cafecuriosity

Window On A Green Sahara

Much of the commentary on the booming Gulf economies centers on speculation of how sustainable it all is. Just how precarious human existence can be, was illustrated last month when National Geographic published details of its spectacular discovery of the largest Stone Age graveyard yet found in the Sahara. The site named Gabero lies in Niger, beside a dried out lake and dates back over 10,000 years. It contains the remains of two very different civilizations - the Kiffian and the Tenerian, cultures separated by more than 1,000 years. Over two hundred graves were found, together with stone tools, beads, harpoon points, fishhooks and potsherds and skeletons of elephants, giraffes, warthogs, pythons, crocodiles, hartebeests and the imposing 6 foot long Nile perch. Now the Sahara has been desert for quite some time, so how did a lake suddenly appear in the Tuareg's Tenere Desert? Twelve thousand years ago, the Earth's orbit wobbled slightly, shifting Africa's wet season north. Rain and floods caused the desert to bloom. Lakes formed, attracting the Kiffian, animals and fish. The wobble eventually smoothed itself out returning the Tenere's arid climate, before repeating itself rather less vigorously 1,000 years later, enabling the Tenere to eke a living from the region's shallower lakes. Whether historically high oil prices will prove to be the Emirates equivalent of the orbital 'wobble' remains to be seen. History however is replete with desert civilizations which bloomed before being swallowed once more by the desert's shifting sands.

PS. The graveyard was discovered by accident by members of an expedition hunting serendipity headed by University of Chicago Professor Paul Sereno!  http://news.nationalgeographic.com/news/2008/08/080814-sereno-sahara-missions.html  Image: Expedition highlight, the stunning triple burial comprising a woman entangled with two children, National Geographic

Oops It Was Us (47,000 Years Ago)

It is amazing how serendipity can re-shape scientific theory. After decades of arguing over whether human hunting or climate change was responsible for driving the world's megafawna into extinction, one island bobbed literally in the eye of the hurricane. Tasmania once boasted a thriving zoo of marsupials resembling; leopards, rhinos, ground sloths, and a brace of short and long-faced kangaroos that browsed the lush vegetation like antelopes. Humans had been absolved of culpability for their demise mainly because the megafawna was thought to have died out before hunters were able to cross the land bridge from mainland Australia (approx 43,000 years ago). No longer! A group of cavers exploring a network of caves under Mt Cripps in north-west Tasmania stumbled serendipitously over skeletons of Tasmania's megafawna species. Alas, these remains showed some species were wandering Tasmania's misty forests 2,000 years after human hunters found their way onto the island. Given the climate was relatively stable around that time, human over-hunting has been fingered for their demise. 

PS. It's all Darwin's fault! Ever since Darwin discovered the remains of giant sloths in South America in the 1830's, debate has raged over whether human hunting or climate change was the driving force behind the mass extinctions.

http://www.exeter.ac.uk/news/newsprehistoric.shtml   Image: 1. Artist's reconstruction of Palorchestes azael, a ground sloth like marsupial weighing 500 kg, University of Exeter, 2. Skull of Palorchestes azael, University of Exeter 

Beyond Bones

One of the most evocative scenes from 'Walking With Dinosaurs' was the image of a giant pterosaur snatching unsuspecting fish on the wing. It was a stereotype that took hold in the popular imagination. Now it seems not all these big lugs skimmed over the heads of dinosaurs 230 to 65 million years ago. Like Africa's secretary bird and the European stork, some stalked their prey on foot. The azhdarchids a branch of the pterosaur family were particularly suited to like on the hoof. Most of their fossils come from land sediments far from the shallow seas pterosaurs usually depicted in and these fossils feature small feet, long limbs and long toothless bills. They also had long stiff necks not well suited to snatching food while airborne but perfect for grabbing ground dwelling prey. Azhdarchids were first discovered in the 1970's. They were distinguished by 10 metre+ wingspans with the biggest being able to look a giraffe in the eye! So much for stereotypes!

