Talks, field trips and events organised by west country geological organisations are publicised on this blog. Discussion about geological topics is encouraged. Anything of general geological interest is included.
THIS ARTICLE was brought to my attention by a mention in the Earthlogs blog. It is based on the paradox that life needs water but water destroys DNA and RNA.
The way round this is to be in an environment which is intermittently wet and dry - a puddle! And, on the early Earth, a puddle in a meteor impact crater! This would have all the components needed for this view of the origin of life.
You can recreate these conditions in a chemistry laboratory and the results are interesting. But you cannot do it outside on Earth. But how about Mars? Some water, meteorite impacts and great preservation!
So next year a NASA rover called Perseverance will land in the Jezero Crater to look for the building blocks of life.
This is an easily read introduction to current thinking on the origins of life - well worth reading!
Nasa's Perseverance rover will search for signs of life in Jezero Crater on Mars.
I came across THIS ARTICLE in the Guardian. (Other newspapers are available). It tells of a very strange creature - Ubirajara jubatus - from (what is now) Brazil. If you have access you can see the original article HERE. There is more about it HERE.
On the inside it is fairly ordinary, but on the outside it is extraordinary.
An artist’s rendering of Ubirajara jubatus. Photograph: Luxquine/Wikimedia Commons
The articles tell you all about the creature, but what intrigued me was that one of the authors is Dave Martill of Portsmouth University, who led a GA excursion to Morocco in 2018. I was on the excursion and Dave mentioned that he could no longer go to Brazil because he had been accused of illegally exporting a fossil. This he denied, fiercely!
I suspect this is the fossil concerned. I am sure Dave would like to find another one.
HERE is a book review which tells you all you need to know about hominids in an easily approachable way. I might even be tempted to buy the book! Enjoy!
THIS ARTICLE based on THIS ACADEMIC JOURNAL ARTICLE reports that mass extinctions follow a cycle of about 27 million years. And they are associated with major asteroid impacts and devastating volcanic eruptions. But what controls the cyclicity remains unknown.
Explain that convincingly and your reputation is made!
Much of the groundwork for the academic paper is based on Mike Benton's work. But it goes into statistical analysis which flies a considerable distance above my head. But they come out of this convinced of the 27.5 My. periodicity.
An illustration - only glancingly relevant to the article but more interesting than the statistical graphs
Carrying out marine geology at sea, the role of technology in discovery
Whereas many aspects of Earth’s geology are visible at the surface, and thus open for speculation, in the oceans the seabed is obscured. The history of the subject has therefore involved a series of incremental discoveries as new technology has been developed and then deployed by geologists. This can be seen from the early methods used in mapping routes for telegraph cables across the oceans. Sonar techniques were developed rapidly through World War II and during the Cold War, techniques that turned out to be extremely valuable for revealing the seabed’s morphology and geology.
The Guardian, and I presume other newspapers (but not the FT), has AN ARTICLE linking the end of Doggerland with the Storegga underwater landslides and the resulting tsunamis. It is based on THIS PAPER.
There is much evidence for the Storeggs tsunamis in Scotland, Northern England and Norway, but until now, nothing in the southern North Sea.
But now, after mapping valleys and lakes in, what was, Doggerland, researchers have drilled and identified a tsunamiite. But they conclude that, although locally catastrophic, the demise of Doggerland was due more to sea level rise than to a single tsunami.
The mystery is - where are the archaeological remains?
A mature WEGA member has some old magazines available for anyone who wishes them.
She writes:-
----------------------------------
Available are #s 45, 47-60, 62-654,66-81,83,85-97 and 99-110 of“ Down to Earth”
and
#s 23-35 (missing#33) of “Earth Heritage”
I am not agreeable to handing out single copies. Recipient must take all available of either series and do any picking and choosing on their own territory. First come, first served.
If these magazines are unwanted they will go for recycling with the Council collection in a few weeks time. Soon or never!
----------------------------
If you are interested contact me at graeme@churchard.com and I will give you the contact details.
