Dating an early Mammal Tooth to the very end of the Cretaceous

On Friday 9th November we published an article about the discovery of an ancient tooth, believed to come from an early ancestor of ungulates (hoofed mammals) from 65 million years ago.  The discovery had been made in India, and this find was important as very little is known about Late Cretaceous mammals.

To read article: Very ancient udders! Mesozoic cow discovered in India.

Mammal Tooth

At first we queried whether the tooth had indeed been recovered from late Maastrichtian strata, thus placing this tooth at the very end of the age of Dinosaurs 65 million years ago.  The diversification and geographical distribution of mammals is still very poorly understood at this particular time in Earth’s history.  Material from the southern continents (Gondwanaland) is particularly rare, with most mammal fossils from this particular faunal stage having been recovered from the Northern Hemisphere – Laurasia.

However, one of the research scholars who worked on this particular discovery, Omkar Verma of the department of Geology (University of Jammu), was able to furnish us with a little more information.  From the articles and research papers that we were sent, it seems that the tooth was dated using other micro-fossil remains that had been recovered from the same matrix and the same site.  In particular remains of an ancient fish (a ray) Igdabatis indicus; and evidence from the many types of ostracod (crustaceans) and their carapaces indicates that the tooth came from the Maastrichtian faunal stage, placing this ancient mammal at the time of the last of the dinosaurs.

Dating the Fossils

Dating of fossils using “key” or “indicator” species which have a more precise date assigned to them in the palaeontological record is called biostratigraphy.  The remains of I. indicus are associated with the very late Cretaceous and so it seems that the mammalian tooth can be dated to that time period as well.

Ostracods, are still abundant today (the date back to the Cambrian period) and live in both marine and freshwater environments, there are thousands of different genera.  As the carapace or shell can enclose the entire body including the legs they are often referred to as “seed shrimps”, but their importance to micro-palaeontologists cannot be underestimated.  The huge numbers of micro-fossil remains and their prevalence all over the world enables scientists to accurately date geological deposits and thus assist in the dating of rarer finds such as in this case, the ancient mammalian molar from an ancestor of cows.

To view replicas of prehistoric mammals and other extinct creatures: Papo Dinosaur and Prehistoric Animal Models.

If you want to find a new Dinosaur Species- try looking in a Museum’s Vaults

The romantic notion of an earnest young palaeontologist exploring the base of a cliff away from the rest of the dig team and uncovering their very own brand new genus of dinosaur is a bit fanciful, but these occasions do occur.  However, sometimes amazing discoveries can be made by simply re-examining earlier finds in museum collections.

This is precisely what happened to Mike Taylor, a PhD student from the University of Portsmouth who has discovered a brand new type of sauropod (long-necked dinosaur) whilst studying at the Natural History museum – London.

New Dinosaur Species

For Mike, who has been studying the vertebrae of sauropods for 5 years as soon as he saw the strange partially complete fossil bone, he knew it was very different from fossil vertebrae he had seen before.  The isolated bone represents a posterior part of the dorsal vertebrae section of an elephant-sized sauropod.  The fossil was unearthed in the early 1890s in Ecclesbourne Glen, near Hastings in the county of Kent.  Unfortunately since palaeontology was very much in its infancy and the importance of accurate mapping of find locations was not well understood, no detailed records were kept of the actual site.

Acquired by the London Natural History Museum

The fossil was acquired by the Natural History museum and briefly reviewed by the English palaeontologist Richard Lydekker in 1893, but after this it was simply stored in the vaults – that is until a very observant PhD student came along and noted its significance.

Xenoposeidon proneneukus

This new dinosaur has been named Xenoposeidon proneneukus, which means “alien sauropod – forward sloping” in homage to another sauropod called Sauroposeidon discovered in Western North America and because the upper portion of this single bone slopes forward.  It has been estimated that this animal lived during the early Cretaceous approximately 130 million years ago and from the shape and structure of this single dorsal vertebra it appears to represent a totally new family of Sauropoda.

Mike’s work is to published in the academic journal “Palaeontology” and here’s hoping that his diligence and hard work leads to more exciting discoveries in the museum’s collection.

More Dinosaurs Awaiting Discovery

Having been privileged to visit behind the scenes at a number of museums, the fact that new species of dinosaur (and even new families) can be found does not really surprise us.  For example, the Natural History museum has over 70 million specimens in its collection, the vast majority in storage.  Many of the fossils unearthed in the past have been misidentified and mis-labelled so there may be other fascinating finds awaiting discovery.

Once whilst at the Royal Tyrrell museum in Alberta, Canada we calculated that in their fossil depository, the tonnes and tonnes of burlap covered fossil bearing rock would take over 100 years to prepare and describe properly.  One hundred years, if every single palaeontologist and team worker stopped what they were doing and then spent 8 hours a day working on the museum’s back catalogue.

For dinosaur and prehistoric models and figures including sauropods: CollectA Deluxe Prehistoric Animal Figures.