November 16, 2011 | 16
In the interests of recycling unused bits of text (another recurrent theme here at Tet Zoo), the recent article on The Great Dinosaur Discoveries prompted me to dig out and recycle the draft text I wrote on Spinosaurus, and here it is (now with citations added). After all, I won’t be using it anywhere else and it’s now redundant. I happily admit that the text is brief, introductory, tells a story that’s been covered by many other authors on previous occasions [Laelaps covered the same story here in 2007], and won’t say anything that isn’t already familiar to anyone who is above level 5 on the scale of dino-geekdom. Whatever, enjoy, and feel free to tell everyone about the many exciting developments that happened in spinosaurid science during recent decades.
In 1915, German palaeontologist Ernst Freiherr Stromer von Reichenbach (1871-1952) described a remarkable collection of theropod remains (Stromer 1915). These were collected from Upper Cretaceous rocks (probably dating to the Cenomanian) by fossil collector Richard Markgraf at the Egyptian site of El-Bahariya during 1912. Stromer named the animal represented by these remains Spinosaurus aegyptiacus: the ‘Egyptian spine lizard’. Despite the fact that – even today – it is poorly known and represented by incomplete and unarticulated bones, its remarkable anatomy means that it has also been one of the most famous, most-remarked upon theropod dinosaurs
Stromer described this material in a very thorough, beautifully illustrated monograph. Photographs of the specimen brought to attention in 2006 have shown that Stromer’s illustrations are essentially accurate (Smith et al. 2006).
Compared to the other theropods known during the early 1900s, Spinosaurus was very different. In contrast to other theropods, the Spinosaurus dentary bone in the lower jaw had a squared-off end which was deeper than the adjacent body of the jaw. The dentary was also unusual in that the teeth at its tip seemed to be particularly long compared to the others, and in that the teeth were more widely spaced apart than is usual. Its shape indicated to Stromer (1915) that its owner must have had a longer, narrower snout than normal big theropods. The teeth of Spinosaurus also differed from the gently recurved, laterally compressed, serrated teeth more typical for theropods, in that they were rounder in cross-section, had a straight central axis, and lacked serrations.
The other way in which Spinosaurus differed from other theropods was in its extraordinarily elongate neural spines. Up to 2 m long in the longest spines, they were definitely present on the dorsal vertebrae: the sacral and caudal vertebrae probably possessed much shorter spines. Stromer was unsure as to why Spinosaurus had these elongated vertebral spines, but briefly compared them with tall neural spines seen on other dinosaurs, and with those of bison and some chameleons and other lizards. In bison, these tall spines are of course covered in muscle and fat and form a huge hump, but Stromer felt it unlikely that a large predator would be equipped with such a structure. Instead, he concluded that Spinosaurus had a tall, narrow sail-like structure. This is an idea that was to remain popular afterwards.
Stromer didn’t provide a reconstruction of Spinosaurus in his original description, but eventually did so in 1936. Spinosaurus was depicted as a gargantuan, sail-backed theropod, and despite his realisation that the lower jaw was peculiar and different from that of other theropods, he imagined it to be associated with a fairly normal, deep-snouted skull like that of a megalosaur or allosaur (Stromer 1936). In fact his reconstruction – depicting Spinosaurus in the kangaroo-like posture established for bipedal dinosaurs by Louis Dollo and other 19th century workers – does not make Spinosaurus look that remarkable, save for its tall vertebral spines. In the absence of further information, this reconstruction persisted for decades and Spinosaurus was still being illustrated this way as recently as the 1980s (it was sometimes depicted as capable of part-time quadrupedality, as in this painting by Giovanni Caselli from the 1970s).
The loss of Stromer’s Spinosaurus
Today we know that Stromer actually had the type specimen of Spinosaurus wall-mounted in the museum (the Paläontologische Staasssammlung at Munich). Sadly, however, Stromer’s original material was destroyed during Allied bombing raids on Munich in April 1944. Stromer had made repeated requests to the head of the museum that the fossils be moved away somewhere safer, but this never happened. With the fossil destroyed, palaeontologists working in the decades that followed had to rely on Stromer’s drawings and descriptions when comparing this dinosaur with others. Not until the last decades of the 20th century were scientists to get a better idea of what Spinosaurus really looked like.
For previous Tet Zoo articles on Spinosaurus and other spinosaurids, see…
Refs – -
SMITH, J., LAMANNA, M., MAYR, H., & LACOVARA, K. (2006). NEW INFORMATION REGARDING THE HOLOTYPE OF SPINOSAURUS AEGYPTIACUS STROMER, 1915 Journal of Paleontology, 80 (2), 400-406 DOI: 10.1666/0022-3360(2006)080[0400:NIRTHO]2.0.CO;2
Stromer, E. 1915. Ergebnisse der Forschungreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltier-Reste der Baharîje-Stufe (unterstes Cenoman). 3. Das Original des Theropoden Spinosaurus aegyptiacus nov. gen., nov. spec. Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften Mathematisch-physikalische Klasse 28 (3), 1-32.
- . 1936. Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. VII. Baharije-Kessel und -Stufe mit deren Fauna und Flora. Eine ergänzende Zusammenfassung. Abhandlungen der Bayerischen Akademie der Wissenschaften, Mathematisch-naturwissenschaftliche Abteilung, Neue Folge 33, 1–102.