Roger Steer has brought THIS WONDERFUL RESOURCE to my notice. It is an excursion guide to the rocks of the built environment, mostly of London, but with a little of Birmingham and Doha, Qatar. It is mainly the work of Ruth Siddall of University College, London, following on from the work of Eric Robinson.
The amount of work which has gone into the many articles is phenomenal. I learned more about Larvikite by reading the London Pub article than I knew before. It is not a syenite but a monzonite with equal amounts of plagioclase and K-feldspar. These are in the form of interlaced laminae forming an antiperthite. These antipethitic feldspars are iridescent and this is known as schillerescence.
But it is not only igneous rocks which are discussed in detail. The fossils of Portland Stone are described and illustrated.
Two sections through once articulated valves of L. gibbosa, now
leached away. By chance, the mason has cut through along the long axes of the shells
giving the effect of ‘angel wings’. The ribs and costae can be seen on the upper
example of the two. Once again, this is from the Roach used on the new wing of BBC
Broadcasting House.
One photograph illustrates that this is indeed Urban Geology - the scale is indicated by a fag end!
I have just started reading this huge archive and it is a cornucopia of geological insights and delights! A pity it is mostly in London.
A correspondent has brought THIS ARTICLE to my attention. With great difficulty I avoid all scatological humour and tell you that it is about Rhaetian food webs in the Bristol area. The research material was coprolites from Chipping Sodbury. CT scans were taken of the coprolites and the contents (remarkably well preserved) identified.
The animals of the Rhaetian sea were all carnivores and they ate each other. The one rule was - If it is smaller than you, eat it!
The article, which is a precursor for a paper which will be published in the Proceedings of the Geologists' Association, is largely concerned with building a food web of the Rhaetian Sea. What I find fascinating is the preservation of the bones. Modern animals have stomachs which can dissolve bones. For these creatures going to the toilet must have been painful!
CT scan of coprolite specimen, BRSMG Cf15546, in different views, showing tuberculated bone (blue) from a fish skull, and two vertebrae from the tail of the marine reptile Pachystropheus, in yellow and green.
Marie Cueille, and Palaeobiology Research Group, University of Bristol
I have been facinated by Kerguelen since reading "Desolation Island" by Patrick O'Brian - the fifth book in his Aubrey - Maturin series. Desolation Island is, of course, Kerguelen.
Another reason to find the place interesting is THIS ARTICLE which tells us that the Kerguelen Plateau was a Large Igneous Province (LIP) which erupted for over 30 million years. Most LIPs last less than 5 million.
Eruption started at 122 million and lasted until 90 million. From about 100 million to 20 million years ago it was above sea level, with trees growing. These have been recovered in recent deep sea drilling.
The plateau has since subsided with only Kerguelen and Heard and McDonald islands poking above the waves. Most is at depths of 1,000 to 2,000 metres. The surrounding oceans are at 4,000m.
The article gives a lot of the details and is an easy read - well worth looking at.
The thought of huge islands (half the size of Australia) disappearing gives one food for thought!
Location of the Kerguelen Plateau in the Indian Ocean. NATIONAL GEOPHYSICAL DATA CENTER
A correspondent has brought the following articles from the Geol Soc to my attention - Thank You!
To get the rest of this post click the second read more at the bottom of the page - there is a LOT MORE!
Free for a limited timeLadies with hammers – exploring a social paradox in early nineteenth-century Britain
By M. Kölbl-Ebert
In the early nineteenth century, long before the Geological Society of London opened its doors to female members, geology was a fashionable science in Britain. Numerous women collected fossils and minerals, and read or even wrote popular geology books. There was also a considerable number of female helpmates to renowned pioneers of geology, acting as secretaries, draughtswomen, curators and field geologists...read more
Earth Logs, a favourite source of mine, in THIS ARTICLE has brought THIS WONDERFUL ARTICLE to my attention. It has, in reasonably clear fashion, all you need to know about life before the Cambrian.
Was there a Cambrian Explosion of life - perhaps not. The article has lots of pictures and references to follow.
