This is the Brontosaurus that I grew up with:

It’s by Kenyon Shannon, found on page 14 of The How And Why Wonder Book of Dinosaurs (Geis 1960). I call it Brontosaurus rather than Apatosaurus because this outdated rendition is forever tied to the outdated name in my mind.

It would be terribly easy to pick holes in this representation — the completely wrong head, the bizarre croc-like eyes, the incorrect attitude of the head, the tubular shape and much too thin profile of the neck, the full set of manual unguals and so on. But the part that’s most shocking to me is just how darned fat it is.

Even given that Apatosaurus was among the most robustly build of sauropods — certainly the most robust diplodocoid — how wrong is that super-fat forearm? Here, for comparison, is an Apatosaurus humerus:

Right humerus of Apatosaurus ajax NSMT-PV 20375 in (left to right) anterior, medial, lateral and posterior views, and (top to bottom) proximal and distal views. From Upchurch er al. (2005:fig. 5)

And here is the lower arm:

Right forearm of Apatosaurus ajax NSMT-PV 20375. A: “anterior” (more like anterolateral) view with ulna to left, radius to right; B: “posterior” (more like posteomedial) view with radius to left, ulna to right; C; proximal view; D: distal view.

Put them together and you can get some impression of the proportions of the complete forelimb:

In short: it’s a solidly built animal; but the Shannon depiction that we started with is not merely solid, it’s what we refer to as “a lardy bloater”. Just say no.

References

• Geis, Darlene. 1960. The How and Why Wonder Book of Dinosaurs. Price Stern Sloan, Los Angeles. 48 pages. ISBN: 0-8431-4250-2.
• Upchurch, Paul, Yukimitsu Tomida, and Paul M. Barrett.  2005.  A new specimen of Apatosaurus ajax (Sauropoda: Diplodocidae) from the Morrison Formation (Upper Jurassic) of Wyoming, USA.  National Science Museum Monographs No. 26.  Tokyo.  ISSN 1342-9574.