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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.

Lessiniabatis

Lessiniabatis aenigmatica was a rather strange stingray.

It lived around 50-48 million years ago during the early Eocene, in a shallow warm sea covering what is now Italy, with its three known fossil specimens all coming from the fish-rich Monte Bolca fossil beds.

About 60cm long (~2′), it had a round pancake-like body similar to many modern seafloor-dwelling stingrays – but uniquely it was also almost tailless, with only a tiny, slender, stingless tail.

It wasn’t a particularly strong swimmer, instead probably spending most of its time buried in the muddy seafloor sediment. When on the move it likely swam along just above the surface of the seafloor using undulations of its fins, foraging for smaller bottom-dwelling animals like worms, molluscs, crustaceans, and fish.

Megapterygius

Most mosasaurs all had very similar body plans: they were streamlined scaly monitor-lizard-like marine reptiles with four rounded paddle-shaped flippers, and many of them also had large shark-like tail fins.

But Megapterygius wakayamaensis here seems to have been doing something a bit different.

Living towards the end of the Cretaceous, about 72 million years ago, in the waters covering what is now western Japan, this mosasaur was around the size of a modern orca, roughly 6m long (~20′).

Unlike other known mosasaurs its flippers were huge, bigger than its own head and distinctively wing-shaped, with the back pair being larger than the front. This is an arrangement oddly reminiscent of the unrelated plesiosaurs, and may suggest a convergent sort of highly maneuverable “underwater flight” swimming ability – but unlike plesiosaurs Megapterygius also still had a powerful fluked tail, so how exactly all of its fins worked together is still unknown.

It’s also the first mosasaur known to preserve potential evidence of a dorsal fin. Some of its back vertebrae show a change in orientation at the point where a fin base would be expected to be, closely resembling the vertebrae shape of cetaceans like the modern harbor porpoise.