Reconstruction Errors

Megalosaurus | Iguanodon | Apatosaurus | Tyrannosaurus rex

Megalosaurus
Megalosaurus was the first dinosaur to be found and named, in 1824. It is therefore not surprising that mistakes were made in its reconstruction, made worse as only a partial skeleton was discovered. No such creature had previously been observed, so mythology, particularly dragons, were used as a reference point for the reconstruction, and the skeleton was assembled on all fours and with a very large head.


















Two early representations of Megalosaurus. On the left is one drawn by Goodrich, the one on the right by Richard Owen. Note the similarities in body structure and shape. Both drawn in 1854.

In 1852, Benjamin Waterhouse Hawkins was commissioned to a build a model of Megalosaurus, as part of the Great Exhibition of 1851, and the exhibition of dinosaurs created still exists today. The models were life size, with the Iguanadon model substantial enough to play host to a dinner party for more than twenty guests, but anatomically inaccurate. However, the survival of these models allows a window back into the mind set of early palaeontologists as they attempted to make sense of the bizarre remains unearthed from quarries and cliffs around Britain.

When theropods were discovered in North America, a more accurate bipedal posture was developed. It is worth noting, however, the Megalosaurus skeleton was reconstructed before any vertebrae were discovered. In fact, Friedrich von Huene, when assembling the skeleton, used the backbones of Altispinax, a genus of spinosaurid dinosaur with a high-spined dorsal vertebrae. As a result, many reconstructions have a deep spinal ridge, or small sail, like that of Spinosaurus. Since the discovery of more fossils it has now become apparent that the sail is incorrect and the modern reconstruction can be seen below.


A drawing of the modern interpretation of Megalosaurus.

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Iguanodon
Named shortly after Megalosaurus, this was the second dinosaur ever described. Based on limited fossils stumbled upon by Mary Ann Mantell and studied by her husband Gideon Mantell. Based on similarities in teeth between Iguanodon and modern iguanas, Gideon Mantell reconstructed Iguanodon as a large version of a modern iguana and similarly to Megalosaurus it was reconstructed as quadrapedal (and pachydermal). An unusual fossil spike was positioned on its nose much like a modern rhinoceros.
















Drawing on the left is the interpretation of Goodich, and on the right a drawing by Gideon Mantell with his assumed relative positions of the fossils he had found.

In 1878 a group of 38 individuals were found in a coal mine in Belgium. The complete skeletons showed that Iguanodon was capable of bipedalism, and all of the skeletons were reconstructed in a upright wallaby/kangaroo posture. The spike was also correctly placed on Iguanodon's thumbs.
















A reconstruction of one of the 38 Iguanodon skeletons from Belgium.

More recent reconstruction work suggest that Iguanodon was probably a combination of the two earlier reconstructions. It showed that Iguanodon was mainly quadrapedal, but capable of bipedalism. The later reconstruction was wrong in that the wallaby posture would have involved breaking the vertebrae in the tail.











An artistic drawing of the modern reconstruction of Iguanodon.

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Apatosaurus
Apatosaurus also previously known commonly as Brontosaurus (due to a rush to name new species, it was given two different names by Edward Drinker Cope and Othniel Charles Marsh, but Apatosaurus was the first published so is now the name used), was first discovered as almost an entire skeleton with the exception of the skull. In the rush to reconstruct the entire skeleton and name it a nearby sauropod skull was used. This skull was closely related to a Camarasaurus.


A Camarasaurus skull, similar to the one originally on all Apatosaurus skeletons.

Since the first reconstruction there have been more fossil discoveries including the correct skull and since all of the Apatosaurus skeletons have had the incorrect skull replaced.


The modern Apatosaurus skull correctly in place.

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Tyrannosaurus rex
Even the tyrant lizard king was not safe from the reconstruction errors of earlier palaeontologists. Much like the second reconstruction of Iguanodon, Tyrannosaurus rex was reconstructed very upright with its tail dragging on the ground. We know that this reconstruction would be impossible as it would result in fractures in the tail, hips, back and neck. Films like Jurassic Park helped raise awareness that Tyrannosaurus rex actually held its body almost parallel to the ground.


Animation showing the change in posture associated with the reconstructions of Tyrannosaurus rex.
"Tyrannosaurus rex: posture." Online Animated GIF. Encyclopędia Britannica Online. 1 May 2008 http://www.britannica.com/eb/art-60359.

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