Spinosaurus – The Largest Land Carnivore of All Time?

T. rex versus Spinosaurus – Giant Killers

Scientists knowledge of dinosaurs has greatly improved over the last decade or so. New fossil finds coupled with new research techniques have enabled palaeontologists to learn a great deal about these reptiles. When we visit schools or work in museums our staff get bombarded with questions and one of the most popular is – which is the largest, meat-eating dinosaur of them all? To be truthful, this is a difficult question to answer, but amongst the contenders would be Spinosaurus (Spinosaurus aegyptiacus), a strange, sail-backed dinosaur that may have reached lengths in excess of 18 metres.

Spinosaurus featured in the first episode of the BBC television series “Planet Dinosaur”. This episode was entitled “Lost World” and focused on the dinosaur discoveries from North Africa. This part of the world around ninety-five million years ago was home to a variety of huge prehistoric animals, giant crocodiles, enormous Sauropods and at least two super-sized meat-eaters. The carnivores in question are Carcharodontosaurus and perhaps the largest meat-eater of them all – Spinosaurus.

A Tale of the Tape

Just like two heavy-weight boxing contenders, let us look briefly at what we know about Spinosaurus in comparison to T. rex.

T. rex – length = 13-14 metres, weight 5.5 to 7 Tonnes, size of skull 1.75 metres

Spinosaurus – length 12-18 metres, weight 4 to 20 Tonnes, size of skull 2 metres

Based on these statistics, it looks like Spinosaurus is the bigger animal, but we have to take into account the actual fossil evidence, when we do a more confusing picture emerges.

There are something like thirty T. rex fossil specimens known, with at least half a dozen or so individual skeletons with at least 40% of the complete fossil material, including skull material. However, for Spinosaurus the fossil record is far less complete. Only six specimens have been found to date. Most of what palaeontologists know about Spinosaurus comes from this scant material and by scaling up the fossil bones from related genera such as Suchomimus, Baronyx and Irritator.

The most complete Spinosaurus fossils found to date were discovered by a German led expedition to the Western Egyptian desert. This expedition was headed by Ernst Stromer von Reichenbach, who perhaps should be as famous today as the likes of Cope and Marsh. However, Stromer was dogged by misfortune and the story of Spinosaurus is one of lost opportunities and mistakes.

The Discovery of Spinosaurus

In November 1911, Stromer’s party set sail for Egypt, on a quest not to find dinosaurs but to find evidence of early hominids. Stromer believed (quite rightly as it turned out), that mankind originated in Africa. In the early part of the 20th Century there were two contrasting theories as to the origins of our own species. Some scientists believed that H. sapiens evolved in Europe, whereas, other scientists, Stromer included believed that mankind originated in Africa. Stromer’s party explored a number of areas before visiting the Bahariya Oasis in western Egypt, what they thought would be Eocene aged deposits, a potential location for primate fossils. The team discovered the remains of several new types of dinosaur including two huge predators – Carcharodontosaurus and perhaps most famously of all Spinosaurus.

The remains were fragmentary, part of the lower jaw, some vertebrae, plus of course those huge neural spines, the largest of which was nearly six feet high. It is these spines that give this dinosaur its name, the spines are believed to have supported a huge sail-like structure on the animal’s back. Quite what this device was used for (thermoregulation, fat storage, visual signalling) remains unclear. However, Stromer was aware that he had some huge, fossilised bones to contend with.

He was taken aback by the size and scale of the specimens that the expedition collected, he was quoted as saying “… I don’t know how to conserve such gigantic species”. The team ended up mixing flour and water to make a paste and tearing strips of cloth which they then soaked in this mixture and applied to the fossils to make a sort of protective jacket for their finds.

Getting the fossils back to Germany proved very difficult. Egypt was under British control and on the eve of the First World War, diplomatic relations between Britain and Germany were strained. One crate was able to leave the country, but the remainder stayed in Egypt until after the war ended. They were not finally returned to Stromer until 1922.

Spinosaurus (Spinosaurus aegyptiacus) was formally named and scientifically described by Stromer in 1915. Stromer thought that this Egyptian dinosaur was at least as big as Tyrannosaurus rex, which had been named just nine years earlier.

Unfortunately, the crates that were returned to Germany in 1922 contained fossils that had become damaged. Many of the specimens were in a bad way and Stromer set about spending the next decade or so repairing them and studying them. More descriptions, drawings and even some photographs of the Spinosaurus fossils were made, but in the 1930s Stromer fell out of favour with the Nazi Party and had greater and greater difficulty in getting his work published.

April 24th/April 25th 1944 – Fossils Destroyed

Stromer had pleaded with the authorities to remove his Spinosaurus fossil material and other specimens out of the Munich museum where they were stored for much of the Second World War. As Allied bombing raids became more frequent Stromer urged the authorities to let him transport the specimens to a safe storage area such as a coal mine or other underground facility. His pleas went unheeded and his luck finally ran out on the evening of April 24th, morning of April 25th 1944 when a British night bombing raid effectively flattened the museum and the surrounding area. Stromer’s life’s work was all but destroyed, including the Spinosaurus fossils. His holotype specimen is no longer around and not available therefore for study. Only a few tantalising photographs of Stromer’s Spinosaurus fossils remain.

Morocco – New Discoveries

A number of other, fragmentary Spinosaurus fossils have been found since Stromer’s time. Not in Egypt but in Morocco, this has led scientists to describe a second potential Spinosaurus species. The Canadian palaeontologist Dale Russell has studied the Moroccan fossil material, some of which was provided by an Italian museum which had originally received this specimen from the collection of a private individual. Although, still very fragmentary, scientists have named and described a second species of Spinosaurus – Spinosaurus maroccansus, although this second species is not fully accepted by the scientific community as being a separate species.

In terms of confirming the size of Spinosaurus, based on the fossil evidence that remains and on the holotype from the Bahariya Oasis of Egypt, we can state that this Theropod was very big, whether or not it is the largest land carnivore ever to have existed is more difficult to say. Further research and more complete fossil specimens are needed.

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