Organisms named Fractofusus cover the sea floor some 560 million years ago, in a reconstruction of fossils from Newfoundland, Canada. Credit: Dr Charlotte G. Kenchington
Pterosaurs - flying dinosaurs - were around for 150 million years and over that time their flying eficiency improved by 50%. Easy to say but how do you prove it? In THIS PAPER Mike Benton shows how it was done.
Pterosaurs increased their flight efficiency over time – new evidence for long-term evolution
With a wingspan of 12m–15m, Quetzalcoatlus was one of the largest flying animals that ever lived. Indeed, it seems astonishing that such monsters could fly at all. Yet over a period of more than 150 million years, pterosaurs (the flying cousins of dinosaurs) became increasingly efficient at flying as they evolved from small animals the size of a starling to become giants of the sky.
Our new research shows that pterosaur flight efficiency improved by 50% over the period from 230 million years ago to their extinction 66 million years ago. This enabled them to fly for over much greater distances for long periods of time.
This may seem like a remarkable or even foolhardy conclusion to draw from a study of fossils, but we have developed methods to extract the data. What’s more, this finding goes to the roots of how Darwinian evolution works, suggesting that lifeforms can continue to adapt to their environment over very long spans of time.
Pterosaurs were active, warm-blooded animals, insulated with whiskery feather-like structures all over their bodies. They flew using leathery wings made from skin supported by an especially long fourth finger that extended from their elongated arms.
To calculate the efficiency with which different pterosaurs flew, we first needed to know how heavy they were. So we made estimates based on the size of 16 species for which we have relatively complete skeletons and cross-checked our figures with those of birds and bats to make sure they were reasonable.
A flock of Rhamphoynchus in flight.Mark Witton/University of Reading, Author provided
We also estimated the basal metabolic rate (BMR, the energy expended by an animal when at rest) for each pterosaur species from a large sample of BMR and body mass measurements for birds. We were then able to create an “efficiency of flight index” based on estimates of how much energy each species would have needed to travel at its ideal speed, just fast enough to defy gravity, relative to its body mass.
By modelling reasonable values for other species, we came up with figures for 128 different pterosaurs, which we then mapped on an evolutionary tree that showed how flight efficiency changed over time as the species evolved. We found that for all pterosaurs except azdarchoids, there was a significant increase in body size, wingspan and flight efficiency. We used what’s known as a “Bayesian modelling approach” that repeated and improved the analysis billions of times, considering all possible combinations of all possible sources of error.
Body mass rose from a mean of 0.6kg in the Middle Jurassic epoch to 6.05kg in the Late Cretaceous. In the same time, mean flight efficiency increased substantially. Much of this increase in efficiency was related to increasing body size – bigger pterosaurs naturally flew more efficiently. But once body size was excluded, we found that flight efficiency still increased by some 50%.
The azhdarchoids, a group of pterosaurs with very long legs and necks, seem to have bucked the trend and showed decreasing flight efficiency with increasing body size. They were evidently following their own evolutionary route to excessively huge body sizes, meaning that evolving to become larger gave them other advantages on the ground and they became less dependent on flight to get around.
The azhdarchoid pterosaur Hatzegopteryx, with a 10m wing span, was not a great flier.Mark Witton/University of Reading, Author provided
A test of Darwinian evolution
Our findings don’t just tell us something interesting about pterosaur evolution, but provide useful evidence about evolution itself. A core assumption of Darwinian evolution is that adaptation by natural selection drives successful organisms to improve in some way. Within populations, the fittest organisms survive, and their fitness is measured not only in their successful adaptations but also because they breed and pass on their successful genes.
An important question for scientists has long been whether we can measure these improvements through longer spans of time, say between species and over millions of years. In arms races between predators and prey, the lion runs faster to catch its prey, but the wildebeest runs faster to escape. But they don’t keep evolving faster and faster speeds forever – ultimately they are limited by material constraints.
