Ancient Teeth News: Tiny Teeth Reveal First Mammals Lived Like Reptiles

Written By Kevin Kerfoot / Reviewed By Ray Spotts

Researchers from the University of Bristol, UK and University of Helsinki, Finland suggest that 200 million-year-old teeth belonging to the earliest mammals functioned like their cold-blooded counterparts - reptiles, leading less active but much longer lives. This marks  the first time palaeontologists have been able to study the physiologies of early fossil mammals directly, and revises what was previously believed about our earliest ancestors.

The researchers scanned fossils of teeth the size of a pinhead from two of the earliest mammals, Morganucodon and Kuehneotherium,  using powerful X-rays, shedding new light on the lifespan and evolution of these small mammals, which roamed the earth alongside early dinosaurs and were believed to be warm-blooded by many scientists.

This allowed the team to study growth rings in their tooth sockets, deposited every year like tree rings, which could be counted to tell us how long these animals lived.

The results - published in Nature Communications - indicated a maximum lifespan of up to 14 years – much older than their similarly sized furry successors such as mice and shrews, which tend to only survive a year or two in the wild.

“We made some amazing and very surprising discoveries. It was thought the key characteristics of mammals, including their warm-bloodedness, evolved at around the same time,” says lead author Dr. Elis Newham, Research Associate at the University of Bristol.

“By contrast, our findings clearly show that, although they had bigger brains and more advanced behavior, they didn’t live fast and die young but led a slower-paced, longer life akin to those of small reptiles, like lizards.”

Advanced Imaging Technology to study ancient teeth

The advanced imaging technology was the brainchild of Dr. Pam Gill, Senior Research Associate at the University of Bristol and Scientific Associate at the Natural History Museum London, who was determined to get to the root of its potential. By scanning the fossilized cementum, the material which locks the tooth roots into their socket in the gum and continues growing throughout life, she hoped the preservation would be clear enough to determine the mammal’s lifespan.

“A colleague had a tooth removed and told me they wanted to get it X-rayed, because it can tell all sorts of things about your life history,” Gill says. “That got me wondering whether we could do the same to learn more about ancient mammals.” 

An ancient tooth specimen belonging to Morganucodon was scanned using high-powered Synchrotron X-ray radiation. Although the cementum is only a fraction of a millimeter thick, the image from the scan was so clear the rings could literally be counted.

This marked the start of a six-year international study, which focused on these first mammals, Morganucodon and Kuehneotherium, known from Jurassic rocks in South Wales, UK, dating back nearly 200 million years.

The researchers took about 200 teeth specimens, provided by the Natural History Museum London and University Museum of Zoology Cambridge, to be scanned at the European Synchrotron (ESRF), the world’s brightest X-ray light source, and the Swiss Light Source.

“We digitally reconstructed the tooth roots in 3-D and these showed that Morganucodon lived for up to 14 years, and Kuehneotherium for up to nine years,” Newham continued. “I was dumbfounded as these lifespans were much longer than the one to three years we anticipated for tiny mammals of the same size.”

“They were otherwise quite mammal-like in their skeletons, skulls and teeth. They had specialized chewing teeth, relatively large brains and probably had hair, but their long lifespan shows they were living life at more of a reptilian pace than a mammalian one. There is good evidence that the ancestors of mammals began to become increasingly warm-blooded from the Late Permian, more than 270 million years ago, but, even 70 million years later, our ancestors were still functioning more like modern reptiles than mammals”

48,000-Year-Old Tooth

The most recent Neanderthal finding is a milk-tooth found in the vicinity of the Berici Hills in the Veneto region and bears evidence of one of the last Neanderthals in Italy. This small canine tooth belonged to a child between 11 and 12 that had lived in that area around 48,000 years ago. The study - carried out by a group of researchers from the Universities of Bologna and Ferrara - was published in the Journal of Human Evolution.

The genetic analysis reveals that the owner of the tooth found in Veneto was a relative - on their mother's side - of Neanderthals that had lived in Belgium. This makes this site in Veneto a key area for comprehending the gradual extinction of Neanderthals in Europe.

"High-resolution prehistoric field-archaeology allowed us to find the tooth, then we employed virtual approaches to the analyses of its shape, genome, taphonomy and of its radiometric profile,” says Matteo Romandini, lead author and researcher at the University of Bologna. “Following this process, we could identify this tooth as belonging to a child that was one of the last Neanderthals in Italy.”

"This small tooth is extremely important," added Stefano Benazzi, professor at the University of Bologa and research coordinator. "This is even more relevant if we consider that, when this child who lived in Veneto lost their tooth, Homo Sapiens communities were already present a thousand kilometers away in Bulgaria".

The tooth was analyzed by employing highly innovative virtual methods. "The techniques we employed to analyze the tooth led to the following discovery,” added Gregorio Oxilia and Eugenio Bortolini, co-authors of the study and researchers at the University of Bologna. "According to this dating, this little milk-tooth is the most recent finding of the Neanderthal period in Northern Italy and one of the latest in the entire peninsula."

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Written By:

With over 30 years of writing and editing experience for newspapers, magazines and corporate communications, Kevin Kerfoot writes about natural health, nutrition, skincare and oral hygiene for Trusted Health Products’ natural health blog and newsletters. 

Reviewed By:

Founder Ray Spotts has a passion for all things natural and has made a life study of nature as it relates to health and well-being. Ray became a forerunner bringing products to market that are extraordinarily effective and free from potentially harmful chemicals and additives. For this reason Ray formed Trusted Health Products, a company you can trust for clean, effective, and healthy products. Ray is an organic gardener, likes fishing, hiking, and teaching and mentoring people to start new businesses. You can get his book for free, “How To Succeed In Business Based On God’s Word,” at www.rayspotts.com.