Anchiornis huxleyi Beijing specimen BMNHC PH828.
Because many creationists never seem to have progressed beyond the teleological thinking typical of toddlers, they assume that everything must have agency and must be directed towards some intended end.
That habit of mind was highlighted a few years ago in a study showing that the persistence of teleological thinking into adulthood is associated with the cognitive style underlying both creationism and conspiracism.
This goes a long way towards explaining why creationists so often invoke conspiracies to explain away the evidence against their beliefs, and why debating them can resemble arguing with toddlers who know little, understand less, and yet imagine themselves in possession of profound truths.
Any serious study of evolution, however, quickly shows that there is no plan, no foresight, and no directing intelligence. Evolution has no destination in mind. The only “direction” it has is whatever changing environments impose on it, favouring traits that happen, at any given time, to work best and leave the most descendants.
A recent study by a team led by Dr Yosef Kiat of the School of Zoology at Tel Aviv University’s George S. Wise Faculty of Life Sciences and the Steinhardt Museum of Natural History, working with colleagues in China and the United States, provides a striking illustration of that point. Their paper, published on 21 November 2025 in Communications Biology, suggests that some feathered dinosaurs in the anchiornithid lineage of pennaraptoran theropods may have evolved the ability to fly, only to lose it again when environmental change made flight no longer advantageous.
In other words, evolution did not move steadily towards some grand objective. It produced flight when flight was useful, and abandoned it when it was not. Feathers, which may briefly have served an aerodynamic role in these animals, appear then to have reverted primarily to their earlier functions of insulation and temperature regulation.
The key evidence comes from moulting patterns. In living flying birds, feathers are moulted symmetrically so that the bird can retain its ability to fly. In flightless birds, by contrast, moulting can be irregular and apparently disorganised. By examining fossils of these dinosaurs from Chinese deposits, the researchers identified this latter pattern in animals that otherwise appear to have possessed anatomical adaptations for flight.
The Evolution of Feathered Dinosaurs and Early Flight. The discovery that many small theropod dinosaurs possessed feathers has fundamentally changed our understanding of both dinosaurs and the origin of birds. Far from being a sudden innovation, feathers evolved gradually within a diverse group of carnivorous dinosaurs known as the maniraptoran theropods, a branch of the larger theropod lineage that also includes Velociraptor and Tyrannosaurus.Their findings are summarised in a news release published by the American Friends of Tel Aviv University.
From Insulation to Flight
The earliest feathers were simple, hair-like filaments, probably evolving for insulation or display, not flight. Over time, these structures became more complex—branching into vaned feathers capable of aerodynamic function. This progression is well documented in fossils from the Jurassic and Early Cretaceous deposits of northeastern China.
Crucially, this sequence shows that flight was not the original purpose of feathers. Instead, feathers were later co-opted (exapted) for gliding and eventually powered flight—an example of evolution repurposing existing structures for new functions.
Anchiornithids and Early Experiments in Flight
The anchiornithids, a group of small, feathered dinosaurs closely related to early birds, lived around 160 million years ago in the Late Jurassic. Fossils such as Anchiornis show well-developed feathers on both the forelimbs and hindlimbs, suggesting a “four-winged” body plan.
These animals were likely gliders or weak fliers, representing one of several evolutionary experiments in aerial locomotion. Other lineages, such as the dromaeosaur Microraptor, show similar adaptations, indicating that flight (or near-flight) may have evolved multiple times within this broader group.
The Origin of Birds
Modern birds evolved from within this radiation of feathered theropods. The famous fossil Archaeopteryx (c. 150 million years ago) combines clear dinosaurian traits (teeth, long bony tail, clawed fingers) with fully developed flight feathers, marking a transitional stage between non-avian dinosaurs and true birds.
Importantly, this transition was not linear. Different lineages experimented with different combinations of traits—some leading to modern birds, others ending in extinction.
Loss as Well as Gain
Just as flight evolved more than once, it was also lost repeatedly. Some feathered dinosaurs—and many later birds—reverted to a fully terrestrial lifestyle when flight no longer conferred an advantage. In such cases, feathers often reverted to their earlier roles in insulation, display, or brooding.
This pattern—gain, modification, and loss—illustrates a key point about evolution: it has no long-term goal. Traits persist only as long as they are advantageous in a given environment. When conditions change, even complex adaptations like flight can be reduced or abandoned.
