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True to Life?

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Species: ajax, louisae
Range: Late Jurassic (Tithonian, 150-145 MYA) from Arizona to South Dakota, including Utah, Wyoming, and Oklahoma
Size estimate: 70-75 ft length, 18-25 tons
Discovery: Othniel Charles Marsh, 1877
Classification: dinosauria, saurischia, sauropoda, diplodocidae, apatosaurinae

True to Life?

Since no one has ever seen a living dinosaur, and the missing pieces of the fossil record withhold important clues to their appearance, no artistic representation of a dinosaur ever gets it 100% right. On top of that, new discoveries can change our ideas of extinct creatures drastically. So, how close does this sculpture come to what we currently know of the original animal?

• Ironically the most important details to get right on such a big animal are found on one of its proportionately smallest parts: the head. Scientists and artists got it wrong on its close cousin Brontosaurus by putting Camarasaurus’ boxy head on the end of its neck, and that changed its image for many decades. Unlike the classic Brontosaurus mistake, this sculpture’s head is based on the correct fossil material. Sadly, it buries that skull under too much soft tissue. While we lack direct impressions of dinosaur faces in most cases, evidence on their skulls shows that like other reptiles and quite unlike mammals, dinosaurs did not grow many muscles on their faces. Their heads for the most part were literally skin and bone. Recent studies have argued effectively that dinosaurs did not have cheeks (though ceratopsians may have come up with something similar, and a few other species seem to have created interesting workarounds to help with chewing), so the cheeks on this sculpture likely do not represent the original animal well.
• Lips are another issue, and quite controversial because some evidence shows that dinosaurs and their closest relatives were developing exceptions to rules seen among lizards, eventually culminating in birds’ beaks. Some studies tepidly suggest that sauropod mouths had partial beaks, but they don’t cite much evidence and don’t go into detail. This sculpture’s portrayal therefore works like Schroedinger’s Cat: we don’t know if it’s correct, but it could be. Just don’t expect it to smile—that would require facial muscles that Apatosaurus definitely did not have.
• Thankfully this sculpture does not go so overboard on a fleshy face as some suggested in the 1970s and 1980s—sauropods did NOT have elephant-like trunks. However, this sculpture does incorporate another defunct nose model: the forehead nostrils which loosely recall a whale’s blowhole. A study by Larry Witmer in 2001 argued convincingly that soft tissue nostrils do not follow the skeletal nostrils so closely in most bony animals. Our own noses exemplify this, what with the bendy cartilage that points our nostrils downward, redirecting the apparent airflow of our forward-facing bony nostrils. Some other sauropods in the Park do a better job of portraying this point. That said, imagining human-like noses, trunks, or other fleshy randomness doesn’t follow evidence either—the nostril holes would just show up lower down the snout somewhere.
• Excess flesh gives this sculpture’s neck a mammalian look and obscures one of Apatosaurus’ most distinctive features. The necks of many sauropod families, especially the diplodocid group which includes Apatosaurus, exhibit extreme weight-saving features, making a heavy wattle unlikely, even one as conservative as seen here. On top of that, Apatosaurus and Brontosaurus necks both have a noticeably triangular cross-section, making the back of the neck roundish but the underside flat. That cross section is not especially visible here with the loose neck folds.
• Sauropod neck posture also excites controversy. Some models hypothesize that sauropods generally could raise their heads as shown by this sculpture. Others model them more as mobile suspension bridges, with neck stretched forward and tail backward. This sometimes correlates with snout shape, and therefore feeding habit. Apatosaurus’ cousin, Diplodocus, likely followed the latter model due to its elongated neck vertebrae and a system of ligaments acting like the cables of a suspension bridge. Diplodocus’ snout shape corresponds to a low-browsing/grazing habit, further supporting the idea that even if it could raise its head as shown here, it may not have done so often. While Apatosaurus shares the blunt snout of a low browser, its neck vertebrae do not share the elongated shape of Diplodocus’. As such, it may have had different motivations for adopting an upright neck posture and may have done so more often. We can chalk this point up to “plausible but still unknown” for now.
• Artists have often depicted sauropod feet using elephants as a model. This sculpture is no exception to that pattern, but this does not match the anatomy of the living animal. Apatosaurus’ front feet should have large claws pointing inwards like thumbs but should not have any other fingernails or hooves visible. They may have used these claws in much the same way as we use our big toes, as traction for steering. Apatosaurus’ hind feet bore three claws, with the other two lacking nails. The fact that sauropods retained all five digits on both front and back feet earned them their name, which means “lizard feet.” For a good look at sauropod skeletal anatomy, check out our Moabosaurus full skeletal mount and the Canarasaurus leg skeleton inside.
• Check out the left forelimb on this statue. Most dinosaurs could not adopt such a posture thanks to particular limitations in their joints. Unlike mammals, they could not cross their radius bone over their ulna, and therefore could not rotate their wrists very far. Most of them were stuck with their palms facing inward. However, sauropods as a group seem to have shifted their radius into taking a new, more structurally stable position which turned their wrist joints and caused their hands to take on a partially tubular arrangement. This made their forelimbs more like columns and helped accommodate larger sizes, as well as leading to a more efficient system of joints for walking on their forelimbs. As of this writing, no studies seem to have determined the absolute limits of the range of motion of Apatosaurus’ forelimb, but the joints are at least in favor of Apatosaurus’ ability to assume a position similar to this statue’s pose.
• Of course, tail dragging has been shown as an artistic no-no when it comes to portraying dinosaurian anatomy correctly. True, a few sauropod trackways show a rare tail drag mark, but they are an exception and come from the far end of the tail. Bending the tail to the ground at its base would not only require dislocating the vertebrae, it would also mess up major muscles necessary for the animal to walk. It’s also unlikely that the whippy portion of the tail could curl as shown here, due to tough ligaments and possibly large overlapping scales.
• Speaking of scales, we do have impressions of diplodocid skin. Unlike the elephantine skin shown here, Apatosaurus’ and other sauropods’ skin had small scales covering larger fleshy bumps in most areas. It may have also borne an iguana-like fringe of scales along its back and/or large ornamental scales along its flanks. Though these scales did not turn completely bony like the scutes on Magyarosaurus (check it out on the Lost Trail), they may have looked similar. Suffice it to say that Apatosaurus and its kin would have looked considerably bumpier than they are often portrayed.
• This sculpture represents a fairly small individual for Apatosaurus. It’s not all that much bigger than the Maiasaura which share its immediate neighborhood, even though its long neck and erect head make it appear much larger. As one specimen from Oklahoma shows, big Apatosaurus might rival even Supersaurus in weight, though they wouldn’t get as long based on body proportions. If this sculpture approximated that specimen, it might approach 50% larger than it is now.
• Behind the Scenes: In 2018, a severe windstorm downed several trees in the Mystery Trail area of the Park. One of them landed on this Apatosaurus sculpture but caused no damage. It was not discovered until later in the cleanup process because it was leaning against the sculpture’s right hip and did not look like it needed to be removed. That’s one tough statue! Still, like most other sculptures in the Park, it wouldn’t be wise to interact with this sculpture for numerous reasons.