In 1973, evolutionary biologist Leigh Van Valen put forward his “Red Queen hypothesis” of Darwinian evolution to try to resolve this conundrum. Van Valen realised that the environment in which an organism lives is not constant but is changing all the time. And so the organism has to keep evolving and adapting just to maintain its status quo. As the Red Queen in Lewis Carroll’s Through the Looking-Glass said: “It takes all the running you can do to stay in the same place.”
Our results suggest that organisms can become more efficient over a very long period of time. The Red Queen hypothesis likely explains most situations where organisms are in some kind of balance with each other within their ecosystems. But our work shows that actual net improvements in physical performance can happen. This perhaps supports a central assumption of Darwinian evolution that has been nearly impossible to test until now.
This is not likely to affect you in the UK - unless you are in a train near Stonehaven! - but good to know for visits to more exotic parts. THIS ARTICLE summarises THIS LONG ARTICLE which goes into exhaustive details of how a landslide can kill you.
The advice is straight forward.
Before
Check if there are potential dangers of a landslide.
Live in the downhill side of a house.
During
Move upstairs
Go to interior, unfurnished areas
Open downhill doors and windows
After
Make noise so rescuers can find you
Don't
Open a door out of curiosity
Shelter beside large furniture
The article goes into much more detail, giving reasons for the survival strategies.
P.S. In the accident near Stonehaven it wasn't the landslide that caused the deaths but the train being derailed when it ran into the relatively small amount of landslide debris.
Geomorphology was never like this in my day! A correspondent has brought THIS ARTICLE to my notice - thank you! It is based on THIS JOURNAL PAPER. The research area was Bhutan.
Rain erodes mountains. Does the removal of material cause mountains to rise because of isostasy? This has been discussed for ever - or so it seems!
The papers describe an attempt to measure this. As you might expect, this is not easy. relief and rainfall at fairly easy to measure but erosion rates are more difficult. The method used here is to measure chemical changes in quartz sand caused by cosmic rays. This goes by the name "detrital cosmogenic nuclide erosion rates".
Presumably fewer changes mean faster erosion. The longer the sand is on the surface the more cosmogenic nuclides and slower erosion.
It is thought that erosion rates are roughly equal to uplift rates as the landscapes are thought to be in equilibrium.
The papers quantify how rainfall affects erosion rates in rugged terrain. And that tectonic activity is affected by rainfall!
The geomorphology i was taught was a descriptive subject. Reading this paper shows thait has changed! But you still get to go to interesting places.
Many organisations have been holding "Virtual Meetings", mostly quite successfully. But I came across THIS REPORT in the Guardian which tells of a less satisfactory event.
Apparently the organisers for the US-based Society of Vertebrate Paleontology used a filter which rejected certain words considered unsuitable. The words suppressed might be unsuitable in many circumstances but not when discussing ancient life.
Not wishing to shock my readership I will not repeat the naughty words - those of you of sufficiently strong minds can read the article. And NO giggling!
A correspondent brought THIS ARTICLE to my attention. It gives a very readable introduction to the rather unusual limnology of Lake Kivu, on the border between Rwanda and the Democratic Republic of the Congo.
The lake is large and the water is stratified. The surface water (the uppermost 60m) is normal. The rest (down to 460m) is full of carbon dioxide and methane, coming from hot springs in the bottom of the lake. And the two layers do not mix.
The unusual separation of layers of the lake is at the core of its volatility (Credit: D Bouffard & A Wuest/AR Fluid Mechanics 2019/Knowable Magazine)
There was a similar situation at Lake Nyos in Cameroon. There was little or no methane here but in 1986 the CO₂ was released (by a landslide) and 1,800 people suffocated. This is unlikely to happen at Lake Kivu, but the lake is constantly monitored.
But lately the methane is being exploited as a fuel source to generate electricity - something which is badly needed in the area.
The article gives you far more information than I have - well worth reading!
The following article has been republished from The Conversation. A link to the original can be found at the bottom of the page.
Do you like this means of quoting the article? - let me know.
