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The first predators and their self-repairing teeth by Staff Writers Nuremberg, Germany (SPX) Sep 26, 2018
The earliest predators appeared on Earth 480 million years ago - and they even had teeth which were capable of repairing themselves. A team of palaeontologists led by Bryan Shirley and Madleen Grohganz from the Chair for Palaeoenviromental Research at Friedrich-Alexander-Universitat Erlangen-Nurnberg (FAU) have been able to discover more about how these organisms were able to grow and regenerate their teeth. The results have now been published in Proceedings of the Royal Society B (DOI: 10.1098/rspb.2018.1614). In a land before time: A fast-moving predator with sharp teeth goes hunting in the prehistoric sea. It spies some prey and advances stealthily. All of a sudden, it goes in for the kill and devours its prey. Some of the predator's teeth have broken, but they will grow back. This is not the description of some prehistoric monster from a horror film, but rather of a conodont. Although these eel-like vertebrates were only a few centimetres long, they are considered the Earth's very first predators. Their small teeth, which are known as elements and are among the most important microfossils, could repair themselves after being damaged. How exactly this happened is difficult to ascertain, as although the fossilised teeth are often found in marine rock, their soft tissue is only rarely preserved. Since only a few examples of soft tissue from conodonts have survived, it is very difficult to determine how they grew.
Microscopes and X-rays provide insight Different materials reflect a different number of electrons back to the microscope. For example, heavy elements reflect electrons more strongly than lighter ones, which is why they are shown in a lighter colour on the image. This method enabled the individual layers to be reproduced and investigated at a much higher resolution than before. By using X-ray spectroscopy where elements are detected by means of the the radiation they emit, the scientists were also able to analyse the chemical composition of each layer.
Three stages of growth After the first stage, a type of larval state, in which food was not digested mechanically (by chewing), conodonts evolved into the first hunters during the second and third stages of growth. During this time, their teeth underwent a metamorphosis - the transition to being predators.
Existing hypothesis has been corroborated This could be compared to the mechanism of retractable teeth used for injecting venom by some species of snake. On the other hand, a theory exists that the teeth were permanently enveloped by tissue and a type of horn cap, allowing new layers to build up over time. The research carried out by FAU scientists has now confirmed the first theory. The results of the research have been published under the title 'Wear, tear and systematic repair: testing models of growth dynamics in conodonts with high-resolution imaging' in the journal Proceedings of the Royal Society B.
How mammal backbones changed during evolution Boston MA (SPX) Sep 24, 2018 Just about any elementary school student can rattle off the characteristics that make mammals special - they're warm-blooded, have fur or hair and nearly all are born alive. A new study suggests mammals are unique in one more way - the makeup of their spine. Led by Associate Professor of Organismic and Evolutionary Biology and Curator of Vertebrate Paleontology Stephanie Pierce and postdoctoral researcher Katrina Jones, the study challenges the notion that specialization in mammal backbones ... read more
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