Friday, 26 October 2012

Blown away by Sandy...but the fossils are fine!

Forgive the lack of blogs these past few days, but I am en-route back to Manchester...via a very windy route. You can imagine my joy when I logged into Weather Underground to see this....

...the awfully nice folks at Weather Underground have allowed me to use this image. All I can say, the image is much prettier than the look on my face, when I found that my flight path was taking through the inner bands of Hurricane Sandy. Thankfully, I am now sat in Washington DC, awaiting my flight for Manchester...not feeling too hungry after a rather lumpy flight. I clutched my precious fossils tight to my chest, as I have promised a few colleagues back home some samples from my new locality...hmmmm, methinks I forgot to mention this new locality in my blogs? Oh well, I had better work on the fossils first and then tell you the full story at a later date. Sorry, but that is how it has to be....but patience is something any budding palaeontologist is more than used to.

Monday, 22 October 2012

Grand Cayman Blue Iguana: A success story in conservation

When was the last time that you heard some sad news about an endangered species and a little piece inside of you quietly wept. That helpless feeling that so often fills you with sadness that another species is going the same way of the dinosaurs. Not so the Blue Iguana. Here is a conservation tale that will hopefully leave you with a little warm glow of success inside. This is the tale of a species that stared extinction square in the face and delivered a salty-sneeze at its doom....with the splendid help of the Blue Iguana Recovery Program (Grand Cayman) (BIRP). This priceless band of eco-warriors have turned the tide for a whole species. Meeting such folks is a humbling experience...but I was lucky to find myself in their hallowed halls (well...enclosures) in the last few days.

The Blue Iguana (Cyclura lewisi) is a breathtakingly beautiful blue beastie... one that the awfully nice folks at BIRP have teased back from the brink of extinction. This was a species that was critically endangered, but is now merely endangered (honest... this is a very good thing!). The population teetered on the brink of extinction only a handful of years ago, with a mere 100 or so individuals left on their number exceeds 1000. The folks at the BIRP know a thing of two about what makes their precious charges breed. More importantly, they have carefully constructed a program that ensure genetic diversity and strength ...a case of watching/controlling who breeds with who! In the case of this species, if you breed with someone too close to the family, your offspring will be infertile...not good for any species, especially one starring into the abyss of extinction.

These beautiful blue blighters struggle on the reproduction front, when compared to their Green Iguana (Iguana iguana) cousins who produce larger egg clutches at least three times a year, compared to the solitary or few eggs produced by the Blue. It must be said that they do get better at producing eggs when they get older, terms of competition for space and food, the Green's win.

However, the Blue Iguana still has something to smile about. With the committed work of the BIRP, this species has recovered its numbers and is ready to go wild again. This is the most incredible facet of this conservation is so rare that a conservation program is so successful that it has to evolve or become extinct. In this rare, but oh so satisfying, moment in the conservation of this species, the BIRP team is looking to change its spots to become managers of a wild population, as opposed to one that has to bump-up numbers. The story of the Blue Iguana is far from over, as there is this interesting transition from breeding in captivity to management of a species in the wild...I dock my hat to the wonderful folks at BIRP for achieving what so many have tried to do..but who have so miserably failed. Methinks there is a trick or two we should learn from this team of interpreted conservation stars!

Thursday, 18 October 2012

Green Iguana or Blue Iguana...that is the question?

Dinosaurs were successful…very, very, very successful. They formed one of the most diverse terrestrial beasties with a backbone to have walked on Earth. There were few ecological niches that they did not thrive in during the Mesozoic era (otherwise known as the ‘Age of Reptiles’. Their ‘piggy-in-the-middle’ position between reptiles (crocodilians, etc.) and birds has made resulted in a great deal of interest in the biology of this group. There has been much debate concerning the metabolism of this group, often resulting in scientists getting a tad hot under the collar!

It is quite clear that “cold-blooded” reptiles and “warm-blooded” mammals are quite different in many ways; both modern groups are likely to differ greatly from their dinosaurian relatives. Lucky for us, the same physical laws apply to all land animals and the physical building blocks (biomaterials) used by dinosaurs are almost certainly relatively conservative in composition when compared to their living relatives. These laws that have built, controlled and honed the bodies of living and extinct animals controls certain distinct characters that dinosaurs might have possessed….this helps us reconstruct these long extinct beasties.

