was actually slightly bigger, suggesting that Z. robustus represented a minor case of insular dwarfism.