Ornithoscelida Rises: A New Family Tree for Dinosaurs

[Takama]

Im just going to not do a hypsilophodon for now.  Shame, though as i really wanted to commision one

[Neosodon]

Neosodon are you forgeting about Kulindadromeous?

First time hearing about Kulindadromeous. But I'm not entirely convinced since the classification of Kulindadromeous is unspecific. It's classified as Ornithischia which according to this new discovery is now the same group that therapods are in. So it could be an exotic misfit plant eating therapod like Therizinosaurus.

[CrypticPrism]

No, there's no way kulindadromeus is a theropod. It's definitely an ornithopod.

[Cloud the Dinosaur King]

Wow, this is revolutionary! I can't believe this! I blame Kulindadromeus and other feathered ornithopods, in a good way.

[CrypticPrism]

Yes, indeed. Btw, cloud, I love your channel.

[Cloud the Dinosaur King]

Yes, indeed. Btw, cloud, I love your channel.

Thank you.

[CrypticPrism]

Yes, indeed. Btw, cloud, I love your channel.

Thank you.

No prob. We should probably get back on topic.

Anyways, can someone explain where sauropods fit?

[Neosodon]

No, there's no way kulindadromeus is a theropod. It's definitely an ornithopod.

How do you know?

[CrypticPrism]

No, there's no way kulindadromeus is a theropod. It's definitely an ornithopod.

How do you know?

Mainly finger number and more skeletal similarities to heterodontosaurids than, say, a coleurosaur.

[Neosodon]

No, there's no way kulindadromeus is a theropod. It's definitely an ornithopod.

How do you know?

Mainly finger number and more skeletal similarities to heterodontosaurids than, say, a coleurosaur.

I agree it looks like an ornithapod but I can't find anywhere were it's actually classified as an ornithapod. So scientists must not really be sure.

[CrypticPrism]

On Wikipedia's article on kulindadromeus, it is considered part of ornithschia. Or whatever we're calling that group now.

[Loon]

In all seriousness, this is really interesting, and, forgive the pun, rather ground shaking in the grand scheme of things. I always found the relationship between the two saurischian groups to be rather strange.

[CrypticPrism]

I always found the relationship between the two saurischian groups to be rather strange.

Amen.

Amen.

[Neosodon]

Oops, ornithischia is not the same as ornithosceldia. The names look similar so I got them confused earlier.

[The Atroxious]

Jeez, this thread is moving faster than a falcon in a stoop.

This is really interesting news. Seems like this decade is going to be one of the more revolutionary times of paleontology. Personally, I can't wait to see how this plays out. I can't say I ever expected to see Herrerasaurus proposed to be closer to sauropoda than to theropoda, and theropoda to be proposed as a sister group to ornithischia, but at the same time it makes some sort of sense in my mind. I'm no paleontologist, but I have noticed that there are quite a lot of superficial similarities between early theropods and early ornithischians, while early sauropodomorphs seem decidedly different. Such similarities don't necessarilly mean much, but in light of this new argument, they become an interesting thing to note.

One thing that occurs to me is that, should these changes become part of the scientific consensus, where would that leave saurischia on the dinosauriform family tree? If dinosauria is defined as Megalosaurus+Iguanodon+MRCA or Passer+Triceratops+MRCA, effectively using theropoda and ornithischia to define dinosauria, is there a chance that saurischians could be reclassified as their own branch of dinosauriformes instead of true dinosaurs upon further study? It seems unlikely due to the autapomorphies, but it was a topic that came up in real life for me today, so I've been wondering about this.

[CrypticPrism]

Probably unlikely. I think that this just ties the group closer together, the image here doesen't do it justice. Sauropods are still related to theropods (I believe.)

[HD-man]

Personally, I don't find this convincing for a number of reasons.  I'll wait for several response papers before worrying too much about major changes in classification.  Additionally, in this study Eoraptor is suggested to be more closely related to Heterodontosaurus than to Panphagia, with Eoraptor and Heterodontosaurus being part of "Ornithoscelida" which Panphagia isn't a member of.  However, to me it seems Eoraptor is very similar to Panphagia, while Heterodontosaurus looks very different to these two.  In his Eoraptor skeletal, Scott Hartman even mentioned how similar Eoraptor is to Panphagia.

Panphagia: http://scotthartman.deviantart.com/art/All-Eater-213027613
Eoraptor: http://scotthartman.deviantart.com/art/Dawn-Thief-281226156
Heterodontosaurus: http://scotthartman.deviantart.com/art/A-mouth-full-of-different-teeth-363337739

I don't think Herrerasaurus was ever considered a theropod, instead I do believe it was at one time considered close to the ancestral condition for the whole of dinosaurs.

Herrerasaurus has been considered to be a theropod by palaeontologists and has been found to be one in some phylogenetic analyses.

This.

[Halichoeres]

One thing that occurs to me is that, should these changes become part of the scientific consensus, where would that leave saurischia on the dinosauriform family tree? If dinosauria is defined as Megalosaurus+Iguanodon+MRCA or Passer+Triceratops+MRCA, effectively using theropoda and ornithischia to define dinosauria, is there a chance that saurischians could be reclassified as their own branch of dinosauriformes instead of true dinosaurs upon further study? It seems unlikely due to the autapomorphies, but it was a topic that came up in real life for me today, so I've been wondering about this.

The authors redefine Dinosauria as the least inclusive clade includnig Passer + Triceratops + Diplodocus. Dinosauria has such a long history and has had such a stable composition that I think people will go to some lengths to not disrupt it. I would be very surprised to see anyone try to argue that this means that herrerasaurids and sauropodomorphs aren't true dinosaurs.

[Libraraptor]

Wow. This would be stunning but I am still careful.  Couldn't it also be that these scientists think "Well after all this feathered dinosaurs stuff we are afraid that public slowly loses interest and hence maybe we our jobs so let's quickly throw in something really weird to start a brand new controversity?"

[CityRaptor]

Sounds like one of those conspiracy theories.