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Re: Fw: late night thoughts: misunderstand what?

......... I understood you earlier as saying that _average_ bodysize had not
changed through time.

Rather, there is no trend in sauropod body size.

The above statement means that the maximal sauropods are equal through time,
a much more radical statement. In other words, at any timeslice in the total
time of their existence, the largest sauropods known from that
timeslice are equal to those found in any other timeslice.

Not necessarily -- I'm just saying that there's no trend in sauropod body size.

I learned years ago that the largest sauropods known from the L. Jurassic
are larger than the largest known from the L. Triassic, whether measured
by height at the shoulder, or weight,

Correct, but you must take phylogeny into account. (I said science is a lot of work!) The Early Jurassic *Gongxianosaurus* already reached 15 m in length, more than all other Early Jurassic and many Middle Jurassic sauropods, but it is very basal, more so than the Late Triassic *Antetonitrus* and *Isanosaurus* for example. Likewise, there's a 1 m long humerus from the end-Triassic of Thailand attributed to an adult *Isanosaurus*; that hints at a 15 m long animal, too.

and that the very largest known are actually from the Cretaceous. Has this changed?

Well... *Amphicoelias fragillimus*, from the Late Jurassic, is a size class of its own. Then comes the trackmaker of *Breviparopus*, estimated to be 48 m long last time I checked, and Middle Jurassic in age. Next are *Argentinosaurus* and *Paralititan* from the "middle" Cretaceous together with *Turiasaurus* from the Late Jurassic and *Puertasaurus*. The distribution of giants and supergiants among the sauropods looks rather chaotic from the Middle Jurassic onwards.

How big is the earliest known sauropod?

No matter which one that is (it's not easy to correlate between continents), it's a lot bigger than *Anchisaurus*, the smallest known sauropod, which is a lot younger. :-) Importantly, the reconstructed size of the _really_ first sauropod is also above that of *Anchisaurus*. Some sauropods got smaller, not larger.