TAU research about dinosaurs sheds light on the evolution of flight
160-million-year-old fossils reveal the complexity of wing evolution
A new study led by a Tel Aviv University (TAU) researcher examined dinosaur fossils preserved with their feathers and found that these dinosaurs had lost the ability to fly. According to the researchers, this finding offers a glimpse into the functioning of creatures that lived 160 million years ago and their impact on the evolution of flight in dinosaurs and birds.
160-million-year-old Anchiornis fossils.Photo: Tel Aviv University
The finding suggests that the development of flight throughout the evolution of dinosaurs and birds was far more complex than previously believed. In fact, certain species may have developed basic flight abilities and then lost them later in their evolution, the researchers say.
The study was led by Dr. Yosef Kiat of the School of Zoology at TAU’s George S. Wise Faculty of Life Sciences and the Steinhardt Museum of Natural History, in collaboration with researchers from China and the United States. The article was published on November 21, 2025, in the journal Communications Biology.
The dinosaur lineage split from other reptiles 240 million years ago. Soon afterwards (on an evolutionary timescale) many dinosaurs developed feathers — a unique lightweight and strong organic structure, made of protein and used mainly for flight and for preserving body temperature. Around 175 million years ago, a lineage of feathered dinosaurs called Pennaraptora emerged, the distant ancestors of modern birds and the only lineage of dinosaurs to survive the mass extinction that marked the end of the Mesozoic era 66 million years ago. As far as we know, the Pennaraptora group developed feathers for flight, but it is possible that when environmental conditions changed, some of these dinosaurs lost their flight ability — just like the ostriches and penguins of today.
Dr. Yosef Kiat, corresponding author
School of Zoology
Faculty of Life Sciences
Tel Aviv University
Tel Aviv, Israel.
In the study, nine fossils from eastern China were examined, all belonging to a feathered Pennaraptoran dinosaur taxon called Anchiornis. A rare paleontological finding, these fossils and several hundred similar fossils were preserved with their feathers intact, thanks to the special conditions prevailing in the region during fossilization. Specifically, the nine fossils examined in the study were chosen because they had retained the color of the wing feathers — white with a black spot at the tip.
Feathers grow for two to three weeks. Reaching their final size, they detach from the blood vessels that fed them during growth and become dead material. Worn over time, they are shed and replaced by new feathers in a process called molting.
Birds that depend on flight, and thus on the feathers enabling them to fly, molt in an orderly, gradual process that maintains symmetry between the wings and allows them to keep flying during molting. In birds without flight ability, on the other hand, molting is more random and irregular. Consequently, the molting pattern tells us whether a certain winged creature was capable of flight.
Dr. Yosef Kiat.
The preserved feather coloration in the dinosaur fossils from China allowed the researchers to identify the wing structure, with the edge featuring a continual line of black spots. Moreover, they were able to distinguish new feathers that had not yet completed their growth, since their black spots deviated from the black line. A thorough inspection of the new feathers in the nine fossils revealed that molting had not occurred in an orderly process.
Based on my familiarity with modern birds, I identified a molting pattern indicating that these dinosaurs were probably flightless. This is a rare and especially exciting finding: the preserved coloration of the feathers gave us a unique opportunity to identify a functional trait of these ancient creatures, not only the body structure preserved in fossils of skeletons and bones.
Feather molting seems like a small technical detail, but when examined in fossils, it can change everything we thought about the origins of flight. Anchiornis now joins the list of dinosaurs that were covered in feathers but not capable of flight, highlighting how complex and diverse wing evolution truly was.
Dr. Yosef Kiat.
Publication:
And so, once again, the evidence points not to design, foresight, or purpose, but to a process that is entirely contingent on circumstance. Flight, often held up as one of the pinnacles of biological “achievement”, turns out not to be a one-way evolutionary triumph, but a reversible experiment—gained when useful, and discarded when it is not. There is no grand plan here, no predetermined trajectory towards perfection, only a continual reshaping of life by shifting environmental pressures.
For creationists, this presents an uncomfortable reality. If features as complex and apparently “well-designed” as wings and flight feathers can evolve, be modified, and even be lost altogether, then the notion of a fixed, optimal design becomes untenable. Instead of neatly engineered systems, what we see are makeshift solutions—adaptations that work well enough for a time, but are always subject to revision, compromise, or abandonment.
The story of Anchiornis and its kin is therefore not just another fascinating chapter in the history of life; it is a clear demonstration of how evolution actually operates. It does not strive towards a goal, it does not plan ahead, and it does not produce perfection. It tinkers, it experiments, and it settles—temporarily—for whatever works. And when conditions change, it starts again, reshaping life in ways that no designer, working to a blueprint, would ever need to do.
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