Triceratops was really another Dinosaur

[n2doc]

Morph-osaurs: How shape-shifting dinosaurs deceived us

28 July 2010 by Graham Lawton
DINOSAURS were shape-shifters. Their skulls underwent extreme changes throughout their lives, growing larger, sprouting horns then reabsorbing them, and changing shape so radically that different stages look to us like different species.

This discovery comes from a study of the iconic dinosaur triceratops and its close relative torosaurus. Their skulls are markedly different but are actually from the very same species, argue John Scannella and Jack Horner at the Museum of the Rockies in Bozeman, Montana.

Triceratops had three facial horns and a short, thick neck-frill with a saw-toothed edge. Torosaurus also had three horns, though at different angles, and a much longer, thinner, smooth-edged frill with two large holes in it. So it's not surprising that Othniel Marsh, who discovered both in the late 1800s, considered them to be separate species.

Now Scannella and Horner say that triceratops is merely the juvenile form of torosaurus. As the animal aged, its horns changed shape and orientation and its frill became longer, thinner and less jagged. Finally it became fenestrated, producing the classic torosaurus form (see diagram, above).

more

http://www.newscientist.com/article/mg20727713.500-morphosaurs-how-shapeshifting-dinosaurs-deceived-us.html

[aquart]

1. What possible advantage would there be to losing horns as an adult?

[mike_c]

3. depends entirely on what they used the horns for....

If juveniles were more susceptible to predation than fully grown adults, then the horns might have been useful for defense while immature but an unnecessary metabolic investment for adults. On the other hand, maybe juveniles used them to compete with adults by rooting up lower quality resources in locations where the larger adults dominated higher quality (easier to obtain) resources. Another possible reason is that juveniles might have needed them to succeed in social interactions, such as inter-juvenile competition to establish mating hierarchies that, once established, were dominated by the adults who simply continued them. Or maybe juveniles used them to signal mating condition or some other state that communicated socially important signals that were unnecessary for adults. I'm just speculating-- none of this is my field, but there are numerous known examples of all three evolutionary alternatives. And of course there are more possibilities too, I'm sure.

[PetrusMonsFormicarum]

2. Very interesting

I was thinking along these same lines last month when I saw a row of six-plus triceratops skulls at the Museum of the Rockies in Bozeman, Montana.

[Odin2005]

4. This is very interesting!

[lostnfound]

5. I've been thinking this for years, that there were fewer types of dinos than they think

Variation in size might have been more greater in that world than it is in our own. THere are genes that shut off growth in animals and humans today; occasionally they malfunction and individual people can grow to unusual heights and even die from it. What if the genes that shut off growth weren't developed or present in dinosaurs back then?

[dmallind]

6. Admittedly that's a simplistic drawing but what happened to nasal cavity?

It's one thing to lose horns as you mature or have them realigned but how the hell do you reconfigure the nasal cavity?