Dinosaur Ontogeny

Last summer, I had the wonderful opprotunity to attend a lecture by Jack Horner. It was on the topic of Dinosaur Ontogeny. Jack has a new idea going, about the appearences of dinosaur young. He contests, that many species of dinosaurs, especialy from hell creek, are just juveniles of another dinosaur. To start off, you probably know, but baby trikes were born with their horns pointing backwards, and they then grew forward. We also know, that Torosaurus was larger than Triceratops(at lest in the head), and that there has never been a documented Torosaur juvenile. Jack suspects, that Triceratops is just the sub-adult form of triceratops. Now this is not just looking at external features, but internal as well, such as bone density etc.. Along these lines he suspects that Nanotyrannus is just a juvenile Tyrannosaurus, and that Dracorex, and Stygimoloch, are just the juvenile and sub-adult forms of Pachysephalosaurus. Very interesting and convincing (especially from his mouth). What do you think? PS. On a sad note, Brachiosaurus has been changed to the lame (in my opinion) Giraffititan. Now I know hw the people who grew up with Brontosaurus felt.

Flek wrote:PS. On a sad note, Brachiosaurus has been changed to the lame (in my opinion) Giraffititan. Now I know hw the people who grew up with Brontosaurus felt.

What? No it hasn't. B. altithorax still exists. Only B. brancai got renamed.

As for my opinion on this:

The Witch King wrote:My problem with this is the fact that it's virtually impossible to observe. Yes, I'm aware of all of the morphological evidence that they've used to support it. However that evidence fails to take into account the possibility that these might just be animals that are very morphologically similar. We know that there are animals that are very morphologically similar, but are separate species. Take chimps and bonobos for example. By this theory's logic, I could go and say that a bonobo is nothing more then a younger chimpanzee. But we know that much isn't true. Which means that the only way you could conclusively prove that they are the same species is by having the various stages all found in the same area, directly linking A to B to C. Which is virtually impossible.

Don't get me wrong; I agree with the basic concept of the theory. It's just the evidence I question.

Wow, I can not belive I made that mistake! No I meant that Jack thinks that Triceratops is the sub adult form of Torosaurus. Also, with the Graffititan thing, I was just saying I knew how it felt for the people who grew up with brontosaurus when it was changed (only not realy changed, Brontosaurus was just invalid), to apatasaurus. Also, while I agree that more than morphological similarities are needed support this idea, there is more than just superficial morphological evidence. There is evidence in the number and position of teeth supporting the nanotyrannus idea. The Pacheycephalosaur notion, is supported by the fact that Dracorex has very spongey bone, a characteric of juveniles, Stygimoloch has denser, but still spongey bones, and that Pachycephalosaurus has very dense hard bone, characteristic of an adult. Also, the horn position and dome position gives more evidence, but I digress.