Saturday, 15 December 2012

Chemical Ghost of 50 million year old invisible teeth!

On Friday last week our research group published another paper in Applied Physics A that reinforces the use and application of our synchrotron-based imaging technique. The technique permits us to tease-out chemical information from fossils…information that you simply cannot see with the naked eye. Such chemical maps can help us see 'ghosts' of original biological structures that only remain in very dilute concentrations in the fossil.

(a) Optical photograph of BHI-045A (main slab) containing preserved, almost complete fossil reptile skin (Squamata (Reptilia). The reptile consists of intricately preserved skin formed of individual scales, but no visibly preserved hard-tissues (i.e., endoskeleton, inset of boxed area in a). SRS-XRF map of copper (b) and sulfur (c) of BHI-045A resolving the biological material including individual scale detail (insets). Scale bar = 1cm.
The fossil specimen we study in this paper was thought to be a 50 million year old skin moult from a lizard….of some unknown variety. Our work was able to map the presence of teeth that could not be seen in visible light. Our x-ray mapping technique showed the presence of phosphorus from teeth and their precise location relative to the rest of the head and body. This is VERY important as now, our fossil skin cannot be a moult….lizards do not moult their teeth when shedding their skin….so we now know something has wiped-out (disolved) the bone, post-mortem, but preserved the skin…along with a whiff of the original skeleton, albeit the teeth. This changes how we view the taphonomy (from the Greek taphos 'burial' and nomos 'laws')…but also allows us to identify the type of lizard for the first time, based upon the geometry of the teeth.

(a) Magnified view of jaw region of lizard (BHI-045A) in phosphorus showing preserved dentition chemistry. (b) Interpretation of arrangement of preserved dentition red interpreted as teeth belonging to one jaw, blue to another; it is difficult to tell which is the upper and lower jaw. Scale bars = 5mm
This means we can now start looking for traces of animals that are totally invisible in visible light, but shine a bright chemical signature under the powerful gaze of the synchrotron. This 'x-ray vision' will enable palaeontologists to add important information on the biology, anatomy and preservation of ancient life.

Our new paper can be downloaded from this link: N.P. Edwards, R.A. Wogelius, U. Bergmann, P. Larson, W.I. Sellers, P.L. Manning. 2012. Mapping Prehistoric Ghosts in the Synchrotron. Applied Physics A, DOI 10.1007/s00339-012-7484-3

Wednesday, 5 December 2012

Dinosaur of Paradise....

Yesterday I found myself in the hallowed halls of the University of Cambridge Zoology Museum. This is a stunning that mere photographs would simply fail to do justice. This is a museum that everyone must visit at some point in their life. Laid before you is one of the most diverse displays of endless forms most beautiful that elegantly tells the tale of the evolution of life on Earth.

Occasionally in my line of work you get the opportunity to kneel at the alter of evolution and bow ones head in reverence...yesterday was one such day. The collections manager at the Museum, Matthew Lowe, kindly showed me an object from the Cambridge collection that was both stunningly beautiful, but also historically priceless. Matt carefully lifted a glass top from a beautifully crafted case, containing the preserved remains of some Great Bird of Paradise collected in the latter half of the 19th Century...this should be the first clue as to their import. Those of you who have read my prior posts, will have heard my rants on the amazing adaptations and diversity that we see in modern avian theropods (who most call birds). The Great Bird of Paradise almost certainly possesses the most incredible array of feathers to have evolved from dinosaurian stock. Their striking plumage has long captured the eye and imagination of poets, writers and natural historians...but it is the latter that played a key role in the acquisition of this particular specimen.

As I peered at the lifeless form, that is still breathtakingly beautiful even in death...Matt drew attention to the label. I did a double take and realised this sample had been collected by one of the most iconic and influential naturalists to have lived!

Coll. A. R. Wallace.......Splendid!