A new year. A new bad cast. It looks quite good. But it is not. Not at all. Especially when we remember that this is a reproduction taken from a real fossil.
The cast is of a rather perfect paddle (or flipper) of an ichthyosaur. These were enormously successful marine reptiles which were the top predators in the waters while the great dinosaurs were stomping the land. The Order, Ichthyosauria, were on Earth for over 180 million years, spanning the entire Mesozoic Era (which includes, the Triassic, Jurassic and Cretaceous Periods).
With long snouts, streamlined bodies and paddles, they superficially resembled dolphins. They would have even swam to the surface to breathe air, just as dolphins and other marine mammals do today. These extinct marine reptiles are an excellent example of convergent evolution; where different animals independently evolve similar adaptations for similar environments. Convergent evolution works with what is already there, so you can’t evolve an ichthyosaur from a mammal, or an ichthyosaur from a dolphin ancestor. These two groups of animals have lots of differences; dolphins are mammals, whereas ichthyosaurs are reptiles; dolphins swim with their backbone up and down, ichthyosaurs swim with theirs side to side; dolphins only have paddles at the front (pectoral fins), ichthyosaurs have both front (pectoral) and back (pelvic) paddles.
Ichthyosaurs were an awesome group of reptiles. They evolved into at least 77 genera that have been discovered to date (there are 17 genera of dolphin alive today). Some species were as small as an otter, and others could be enormous; one species was as long as two Double Decker buses! Most of the species had sharp pointy teeth to feed on squid, belemnites and fish. Some had much thicker teeth used to crush shellfish, ammonites and other hard food to feast upon. Others had even bigger, thicker teeth for eating other reptiles. Some actually had no teeth, which was a possible adaptation for suction feeding (sucking in small fish in their short snouts).
The strong tail, with a powerful side to side motion, would have been used to push these amazing creatures through the water. The paddles were were for steering the ichthyosaur in the direction it wanted to go. With a smooth streamlined body, the strong tail propelled the big beast through the water, and moving quite fast little tweaks with its paddles to quickly change direction. It would have been a very quick and active swimmer.
This cast is a pretty big one; 70cm long. The animal it belonged to must have been a big beast too. Looking at the specimen from the top to bottom of the picture we can see quite a lot quite clearly. The first big bone at the top is the humerus (the bone in our arm that joins our shoulder to our elbow). Moving down the picture, we see two more bones, the radius and ulna (these are the two bones in our arms connecting our elbow to our wrists). We then see some of the wrist and hand bones and then the finger bones. What is lovely about this cast is that it clearly shows how the ones of this reptile have adapted for life in the water. The bones have shrunk over time and one piece of flesh surrounds them to form a paddle. Beautiful. Same bones as you and I, just a little bit different.
Specimens as good as this are quite rare. A quick Google search shows a few examples of gorgeous ichthyosaur paddles. They can be found, but not enough of them have been found for each museum in the world to have their own. Enter the cast.
We have a few ichthyosaur specimens at Plymouth City Museum and Art Gallery; a couple of vertebrae, a tail, a small specimen folded back on itself, and a paddle. The paddle isn’t good, so it’s quite likely that the museum acquired the cast when it opened a hundred years ago to go along side this real fossil so it was clear what they looked like.
Clearly, compared to the real fossil, the cast is dreadful! The cast does tell the story of evolution simply and clearly; it shows how the bones, the same bones in our arms, have evolved to become adapted for steering an ichthyosaur effortlessly and elegantly through water.
But, and a really big but, (and to paraphrase those legendary, classical lyrics, I do like big buts and I can not lie); it is a pretty naff cast. It fails to do what casts are really supposed to do. Surely the point of a fossil cast is to create a reproduction of the real specimen so it looks as good as the real thing? Maybe I am missing the point of fossil casts.
The cast is simple, lacking the intricate detail in casts we may see today. The finishing touches of paint ‘to bring the cast to life’ fail to do just that. These things make the cast look fake. Of course it is fake, because it is not a real fossil. But a cast should not look so fake. Painting something brown on a grey background unfortunately doesn’t make it look like a fossil. Perhaps tastes have changed in a hundred years, maybe we expect too much. But really? Am I wrong in thinking a few artistic shades of brown may create more of a realistic finish? This cast is bad. It looks fake, and this is where it fails straight away.
It’s not as bad as the ghost in the rock, but it is bad.