Another preconception in the fossil world held that woolly mammoths were one homogenous group. Mitochondrial DNA suggested there were two groups of the ancient beasts, one died out 45,000 years ago long before man made an appearance. The study suggested the two groups diverged more than 1 million years ago. Prior examination of the fossil record hadn't suggested this relationship. A further curiosity concerned the source of the DNA samples comprising the study. One was taken from the Adams mammoth discovered in 1799 and stored at room temperature for 200 years! Bizarrely, we now know more about the woolly mammoth than we do about the mitochondrial genomes of the Indian and African elephants!   

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0002271   http://live.psu.edu/story/31284   Image: 1. A group of Quetzalcoatlus a type of giant azhdarchid, Mark Walton, 2. Partially frozen mammoth remains, Mammuthus Khatanga/Tom Gilbert, 3. Woolly mammoth, Ice Age Museum, Moscow.

Australian Fossils Take the Stage

Diprotodon is my kind of Pleistocene megafauna. Picture a 2.5 tonne, 1.8 m tall wombat spread from the islands of Bass Straight to Far North Queensland and across to Western Australia. Conventional wisdom recognizedeight distinct species of Diprotodon which came in a bewildering range of sizes. It turns out however that male Diprotodons liked their girls big! University of Queensland researchers discovered Diprotodon females were two-thirds the size of their men folk! Moreover rather than those eight species, there were only one with the previous differences being explained simply by the size difference between the sexes!

Further south, Museum Victoria researchers found the world's oldest mother and baby. The placoderm fish fossil clearly shows the embryo attached to its mother by its umbilical cord. This discovery pushes back the date of a live birth by 200 million years. Found at the Gogo fossil site in Fitzroy Crossing in the Kimberley, the specimen dates back 380 million years, has exceptional detail and fittingly has been named Materpiscis attenboroughi after Sir David Attenborough who featured the Gogo fish site in his ground-breaking 'Life on Earth' series.

http://www.uq.edu.au/news/index.html?article=14933   http://museumvictoria.com.au/About/MV-News/2008/Mother-fish/   Image: 1. Dr Price & Diprotodon fragments, University of Queensland, 2. Placoderm gives birth, Museum Victoria

Continuity Suggests New Stonehenge Insights

Few civilisations spring fully formed from the earth. Most represent either a continuation of existing an civilisation or a reactive break with tradition. Nowhere is this better illustrated than at the iconic Stonehenge. Once thought to be an evocative representation of a single idea, Stonehenge is now seen as either a development of a dominant culture or as a series of evolutionary changes. Approximately 500 metres north of Stonehenge is a feature known as the Cursus. Discovered in 1723 it is 100 metres wide and runs for about a mile. Carbon dating by the University of Manchester of an antler pick used to dig the Circus revealed a sensational date of 3,500 years BC - 500 years older than Stonehenge. It now appears Stonehenge was built within an existing complex of standing monuments, including the Cursus.

Further evidence of the cultural continuity as a driving power behind Stonehenge emerged when University of Sheffield archaeologists radiocarbon dated remains from human cremation burials. The burials tested were excavated in the 1950s but had never been sampled. The dates showed the site around Stonehenge had been in continuous use from 3,000 BC to after the sarsen stones were erected in 2,500 BC. The burials are initially few in number, expanding in later decades. Archaeologists now speculate Stonehenge was erected by ancient chiefs and became the internment site for them and their family. Stonehenge has been a special place for 500 years, remaining vibrant due to the relationship links associated with the site. Continuity saw the site itself remain in use while the manifestation of that usage morphed.

http://www.manchester.ac.uk/aboutus/news/display/?id=3719   http://www.shef.ac.uk/mediacentre/2008/1024.html   Image: Recently discovered antler pick used to dig the Circus, University of Manchester, 2. Excavation site, University of Manchester, 3. Stonehenge, Clint Scholtz

Fossil Frolics

Yemen made the news this week - with not an AK47 in sight, with the announcement of the discovery of Arabia's first dinosaur trackway. Dating back 150 million years to the Late Jurassic - Early Cretaceous, the trackway preserved footprints from a large ornithopod dinosaur and 11 sauropods traveling together. Spotted by a Yemeni journalist in 2003, 50 km north of the capital Sana'a, the tracks were categorized in 2006. The find took a while to work through our labyrinthine scientific publication process - so much for the knowledge superhighway! You'd think a dinosaur trackway would be easy to spot but the surprisingly, the imprints are too big to be easily discerned with the eye especially when obscured by dirt and debris. The family tracks provide an interesting snapshot of dinosaur flocking behaviour. Very few fossils have been found in Arabia so this discovery hints of more to come!

