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Re: How Did Hadrosaurs Survive?



>Giant sauropods weren't built for speed, tyrannosaurs were. Bakker just
wrote there's no evidence larger theropods were slower; longer legs probably
conferred faster speed.<
But did he do biomechanical analysis. Once again, I suggest you check out
the paper.

>That ratio doesn't seem credible. More T. rex specimens were found recently
in the Hell Creek than edmontosaurs; Triceratops is most abundant.<
Because people are more interested bringing home a Tyrannosaurus over
another Edmontosaurus.

>Same for Scollard, Lance, Frenchman, Ferris, probably the Naashoibito.
Hadrosaurines are virtually the only remaining NA hadrosaurs of the late
Maastrichtian.<
Isn't Charonosaurus Maastrichtian?

>It's probable, given elevated metabolic rates and correspondingly great
food demands.<
And the great amount of food provided by one hadrosaur kill. Modern
predators don't hunt all the time, it is unlikely that dinosaurs did either.

>Where?  AFAIK, all identifiable hadrosaur remains in far inland
environments of Lancian age e.g. Naashoibito, are hadrosaurine<
Farther away from the coast. Deep within forests not on floodplains.
Dry-weather environments. Mountains. Lots of places don't get preserved in
the fossil record.

>Sure, it was less able to evade T. rex. If hadrosaurines were better able
to compete for food, why didn't the lambeosaurs disappear much earlier? Why
were they still abundant in the late Edmontonian period, just prior to T.
rex?<
Because replacement doesn't happen overnight.

>But there are about 3 sites which have yielded T. rex specimens found in
association with others of their kind. It probably was a pack hunter.<
A reference would be useful, if you could.

>It is logical, and lambeosaurs were also relatively bulky.<
Could I get some ratios/measurements, please?

>I don't think so; it seems far more likely that hadrosaurs fled, and fought
only as a last resort. If hadrosaurs had regularly attempted to stand their
ground, weapons and or armor would have been selected for. Instead they
evolved keen senses and longer legs, and "hooves".<
Zebra don't have weapons, and still manage to not get hunted to extinction
by lions, leopards, and cheetahs.

>I know; I was just pointing to the absence of such weapons as evidence for
a noncombative survival strategy.<
Or a different mode of display. I think what a lot of us think of as
defensive weapons (ceratopsian horns, etc.) may really be display (like
modern antelopes, deer, etc.), with defense as a secondary consideration.

>It would have bitten into the upper thigh or flanks.<
Yet the healed bite wound is on the tail...

>Not according to Bakker and Paul, see PDW. Tyrannosaurs also had the
advantage of more efficient avian-like respiration.<
See my first statement.

>But it lived at least 4 million years before T. rex, whose closest ancestor
must have been something like T. bataar, which was roughly contemporaneous
with the late Edmontonian fauna.<
Yet, if I'm remembering correctly, GSP suggested that Daspletosaurus was
actually a synonym Tyrannosaurus. If they are close enough to suggest they
were congeneric, could their impact have been so different.

>If longer legs conferred no advantage, why were they selected for among
tyrannosaurs and hadrosaurs by
the Lancian? Why did T. rex monopolize the top predator niches, including
prey which fled; why didn't Albertosaurus persist like the cheetah alongside
the lion if it were faster?<
They were selected because the animals were getting bigger. No theoretical
speed increase is needed, when we can measure the increase in size in both
hadrosaurs and tyrannosaurs. The prey which was getting larger, in order to
survive, and the predators needed to either A)get bigger to be able to
continue to hunt B)go extinct, if the animal was already specialized in its
niche, and not able to adapt as fast.
Peace,
Rob

Student of Geology
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