Shop Mobile More Submit  Join Login
×
  • Photo
Download JPG 1200 × 793




Details

Submitted on
April 13, 2010
Image Size
241 KB
Resolution
1200×793
Link
Thumb
Embed

Stats

Views
9,470 (2 today)
Favourites
256 (who?)
Comments
34
Downloads
3,796
×
Velociraptor and protoceratops by Olorotitan Velociraptor and protoceratops by Olorotitan
Velociraptor and protoceratops
Add a Comment:
 
:icondinu1999:
dinu1999 Featured By Owner Dec 2, 2014  Hobbyist Digital Artist
That looks great!
Reply
:icontrisdino:
trisdino Featured By Owner Apr 29, 2014
The anatomy is top notch, and I love the velociraptors plumage. My only problems are that the raptors feathers end a bit to early on the head, and that the protoceratops lack guills.
Reply
:iconlordofstamps:
LordOfstamps Featured By Owner Aug 8, 2014
We don't know if protoceratops had the same quills as psittacosaurus. I think those quills first evolved in heterodontosaurids and it's possible the later ceratopsians lacked those quills. We'll have to find more fossils to find out.
Reply
:icontrisdino:
trisdino Featured By Owner Aug 8, 2014
Let me ask you this: Why would they lack them? Why? What is one good reason for them to have lost them? There is none.

Evolution does not just remove large traits such as the entire integument of an animal unless there is VERY strong pressure against it. Look at the amount of mammals with no fur at all, I mean, even elephants and naked mole rats have it, in fact, aquatic mammals are the only mammal species I can think of without any form of fur. Even if there was some pressure against large quills, the odds of them disappearing completely are unrealistically small, this we can see just by watching the way integument has evolved in modern animals possessing analogues of it, meaning feathers and fur. 
Reply
:iconlordofstamps:
LordOfstamps Featured By Owner Edited Aug 8, 2014
Oh and another thing. I don't think mammalian integument is a good comparison for the quills on psittacosaurus. It is unlikely they were used for thermoregulation like fur and feathers (one interesting suggestion I've heard is that psittacosaurus was semi-aquatic and the quills were covered by a layer of skin and formed a "fin"). From what we know so far, they seem to be confined to the tail. They were probably used for sexual display.
Reply
:icontrisdino:
trisdino Featured By Owner Aug 8, 2014
Feathers and fur are also used for sexual display, and even if they were not, that is not the point. Not to mention, quills probably shared a common ancestor with feathers. 
Reply
:iconlordofstamps:
LordOfstamps Featured By Owner Aug 9, 2014
You're completely ignoring the fact that the quills were located on the tail, not covering the entire body. They weren't used for thermoregulation at all. You're statements on hair loss in mammals doesn't apply to quills that weren't used for thermoregulation. Hell, similar quills were found on Tianyulong, a Heterodontosaur. This suggests they're a primitive trait. The earliest known Ceratopsian is Yinlong, which shares some features with Heterodontosaurs. Yinlong probably had these quills too. Maybe the quills were lost in favor of the head crests and horns on later Ceratopsians? Maybe they weren't. The point is there is no way to know for certain. Stop acting like you do know for sure.
Were they homologous with feathers? We can't say yet. It's still possible they evolved independently like the pcynofibers on pterosaurs. As for Kulindadromeus, some of the structures on that animal are unlike those of any feathered dino known so far (the ribbon-like structures on it's lower legs). In my opinion this doesn't suggest a homology. The quills on Ornithischians could have first arose in Heterodontosaurs or something similar and could have took on a thermoregulatory role later on in primitive Neoornithischians (maybe they were a forerunner to the armor on Stegosaurs and Ankylosaurs?).but I could be wrong. Unlike you, I'm not pretending to know anything for sure.
Reply
:icontrisdino:
trisdino Featured By Owner Aug 9, 2014
I think you must have misunderstood something, I am not claiming to know anything for sure, but I do know it better than you are letting on. No, the quills on Pisttacosaurus were not used for thermoregulation, they were probably used for display. Are you going to claim that fur is never used for display? Probably not. Okay, so, are you going to claim that ALL animals with fur use it for thermoregulation? Probably not. Now, are you going to claim that all animals with fur even NEED it? Probably not.

If a trait is ancestral, unless a solid reason for it to have de-evolved is found, assuming that it is still present is the default. If I put a box on the floor of a room while you are watching, and we then leave the room, only to come back a day later, and I ask you, right before we enter "do you think the box is still there?", your answer would probably be "yes". You could not be certain, but in the absence of evidence to the contrary, with no signs of broken windows and the door locked, you will assume that the box is still in there. Likewise, in the absence of evidence for the loss of quills, we will assume that they are still present. 
Reply
:iconlordofstamps:
LordOfstamps Featured By Owner Aug 9, 2014
But you are comparing tail quills that probably weren't used for thermoregulation to fur that covers the entire body of an animal thats unrelated to Psittacosaurus. That's like comparing human eyes to frog feet.

But guesswork is not the same as fossil evidence.
Reply
(1 Reply)
:iconlordofstamps:
LordOfstamps Featured By Owner Aug 8, 2014
I'm just saying that there isn't any solid proof that they had them. I'm not saying they didn't. There's no way to know unless we find a protoceratops fossil with skin impressions.
Reply
Add a Comment: