It's already certain that small raptors like Velociraptor were almost entirely covered in feathers, somewhat resembling terrifying turkeys. XD
But was the same true for their larger and heavier relatives like Deinonychus and Utharaptor? Or were they perhaps satisfied with a covering of feathers on their legs, back, neck, and tail?
I know this is mostly speculation, because the fact that they had feathers at all, from what I understand, is based on their relationship, not because there's any hard evidence that these larger dromaeosaurs actually had them.
Am I wrong?
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I belive utahraptor was found to have some quill knobs(attachment point for big feathers), which you only have if you have big feathers. But beyond that we don’t really know how feathered they were.
However yutyrannus is much much bigger, so basically any form on the covering is theoretically possible.
Are you thinking of the Velociraptor quill knobs? I don't think there's any direct evidence for feathers demonstrated from Utahraptor.
That is very possible.
Isn't the density of the potential feather cover related to thermal regulation? Meaning, the larger the theropod, the fewer feathers it would need because the greater its mass, the easier it is to retain heat. Is that how I should understand it?
There is a correlation, but there also is a correlation between size of feathers and ability to fly, yet peacock males exits. Aka, there are many things that could affect how feathered they were, from climate to sexual selection. They could also be fully covered, but just have shorter feathers, so.. many options.
The raptor prey restraint is an example. If Utahraptor still employed this killing method despite its size, it would need “wing” feathers to do so.
It is worth noting that Utah in particular wouldn't have been as effective at it with its more blade-shaped sickle being better for slashing.
But thats not really related to its size either. I think its the same with Achillobator though? If Dakotaraptor is valid, its most likely the most Feathered large raptor
Male peacocks can fly tho
They can fly, but not particularly well. To the point that they drop the truly big feathers outside of mating season, if I’m not misremembering completely.
They fly really well even with the large feathers
Regulation means control, so it helps both keep cool and keep warm. This is why ostriches have thick feather coverage.
Feather/hair/fuzz reduction in larger animals is a function of thermoregulation. If an animal has a low ratio of internal volume : external area, it sheds heat more rapidly, so needs extra insulation to trap the heat in. But the higher that ratio gets (ie. the chunkier the animal is), the less heat is shed, and eventually there's an inverse problem where the animal needs special adaptations to prevent it overheating.
The thing is that dromaeosaurid feathers weren't purely for thermoregulation, we know for a fact that the closely related oviraptorosaurs used their wings during brooding to cover the eggs. It's also theorised that the wings would have provided advantages to maneuvrability, stability, and ability to traverse steep inclines. The largest known dromaeosaurid with good feather impressions (Zhenyuanlong, roughly the same size as Velociraptor) has no feather reduction at all, and in fact has unusually long wing feathers (albeit anchored to unusually short arms for a dromie).
So it's likely that even the largest dromaeosaurids would have retained wing feathers, because they had key lifestyle functions unrelated to thermoregulation. But even in terms of heat loss... the largest dromaeosaurids weren't huge by theropod standards. Utahraptor was half a tonne, and quite a long animal, so I think had a relatively low volume:area ratio. Yutyrannus was around 3 times that weight, and had a full fluffy covering... admittedly in a cold-ish area (equivalent average temperature to Britain today), but still.
When you look at the eight-tonne Tyrannosaurus, it stands to reason that it would have mostly or completely lost its ancestors' fluffy coat, but with Utahraptor, it's unlikely. What I'd expect is shorter body feathers than the smaller genera, maybe with bare regions in the legs and underbelly like Ornithomimus. But no more reduction than that. Deinonychus I'd expect to have coating closer to Sinornithosaurus or Zhenyuanlong; little reduction if any.
Think of it like this: we have wooly mammoths and wooly rhinos, and their virtually hairless close relatives.
I think most dinosaur families worked in the same way. Some would be heavily feathered if they lived in environments that got really cold. Others would be totally scaled if they lived in environments that were warm.
We know that feathers are modified scales. There are probably genetic switches that activate a scale to feather production. This seems to be the case with modern birds. For example, there are certain mutations in chickens and pigeons that cause their foot scales to become feathers.
Not to mention such birds as ptarmigan that have scaled feet in the summer and feathered feet in the winter. I see no reason why some dinosaurs may have done something similar depending on the season.
The arm bones attributed to Dakotaraptor have quill knobs, and that’s on a polar-bear sized animal. Even if the bones turn out to not be Dromeosaur in origin, it shows that even large animals in warm swampy hell creek could be fully feathered.
I believe I’ve also heard of quill knobs on Utahraptors found in the Utahraptor block but I’m not aware of anything published so take that with a big grain of salt.
It’s interesting to note that all large extant birds maintain luxurious feather coats no matter the climate.
“Somewhat resembling terrifying turkeys” tf kinda turkeys are all of you looking at?