Teeth evolution in mammals not a one-time affair

November 14th, 2007 - 8:14 am ICT by admin  
Scientists came forward with the new theory after finding the fossilized skeletal remains of the new species, Pseudotribos robustus, in 165-million-year-old lakebeds in the Inner Mongolia region of northern China.

From the creature’s build and makeup, paleontologists believe that the 4.7-inch-long creature was a very strong digger that ate insects and plants.

However, what has the scientists really excited, is the creature’s teeth.

“This thing is very advanced in terms of its tooth structure,” National Geographic News quoted Richard Cifelli, a paleontologist at the University of Oklahoma in Norman, as saying.

“It has departed considerably from the ancestral pattern where it could only cut up things; now it can grind things up,” he added.

This is the same dental adaptation that is believed to have flourished in today’s mammal lineages. The advent of the cut-and-grind tooth is generally considered the driver for the vast diversity of mammals alive today.

According to scientists, since ‘Pseudotribos robustus’ belongs to a different and long-lost lineage, it must have evolved the cut-and-grind tooth independently.

“This is an example of a process known as convergent evolution as it shows that a key feature evolved in two completely different ways, but with the same final outcome,” said Hans-Dieter Sues, associate director for research and collections at the Smithsonian National Museum of Natural History in Washington, D.C.

The first two-thirds of mammalian history takes part in the age of the dinosaurs. During that time it has been thought that mammals remained in much the same form: small, furry, nocturnal, insect-eating animals that skirted around dinosaurs.

“[Pseudotribos robustus] helps to show that the earliest mammals coexisted with the dinosaurs are far more diverse than we ever have imagined,” study author Luo said.

The find also adds to a growing body of evidence suggesting that early mammals were much more diverse than previously thought.

The study appears in the current issue of Nature. (ANI)

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