No protofeathers on pterosaurs

Pterosaur melanosomes support signalling functions for early feathers

“…1c–f ) and thus cannot be explained by superposition of monofilaments 35 . Nor does branching reflect degradation of monofilaments 35 —branched feathers show a consistent morphology, unlike the random pattern of fragmentation expected from decay. Further, the branched feathers 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.…”

“…Feathers are remarkable integumentary innovations that are intimately linked to the evolutionary success of birds 10 and occur in diverse non-avian dinosaurs from the Middle Jurassic onwards 1 . The early evolutionary history of feathers, however, remains controversial as relevant fossils are rare 3 , 11 . Integumentary appendages in pterosaurs, traditionally termed pycnofibres, were recently reinterpreted as feathers on the basis of preserved branching 2 but their homology with feathers is debated 3 , 11 and their functions remain unclear 4 .…”

“…The early evolutionary history of feathers, however, remains controversial as relevant fossils are rare 3 , 11 . Integumentary appendages in pterosaurs, traditionally termed pycnofibres, were recently reinterpreted as feathers on the basis of preserved branching 2 but their homology with feathers is debated 3 , 11 and their functions remain unclear 4 . 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 12 .…”

“…Critically, Tupandactylus includes many isolated (non-superimposed) feathers where branching is obvious (Fig. 1c–f ) and thus cannot be explained by superposition of monofilaments 35 . Nor does branching reflect degradation of monofilaments 35 —branched feathers show a consistent morphology, unlike the random pattern of fragmentation expected from decay.…”

“… Remarkably well-preserved soft tissues in Mesozoic fossils have yielded substantial insights into the evolution of feathers 1 . New evidence of branched feathers in pterosaurs suggests that feathers originated in the avemetatarsalian ancestor of pterosaurs and dinosaurs in the Early Triassic 2 , but the homology of these pterosaur structures with feathers is controversial 3 , 4 . Reports of pterosaur feathers with homogeneous ovoid melanosome geometries 2 , 5 suggest that they exhibited limited variation in colour, supporting hypotheses that early feathers functioned primarily in thermoregulation 6 .…”