dinosaur – Nix Illustration

Spectember 2023 #04: Some Aukward Birds

An anonymous submitter asked for a “penguin/auk-like relative of Pelagornis“:

A shaded sketch of a speculative flightless seabird related to the extinct "pseudotooth" bird Pelagornis. It has a long slender beak with serrated tooth-like edges, a penguin-like body, flipper-like wings, large webbed feet, and a stumpy tail.

Odontopinguinus vomitus represents an unusal early branch of the pelagornithids that didn’t take up long-distance soaring, instead specializing for a pursuit diving lifestyle convergently similar to that of the contemporaneous early penguins, and the later auks and plotopterids.

About 1.2m tall (~4′), it has a more slender spear-like beak than its relatives, with forward-pointing pseudotooth serrations. Like other pelagornithids these “teeth” are fairly fragile, so it feeds primarily on soft-bodied fish and squid, pursuing them underwater with wing-propelled underwater “flight”.

Much like procellariiformes they’re also rather stinky birds, producing musky preen oil and projectile vomiting foul-smelling stomach contents at threats and rivals.

And another anon wanted to see a “big flightless marine duck”:

A shaded sketch of a speculative flightless marine duck. It has a goose-like beak with protruding comb-like structures at the sides (giving it the superficial appearance of having teeth), a long neck, a long loon-like body with vestigial folded wings, large cormorant-like webbed feet position far back, and a short tail.

Thalassonetta anambulatus is descended from the already mostly-flightless steamer ducks. At around 2m long (6’6″) it’s massive for a waterfowl, with vestigial wings and large webbed feet used to propel itself while diving.

With its rather elongated and heavy body and loon-like leg configuration it’s no longer able to walk on land – and it’s actually almost fully aquatic, only awkwardly hauling out into isolated island beaches to molt and breed.

It feeds mainly on molluscs, crustaceans, and other marine invertebrates, using the large lamellae in its bill to strain them out of soft seafloor sediments.

Spectember 2023 #01: Kiwi Alvarezsaur

It’s #Spectember time again!

I’m still trying to work through that big pile of speculative evolution concepts from a few years ago, so I’m hoping to make this month sort of a “lightning round” to finally clear out the backlog.

(I’m not going to set a definite posting schedule this year because things are pretty chaotic right now. But I’ll try to fit in as many as I can!)

So let’s start off with a concept from an anonymous submitter, who requested a “kiwi/sengi niche alverezsaur”:

A shaded sketch of a speculative dinosaur. It has a long narrow snout, small eyes, and whiskery facial feathers like a kiwi bird, a round fuzzy body, short chunky arms with large hooked thumb claws, long slender legs, and a long tail with a tufted fan at the tip.

Khamartaia dolabella is similar in size and build to Shuvuuia, about 1m in length (3’3″), with slender legs and stumpy arms with massive thumb claws. Unlike its close relatives, however, it has small eyes and fairly poor vision, relying more on its other senses to forage around during the darkness of night.

It has an acute sense of smell, and its long narrow snout is full of highly touch-sensitive nerves, allowing it to probe around for invertebrate prey in soil, undergrowth, and cracks and crevices. Its chunky thumb claws are used to dig up burrows and to tear through bark to access deeper insect nests.

It mainly relies on its long legs to sprint away from threats, although with its poor eyesight these escapes are often rather ungainly.

Crystal Palace Field Trip Part 2: Walking With Victorian Dinosaurs

[Previously: the Permian and Triassic]

The next part of the Crystal Palace Dinosaur trail depicts the Jurassic and Cretaceous periods. Most of the featured animals here are actually marine reptiles, but a few dinosaur species do make an appearance towards the end of this section.

A photograph of a Crystal Palace ichthyosaur statue, posed hauled out of the water like a seal or crocodile. It's partially obscured by plant growth, and is in a state of slight disrepair – moss and lichen patches cover its sides, and a plant is growing out of a crack on its back. A moorhen can be seen in the water swimming towards it.

Although there are supposed to be three Jurassic ichthyosaur statues here, only the big Temnodontosaurus platyodon could really be seen at the time of my visit. The two smaller Ichthyosaurus communis and Leptonectes tenuirostris were almost entirely hidden by the dense plant growth on the island.

Two photographs of the Crystal Palace ichthyosaurs. On the left the island is clear of foliage and all three can be seen; and on the right is the current overgrown state. — Ichthyosaurs when fully visible vs currently obscured
Left side image by Nick Richards (CC BY SA 2.0)

Two photographs of the large Crystal Palace ichthyosaur, showing closer views of the eye, flipper, and tail fin. Int he background a second ichthyosaur can be seen through the foliage. A moorhen is pecking around near the flipper. — *Head, flipper, and tail details of the Temnodontosaurus. A second ichthyosaur is just barely visible in the background.*

Ichthyosaurs were already known from some very complete and well-preserved fossils in the 1850s, so a lot of the anatomy here still holds up fairly well even 170 years later. They even have an attempt at a tail fin despite no impressions of such a structure having been discovered yet! Some details are still noticeably wrong compared to modern knowledge, though, such as the unusual amount of shrinkwrapping on the sclerotic rings of the eyes and the bones of the flippers.

