Archaeopteryx

Type Species: Archaeopteryx lithographica

Classification: Dinosauria – Saurischia – Theropoda – Coelurosauria – Maniraptora – Paraves – Avialae – Archaeopterygidae

Time Period: Late Jurassic 

Location: Europe 

Diet: Carnivore

Archaeopteryx’s name means ‘Ancient Wing/Feather’, and for a long time it was thought to be the oldest known member of the Avialae (‘birds’), at least until earlier specimens were unearthed in China as far back as the Middle Jurassic. This Late Jurassic paravian lived among the cycad- and conifer-dotted wooded islands of prehistoric Germany, mingling with small lizards, pterosaurs, other paravians, and small theropods such as Compsognathus. Multiple specimens have been uncovered in what’s known as Solnhofen Lagoon, which during the Late Jurassic was interspersed with dozens of small islands. Archaeopteryx was similar in size to a Eurasian magpie, though larger individuals could reach the size of a raven. The largest species grew to about one and a half feet in length and would’ve weighed just over two pounds. Though originally considered to be the first bird, many paleontologists decry this statement, for Archaeopteryx had more in common with non-avian theropods – particularly dromaeosaurs and troodontids – than with birds. Just for beginners, it had toothy jaws, three clawed fingers on each hand, a lony bony tail, and hyper-extendable ‘killing claws’ on its feet. Though it had feathers, these are a shared morphology between birds and many different theropod classes. Because it’s morphologically closer to non-avian dinosaurs than modern birds, many have considered it a ‘transitional fossil’ between non-avian dinosaurs and avian dinosaurs and their modern-day descendants. Ironically, this ‘transitional fossil’ appears millions of years after more advanced paravians such as Serikornis and Anchiornis.

Archaeopteryx’s feathers were similar in structure to modern-day bird feathers. Its feathers were asymmetrical and showed the same structure as modern birds’ flight feathers: vanes given stability by a barb-barbule-barbicel arrangement. The tail feathers, too, were assymetrical with firm vanes. Its thumb didn’t yet bear a separately movable tuft of stiff feathers. Serious studies of Archaeopteryx feathers have been done one specimen dubbed ‘the Berlin specimen’. In this species, its legs had ‘trousers’ of well-developed feathers that are firm and capable of supporting flight. Pennaceous feathers ran along its back; these were asymmetrical and firm, though not as stiff as the flight-related feathers; thus these were similar to the contour feathers of the body plumage of modern birds. Aside from these feathers, the rest of the Berlin specimen was covered in a type of ‘proto-down’ similar to that found in the Early Cretaceous Sinosauropteryx. This ‘proto-down’ was decomposed and fluffy, and it may even have resembled fur in real life (though the fact that it wasn’t fur would be clear up-close under a microscope). This ‘proto-down’ went as far as the lower neck. In all species, the upper neck and head are clear of feathers. This is explained in one of two ways: either Archaeopteryx simply lacked feathers or proto-down on the upper neck and head, or this is an artifact of preservation. In the latter scenario, Archaeopteryx indeed had feathers (or, more likely, proto-down) on its upper neck and head, but these features were lost in death. Scientists believe most Archaeopteryx specimens became embedded in anoxic sediment after drifting for quite some time on their backs in the sea; in these anoxic waters, their corpses wouldn’t be scavenged, for marine life would be limited to smaller organisms that can survive such oxygen-depleted waters. While drifting on the waves, the head, neck, and tail bent downwards, with the body floating atop. They began to rot before they sank under the waves, resulting in loosening tendons and muscles resulting in the infamous ‘death pose.’ The skin, already softened by decay and by underwater friction, wouldn’t be able to keep hold of feathers or proto-down. Before the corpse settled to the seabed, those parts underwater – the neck, head, and tail – would begin to lose their feathers. The more firmly attached body feathers would’ve remained intact by the time the corpse settled on the seabed to be covered with sediment and fossilized for our enjoyment. 

