Qinornis

66 million years ago, the end-Cretaceous mass extinction wiped out all dinosaurs except for the avian bird lineage.

…Or did it?

But I’m not talking about the dubious claims of non-avian dinosaur fossils found in places they shouldn’t be. This is about something else entirely: an unassuming little bird known as Qinornis paleocenica.

Living in Northwest China during the mid-Paleocene, about 61 million years ago, Qinornis was roughly pigeon-sized at around 30cm long (12″). It’s known only from a few bones from its legs and feet, but those bones are unusual enough to hint that it might have been something very special.

Uniquely for a Cenozoic bird, some of its foot bones weren’t fully fused together. This sort of incomplete fusion is seen in both juvenile modern birds and in adults of non-avian ornithurine birds from the Cretaceous – and the Qinornis specimen seems to have come from an adult animal.

If it was fully grown with unfused feet, then that would suggest it was actually part of a “relic” lineage living 5 million years after the mass extinction, surviving for quite some time longer than previously thought.

The last known non-avian dinosaur.

Silesaurus

Silesaurus opolensis here was a type of dinosauriform – a reptile very closely related to the ancestors of true dinosaurs, but not quite actually a dinosaur itself.

Living in Poland during the Late Triassic (~230 million years ago), it was a quadrupedal animal roughly the size of a large modern dog, about 50cm tall at the shoulder (1’8″) and 2m long (6’6″). The front of its lower jaw was toothless and covered with a keratinous beak, and there may have been a corresponding much smaller beak at the very tip of its upper jaw, too.

It was originally thought to be a herbivore, but coprolites full of insect remains suggest it was probably more of an omnivore, possibly foraging by pecking in a convergently similar manner to its distant bird cousins.

In fact, one of those pieces of Silesaurus poop was recently found to preserve a new species of tiny beetle in incredible detail.

Brontornis

Brontornis burmeisteri was one of the largest flightless birds known to have ever existed, standing around 2.8m tall (9’2″) and estimated to have weighed 400kg (~880lbs).

Known from the early and mid-Miocene of Argentina, between about 17 and 11 million years ago, it’s traditionally considered to be one of the carnivorous terror birds that dominated predatory roles in South American ecosystems during the long Cenozoic isolation of the continent.

But Brontornis might not actually have been a terror bird at all – it may have instead been a giant cousin of ducks and geese.

The known fossil material is fragmentary enough that it’s still hard to tell for certain, but there’s some evidence that links it to the gastornithiformes, a group of huge herbivorous birds related to modern waterfowl.

If it was a gastornithiform, that would mean it represents a previously completely unknown lineage of South American giant flightless galloanserans. And, along with the gastornithids and the mihirungs, it would represent a third time that group of birds convergently evolved this sort of body plan and ecological role on entirely different continents during the Cenozoic.

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.

Shri

About 72 million years ago, in the Late Cretaceous of what is now Mongolia, a dead dromaeosaurid dinosaur lost its head.

30 years ago, in 1991, its headless fossilized remains were discovered during a joint Mongolian Academy of Sciences / American Museum of Natural History expedition in the Gobi Desert.

For a long time the specimen was known only by the nickname of “Ichabodcraniosaurus”, in reference to a character haunted by a headless ghost in the story The Legend of Sleepy Hollow – but now it’s finally been given a full scientific description and a proper name.

Say hello to the first new non-avian dinosaur of 2021, Shri devi!

Named after a buddhist deity, this little dinosaur was around 2m long (6’6″), roughly the size of a modern peacock or wild turkey. It was a very close relative of Velociraptor, but lived in a slightly different part of the ancient Gobi than its famous cousin, giving us a glimpse of how dromaeosaurid species varied across that region.

A map of the Gobi region of Mongolia and China, showing locations where various dromaeosaurid dinosaur fossils have been found.
[ From fig 28 in Turner, A. H. et al (2021). A New Dromaeosaurid from the Late Cretaceous Khulsan Locality of Mongolia. American Museum Novitates. https://doi.org/10.1206/3965.1 ]

Eons Roundup 9

New year, new PBS Eons commission roundup day!

