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 ]

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.

Weird Heads Month #12: Double-Crested Dinosaurs

Dilophosaurus wetherilli is a fairly recognizable dinosaur thanks to its memorable appearance in the Jurassic Park franchise – but unfortunately that also means the popular image of it is completely wrong.

Rather than a small frill-necked venom-spitting creature, this early theropod was actually rather large, reaching around 7m long (~23′), and along with its distinctive double crests it also had a narrow snout with large teeth and a distinctive notch at the front of its lower jaw.

It lived in North America during the early Jurassic, about 196-183 million years ago, and while it wasn’t venomous its notched jaws were probably capable of delivering powerful bites to small struggling prey, much like the similar-looking ornithosuchids in the Triassic. Some structural similarities to the skulls of spinosaurids suggest it may have primarily eaten fish.

Its two bony crests were probably used for visual display, with juveniles only having small crests that fully developed as they matured. They also may have had a more extensive keratinous covering, so it’s not clear what their actual shape and full extent was in life.

Kalligrammatids

Did you know butterflies weren’t the first insects to look like butterflies?

Lepidopterans (the group of insects containing moths and butterflies) have been around since the Late Triassic – but it wasn’t until the diversification of flowering plants during the Cretaceous that recognizable moths would have evolved, and true butterflies didn’t actually appear until the early Cenozoic.

Before then, back in the mid-Jurassic about 165 million years ago, a completely different group of insects convergently evolved remarkably butterfly-like features such as large colorful scaled wings and long sucking proboscises.

Known as the kalligrammatids, these insects were giant members of the lacewing group, related to modern forms like antlions and owlflies. But unlike their predatory relatives the kalligrammatids were specialized pollinators, possibly having a mutualistic relationship with the flower-like cones of bennettitales or the pollination drops of some types of conifers. They seem to have originated in China and were found across Asia and Europe by the Late Jurassic, but a few fossils from South America suggest they were even more widespread and may just have a poor fossil record.

They reached wingspans of up to 16cm (~6″), comparable to some of the largest modern butterflies, and often sported conspicuous anti-predator markings on their wings such as stripes and eyespots – so it’s not surprising that they’re often nicknamed the “butterflies of the Jurassic”.

A fossil of a butterfly-like insect. Stripes and eye-spot markings are preserved on its wings.
Markings preserved on the wings of Oregramma illecebrosa, from Yang et al (2014) | CC BY 2.0

Rather ironically, the extinction of the kalligrammatids was probably linked to the rise of the flowering plants that the true butterflies would later be so dependent on. As flowers diversified and plants like the bennettitales declined, the kalligrammatids dwindled and disappeared, with the last known fossil record coming from the mid-Cretaceous of Brazil about 113 million years ago.

But while they were around, I do wonder if they also exhibited some similar behaviors – such as mud-puddling for extra nutrients, and specifically the habit of drinking the tears of larger animals that we see in some species. Perhaps some non-avian dinosaurs like this Dilong occasionally put up with kalligrammatids sitting on their faces!

Vespersaurus

For around 50 years some very unusual dinosaur tracks have been found in ancient desert sediments in South America: strange footprints showing the impression of only a single toe, a walking style never before seen in any reptiles.

And recently a fossil of what might be the track maker has actually been found.

Named Vespersaurus paranaensis, this new species lived during the Late Cretaceous of Brazil (~90 mya) and was a member of the noasaurid family of theropods, closely related to the weird-jawed Masiakasaurus from Madagascar.

Measuring about 1.5m long (~5′), Vespersaurus was fairly lightly built with legs proportioned for running – and its feet were absolutely unique. Although it had the standard three main toes of a theropod, it bore its weight entirely on the middle toe and held the other digits off the ground. The two raised toes on each foot also had large knife-like claws which may have been used during hunting, vaguely similar to the sickle claws on the feet of dromaeosaurs. But unlike dromaeosaurs these claws weren’t highly curved or pointed, suggesting Vespersaurus used more of a scratching and slashing technique rather than the raptors’ puncture-and-restraint strategy.

Much like ancient horses, it may have developed its single-toed stance as an adaptation for more efficient fast running, possibly to avoid larger predators or to chase down small fast-moving prey like hopping desert mammals.

The known one-toed fossil footprints are actually slightly older than the Vespersaurus fossil, and similar tracks in Argentina have been found dating back to the Late Jurassic (~150mya), so there may have been a long lineage of “one-toed” desert-dwelling noasaurids in South America that haven’t been found yet.

Glowing Dinosaurs

Many modern birds are capable of seeing into the ultraviolet regions of the electromagnetic spectrum, and some of their non-avian dinosaur ancestors might have had the same sort of vision. And much like their living relatives, that means various parts of their bodies and plumage may also have been UV-reflective and UV-fluorescent.

So here’s a Velociraptor with some speculative UV coloration – although this is just what it would look like to human eyes under a blacklight. What it would actually look like to a creature that can see extra colors is impossible to depict on a screen designed for trichromatic vision!

Island Weirdness #08 – Balaur bondoc

When Balaur was described in 2010 it was initially thought to be a dromaesaurid closely related to Asian forms like Velociraptor. With its particularly stocky legs built for strength rather than speed, two-fingered hands, and two large sickle claws on each foot, it was interpreted as a weird highly specialized predator terrorizing the other Hațeg Island species at the end of the Cretaceous. Although only 1.8m long (5’10”), it was hypothesized to have taken down prey much larger than itself with powerful slashing kicks.

But later analyses cast doubt on this interpretation.

A lot of the anatomical features of Balaur’s skeleton were odd for a dromaeosaurid, but matched those of avialans – a group of close evolutionary “cousins” to the dromaeosaurids, containing Archaeopteryx and the common ancestors of all modern birds. And, by 2015, multiple studies had confirmed Balaur wasn’t really a “raptor” but instead a little further along on the bird lineage.

So now our picture of this dinosaur is very different: a chunky-bodied island bird, grown large and secondarily flightless sort of like a Cretaceous equivalent to the dodo. Its double sickle claws were probably adaptations for climbing and perching in trees, and based on similar avialans it was likely a herbivore rather than a hypercarnivore.

Qianzhousaurus

Qianzhousaurus sinensis, a tyrannosaur from the Late Cretaceous of southern China (~72-66 mya). Measuring about 9m long (29′6″) it had an unusually long and slender snout for a tyrannosaur, leading to its nickname of “Pinocchio rex”.

The only other known long-snouted tyrannosaur was the closely related Alioramus from Mongolia – but since only juveniles of that genus have been found so far, it’s also possible that Qianzhousaurus was actually just a fully-grown species of Alioramus.