Some plant-eating dinosaurs chewed through thousands of teeth

Looking back at the Cretaceous period, one cannot help but marvel at the dominance of the hadrosaurs, often referred to as duck-billed dinosaurs. The most advanced herbivores of their time, hadrosaurs, with their formidable teeth, were anything but passive eaters.

New research reveals that these colossal creatures went through average teeth every two months, all thanks to their voracious appetite for plants. They may have had hundreds of thousands of teeth throughout their lifetime.

Embarking on a Jurassic journey

To comprehend the dietary dynamics of these herbivores, we need to navigate back in time and trace the evolutionary trajectory of the ornithopods – a group of dinosaurs that encompassed the likes of Iguanodon, Hypsilophodon, rare rhabdodontids, and, of course, the hadrosaurs.

These plant-eating machines, comparable to modern-day cows and sheep in their feeding frenzy, first made their appearance in the Middle Jurassic. By the time the Cretaceous period took over, they were the reigning herbivores across vast swathes of the world.

The journey of hadrosaurs is much like a small start-up company evolving into a multinational corporation.

Hadrosaurs used teeth as tools

The research was led by Dr. Attila Ősi from Eötvös Loránd University in Hungary. She highlights the drastic changes in the teeth and jaws of ornithopods during their evolution.

The Iguanodon, an early member of the group, took over 200 days to form their teeth and consumed at least the same amount of time to wear them down through chewing.

Fast forward to the end of the Cretaceous, and we see that hadrosaurs gnawed through their teeth in merely 50 days.

Clearly, the later ornithopods were binge-eating on tough plants that rapidly eroded their teeth. They needed to deploy reinforcements, building up reserves of teeth in their skulls to prevent themselves from going hungry.

Herbivory: Harder than it looks

Being a vegetarian isn’t an easy job, especially if you’re a dinosaur. While meat dissipates easily in the gut, plants are composed of tough fibers and complex carbohydrates that are a bit more challenging to digest.

It calls for teeth to lead the charge, breaking open plants and cutting them into smaller pieces for gut bacteria to disintegrate more efficiently.

“Across a herbivore’s life, its teeth gradually wear down,” explained study co-author Professor Paul Barrett. The constant wear and tear eventually led to the end of the tooth and subsequently the end of the animal, at least in the case of some mammals.

However, reptiles appear to have dodged this dental dilemma by continually producing new teeth. As a result, dinosaur teeth have become the holy grail for researchers delving into early animal evolution.

Transformation of ornithopod chompers

The study focused extensively on the teeth and jaws of ornithopods, the planet’s most advanced herbivores in their time. Examination of well-preserved skulls offers a glimpse into the transformation of the dinosaurs’ skulls, with increasingly complex features best suited for plant-eating.

“At the start, they had single rows of fairly simple teeth with limited wear, probably because these dinosaurs focused on fruits and softer plants,” said Professor Paul.

These early ornithopods evolved into hadrosaurs with numerous teeth, a large blade-like edge on one side, and ridges on the other. This unique structure ensured sharp teeth as they ground against each other.

The evolution of ornithopods also marked new ways of jaw movement, allowing them to grind plants down even further. Their bodies grew larger to house more extensive guts better suited to release nutrients from plants.

Mystery of hadrosaur teeth

So what triggered this evolution of tough teeth? Scientists believe that the diet of dinosaurs was dictated by the kind of plants available. One theory suggests that the rise of flowering plants might have influenced their dietary preferences.

Microscopic wear patterns on teeth indicate changes in the type of plants consumed by dinosaurs over time. Could the emergence of flowers be the reason?

“While it is suspicious that the flowering plants start to diversify around this time, they were still pretty uncommon at the time,” noted Professor Paul.

Future of fossil research

With their study on ornithopods completed, the team aims to extend their research to other herbivorous dinosaurs, like the ankylosaurs or the horned dinosaurs. Unveiling the dietary preferences and subsequent evolution of these creatures could help us better understand why they thrived during their time.

“If we can find out what changes herbivores were going through at the time, it will give us a much better chance of understanding the place of these dinosaurs in the ecosystems of the Mesozoic Era,” said Dr. Attila.

The teeth of dinosaurs offer a fascinating window into the world of the Cretaceous period, unraveling the mysterious ways in which these creatures evolved and thrived.

So, the next time you’re biting into your favorite plant-based snack, spare a thought for the complex evolutionary processes that enabled us and our ancient ancestors to enjoy our greens. Who knew teeth could tell such compelling tales?

The study is published in the journal Nature Communications.

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