The ancient walruses Neotherium and Valenictus, from “How the Walrus Got Its Tusks”
https://www.youtube.com/watch?v=BKDGYGV2LK8


The nodosaurid ankylosaur Borealopelta, in both alive and “bloat-and-float” carcass states, from “The Dinosaur Who Was Buried at Sea”
https://www.youtube.com/watch?v=a-UZXBF63z4


The ankylosaurid ankylosaurs Gobisaurus and Dyoplosaurus, from “How Ankylosaurs Got Their Clubs”
https://www.youtube.com/watch?v=lRt-4SdzWrk

Leptostomia

Leptostomia begaaensis here is a recently-discovered pterosaur that lived during the mid-Cretaceous period, around 100 million years ago.

Its fossil remains were found in the Kem Kem beds of Morocco – ancient river deposits famous for yielding some of the newer specimens of the bizarre aquatic dinosaur Spinosaurus – and consist of just a couple of small pieces of jaw bones.

But those fragments are rather weird for a pterosaur.

While it’s hard to tell for certain from such meagre remains, Leptostomia might have been part of the azhdarchoid lineage, related to both the elaborately-crested tapejarids and the terrestrial-stalking giants like Quetzalcoatlus. And if it was indded an azhdarchoid it was an especially tiny one, possibly the smallest known member of the whole group. Based on the proportions of its relatives it would have stood just 30cm tall (1′) with a wingspan of 60-70cm (2′-2’4″), roughly comparable in size to a modern pigeon.

And it had an incredibly long beak that tapered to a thin delicate tip, resembling the beaks of modern probe-feeding shorebirds more than any other known pterosaur. It may have been specialized for the same sort of ecological niche, poking around in mud and shallow water for small invertebrates and snapping them up, possibly detecting its hidden prey using super-sensitive nerve endings in the tip of its beak.

Elsornis

The enantiornitheans (“opposite-birds”) were the most diverse and widespread group of Mesozoic birds, existing all around the world throughout the Cretaceous period. They retained claws on their wings and had toothy snouts instead of beaks, and while most of them lacked the lift-generating tail fans of modern birds they appear to have still been very adept fliers.

But Elsornis keni here was doing something different.

Known from the Late Cretaceous of Mongolia, about 80 million years ago, this opposite-bird  lived alongside famous dinosaurs like Velociraptor and Protoceratops in what is now the Gobi Desert. Only a single partial specimen has ever been found, so its full life appearance is unknown and this reconstruction is somewhat speculative, but it would have been around the size of a pigeon at 25cm long (10″) – not including any decorative tail feathers it may have had, similar to other enantiornitheans.

It wing and shoulder bones were very odd for an opposite-bird, with proportions that don’t match anything capable of competent flight. Instead Elsornis appears to have been a flightless enantiornithean, a representative of a previously unknown terrestrial lineage.

Spectrovenator

(This is a couple of days late for Halloween, but since this October saw the description of a new dinosaur species with a particularly spooky name, I couldn’t resist putting it into the schedule anyway.)

Spectrovenator ragei was an early member of the abelisaurid lineage, living in southeastern Brazil during the Early Cretaceous, about 120 million years ago. It was one of the smallest known abelisaurids, measuring just 2m long (6’6″), and lacked a lot of the skull specializations seen in larger-bodied Late Cretaceous forms like Carnotaurus, suggesting it was more of a generalist predator.

Its genus name translates to “ghost hunter” due to it being found underneath the fossil remains of another dinosaur entirely – a “ghost” unexpectedly appearing when the specimen was being prepared – but it’s extra appropriate since it also helps to fill in a rather sizeable ghost lineage in the fossil record of abelisaurids.

Anzu

Named after the mythological bird-like Anzû – and also nicknamed “the chicken from hell” – Anzu wyliei was one of the larger known oviraptorosaurs, measuring about 3m long (9’10”).

Its fossils are some of the most complete for a North American member of this dinosaur group, with four different specimens representing about 80% of the whole skeleton.

Living right at the end of the Cretaceous, about 66 million years ago in North Dakota and South Dakota, USA, Anzu inhabited the ancient floodplains of Hell Creek and appears to have been a fairly fast-moving omnivorous generalist. It had a large crest on its head made of rather fragile thin-walled bone, which may have been used for display or sound amplification similar to the casque of modern cassowaries.

Some of the fossil specimens also show evidence of healed injuries, including a broken rib and an arthritic toe.