All about dinosaurs, fossils and prehistoric animals by Everything Dinosaur team members.
22 08, 2018

A Challenge to the Aquatic Spinosaurus Theory

By |2023-10-28T09:01:25+01:00August 22nd, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|3 Comments

Was Spinosaurus aegyptiacus at Home in the Water?

New research utilising computer modelling to study the buoyancy of Spinosaurus (S. aegyptiacus) by Dr Donald Henderson of the Royal Tyrrell Museum (Alberta, Canada), challenges the idea that this sail-backed theropod was adapted for a semi-aquatic way of life.

The research suggests that Spinosaurus could float and keep its head clear of the water to enable it to breathe, but other theropods could also float in positions that enabled them to breathe freely, but with its pneumatised skeleton and system of air sacs, diving for food was probably beyond Spinosaurus, thus hindering its ability to be an effective semi-aquatic, pursuit predator.  Dr Henderson concludes that Spinosaurus may have been more at home wading through water, specialising in hunting along the shoreline or in shallow water, but still remaining a competent terrestrial predator.

Spinosaurus May Have Been a Shallow Water or Shoreline Predator

From paddler to swimming the “evolving” image of Spinosaurus.  New research proposes that Spinosaurus aegyptiacus was a shallow water predator and not capable of diving for its dinner.

Picture credit: BBC

Challenging the 2014 Scientific Paper

Dr Henderson set about creating three-dimensional computer models of Spinosaurus and several other theropods including Allosaurus, Coelophysis, the ornithomimid Struthiomimus, Tyrannosaurus rex and another member of the Spinosauridae family – Suchomimus tenerensis.  Dr Henderson, who is the Curator of Dinosaurs at the Royal Tyrrell Museum of Palaeontology, located in Drumheller, southern Alberta, wanted to test the hypothesis proposed by Dr Nizar Ibrahim and colleagues published in September 2014, that hypothesised that S. aegyptiacus was quadrupedal and a semi-aquatic dinosaur, a first for a member of the Theropoda.

To read Everything Dinosaur’s article about the 2014 scientific paper: Spinosaurus – Four Legs are Better than Two.

Intriguingly, the interpretation of Spinosaurus, as proposed by Ibrahim et al, was used as the basis for the digital Spinosaurus model by the Royal Tyrrell Museum researcher.

Views of the Theropod Body Plans Used to Test Buoyancy

Digital models of Theropods used in floatation tests.
Theropod body plans used in the floatation tests, dorsal and lateral views.

Picture credit: PeerJ/Dr Henderson (Royal Tyrrell Museum)

The picture above shows the digital body plans used to test the theoretical buoyancy of different types of theropod dinosaur.


A).  Coelophysis bauri

B).  Struthiomimus altus

C).  Allosaurus fragilis 

D).  Suchomimus tenerensis (Baryonyx tenerensis) – it has been suggested that Suchomimus and Baryonyx fossil material might represent the same genus (Holtz, 2012; Sues et al., 2002), this conclusion was used in this study.

E).  Spinosaurus aegyptiacus – the body plan based on the body shape proposed by Ibrahim et al in the 2014 paper.

F). Tyrannosaurus rex

Testing Buoyancy in Freshwater

To ensure that the digital models were able to replicate the orientation and depth of immersion in freshwater, Dr Henderson tested the software using a model of an alligator (A. mississippiensis).  Furthermore, he assessed the buoyancy of a computer generated model of an emperor penguin (Aptenodytes forsteri), which is also a member of the theropoda.

Dr Henderson explained:

“Science is self-correcting.  Research is a competitive scientific process that continually generates new information and ideas, so here’s some of the self-correcting in action.”

Testing the Stability and Buoyancy of Spinosaurus (S. aegyptiacus)

Testing the buoyancy and stability of Spinosaurus.
Testing the stability and buoyancy of Spinosaurus in freshwater.

Picture credit: PeerJ/Dr Henderson (Royal Tyrrell Museum)

Spinosaurus Could Float But So Could Other Theropods

Dr Henderson’s digital models demonstrated that Spinosaurus could indeed float with its head above water, enabling it to breathe freely.  However, the models of other theropod dinosaurs demonstrated similar results.  This was not unexpected as most tetrapods can successfully float and swim, the shape of Spinosaurus did not necessarily give it an advantage over the body shape of other dinosaurs when it came to stability in water.

Alligators Much Better Suited to Water Than Spinosaurus

The stability of a Spinosaurus in freshwater was also compared to the digital alligator. When tipped to the side, the alligator model returned to its original topside position.  Such behaviour is seen in semi-aquatic animals, they have the ability to right themselves when floating.  The Spinosaurus model did not perform well in the same tests.  When tilted, the model rolled over onto its side, demonstrating very little lateral stability in water.  The research implies that Spinosaurus would have easily tipped over and would have had to use its limbs constantly to maintain an upright posture in the water.

Assessing the Centre of Mass

One of the key points of the 2014 paper, was that an anatomical study based on the known Spinosaurus fossil material (which represented numerous individuals of different sizes), indicated that this dinosaur walked on all fours.

