Jiangxichelys neimongolensis

Jiangxichelys neimongolensis was a terrestrial turtle that was part of an extinct group known as nanhsiungchelyids, whose closest living relatives today are the aquatic softshell turtles.

(This species was previously known as “Zangerlia” neimongolensis, but has since been moved into the genus Jiangxichelys instead.)

It lived towards the end of the Cretaceous, about 75-71 million years ago, in what is now the Gobi Desert – which at the time was more of a semi-arid climate with both rivers and sand dunes.

Its 60cm long (~2′) carapace had a long wide shape that made it appear rather flattened from the front, but not to quite as much an extreme as its larger American cousin Basilemys.

Several fairly well-preserved specimens have been found that appear to have been buried alive, probably either engulfed by sudden sandstorms or trapped in collapsing burrows. This has preserved some anatomical details previously unknown in nanhsiungchelyids, such as the pattern of scales on top of the head and the presence of large bony osteoderms on the underside of the front toes, which may have aided with traction on loose sandy ground.

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April Fools 2024: The Curious Case Of The Chunky-Necked Ceratopsians

Much like the aquatic Compsognathus featured here a couple of years ago, not every novel idea that came out of the Dinosaur Renaissance was a winner.

And one of the oddest examples came from author/illustrator John C. McLoughlin.

His 1979 book Archosauria: A New Look at the Old Dinosaur featured an unusual interpretation of ceratopsian dinosaurs’ characteristic bony frills, proposing that they were actually muscle attachment sites for both powerful jaw muscles and enormous back muscles to help hold up their large heavy heads. This would have completely buried the frill under soft tissue, giving the animals massive thick necks and humped shoulders, and resulted in an especially weird reconstruction of Triceratops with a grotesque sort of wrinkly sewn-together appearance.

This concept didn’t entirely originate from McLoughlin – three years earlier in 1976 he’d illustrated Ronald Paul Ratkevich’s book Dinosaurs of the Southwest, which seems to have been the inspiration for Archosauria’s fleshy-frilled ceratopsians. A few paleontologists had also proposed jaw muscles attaching onto the frills during the 1930s and 1950s, and there’s even a book from as far back as 1915 that also shows the top of a Triceratops’ frill connected to its back! But McLoughlin’s Archosauria image is still by far the most extreme and infamous version of the idea.

There were a lot of things in Archosauria that were actually very forward-thinking for the time period, such as putting fuzz and feathers on small theropods and depicting non-avian dinosaurs as active fast-moving animals. The unique ceratopsian reconstructions, however, never caught on for several big reasons:

Firstly, all that hefty muscle tissue would have locked ceratopsians’ heads firmly in place, unable to move at all, which just doesn’t make sense biomechanically. Then there was the lack of skeletal evidence – muscles that big should have left huge visible attachment scars all over the frill bones, and there was no sign of anything like that on any fossil specimens. Finally, it turns out the ceratopsian head-neck joint was actually highly mobile, suggesting their heads were free to make a wide range of motions in life.

As wrong as they were even at the time, McLoughlin’s ceratopsians were still an interesting speculative idea, and notable for advocating for fleshier dinosaur reconstructions at a time when paleoart was trending towards shrinkwrapping.

Further reading under the cut:

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Kermitops

Despite being named after the famous Muppet frog, Kermitops gratus here wasn’t actually a frog itself. Instead it was a close relative of the common ancestor of all modern amphibians, part of a grouping of amphibian-like animals known as amphibamiform temnospondyls.

Living in what is now Texas, USA, during the mid-Permian, about 275 million years ago, Kermitops would have resembled a chunky salamander. Only its fossil skull is known, so its full body size is uncertain, but based on the proportions of related amphibamiformes it was probably around 15-20cm long (~6-8″).

Although its discovery helps to fill in the very sparse fossil record of the early evolution of modern amphibians, it’s also complicated matters more than expected. Previously it was thought that the characteristic skull anatomy of modern amphibians evolved in a clear sequence, but Kermitops has a unique mix of features that doesn’t fit this idea – suggesting that there was a lot of convergent evolution going on in amphibamiformes at the time.

Eurotamandua

Eurotamandua joresi lived during the mid-Eocene, about 47 million years ago, in the lush subtropical forests that covered what is now central Germany.

When it was first described in the early 1980s it was classified as an anteater due to its close resemblance to some modern species… but there were big problems with this interpretation. Anteaters have a sparse fossil record, but they’re known to have originated during the early Eocene in the isolated island continent of South America – so Eurotamandua’s ancestors making it all the way to Europe within just a few million years would be pretty remarkable!

Also, on closer inspection it didn’t have the distinctive skeletal features of a xenarthran mammal, suggesting it wasn’t an anteater after all.