Given half a chance, you will fund many palaeontologists chasing living beasties that form one or the other side of this evolutionary ‘bracket’ that provides the missing pieces of information to help us reconstruct dinosaurs. This week, I have been lucky enough to observe a rather large terrestrial (land-based) reptile…the Iguana….in my own attempts at understanding more about the physiology and behavior of living reptiles. As an aside, it was the teeth of the living Iguana that helped Gideon Mantell come-up with a name for his Lower Cretaceous Iguanodon (literally, ‘Iguana tooth’), based solely upon their similarity in tooth morphology (shape). This was the 2nd dinosaur to be named in 1825 a year after Buckland had described Megalosaurus. So, you can imagine my excitement for getting to see Iguana in the field!

The Cyaman Brac Iguana (Cyclura nubila caymanensis) you see in these images are all from Cayman Brac Island (not surprising)…as I have yet to see the famous and despicably endangered Blue Iguana (Cyclura lewisi) of Grand Cayman. I hope to see my first Blue Iguana this weekend…damn exciting!

A fun thing to note with the Iguana is the typical reptilian sprawl of their limbs. This has been used by some to suggest that dinosaurs (with their more upright 'mammalian-type' limbs) were very different when it came to metabolism....oops...I must run to give a lecture. I must finish this thought later!

Wednesday, 17 October 2012

Caves, humidity, bugs and beasties

My arms and legs look like successful taget practice for the bug and mosquito bite-fest that was seemingly taking place in Cayman Brac. My blood is clearly the preferred diet of beasties as my colleagues appear much so, I am now considered the best insect repellent to have along in the field. Trying to avoid bugs, we started to explore some of the subterranean lairs of the 'Brac'...with our splendid local guide, TJ. As we climbed the relatively sheer wall of the Brac, it was clear there were dark recesses lurking in some of the karst limestone. This was where we were now headed.

As we climbed higher up the sheer wall of the Brac, we could finally see the ocean again as we topped-out over the canopy that cloaked the base of the cliff. TJ then disappeared ...into a hole in the wall (Alice in Wonderland style!), just large enough to scramble inside on your belly. Looking back over our shoulders  all you could see was the bright light of day, however the direction of travel was rather dimmer...

This was no tourist attraction, but a cave that had only been visited a few times by TJ and very few others. In terms of caving, you rarely get a chance to tread where only a few have trodden...humans that is! All we had to light our way were a few flashlights that our friendly guide had brought along. Every now and then TJ would call back offer say helpful advice, like..'This is a tight might have to breathe in a bit' or 'This is a great entrane, I got stuck here for half an hour last time...till I could free myself!'...I looked at TJ's stature and realised I was approximately twice his body mass and circumference...this was going to be a fun and rather tight subterranean trip!

As we pushed deeper into the limestone caverns, I could see we were travelling back in time though a coral reef system that was once teeming with life. The fossil evidence of corals and shells was all around us. We were literally walking on shells...albeit fossil ones. I have to admit, that crawling on my belly in the pitch-black, in what seemed 100% humidity and 35 Celsius not usually my idea of fun...but then a cavern or two would open-up and make the trip so worth while....

The caverns and tunnels have been etched away through the action of ground waters over the past few thousands of years, fuelled by slightly acidic rain and the organic rich soils that cap the whole of the Brac...courtesy of all that vegetation. This was one of many sites that TJ kindly extruded our bodies to see though the sharp, karst limestone...but I also promised you some animals of the Brac...this will be my next it is some of these animals that might hold clues into dinosaur physiology.

Monday, 15 October 2012

Fossilised giant that replays ancient sea-levels

This weekend I visited Cayman Brac, a small island a mere 90 miles northeast of Grand Cayman. One of the largest fossil structures that can exist on a continent is preserved here on these azure shores. This is no giant sauropod or bleached bones of an enormous whale, but the echo of an ancient shoreline. Yes, a beach can become a fossil, if you know where to look!

