This article is from
Creation 44(4):48–49, October 2022

Browse our latest digital issue Subscribe

Why were ichthyosaurs and plesiosaurs so huge?


The pre-Flood ocean was once filled with marine reptiles, some of which were huge. They include:

Ichthyosaurs, whose name means ‘fish lizard’ (ἰχθύς ichthys = fish). These looked superficially like fish or dolphins; only the skeleton shows they were reptilian. They had a wide variety of sizes, from quite small to huge.

© Patrick Guenette | Dreamstime.comichthyosaurs-plesiosaurs
Late 19th century artist’s rendering of a plesiosaur (left) and an ichthyosaur

Plesiosaurs, whose name means ‘near lizard’ (πλησίος plēsios = near). They looked nearer to land reptiles than the ichthyosaurs that were discovered not long before. Plesiosaurs had distinctive long necks and long tails. They also had a unique mode of propulsion with powerful flippers—not rowing, but more like ‘flying’ through the water. (So, too, did the short-necked and long-headed pliosaurs.) Some plesiosaurs were among the longest marine reptiles.

Some recent discoveries shed more light on some of the larger creatures, and why great size was a design feature.

Giant ichthyosaurs

Of all animals that ever existed, only three groups were extremely huge, with masses over 10–20 tonnes (t). The biggest were the whales—the blue whale is the heaviest animal in history. The heaviest on land were the sauropods: the dinosaurs with long necks and tails. But the giant ichthyosaurs rivalled the big dinosaurs and sperm whales (males 15–18 m (49–58 ft), 32–41 t).

For example, Shonisaurus popularis (15 m (49 ft), 30 t) and Shastasaurus sikkanniensis (21 m (69 ft), 75 t).1

Some teeth discovered might be from even larger specimens. One tooth measured 6 cm wide at its base, suggesting that the creature could have been up to 54 m in length, larger even than the blue whale (30 m). But as so often, the problem concerns fragmentary remains: can we really deduce so much from just one tooth? Lead study author,2 paleontologist P. Martin Sander of the University of Bonn (Germany) explained: “It is hard to say if the tooth is from a large ichthyosaur with giant teeth or from a giant ichthyosaur with average-sized teeth.”3

Sander also pointed out, “Bigger is always better. There are distinct selective advantages to large body size. Life will go there if it can.” He documents a clear hydrodynamic advantage of size as well, as is outlined in the next section.

But it’s notable that according to evolutionary ‘dating’, the big ones appeared and died out earlier. Ichthyosaurs supposedly evolved 250 Ma (million years ago), or early Triassic. The big ones allegedly died out 200 Ma, while only the smaller ones lasted until 90 Ma, late Cretaceous, but before the alleged end-dinosaur extinction of 66 Ma.

These ‘dates’ make better sense as stages of Noah’s Flood, which was one year long.4 The Flood also makes sense of why fossils of giant sea creatures could be found high in the Swiss Alps.2 During the Noahic Flood, the African tectonic plates pushed against the European plate. The consequent upheaval caused the sea floor to buckle upwards, resulting in what we now call the Alps.

Giant marine reptiles—why bigger is better

The ichthyosaurs were streamlined like dolphins and sharks. But plesiosaurs with their long necks seem much more ungainly. The longest and heaviest was Elasmosaurus at 14 m long and weighing 2 t. Its neck alone was about 7 m long, one of the longest necks of any animal. It also had a record number of vertebrae—72.

This huge number meant that Elasmosaurus’ neck was quite flexible. However, this flexibility had limits. Analysis of its vertebrae shows that the neck was best for bending downwards, rather than sideways or upwards. This suggests that it mainly swam while hunting for prey in the water below or on the seafloor.5 But how did it manage to swim without its neck causing lots of drag?

To try to solve the mystery, scientists at the University of Bristol performed computer flow simulations of 3D models of various marine creatures.6 They discovered that while ichthyosaurs had lower drag than plesiosaurs, the difference was minor on creatures with large bodies. So the length/cross-section ratio was not a good indicator of drag.7

The studies showed that Elasmosaurus could swim quite well, as its very large torso compensated for its long neck. By the same token, a creature with the proportions of Elasmosaurus needed to be large to avoid excess drag. Furthermore, as long as the neck was not more than twice as long as the torso, the length can vary without increasing drag much. Thus there is the wide variation in fossil plesiosaurs.

As always, the scientists paid homage to evolution, claiming that the drag of long necks “was cancelled out by the evolution of big trunks”.2 But the actual observations are better explained by design by a Master hydrodynamical engineer (on Day 5 of Creation Week).

Posted on homepage: 4 March 2024

References and notes

  1. Sperm Whale, American Cetacean Society, acsonline.org, 2018. Return to text.
  2. Sander, P.M. and 3 others, Giant Late Triassic ichthyosaurs from the Kössen Formation of the Swiss Alps and their paleobiological implications, J. Vertebrate Paleontology, e2046017, 27 Apr 2022. Return to text.
  3. Gleeson, S., ‘Fish lizard’ fossils found in Swiss Alps showcase some of the largest creatures to ever live, usatoday.com, 29 Apr 2022. Return to text.
  4. Walker, T., The geology transformation tool, Creation 43(2):18–21, 2021; creation.com/geology-transformation-tool. Return to text.
  5. Noè, L.F. and 2 others, An integrated approach to understanding the role of the long neck in plesiosaurs, Acta Palaeontologica Polonica 62(1):137–162, 2017. Return to text.
  6. Gutarra, S. and 4 others, Large size in aquatic tetrapods compensates for high drag caused by extreme body proportions, Nature: Communications Biology 5:380, 28 Apr 2022. Return to text.
  7. University of Bristol, Large bodies helped extinct marine reptiles with long necks swim, new study finds, phys.org, 28 Apr 2022. Return to text.

Helpful Resources

Dragons of the Deep
by Carl Wieland
US $17.00
Hard cover
Flood Fossils
by Vance Nelson
US $33.00
Hard cover
Monumental Monsters
by Vance Nelson
US $33.00
Hard cover
Refuting Evolution
by Jonathan Sarfati
US $12.00
Soft cover
How Noah's Flood Shaped Our Earth
by Michael J Oard, John K Reed
US $17.00
Soft cover