Instead more recent studies have identified it as a close relative of pangolins, part of an early branch of the group that didn’t have the characteristic large scales.

About 90cm long (~3′), Eurotamandua would have a lifestyle much like the anteaters it convergently resembled, using its large claws to rip open ant nests and a long sticky tongue to feed.

Dinocephalosaurus

Dinocephalosaurus orientalis was a fully aquatic protorosaur reptile living in what is now southwest China during the mid-Triassic, about 244 million years ago.

Up to 6m long (~19’8″), it had a long serpentine body with paddle-like limbs and an especially elongated neck – but despite the superficial similarities to its semi-aquatic cousin Tanystropheus, Dinocephalosaurus’ long neck appears to have been independently evolved.

Much like the similarly-shaped elasmosaurs, its neck may have had a “stealth” function, allowing it to bring its jaws closer to targets before the rest of its body was visible, then using side-to-side snapping bites to catch its prey in its interlocking “fish-trap” teeth.

A preserved well-developed embryo inside one specimen also suggests that Dinocephalosaurus gave birth to live young, making it one of only two archosauromorph lineages known to have ever evolved this reproductive strategy.

Hemingwaya

Hemingwaya sarissa here was one of the earliest known billfish, related to modern sailfish and marlin. Living during the late Paleocene, about 58 million years ago, it inhabited the area around what is now Turkmenistan, in the warm shallow waters of the western Tethys Sea that covered much of central Asia at the time.

It was rather small compared to its modern relatives, just 30-40cm in length (~1′-1’4″), with a long streamlined body armored with six rows of scutes. Its slender snout was lined with tiny teeth, and both its first dorsal fin and first anal fin were tall and elongated. 

It probably wasn’t a very active swimmer, instead hovering near the surface and catching smaller prey with quick bursts of speed.

Patagomaia

Although most Mesozoic mammals were rather small, a few different lineages produced some pretty hefty-sized forms – most notably the metatherian Didelphodon, the gondwantherians Adalatherium and Vintana, and the eutriconodont Repenomamus.

And now we’ve got another one to add to that list.

Patagomaia chainko lived towards the end of the Cretaceous, about 70 million years ago, in what is now Patagonia near the southern tip of South America. Known from some partial leg and hip bones, it was potentially the largest known Mesozoic mammal yet discovered – estimated to have been similar in size to a modern bobcat, roughly 50cm tall at the shoulder (~1’8″) and weighing around 14kg (~31lbs).

Distinctive anatomical features of the bones indicate it was an early therian mammal, the group that contains both modern marsupials and placentals, but it can’t currently be classified any more specifically than that. Mesozoic therian fossils are very rare in the southern continents, so Patagomaia‘s presence in late Cretaceous South America adds to their known range and diversity, as well as providing an example of surprisingly large body size for the time.

Without more material it’s impossible to tell what Patagomaia‘s ecology was. I’ve gone for a fairly generic life appearance here, and while what’s known of its joints and muscle attachments doesn’t indicate climbing specializations, plenty of unexpected tetrapods still like to get up on tree branches.

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?

Panacanthocaris

Panacanthocaris ketmenica* here was a member of an extinct group of crustaceans known as kazacharthrans – close relatives of modern tadpole shrimp known mainly from Central Asia during the mid-to-late Triassic (but with possible German relatives from both the late Triassic and further back in the late Paleozoic).

Fossils of Panacanthocaris have been found in Kazakhstan and northwest China, dating to about 235-221 million years ago. It was fairly big compared to most of its modern cousins, reaching at least 10cm in length (~4″), and had distinctive spines around the edges of its carapace and its telson.

It’s not clear if it had eyes – there’s a single opening near the front of its carapace that may have housed some, and so I’ve depicted it here with just one naupliar eye similar to the “third eye” of tadpole shrimp.

It probably had a fairly similar lifestyle to its modern relatives, living in shallow freshwater and temporary pools and opportunistically feeding on everything from algae to smaller aquatic animals.

(* Sometimes also called P. ketmenia. May also be the same thing as Iliella spinosa, but until that paper is officially published the current name still stands.)

Miomancalla

The mancallines were a lineage of flightless semi-aquatic birds closely related to auks. Known from the Pacific coasts of what are now California and Mexico, between about 7.5 and 0.5 million years ago, they convergently evolved a close resemblance and similar lifestyle to both the recently-extinct North Atlantic great auk and the southern penguins.

Miomancalla howardi here lived in offshore waters around southern California during the late Miocene (~7-5 million years ago). The largest of the mancallines, it just slightly beat out the great auk in size – standing around 90cm tall (~3′) and weighing an estimated 5kg (11lbs).

Like great auks and penguins it would have been a specialized wing-propelled diver, swimming using “underwater flight” to feed on small bait fish. It probably spent much of its life out at sea, probably only returning to land to molt and breed.