In this new research, the centre of mass of the digital model of Spinosaurus was found to be close to the hips, similar to what is seen in other theropods.  This contradicts the 2014 research, as Dr Ibrahim and his colleagues proposed that S. aegyptiacus had a centre of mass located towards the centre of the torso.  With the centre of mass located further forward, it suggests a quadrupedal form of locomotion, however, Dr Henderson’s research indicating a centre of mass positioned over the hips suggests that Spinosaurus could have walked around on land quite happily on just its hind legs (bipedal).

The Position of the Centre of Mass Would Affect Locomotion on Land

Different interpretations of Spinosaurus fossil material.
Different interpretations of the body plan of Spinosaurus.  The red asterisk suggests the centre of mass for each figure. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The models featured in the image above are from the CollectA Deluxe range.

To view this range of prehistoric animal models: CollectA Deluxe Prehistoric Life Models.

Spinosaurus Probably Couldn’t Dive

Dr Henderson’s models also found Spinosaurus to be unsinkable.  Living aquatic birds, reptiles, and mammals all have the ability to submerge themselves to pursue their prey underwater. Although the bones of Spinosaurus might be more dense than other carnivorous dinosaurs, they still were substantially pneumatised.  This anatomical feature in conjunction with the air sac breathing system found in living theropods (birds), probably made it very difficult, if not impossible, for this dinosaur to dive underwater in search of prey.

Dr Henderson concludes that this inability to dive, combined with a centre of mass close to the hips and a tendency to roll onto its side, suggests that Spinosaurus was not a specialised semi-aquatic predator after all.

He added:

“Spinosaurus may have been specialised for a shoreline or shallow water mode of life, but it would have still have been a competent terrestrial animal.”

Few Spinosaurus Bones to Study

However, as there are so very few Spinosaurus fossil bones to study, it is possible that this dinosaur lacked a significant number of avian style air sacs and pneumatised bones.  Even with an increased mass offered by a denser skeleton the digital model when “tweaked” in this way, still suggested that being able to submerge and go underwater would have been a considerable challenge.  Dr Henderson does concede that if it could be shown that the mass deficit represented by the lungs and air sacs was offset by the increased mass of a denser skeleton that might help the claim of a semi-aquatic Spinosaurus.

This is essentially, the central point of the Spinosaurus controversy.  This dinosaur did live in a habitat dominated by large bodies of water.  There were plenty of large fish around for an aquatic predator to eat, but in the absence of fossil evidence, the actual role of Spinosaurus in the North African Cretaceous ecosystem and its habits remain very much open to debate.

The scientific paper: “A Buoyancy, Balance and Stability Challenge to the Hypothesis of a Semi-aquatic Spinosaurus Stromer, 1915 (Dinosauria: Theropoda)” by Donald M. Henderson and published in the academic on-line journal PeerJ.

Visit the Everything Dinosaur website: Everything Dinosaur.

22 08, 2018

Take Care When Visiting the Beach this Bank Holiday

By |2023-10-28T08:51:16+01:00August 22nd, 2018|General Teaching|Comments Off on Take Care When Visiting the Beach this Bank Holiday

Everything Dinosaur Issues a Warning About Dangerous Cliffs

This weekend, it is the August Bank Holiday here in the UK.  This is the last national Bank Holiday before Christmas, a sobering thought, but with lots of families heading to the beach to make the most of the summer weather, team members at Everything Dinosaur have issued a warning about dangerous cliffs on many of the UK’s coasts.

Dangerous Cliffs

Families will be visiting the seaside for lots of reasons, some might even be amateur fossil collectors, keen to find a few choice specimens before the autumn weather rolls in.  However, the exceptional hot, dry spells that much of the country has experienced over the last three months or so has left many of the cliffs overlooking beaches even more dangerous than ever.

A Recent Cliff Collapse at Happisburgh Beach on the Norfolk Coast

dangerous cliffs
Dangerous cliffs along the coast. Picture credit: Everything Dinosaur.

 Picture credit: Everything Dinosaur

Sandstone and chalk cliffs are particularly vulnerable.  These cliffs have become increasingly dry over the summer and when it does rain, the water can make overlying rocks heavier and these overhangs can collapse.  The dry weather followed by sudden downpours makes cliffs very unstable and rock falls are more likely to occur.

Stay Away from the Clifftops and the Base of the Cliff

A spokesperson from Everything Dinosaur commented:

“We want everyone to have a great time if they are planning on a visit to the coast during the holiday period.  However, we would strongly advise that anybody visiting the beach at this time stays away from the cliffs and avoids the clifftops too.”

Would-be fossil hunters should take care to avoid getting to close to the base of cliffs, there are probably plenty of fossils to find further down the beach away from any potential landslips or rock falls.

It is advisable to heed warnings and to listen to advice from the local coastguard.

Instead of visiting the dangerous cliffs, visit the Everything Dinosaur website: Everything Dinosaur.

Go to Top