April 22, 2022 | David F. Coppedge

Are These Really Pterosaur Feathers?

The fuzzy claim says more about Darwin Party groupthink
than actual pterosaur traits

 

 

Some fibers have been found alongside the headcrest scales of a pterosaur. The paleontologists called them “feathers” and the media went nuts. But calling these fibers “feathers” is like calling a broomstick an airplane because witches ride them in cartoons.

Pterosaur discovery solves ancient feather mystery (University College Cork, 20 April 2022).

It always helps defuse hype by starting with the facts. Some fibers were found along the neck of a pterosaur called Tupandactylus. The well-preserved headcrest of this species from Brazil was found on a fossil belonging to a private donor. Scientists at University College Cork, Ireland were able to analyze the specimen before repatriating it to Brazil. They found single fibers and branched fibers. Round and oblong granules within the fibers, seen in electron micrographs, were interpreted as melanosomes—pigment bodies that often give color inside feathers and skin. In birds and other animals, the color often depends on their shapes and are a function of their chemistry. The shapes in this fossil varied within fiber types.

Out of these facts emerged a picture of the evolution of feathers that swept the world into a euphoria of celebration for Darwin.

An artist rendition in the press release shows fibers under the chin and along the backside of the headcrest only. No fibers are shown on the body of the flying reptile. The question is: are these feathers? The champions in the press release are certain of it; readers should recall, however, that the function of the press office at a university is to make its researchers look good (see “The Science Media Racket,” 11 Jan 2016).

This species of pterosaur is famous for its bizarre huge headcrest. The team discovered that the bottom of the crest had a fuzzy rim of feathers, with short wiry hair-like feathers and fluffy branched feathers.

“We didn’t expect to see this at all”, said Dr Cincotta. “For decades palaeontologists have argued about whether pterosaurs had feathers. The feathers in our specimen close off that debate for good as they are very clearly branched all the way along their length, just like birds today”.

The short press release calls these fibers “feathers” eleven more times. That’s all the media needed to hear to fly off into nephelococcygia (loosely translated “cloud cuckoo land”) like a flock of geese rising from a lake in a cacophony of feathers, squawking “evolution” in unison.

A colourful view of the origin of dinosaur feathers (Nature News and Views, 20 April 2022)

Birds and their dinosaur ancestors had feathers, and now it seems that a distantly related group called pterosaurs had them, too. The finding extends the origins of feathers back to long before birds evolved, and sheds light on their role.

Pterosaur fossil suggests feathers may have evolved long before flight (New Scientist 20 April 2022). Reporter Leah Crane lets Maria McNamara wag her tail feathers :

“The specific colours don’t really matter from an evolutionary sense; what matters is that they have these different colours,” says McNamara. “It probably means that the ability to impart colour is something that’s really ancient and that’s tied up in the whole way that feathers were evolved.”

Uncritical Media

A quick search shows dozens of hits on “pterosaur feathers” reverberating around the web in the last two days, without any questioning or doubt about the claim apparently. All the mainstream media are outdoing themselves trying to have the splashiest headlines: e.g., “Pterosaurs were covered with colourful feathers, study says.” Is nobody asking questions?

Maybe the research paper is more modest. McNamara and 10 colleagues published their study in Nature April 20, 2022 as Cincotta et al., “Pterosaur melanosomes support signalling functions for early feathers,” https://doi.org/10.1038/s41586-022-04622-3 (open access). Even though the paper was submitted last October 21, it didn’t reach the public till April 20, having been embargoed. This system gives time for all the news institutions to have their artwork and stories ready to flood the world simultaneously with a one-sided propaganda campaign to preach that ‘pterosaurs evolved feathers’. So is the source paper more modest?

Feathers are remarkable integumentary innovations that are intimately linked to the evolutionary success of birds and occur in diverse non-avian dinosaurs from the Middle Jurassic onwards. The early evolutionary history of feathers, however, remains controversial as relevant fossils are rare. Integumentary appendages in pterosaurs, traditionally termed pycnofibres, were recently reinterpreted as feathers on the basis of preserved branching but their homology with feathers is debated and their functions remain unclear. The small size and lack of secondary branching in pterosaur feathers precludes functions in active flight, but their dense packing and distribution over the body are consistent with thermoregulation. This in turn is consonant with functional hypotheses for small, simple feathers in theropod dinosaurs. Even simple unbranched feathers in theropods, however, functioned in visual signalling, as evidenced by melanosome-based colour patterning. Whether feathers in earlier-diverging taxa also functioned in patterning is unclear: feathers and filamentous integumentary structures in non-coelurosaurian dinosaurs and pterosaurs are rare and their taphonomy is difficult to interpret. As a result, the timing and phylogenetic and ecological context of the evolution of melanin-based colour patterning in feathers is unknown.

