Paleontology News: Old Fossils, New Surprises!
Old fossils can still bring surprises even as we have studied dinosaur and fossils for many years. In fact, it has been 193 years since the world’s first named dinosaur was revealed and still, the famous fossil still has surprises to offer.
The first dinosaur to be scientifically described, Megalosaurus (M. bucklandii), has stepped once more into the spotlight. A team of researchers have discovered five new teeth within the lower jaw fossil of the world’s first named dinosaur.
The picture above shows the original lithograph of the right dentary of Megalosaurus. The jawbone is show in lingual view (top) and in buccal view (middle) with drawings of individual teeth (bottom).
Using state-of-the-art computer tomography scanning technology and three-dimensional computer generated modelling software, the researchers from the Warwick Manufacturing Group (WMG), an academic department at the University of Warwick, in collaboration with scientists from the University of Oxford’s Museum of Natural History have been able to provide new insights about one of the most iconic fossils in the world.
One of the authors of the study, presented this week at the Institute of Electrical and Electronics Engineers (IEEE)’s conference in Italy, Professor Mark Williams stated:
“Being able to use state-of-the-art technology, normally reserved for aerospace and automotive engineering, to scan such a rare and iconic natural history specimen was a fantastic opportunity. When I was growing up I was fascinated with dinosaurs and clearly remember seeing pictures of the Megalosaurus jaw in books that I read. Having access to and scanning the real thing was an incredible experience.”
In 1824, the Reverend William Buckland published a description of various fossils that had been found as quarrying tunnels were excavated at Stonesfield, north of Witney in Oxfordshire. The fossils had been found some years before, the dentary having been placed in the collection of the Oxford Anatomy School at Christchurch College (Oxford) in 1797. Reverend Buckland believed the fossilised bones and teeth came from a giant, antediluvian lizard, hence the name “Big Lizard”, Megalosaurus having been proposed by James Parkinson in 1822.
Using state of the art CT scanning technology and specialist three-dimensional analysis software, Professor Williams took more than 3,000 X-ray images of the world-famous Megalosaurus jawbone, creating a digital three-dimensional computer generated image. The image revealed five previously unseen teeth embedded in the dentary and also provided important insights into historical repairs. It turns out that there is actually less plaster and filler in the fossil, as this technique has allowed scientists to see the extent of the infilling and repairs for the first time.
The specimen is damaged, it is likely that some of the damage occurred when the fossil was excavated but over the two hundred years since the fossil was found some restoration work has taken place. For example, records at the Oxford University Museum of Natural History, where the specimen is housed, show that sometime between 1927 and 1931 repairs to the jawbone took place. The scans show the true extent of repairs on the fossil for the first time, revealing that there may have been at least two phases of repair, using different types of plaster. This new information will help the museum make important decisions about any future restoration work on this iconic fossil.
The analysis also revealed the presence of five teeth that had not been detected before. The teeth consist of the remains of old, worn and broken teeth plus embryonic replacement teeth. Unlike us, Megalosaurus was able to continually replace its teeth throughout its life. The replacement tooth grew inside the jaw, adjacent to the root of the active tooth on the lingual* side of the jaw. A full-sized, but very thin crown formed first and this grew in thickness as more layers of dentine were added. The growth of the embryonic tooth placed pressure on the active tooth root, causing the root to become slowly reabsorbed into the jawbone. The replacement tooth was able to push itself inside the old tooth root and effectively usurp that tooth from the socket in the jaw where it had been located. The old, worn tooth having been weakened, would most likely break and the crown would be lost, permitting the younger tooth to replace it in the jawline. A similar process is seen in extant Crocodylia today.
