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Teeth and Tooth and Incisor

27 December 2020
Biology

Some interesting studies have been published in December. Robert has sent three links, the first of which is at https://phys.org/news/2020-12-prehistoric-dinosaurs-mammals-teeth.html … which has been added to in a later update at https://phys.org/news/2020-12-team-dinosaurs-mammals.html … where we have an apparently surprising connection between the teeth of gorgonopsians and those of mammal carnivores such as the sabre toothed cats. Evolution seems to have been replicating itself – millions of years later. Shades of Rupert Sheldrake. I wonder what he has to say about it.

Gorgonopsians go back to the Permian era. On the geochronological chart they date between 270 and 252 million years ago, juxtaposed between two major extinction events. They come under the umbrella of Synapsids – worth looking up if you have the time. These were, in the past, and suddenly once again, sometimes referred to as 'mammal like reptiles' – which is worth digesting and reading again. An evolutionary stepping stone if you like. This was later modified as synapsids, it was realised, were perfectly developed in their own right – rather than a simple transitory life form.

Previous studies of the Jurassic theropods uncovered a similar arrangement of blade like teeth with serrated cutting edges.  The tissue forming the serrations was made up of both enamel and dentine. At the time they were considered unique to theropods [which include T Rex]. However, nobody had bothered to section gorgonopsian teeth. Serrations on their teeth, it turns out, were very similar. What do paleontologists say. Well, it seems they are turning back towards the idea that Synapsids are on the evolutionary line of mammals, and older than theropods. The serrated blade like teeth are now thought to have evolved on the mammal line – the line that led to mammals via synapsids. This is said to explain why Pleistocene mammals had similar teeth. It seems it is important for these things to be categorised and put in a box. Sheldrake's hypothesis morphic resonance would explain it all a bit differently.

Robert's second link is www.livescience.com/agu-dinosaurs-3d-cretaceous-pompeii.html … the discovery of a pair of dinosaurs buried in what was first described as volcanice ash flow, preserving them in 3D, has brought a media comparison with Pompeii and Mt Vesuvius. However, in this instance, the two prittacosaurs, have a moniker resembling modern day parrots – a prominent beak. Is this more evidence morphic resonance? Prittacosaurs, or parrot faced lizards, were inside a burrow that filled with mud that killed them instantly. This is a bit different from a pyroclasitic flow of ash, lava and gases. Mud, we may note, usually has a watery origin. Is this why Creationists are keen to see the Cretaceous as Noah's flood geology?

Robert's last link is www.newscientist.com/article/2262725-bizarre-dinosaur-had-a-mane-of-fur-… .. which is all about a rather dimunitive dinosaur – but another interesting specimen that has connections to the modern world, and small creatures with a tendency to broadcast an interest in the opposite sex. The remarkable looking animals had a long mane of fur running down their backs, and stiff rod like structures projecting from its shoulders. It is another Cretaceous fossil. It was discovered by German paleontologists in slabs of limestone they came across in NE Brazil. Hiogh resolution x-ray images of the rock face teased out the 50cm torso of the creature. A mite of a dinosaur embedded in limestone. The latter is a form of chalk. Chalk is actually sold as lime for gardens and fields. Limestone can sometimes consist of fossil coral reef structures but in this case the similarity to chalk is apt as the rock is Cretaceous in date. The rods are interesting, and the first thing to come under scrutiny. They were made of keratin and project outward by 15cm – therefore significant appendages. Keratin is also the basic element in toe nails and hair etc. – in the modern world. They look like they were used to attract mates or to intimidate rivals. The mane of fur was also impressive – rising 11cm off the back. The length of the creature is an unknown. Fascinating illumination of past life forms and the similarities they have with modern day life forms.

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