Just how big did Pachycephalosaurus get?

[bjeast]

I'd really like to know how big these dinos got. I did the usual searches on the web and found lengths of 4-5 meters. However, one site gave a length of 8 meters, but with no indication of what this was based on.

I'd really like to know, since I have a figure that is listed at 1/35 scale, but at that scale it's got to be the 8m length. At the smaller sizes, it's more like 1/25 or so. The figure itself needs some significant reworking, but I'd really like to know what scale it really is. Any help you all can give me would be much appreciated!

Thanks!

Brad.

[Tyrannax]

8 meters? I've never heard of them reaching those lengths. I may be wrong, but I believe the average length is around 15 feet...

[stoneage]

I would say 23 feet is about right.

[bjeast]

Thanks for the help!

[brad]

Pachycephalosaurus is mostly known from skull material, so for a long time palaeontologists just had to guess how long it was. The famous AMNH Pachycephalosaurus skull described by Brown and Schlaikjer in 1943 has a greatest median skull length of 642 mm (p. 141 of their paper). If the replica's head is in the ballpark of 18 mm, 1/35 scale would be about right.

I don't know who came up with the 8 m estimate, but I imagine it just came about from comparing it to other dinosaurs with similar skull lengths. New pachycephalosaurin postcranial remains reported in the '90s gave us a better idea of the pachy body proportions, so the length estimate for Pachycephalosaurus got scaled down somewhat (the Battat Pachycephalosaurus reflects the current view).

[bjeast]

Thanks Brad. The replica's skull length is more like 30-32 mm snout to back to skull, so it definitely isn't 1/35, according to that method!