Two Bristol researchers used X-rays from synchrotron sources to count the growth rings of fossil teeth of early mammals from South Wales to gauge their ages and blood flow. And discovered that they were between reptile and modern mammal ranges.
Did warm bloodedness come later?
AND a correspondent has brought THIS RELATED article to my attention - Thank You!
Fossilised teeth reveal first mammals were far from warm blooded
Warm blood is one of the key traits that led to the success of mammals as they evolved from scurrying beneath the feet of dinosaurs to spreading into the wild and wonderful collection of animals we know today. But our new research, which involved X-ray scanning hundreds of fossilised teeth, suggests the first mammals were more like cold blooded reptiles, and that warm blood evolved much later.
Warm blood helps us maintain our body temperature regardless of our environment, allowing us to gather food at night and in cold climates, and helps us stay active for longer than our cold blooded relatives. However, exactly when, why, and how this evolved is still poorly understood.
We know from tiny fossils of bones and teeth that mammals first evolved over 200 million years ago, and had many of the traits we associate with mammals, such as specialised chewing teeth and bigger brains. But the physiologies (how an animal’s body works day-to-day) of these animals is difficult to estimate using traditional methods, as this relates to soft organs that aren’t usually fossilised.
Our new research, published in Nature Communications, now offers a glimpse into the physiologies of the first mammals, by pioneering X-ray imaging to count growth rings in their teeth and measure blood flow through their bones. Although it had previously been assumed that even the earliest mammals were warm blooded, this research suggests that they still had some way to go before developing warm blood and its benefits that we enjoy today.
Long lifespans and slow metabolism
Working with a 20-strong international team of scientists, we have estimated the lifespans of the earliest mammals for the first time. This was done by X-ray scanning hundreds of fossilised teeth found in south Wales of two tiny mammals, Morganucodon and Kuehneotherium, from the Early Jurassic epoch.
High-resolution scans performed at powerful “synchrotron” X-ray sources in Switzerland and France allowed us to count annual growth lines preserved in the fossilised cementum of these teeth. Cementum is the little-known tissue that anchors mammal tooth roots to the jaw, recording every year of an animal’s life by growth lines that can be counted like tree rings to estimate lifespan.
X-ray image of tooth cementum from Morganucodon revealing growth rings.University of Bristol, Author provided
These lines are counted in living mammals by grinding teeth down into thin sections that can be studied using microscopes. As this destroys the tooth, we could not do this with precious museum fossils, and so we used X-ray imaging. Counting rings in our fossil mammal teeth gave a lifespan of 14 years for Morganucodon, and nine years for Kuehneotherium.
These are significantly, and surprisingly, longer lifespans than those of similar, shrew-sized mammals living today whose wild lifespans rarely exceed two to three years. This suggests a dramatically slower metabolism, or pace of life, than living mammals, and instead more closely resembles that of living reptiles.
Low activity levels
The size of the openings for the major blood vessels running through an animal’s limb bones is known to be proportionate to the levels of sustained activity (such as hunting and foraging) that they are capable of: smaller size suggests lower activity levels.
When we measured this in the femur of Morganucodon, we found that, while smaller than living mammals, they were also higher than those of living reptiles. This suggests that early mammals had an intermediate ability for sustained activity, between warm blooded mammals and cold blooded reptiles.
University of Bristol
This combined approach of studying the lifespans and activity levels of early mammals provides the first direct window onto several aspects of how they lived. We can see that our earliest relatives kept a much slower pace of life, but had definitely started on the road to the active lifestyles of living mammals today.
We shall continue these studies through the early mammal fossil record, to shed light on the first steps towards the modern mammalian lifestyle, and when we truly became warm blooded.
A correspondent has brought THIS PAPER to my attention. We used to think that the Alps were built by the Adriatic plate pushing against the Eurasian one, pushing lots of stuff to create the mountains.
But the seismicity of the Alps is characteristic of expansion, not of the compression that you would expect. The paper tries to explain this and other phenomena.