The island, like the rest of the Cayman Islands, is there due to the same submarine ridge that forms the carbonate backbone of these coral-aproned islands. The first thing that you notice about the 'Brac' (a gaelic word for bluff) is the relatively high and sheer limestone cliffs that hoists the main portion of the island ~100 feet above sea level.

As you stand on the road that follows the southern shore of the island, you cannot help but notice the land-shapes or geomorphology. Facing west along the line of the Brac, you stand on what is clearly an almost level surface that gently dips to the south by a few degrees into the beach area and tidal zone.  Facing north, you are met with an almost sheer cliff of the Brac, that runs from east to west, that meets the platform on which you are stood at a sharp 90 degree angle. The base of the cliffs are hidden by dense vegetation, that you have to scramble through to see a geomorphological feature that has a curious explanation. When you reach the cliff base, you see there is a concave notch, seemingly cut-out from the base of the cliff, that runs the whole length of the Brac...both north and south facing walls.

To understand what this feature represents, you only have to walk towards the present-day shoreline of Cayman Brac and watch the waves pound the limestone shoreline. The constant wave action slowly carves a neet concave ridge, just above the gentle slope of the wave-cut platform that allows the waves to continuously roll in from the Caribbean Sea. The feature that so defines this high wall of the Brac, is simply a function of wave action from an earlier time, when sea-level was higher than present day. Around 120,000 years ago the globe was a tad warmer and was basking in the sun of a interglacial phase...literally 'between ice'. The water that was not locked-up in ice-caps caused a global rise in sea-level of a few metres, raising the ancient wave-action to cut the notch at the base of the Brac....what we see today. The subsequent glacial phase, in which we still live, resulted in a global fall in sea-level...stranding the wave-cut platform and distinctive notch as a vast, fossil beach....even a beach can become a fossil...and you too can find them where ever you are around the world, you just have to know what you are looking for!

My next blog will explore the caves and wildlife of Cayman Brac.

Friday, 12 October 2012

Past forward: Mangroves, reefs and Archaeopteryx?

The present can be a key to the past. This is something that the 18th Century Scottish Geologist James Hutton raised when viewing the surficial processes that have sculpted the land-shapes of the United Kingdom. This idea was refined and liberally applied by the famous 19th Century geologist Charles Lyell whose pivotal book, Principles of Geology, accompanied a young Charles Darwin on his voyage of discovery. This basic assumption that many palaeontologists apply to the fossil record relies on the uniformity of natural and physical laws that have governed our planet in both the past and present. This principle of 'uniformitarianism' often drive my colleagues and I to study the tissues, behavior, environments and ecology of living species, so that we may better understand the same in extinct organisms.

This week, I find myself on Grand Cayman…I just pinched myself…and yes, I am still sat on Grand Cayman. I am here to explore some of the most pristine carbonate environments in this corner of the world, so that I might better understand similar environments that I often sample from the fossil record. The submarine ridge that supports the Cayman Islands defines its geology, topography, as well as the rich environments that support a diverse flora and fauna. The carbonate shelf that fringes the islands support prolific coral reef communities while the lagoons and mangrove swamps inland support a vibrant terrestrial community. It is times like this that I realize how little we have to work with when reconstructing ancient communities, of which a fossil assemblage only represents but a fraction of the extinct ecosystem.

Stingrays at Stingray City (Grand Cayman) Image courtesy of Jim 'Rayman' Gobetz

The geological record of life also has a nasty habit of time-averaging samples, so that a fossil assemblage might represent hundreds or even thousands of years, albeit in a single unit of lithified sediment (rock). At the same time, the subtle variation in species and their distribution through time and space can be blurred due to the cumulative affects of taphonomic processes acting upon and concentrating, filtering and/or refining a fossil assemblage…all this and more adding to the difficulties of unpicking the past for palaeontologists. Hopefully, my wading through lagoons, swimming with stingrays, trekking through mangrove swamps and diving into reef systems will provide me with some new insights on this particular fraction of life on Earth…and not a dinosaur in sight! However, I am VERY keen to see if a seabird manages to meet a sticky end in one of the back-bay hypersaline lagoons…maybe a gentle echo of similar environments and taphonomic processes that preserved its distant Jurassic ancestor Archaeopteryx. I am sure that James Hutton would approve.