Dinosaur feathers

[theropod]

Mar 21, 2019 23:24:20 GMT 5 dinosauria101 said:

^Concavenator does not have feathers. That was debunked in its profile here.

No it was not. There have been alternative proposals to the hypothesis that the bumps on the ulna are quill knobs, that’s not the same thing as they neither disproved the original hypothesis, not demonstrated convincingly why theirs should be preferred.
Moreover, the describers, who did conduct rigorous studies on the skeleton over the course of almost a decade, have repeatedly addressed these doubty and maintained that the bumps on the ulna are most likely quill knobs. That includes one conference paper at SVP that specifically refuted the muscle scar or intermuscular crest identity (link→). But you actually mentioned this one yourself on your profile, so I assume I’m not telling you anything new.

A few blog and mailing list posts stand against first hand examination of the specimen and detailed, peer-reviewed studies. The case is not closed (it would be nice if they could do the histological analysis to confirm the identity of the bumps, but they explained that they are hesitant to sample such a rare fossil), but there is certainly a strong imbalance in the respective evidence here. It is fine to have doubts, but to prefer another hypothesis should be based on a compelling reason.

[dinosauria101]

Odd. I could have sworn that was the case.
Well, these ongoing studies are kinda hard to draw good conclusions from

[theropod]

Well as I said, histological confirmation would have been nice. But apart from that, the study has been concluded. At least I count one dissertation, at least 5 published papers sprung from it and several conference contributions. I’d say that is about as good as it gets for a non-avian theropod that’s neither T.rex not Allosaurus or Anchiornis.

[Infinity Blade]

Carnotaurus skin impressions have finally been described!

www.sciencedirect.com/science/article/abs/pii/S0195667121002421

[Infinity Blade]

Cellular structure of dinosaur scales reveals retention of reptile-type skin during the evolutionary transition to feathers

Fossil feathers have transformed our understanding of integumentary evolution in vertebrates. The evolution of feathers is associated with novel skin ultrastructures, but the fossil record of these changes is poor and thus the critical transition from scaled to feathered skin is poorly understood. Here we shed light on this issue using preserved skin in the non-avian feathered dinosaur Psittacosaurus. Skin in the non-feathered, scaled torso is three-dimensionally replicated in silica and preserves epidermal layers, corneocytes and melanosomes. The morphology of the preserved stratum corneum is consistent with an original composition rich in corneous beta proteins, rather than (alpha-) keratins as in the feathered skin of birds. The stratum corneum is relatively thin in the ventral torso compared to extant quadrupedal reptiles, reflecting a reduced demand for mechanical protection in an elevated bipedal stance. The distribution of the melanosomes in the fossil skin is consistent with melanin-based colouration in extant crocodilians. Collectively, the fossil evidence supports partitioning of skin development in Psittacosaurus: a reptile-type condition in non-feathered regions and an avian-like condition in feathered regions. Retention of reptile-type skin in non-feathered regions would have ensured essential skin functions during the early, experimental stages of feather evolution.

www.nature.com/articles/s41467-024-48400-3