The explanation given that, as the Adriatic plate, especially the continental part abutted the Eurasian plate (30 Ma ago), the upper, lighter, crust of Eurasia, separated from the lower, denser mantle. Being lighter it surged upwards (no doubt, at a suitably stately pace) to form the Alps.
The sinking of the lithosphere sucks the Adriatic plate northwards.
Reading the article may help to understand it - I am struggling with it. Where do these wonderful nappes come in?
The Journal article may help but you need some form of subscription to access. THIS gives the abstract. But a "high-resolution, rheologically consistent, two-dimensional visco-elasto-plastic thermo-mechanical numerical model" seems a bit above my pay grade!
THIS ARTICLE gives an interesting perspective on genetics. It is well known that most of us have some fragments of Neanderthal DNA in our genome. This happened when Anatomically Modern Humans (AMH) left Africa and interbred with Neanderthals in Eurasia. A few Neanderthals went the other way but most Africans have very little Neanderthal DNA.
Fast-forward a few millennia and Covid-19 arrived. And it was found that if you had a section of code on chromosome-3 you were more likely to have a severe (unfortunately often fatal) reaction to COVID. And this section of code is very similar to that in the Neanderthal genome!
Professor Maurice Tucker has sent me a PAPER ON VIRUSES which he recently published in "Geology Today" which is very interesting - in several ways!
We are all suffering, directly or indirectly, from the coronavirus. If you want a good introduction to what a virus is, Professor Tuckers paper is a good place to start.
The numbers of viruses in almost anything are phenomenal. A normal size person may have tens of trillions of bacteria in their body, but there may be ten viruses for every bacteria. But they are much smaller. You may have 200 grams of bacteria in your body, but the much larger numbers of viruses may weigh less than 10 grams.
The only way to see a virus is with an electron microscope. So your hand lens will not be of much use to find a fossilised virus. The paper has electron microscope pictures of modern viruses being fossilised. It seems that they can become nuclei for minerals to form around, destroying their shape.
Transmission Electron Microscope (TEM) images from a biofilm showing silica nanoparticles with cores of virus-like particles and solid silica nanoparticles within a bacterial cell (a) and close-up (b), from a hot spring in China. (Images courtesy of Xiaotong Peng, Chinese Academy of Sciences, Sanya, China.)
There is lots of good stuff in the article, including a discussion on the origin of viruses and of life itself. A rewarding read!
Mike Benton of Bristol University wrote THIS ARTICLE last week. So, rather belatedly, it appears here.
The extinction event was rather difficult to recognise. We knew of 5 such events - now we have 6. It happened 233million years ago, in the middle of the Triassic, and is called the Carnian Pluvial Episode (CPE) and seems to have killed off as many species as the asteroid at the end of the Cretaceous.
The ending of the tetrapods left a space which the dinosaurs filled for the next 165million years.
A timeline of mass extinction events. D. Bonadonna/MUSE, Trento, Author provided
The CPE was first noticed in Europe, to which, it was thought to be restricted. Then its time correlation with the eruption of the Wrangellia basalts was noticed. I had not noticed the concept of Wrangellia until now, but it seems to be one of the terranes welded onto the west coast of North America.
The Wrangellian eruptions led to acid rain - it is a Pluvial event! - which acidified the oceans and cleaned off the land surface. When the eruptions stopped so did the rain but temperatures remained high - dinosaur weather!
The effects in the oceans were great. Before the CPE carbonates in the oceans came from microbes. After it was coral reefs and plankton.
this week I found THIS ARTICLE on the Earth-logs blog. It is based on THIS PAPER. It was thought that the carbon came from subducted sedimentary rocks. Then we thought of the basalts in the oceanic crust. Their reaction with aqueous fluids results in carbonates.
Current research uses the isotopic chemistry of carbon and nitrogen in the diamonds and the tiny silicate minerals included in them. Most of these are garnets. From the studies the depth of formation can be indicated and this can help determine the carbon source.
And it seems that the oceanic basalts are the favoured source.
