Elephant tooth evolution rooted in grass

Once they developed a taste for grass, the ancestors of today's elephants swiftly broadened their leaf-only diet
Once they developed a taste for grass, the ancestors of today's elephants swiftly broadened their leaf-only diet and placed their progeny on a new evolutionary track, a study said Wednesday.

Once they developed a taste for grass, the ancestors of today's elephants swiftly broadened their leaf-only diet and placed their progeny on a new evolutionary track, a study said Wednesday.

Early tuskers were moving into open grassland millions of years before their teeth were adapted to grazing, according to a paper in the journal Nature.

The research, based on analysis of the fossil remains of east African proboscideans—the order containing mammals with tusks and trunks like elephants and mammoths—claims to show that animal behavioural "choice" can shape the way a species evolves.

It had been known that grass "grazers" evolved from leaf "browsers"—but not whether this happened before or after they acquired their new teeth.

In the case of proboscideans, the study showed their diet evolving about eight million years ago as a turned the African continent into a more arid place with grassland progressively replacing woodland.

While they still had access to leaves, which their teeth were adapted to chew, these early elephants rapidly started to add substantial amounts of grass to their diet.

The molars of leaf "browsers" are flatter than the higher, much more ridged and wear-resistant teeth that today's elephants use to grind grass, which is tougher than foliage, and the soil that sticks to it.

The change in proboscidean teeth only started about three million years after the dietary shift, according to the study by Adrian Lister of London's Natural History Museum.

"This long delay between the and the evolutionary response suggests that behaviour led the way," he said in a statement.

"The theory that animal behaviour may play an important role in the origin of new adaptations has been discussed for over 100 years, but it has been very difficult to find concrete examples".

Elephants today eat grasses and herbs, leaves, tree bark, fruit and vegetables.


Explore further

When African animals hit the hay: Fossil teeth show who ate what and when as grasses emerged

More information: Paper: dx.doi.org/10.1038/nature12275
Journal information: Nature

© 2013 AFP

Citation: Elephant tooth evolution rooted in grass (2013, June 26) retrieved 23 July 2019 from https://phys.org/news/2013-06-elephant-tooth-evolution-rooted-grass.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
0 shares

Feedback to editors

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more