An illustration comparing the Crystal Palace depiction of an ichthyosaur with a modern interpretation. The retro version has long toothy jaws, very large eyes, a seal-like body, four scaly-looking flippers, and a small eel-like fin on its tail. The modern version is a much more dolphin-like animal with smaller eyes, smooth triangular flippers, a dorsal fin, and a vertical crescent-shaped tail fin.

São Miguel Scops Owl

When owls find their way onto isolated islands lacking any terrestrial predators, they have a tendency to take up that role for themselves – evolving longer legs and shorter wings, and specializing more towards hunting on foot. From New Zealand to Hawaii to the Caribbean to the Mediterranean to Macaronesia, leggy island ground-owls have independently happened over and over again in the last few million years—

—And, unfortunately, they’ve all also become victims of the Holocene extinction, their fragile island ecosystems too easily disrupted by human activity and the arrival of invasive species.

The São Miguel scops owl (Otus frutuosoi) was found only in the Azores on São Miguel Island. About 18cm tall (~7″), it was slightly smaller than its relative the Eurasian scops owl, with longer legs, a wider body, and much shorter wings.

Its wing proportions indicate it would have been a poor flyer, instead primarily hunting on foot in the dense laurisilva forests. Since there were no terrestrial mammals or reptiles on São Miguel at the time, its diet probably mainly consisted of insects and other invertebrates – and it would have in turn been the potential prey of larger predatory birds like buzzards and long-eared owls.

All currently known subfossil remains of the São Miguel scops owl date only from the Holocene, between about 50 BCE and 125 CE. It’s likely that it was extinct by the 1400s, following the settlement of humans in the Azores, destruction of its forest habitat, and the introduction of rodents, cats, and weasels.

Danielsraptor

The evolution of falcons is rather poorly understood. Thanks to genetic evidence we know that they’re closely related to seriemas, parrots, and passerines, but their fossil record is patchy and little is known about the early members of their lineage.

But a group knows as masillaraptorids are giving us a rare glimpse at what some early falconiforms were up to. Known from the Eocene of Europe, these long-legged predatory birds seem to have been caracara-like terrestrial hunters specializing in chasing down prey on foot – although their wings and tails indicate they were also still strong fliers.

Danielsraptor phorusrhacoides lived during the early Eocene, about 55 million years ago, in what is now eastern England. Although only known from partial remains, it was probably around 45-60cm long (~1’6″-2′), and it had a large hooked beak with a surprising amount of convergent similarity to those of the flightless South American terror birds.

Its mixture of falcon-like and seriema-like features may indicate that the common ancestor of both of these bird groups was a similar sort of leggy ground-hunting predator.

April Fools 2023: How Titanis Lost The Right To Bear Arms

Huge, flightless, and carnivorous, the phorusrhacids (or terror birds) were some of the largest apex predators in South America during its Cenozoic “splendid isolation” as an island continent – and they were possibly the closest that birds ever came to reclaiming the ecological roles of their extinct non-avian theropod dinosaur relatives.

And for a while in the late 1990s and early 2000s there was a hypothesis that they’d even re-evolved clawed hands.

This idea was based on the wing bones of Titanis walleri, the only terror bird known to have dispersed northwards during the Great American Biotic Interchange when North and South America became connected via the Isthmus of Panama.

Living during the Pliocene and Pleistocene in Florida and Texas, between about 5 and 1.8 million years ago, Titanis stood around 1.5-1.8m tall (~5-6′) and was heavily built, with long strong legs and a massive hooked beak. Remains of its small wings were incomplete and fragmentary but had seemingly unusual joints, with what looked like a stiffer wrist and more flexible “fingers” than other birds, which led paleontologist Robert Chandler to propose in 1994 that this terror bird species had modified its wings into clawed grasping arms similar to those of dromaeosaurs, used to restrain prey animals while its beak tore them apart.

But the idea of a giant murder-bird with added meathook-hands only lasted about a decade. Further investigation in 2005 showed that Titanis‘ arms weren’t that weird after all – the same sort of joints are found in terror birds’ closest living relatives, the seriemas, and so Titanis really had the same sort of small vestigial wings as many other large flightless birds.

…However, there still could have been some claws on there. Many modern birds actually have one or two small claws on their hands that aren’t visible under their feathers, and terror birds like Titanis having something like that going on is completely plausible – they just wouldn’t have been using them for any sort of specalized predatory function.

Strange Symmetries #23: Convergent Earvolution

Although it’s not visible externally, owls have one of the most striking modern examples of asymmetry. The ears of many species are uneven, with the right ear opening positioned higher up than the left, giving them the ability to pinpoint the sounds of their prey much more accurately.

But surprisingly this isn’t a unique anatomical trait that only ever evolved once in their common ancestor.

Instead, multiple different lineages of owls have actually convergently evolved wonky ears somewhere between four and seven separate times.

