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HEAVY ANKYLOSAURS



Regarding ankylosaurs in marine deposits, Wayne Anderson says:

> This line of thinking (marine ankylosaur remains) reminds me of
> something about armadillos: specifically, that their bodies have a
> specific gravity of <1; that is, they are lighter than water.

I thought armadillos had a specific gravity >1. This would explain why they sink
- in fact they can hold their breath long enough to walk along the bottom of
ponds - and why they have to gulp air when they decide to float. Surely (?)
ankylosaurs, in cases with a lot of armour, were also of high s.g. 

> I'm not suggesting that they went swimming a lot, but rather that
> their bodies, with a high degree of structural integrity, would
> probably survive floating downriver and out to sea far long after
> most dead dinos "disarticulated".  Buoyed by decomposition gases,
> they might stay afloat for some time, affording challenging chew
> toys for the pliosaurs and their friends...
> 
> Seems like a good explanation for "marine ankylosaurs", I think...

Fer sure. I recall Halstead (doubtless other authors have too) suggesting that
this was how dead ankylosaurs got to be turned onto their backs. Halstead
alternatively suggested that large theropods learnt to flip ankylosaurs so they
could chew out the guts, but he concluded that theropods were far too stupid to
learn such a trick. I would disagree (hey, I've kept lizards that learnt more
complex things), but the size and formidability of the bigger ankylosaurs makes
this a highly unlikely possibility. 

At the BMNH we have a fantastic _Euplocephalus_ (the type of _Scolosaurus_ I
think) which is lying on its side. Can't recall if it's on display in the new
exhibit though (used to be in the main hall behind the _Diplodocus_).

"Pardon me for thinking, but there's something under my hair"

DARREN NAISH