But VERY deep diamonds - formed below 660km - may be different. The isotopes suggest that the carbon source is within the mantle and ultimately the stellar dust that accreted to form the earth. But at that depth the carbon is incorporated in metals and carbides. The authors suggest that subducted slabs, reaching that depth, release watery fluids which mobilise the trapped carbon and allow the formation of diamond.
Diamond crystal containing a garnet and other inclusions (Credit: Stephen Richardson, University of Cape Town, South Africa)
A correspondent brought THIS ARTICLE to my attention.
Lystrosaurus is the creature which survived the end-Permian mass extinction. In the Triassic they were found all over Gondwanaland. The specimens used in this study came from what is now Antarctica and South Africa. In Triassic times Antarctica was within the Antarctic Circle, South Africa outside it.
Lystrosaurus is characterised by having tusks, which like elephants tusks, grow throughout their lives. And they have growth rings. The South African specimens have regularly spaced rings, the Antarctic ones have the same but also closely-spaced, thick rings.
a A cross-section of Antarctic specimen UWBM 118025 with a “hibernation zone” highlighted at a higher magnification. Scale bars = 1000 μm. b Well-preserved regular incremental growth marks from the South African specimen UWBM 118028, lacking “hibernation zones”. Arrows denote individual lines with an average spacing of 16–20 μm. Scale bar = 100 μm.
The authors argue that this indicates the Antarctic creatures were hibernating - or something very like it. Which is not really surprising but nice to have some evidence for it.
By chance I came across THIS STORY in the Siberian Times. it seems, that with global warming methane is being released by the permafrost, often with spectacular results.
The new funnel filmed from air by the team of Yamal-based TV station. Picture from July 2020 by Vesti Yamal. Note the figures for scale.
The other pictures in the article are equally spectacular.
This is a rather worrying development. Methane is a more powerful greenhouse gas than carbon dioxide and there is believed to be vast quantities of it captured in the permafrost. If it continues to be released it will trigger a vicious circle.
A correspondent has brought THIS ARTICLE to my notice. It tells of how the genetic material of the tuatara was collected, in collaboration with the iconic species Maori guardians. Without their cooperation the material could not have been gathered.
The genome is 50% larger than the human genome and is one of the largest ever published. One purpose was to reconstruct the creatures evolutionary tree.
A tuatara in New Zealand. Credit: Pete Oxford/NPL
And here is its evolutionary tree - the simple version.
Refining the evolutionary tree for reptiles, birds and mammals. This phylogenetic tree includes six branches: mammals and five branches within a clade called sauropsids, which comprises reptiles and birds. One of these, the Rhynchocephalia, has only one living member, the tuatara. Gemmell and colleagues date the divergence of the Rhynchocephalia from the Squamata to about 250 million years (Myr) ago
a, The tuatara, (S. punctatus) is the sole survivor of the order Rhynchocephalia. b, c, The rhynchocephalians appear to have originated in the early Mesozoic period (about 250–240 million years ago (Ma)) and were common, speciose and globally distributed for much of that era. The geographical range of the rhynchocephalians progressively contracted after the Early Jurassic epoch (about 200–175 Ma); the most recent fossil record outside of New Zealand is from Argentina in the Late Cretaceous epoch (about 70 Ma). c, The last bastions of the rhynchocephalians are 32 islands off the coast of New Zealand, which have recently been augmented by the establishment of about 10 new island or mainland sanctuary populations using translocations. The current global population is estimated to be around 100,000 individuals. Rhynchocephalian and tuatara fossil localities are redrawn and adapted from ref. 1 with permission, and incorporate data from ref. 2. In the global distribution map (c, top); triangle = Triassic; square = Jurassic; circle = Cretaceous; and diamond = Palaeocene. In the map of the New Zealand distribution (c, bottom); asterisk = Miocene; cross = Pleistocene; circle = Holocene; blue triangle = extant population; and orange triangle = population investigated in this study. Scale bar, 200 km. Photograph credit, F. Lanting.
The papers are interesting as they give an insight into modern biology.