The team assigned the branched feathers to the category “open pennaceous vane” (Type IIIa) out of six agreed-on categories for integumentary structures, which range from monofilaments to the barbed pennaceous vanes of birds’ flight feathers. They claim these structures have a “rachis with barbs,” but a look at the photos in Figure 1 seems to make that idea a stretch. The best examples they show look something like fraying cables when curved, nothing like the regularly-spaced barbs on a bird feather branching off both sides of the rachis. Importantly, no secondary barbules are seen.

Asking Critical Questions

Artwork of Tupandactylus c. Bob Nicholls, reproduced by hundreds of reporters. Note the restriction of fibers to the chin and headcrest; none on the body. From the U of Cork press release (click image to read).

If these short, stubby, unruly filaments are to be designated “feathers,” they are a long shot from what most people think when they hear the word. Consider:

  • They have nothing to do with flight. Pterosaurs were strong flyers, but not with the help of the filaments.
  • The authors say nothing about whether the filaments come out of follicles, as with bird feathers. They say nothing about their relation to reptilian scales.
  • No reporters question the authors’ interpretation that the filaments “do not represent structural fibres of the skin that have decayed, as the feathers are restricted to a portion of the skull (occipital process) that should be devoid of such fibres.”
  • The authors suggest the fibers had a thermoregulatory role, but that also seems a stretch, given their low density and isolation to the headcrest. Pterosaurs may have had fur-like pycnofibers [pycno=dense] on their bodies but those are more hairlike or fuzzy than feathers.
  • If the granules were indeed melanosomes, they may have imparted some coloration to the fibers, but so do the melanosomes in hair. That role is not particular to feathers.
  • The authors are only speculating about a possible signaling function for the fibers, because no scientists have witnessed a live pterosaur’s behavior.
  • The paper mentions “soft tissue” 23 times, which should be the real story. To have such exquisite preservation of soft tissue after 115 million Darwin Years seems incredible, but all the reports take the age for granted.

The paper and press release, in short, is heavy on interpretation but light on certainty. Their main goal was to fortify Darwinism:

These tissue-specific melanosome geometries in pterosaurs indicate that manipulation of feather colour—and thus functions of feathers in visual communication—has deep evolutionary origins. These features show that genetic regulation of melanosome chemistry and shape was active early in feather evolution.

And yet how plausible to say that these little tiny fibers on the chin of this animal tell a story about evolution? Even within their own worldview, they know that pterosaurs are evolutionarily distant from both birds and dinosaurs. The authors speak of some mythical “avemetatarsalian ancestor of pterosaurs and dinosaurs” that is not found in the fossil record, where avemetatarsalian is a convoluted way of saying “bird-footed”. They have to concoct an ancestor, otherwise they would have to claim that feathers (speaking loosely) arose independently in dinosaurs, pterosaurs and birds.

Even so, their phylogenetic reconstruction (Fig. 2) shows a surprising scatter in the occurrence of diverse types of integumentary structures among dinosaurs and pterosaurs. As for Tupandactylus, it stands alone late in pterosaur evolution in this scheme, innovating the prized “open pennaceous vane” only to evolve no further, losing its innovation when all pterosaurs went extinct.

The phylogenetic tree (Fig 2) is rather humorous when you examine it. The mythical common ancestors of traits are shown with little pie charts of traits that they must have had to be able to pass them along to their descendants. Many of these supposed innovations were lost by subsequent ‘evolution by subtraction.’ That’s a twist on Darwinian evolution few know about: the ancestors had everything, but their descendants, like prodigal sons, squandered those gifts down the line. Only a few were able to ‘innovate’ those gifts again by ‘convergent evolution.’ What tales these people tell! The authors use the word ‘scenario’ five times.

The Darwin in the tale
The Darwin in the tale
Hi ho, scenario,
The Darwin in the tale.

Lemmings, by JB Greene. Used by permission.

 

 

 

 

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