Scientists discover that the teeth of the pre-historic sea hunters could repair themselves on their own.

The scientific study of life that existed prior to, and sometimes including, the start of the Holocene Epoch falls under the scope of Paleontology. The fact that it includes the study of fossils to determine the evolution of organisms, their environments, and their mutual interaction places it on the border between Geology and Biology. Paleontologists always strive hard to make some amazing discoveries and a recent study proves exactly that. A team of researchers at the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) found that the earliest predators who appeared on Earth 480 million years ago had self-repairing teeth.

Madleen Grohganz and Bryan Shirley led this research and published their findings 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”.

Researchers found that these eel-like vertebrates were considerably small in size but that didn’t stop them from being the first predators of the Earth. Their small teeth called Elements are regarded as one of the most important microfossils due to their ability to repair themselves after being damaged. Scientists couldn’t find the exact reason for this amazing capability because the soft tissue of these fossilized teeth is very difficult to preserve. Having said that, self-repairing teeth were a massive plus to these small conodonts who hunted other creatures for their energy needs.

Scanning through Electron Microscopes

The researchers at the FAU used electron microscopes to analyze the various layers of the teeth of conodonts in their quest to solve the mystery of the self-repairing teeth. The working mechanism of these microscopes revolves around a beam of electrons, which is bombarded on a material placed in front of them. The variation in the number of electrons reflected by different materials enables experts to distinguish them from one another. For instance, heavy elements reflect electrons more strongly than lighter ones.

This allowed the researching team to reproduce and investigate all the layers individually at a much higher resolution than the previous experiments. Similarly, they were able to determine the chemical composition of every layer by making use of the X-ray spectroscopy.

Gradual Growth

The presence of an alternating cycle between wear and growth of new layers proved that these teeth undergo a gradual growth. In addition to that, the fact that the animals of different age had a different shape of the teeth strengthened this claim. The researchers utilized the shape and chemical composition of the teeth to determine that they grew in three stages. They revealed that each of these stages is influenced by the feeding habits of the animal during that phase.

The first of these stages is a type of larval state during which the food is not digested by chewing. Scientists found that these conodonts turned into predators during the last two stages of growth as their teeth underwent a ‘Metamorphosis’ which turned them into predators. It is an iodothyronine-induced biological process involving a relatively abrupt change in the structure of the animal body through differentiation and cell growth. It is present in almost all chordates. Once scientists were able to figure out the growth mechanism of the conodont’s teeth, all they needed was a hypothesis that could support their findings.

Confirms an Existing Theory

Contrary to the growth of human teeth which grow from the inside out, the teeth of conodonts repaired themselves from the outside. Prior to this research, paleontologists had already presented a couple of theories in an attempt to explain the self-repairing capabilities of the teeth of these conodonts. One of these theories suggested that the teeth were permanently enveloped by a horn cap which allowed new layers to replace the wearing-out cells.

On the other hand, scientists proposed that the repair of conodonts teeth took place while they were resting as new layers reinforced the number of cells in the epidermal pockets. They compared this method with the venom injection of some species of snake as they use their retractable teeth while attacking. After performing all their research, the researching team of Shirley and Grohganz concluded in favor of the latter.