December 2025 – Nix Illustration

Flandriacetus

Flandriacetus gijseni was an early beaked whale that lived during the late Miocene, about 8 million years ago, in nearshore marine waters covering what is now the Netherlands.

Around 4m long (~13′), it had a long snout lined with small sharp teeth – unlike modern beaked whales which are mostly toothless – and much like its close relative Messapicetus it probably led a more dolphin-like lifestyle feeding on small fish near the surface.

It’s currently the youngest known example of a long-snouted stem beaked whale, a holdover from a time when these cetaceans were much more ecologically diverse than they are today.

Diamantinasaurus

Diamantinasaurus matildae was a sauropod dinosaur that lived in what is now northeastern Australia during the Late Cretaceous, about 94 million years ago.

It was either part of an early evolutionary branch of the titanosaurs, or at least very closely related to them.

Growing up to around 15m long (~50′), it’s represented by multiple specimens of varying ages, including one of the most complete individual necks of any sauropod. Unlike later-diverging titanosaurs it still had thumb claws on its hands, and it’s unclear if it had any osteoderm armor.

A patch of preserved skin shows polygonal scales with a rough bumpy surface texture — but based on what’s now known from other types of sauropod it probably had a variety of other scale shapes and sizes across different regions of its body.

Recent discoveries of titanosaurian footprints in Mongolia also suggest that the large claws on these sauropods’ hind feet were mostly buried in soft tissue, with only the tips visible in life.

Fossilized gut contents in one specimen indicate Diamantinasaurus was a generalist herbivore eating a wide range of plant species, browsing from low to high foliage heights, and swallowing its bites without chewing. This particular individual wasn’t fully grown, however, and so it may have been in the process of transitioning from a low-level “juvenile” diet to a higher-level “adult” one.

Postschizotherium

Postschizotherium intermedium was a large hyrax that lived during the late Pliocene and early Pleistocene, about 2.5-2.2 million years ago, in what is now northern China.

About 1.5m long (~5′), it had very high-set and sideways projecting eye sockets similar to those of modern hippos, indicating it probably had a similar sort of semi-aquatic lifestyle. The shape of its skull also suggests it may have had a short tapir-like trunk.

Much like modern hippos or capybaras Postschizotherium probably spent much of its time wallowing in bodies of water, and emerging onto land to graze on grasses. Its habitat would have been humid forest and grasslands, alongside other animals such as large horses and bovines, one of the last chalicotheres, woolly rhinos, beavers, macaques, bears, big cats, early lynxes, and scimitar-toothed cats.

Ubaghsicystis

Ubaghsicystis segurae was an echinoderm that lived during the mid Cambrian, about 506-497 million years ago, in what is now Spain. Similar fossils are also known from Morocco, Mexico and Canada, suggesting this genus was quite widespread in marine continental shelf habitats at the time.

It was part of an extinct group known as eocrinoids, which were the earliest known echinoderms to develop stalked bodies and specialized feeding appendages — but despite the name and similar body plan, their resemblance to crinoids was due to convergent evolution rather than any direct relation.

Its globular body was only about 5mm in diameter (~0.2″), with a long stalk at least twice that length ending in a small disc that attached it to the substrate. The upper half of its body was dotted with small holes (called epispires) that probably served a respiratory function, and unlike most other eocrinoids it seems to have had just two slender flexible feeding appendages.

It would have been a suspension feeder, using tube feet to catch food particles floating around in the water, then move it down to its mouth positioned at the base of the two “arms”.

Luoxiongichthys

Luoxiongichthys hyperdorsalis was an early ginglymodian ray-finned fish, related to the ancestors of modern gars, living during the Middle Triassic (~244 million years ago) in coastal tropical marine waters covering what is now southwestern China.

About 15cm long (~6″), it had a large hump on its back shaped like a backwards shark fin. Its deep body was wider at the base, giving it a triangular shape when viewed from the front similar to some modern tropical fish – and suggesting it may have had a similar sort of ecology as a slow but highly maneuverable swimmer feeding on small seabed invertebrates.