Scientists have used electron microscopy and energy-dispersive X-ray analysis to detect the structure of the melanosomes of one of Archaeopteryx’s wing feathers and compared them with those of over eighty modern bird species; the conclusion was that Archaeopteryx’s original feather color was black with heavier pigmentation in the distal tip. In 2013 another study was done that indicated that Archaeopteryx’s flight feathers had complex light- and dark-colored plumage with heavier pigmentation in the distal tips and outer vanes. This type of coloration is consistent with many modern birds in which black melanosomes have structural properties that strengthen feathers for flight. This leads, of course, to the ultimate question: ‘Was Archaeopteryx capable of powered flight?’ Some scientists doubt that it could fly on its own, insisting that it was a ‘glider’ who would climb high into a tree, launch off, and glide to another tree or to the ground. Others argue that it was indeed capable of flight, though its flight mechanisms would’ve differed from those seen in modern birds. That it was capable of some sort of flight is undisputed. The fact that its feathers are asymmetrical hints at flight, for flightless birds tend to have symmetrical feathers; however, some flightless birds have asymmetrical feathers similar to those of Archaeopteryx. However, the degree of asymmetry in this dinosaur’s feathers more closely resemble those of slow-flying birds than flightless ones. If Archaeopteryx was capable of flight, it would’ve been more ungainly than what we’re used to; for instance, recent studies of flight feather barb geometry reveal that modern birds possess a larger barb angle in the feather’s trailing vane, and Archaeopteryx, lacking this large barb angle, would’ve been a weaker flier. Furthermore, the lack of a bony breastbone upon which flight muscles could attach also testifies to weak flying capabilities; detractors from this conclusion speculate that its strong flight muscles may have attached to the thick, boomerang-shaped wishbone, the plate-like coracoids, or even to a cartilaginous sternum. However, even if it had strongly-anchored flight muscles, its shoulder anatomy made it unable to lift its wings above its back, a requirement for the upstroke used by modern flying birds. However, it may have utilized a downstroke for powered flight. If it were capable of powered flight, its power would’ve been hindered by its large wings, which would’ve resulted in a low stall speed and reduced turning radius. The short, rounded shape of the wings would’ve increased drag, but scientists point out that it would’ve also improved its ability to fly through cluttered environments dense with trees and brush. Such heightened aerial mobility would’ve been improved by its hind wings on its legs. 

While much of the debate over Archaeopteryx’s flying ability (or lack thereof) revolves around its feather and anatomical structure, in 2004 some scientists took a different approach, asking themselves, ‘Did Archaeopteryx have a brain suited for flying?’ By analyzing a detailed CT scan of the braincase of an Archaeopteryx, the scientists found that its brain was proportionately much larger than those of most dinosaurs. The regions associated with vision took up nearly a third of the braincase, and other well-developed areas included hearing and muscle coordination. These are all factors seen in modern birds and necessary for aerial locomotion. The scientists also examined the inner ear and discovered that it more closely resembled the ears of modern birds than those of non-avian dinosaurs. Archaeopteryx had a cerebrum-to-brain-volume ratio 78% on the way to modern birds from the condition of non-coelurosaurian dinosaurs such as Allosaurus, which had a crocodile-like brain and inner ears. All this together suggests that Archaeopteryx had the keen sense of hearing, balance, spatial perception, and coordination needed to fly. The studies of Archaeopteryx’s braincase were revolutionary in the debate over its place in the sky, and in 2014 a team of dedicated scientists reported that their consensus was that Archaeopteryx was indeed capable of powered flight, but in a manner distinct and different from that of modern birds. Its modern equivalents would be pheasants and other burst flyers. 

If we were to step back in time to the Late Jurassic Period in Germany, we would find ourselves in the Solnhofen Lagoon among scattered low-lying, semi-arid, sub-tropical islands. The vegetation of these islands consisted of low-lying shrubs and cycads; interestingly, the islands of this lagoon seem to have lacked conifers. Few trunks have been found in the sediments, and tree pollen is absent. It was in this environment that Archaeopteryx lived, and it was a prime environment for a pheasant-like burst-flying hunter. It most likely hunted small prey, seizing it with its jaws if it was small enough, or with its claws if it was larger.