The boreal owl (Aegolius funereus), also known as Tengmalm’s owl, is a small 25cm long (~10″) true owl found across much of the northern parts of both Eurasia and North America. While most other owls’ asymmetrical ear openings are formed just by soft tissue, the boreal owl’s lopsided ears are actually visible in the bones of its skull.

But despite how many times owls have convergently evolved asymmetrical ears, and how successful this adaptation has been for them, for a long time it seemed to be something that no other animals have ever mimicked.

In the early 2000s asymmetric ears were reported in the skulls of some troodontid dinosaurs, which seem to have been nocturnal hearing-based hunters similar to owls, but proper details on this feature still haven’t been formally published.

Then, just a couple of weeks ago, another example was finally announced.

The night parrot (Pezoporus occidentalis) is a small ground-dwelling parrot found in Australia, close to the same size as the boreal owl at around 22cm long (~9″). Critically endangered and very elusive, it’s rarely seen and little is known about it – and it was presumed extinct for much of the 20^th century, until more recent sightings of living individuals confirmed that the species is still hanging on.

Recent studies of preserved museum specimens have revealed that it seems to have poor night vision but excellent hearing, and that its right ear opening is noticeably asymmetrical, bulging out sideways from its skull. Much like owls the night parrot relies on acute directional hearing to navigate in darkness, but since its diet consists mainly of seeds it’s probably not using this ability to locate food sources. Instead it may be listening out to keep track of the precise locations of other parrots, and for the approach of predators – so its sharp sense of hearing may be the reason this unique bird has so far just barely managed to survive the presence of invasive cats and foxes.

Strange Symmetries #17: Spiky Surprise

Styracosaurus albertensis was a ceratopsid dinosaur living during the late Cretaceous about 75 million years ago, in what is now Alberta, Canada. Around 5m long (~16′), it was one of the most elaborately ornamented horned dinosaurs, with a long nose horn and multiple elongated spikes on its frill.

There was actually quite a lot of variation in the frills of Styracosaurus, with varying numbers of long spikes and extra hook-like projections present on some individuals. But one recently-discovered specimen nicknamed “Hannah” is especially surprising – it had a noticeable amount of asymmetry in its skull. The left and right sides show different numbers and arrangements of spikes, so much so that if the two halves had been discovered separately they might have been identified as belonging to two completely different species.

Frill arrangements are often used to define different ceratopsids, so if this level of individual variation and asymmetry existed in other species, too, then we may need to reevaluate some of them.

Strange Symmetries #14: The Tooth About Baryonyx

Almost all toothed theropod dinosaurs had exactly four teeth on each of their premaxillary bones, the paired bones at the very tip of the upper snout.

A diagram of the various bones in the skull of Spinosaurus. — *Spinosaurus* skull by AS | Public domain

The semi-aquatic spinosaurids were an unusual exception to this with six or seven teeth per premaxilla – and one particular member of this lineage seems to have been just a little bit weirder.

Baryonyx walkeri lived during the early Cretaceous, around 130-125 million years ago, in what is now southeast England. About 9m long (~30′), it had distinctive enlarged curving claws on the first fingers of its hands, along with a long narrow snout with a “rosette” at the tip followed by a notch (a shape convergent with the jaws of modern pike conger eels).

And that premaxillary rosette had a strangely asymmetrical arrangement of teeth.

A closer view of the lineart for Baryonyx's premaxillary rosette. The six left teeth are indicated in pink, and the seven right teeth in dark green.

The left side had six teeth, and the right side had seven.

Why? We don’t know!

Baryonyx skull material is rare and fragmentary, so it’s unclear if this was actually a characteristic feature of the species or if the known asymmetric rosette just represents an unusual individual.

Strange Symmetries #11: Step Up To The Plate

Stegosaurs are some of the most popular and recognizable dinosaurs thanks to their unique appearances, with small heads, elaborate back plates, and spiky thagomizer tails.

Closely related to the ankylosaurs, they first appeared in the mid-Jurassic about 170 million years ago. While they lasted until at least the mid-Cretaceous (~100 milion years ago), their heyday was in the latter half of the Jurassic, ranging all across Asia, Europe, Africa, and North America – and the North American species like the eponymous Stegosaurus developed especially elaborate plates in a distinctive asymmetrical pattern, not arranged in pairs like most other stegosaurs but in alternating rows along each side of the midline of their backs.

Hesperosaurus mjosi lived around 156 million years ago during the late Jurassic, in what is now Wyoming and Montana in the Western United States. It was closely related to Stegosaurus but was a little older and a little smaller, about 5-6m long (~16-20′).

Much like its more famous relative its plates seem to have alternated along its back, which may have been an adaptation to maximize visible surface area while minimizing the number of plates, saving on the energy needed to grow such large elaborate ornamentation.

Hesperosaurus might also represent a rare case of possible sexual dimorphism in non-avian dinosaurs, with wider more rounded plates potentially interpreted as belonging to males and taller pointed plates belonging to females.