The Norwegian Blue (of Monty Python fame) jokes flew thick and fast when paleontologists discovered a 55 million year old parrot fossil on the Isle of Mors in Denmark. The Danish Blue, Mopsitta tanta isn't exactly over described given paleontologists unearthed only a single upper wing bone. However this was sufficient for them to give it a name and in the process turn established thinking about the origins of parrots upside down (literally)! The oldest Southern Hemisphere parrot fossil dates to around 15 million years ago, so the thinking now is that the first parrots evolved in the north before later spreading out across the southern tropics. Mopsitta is the oldest and most northern parrot fossil ever found and comes a period when Northern Europe was warm and a shallow tropical lagoon blanketed Germany Southern England and Denmark. 

http://www.plosone.org/doi/pone.0002243   http://www.ircset.ie/news/releases/080515.html   

Image: 1. Ornithopod trackway in Yemen, Nancy Stevens, 2. Artist impression of Mopsitta tanta, Dr David Waterhouse, 3. Mopsitta tanta outline, Dr David Waterhouse, 4. Mopsitta humerus, Dr David Waterhouse,

Putting the Bite On Old Bones

One of the criteria for a PhD is that the research topic should add to science's knowledge base. Not easy when you consider the knowledge explosion. Insects are one of the most abundant life forms on the planet, yet we know little about their evolution thanks to a scanty fossil record. One the other hand, we have a lot of dinosaur bones may with missing bits. Put the two together, add a bit of ingenuity and you have a unique area of research as three Brigham Young researchers discovered. Prof Brooks Britt noticed interesting marks on bones he was studying as an undergraduate. A couple of years later, he teamed up with two other researchers to take another look at what put the bite on 148 year old Camptosaurus bones found in 1995 at Medicine Bow, Wyoming. The culprit proved to be a family of beetles called Dermestidae. Proving that required a combination of molding materials borrowed from their local dentist and an electron microscope capable of providing close ups of the mandibles from bone munching moths, termites, mayflies and dermestid beetles. Trawling through 7,000 fossilised bones showed insect traces to be surprisingly common but only the Camptosaurus showed traces of the dermestid beetles. The research provided new insights into Medicine Bow's local climate (warmer and more humid) at the time of Camptosaurus' demise, and pushing back the dermestid fossil trace record by 48 million years while they were about it!

http://byunews.byu.edu/archive08-MAY-dinobugs.aspx   Image: 1. Mark Britt with Camptosaurus bone, Mark A. Philbrick/Brigham Young University, 2. Groove seen on the tip ofthis verebrae was excavated by dermestid beetle larvae, Mark A. Philbrick/Brigham Young University, 3. Pit excavated by the mandibles of a dermestid beetle, Mark A. Philbrick/Brigham Young University

Sometimes Knowledge Takes Awhile

Today, we often think of knowledge as emerging in real time - we rarely associate patience with knowledge creation. Yet in many fields, discoveries can take years to develop. Paleontology is one of my favourite fields of discovery. Recently, paleontologists unveiled six new bat species, representing 33 specimens dating back 35 million year - the results of 25 years of painstaking fieldwork. Few bat fossils have been found in Africa so these specimens will change the accepted interpretations of bat evolution. Conventional wisdom (US centric) had bats evolving in the Northern hemisphere. This latest research indicates modern bats only diversified after first migrating out of Africa. New World bats apparently have ancient roots deep in the heart of the Old World!

For fifty years paleontologists have been 'robustly' debating, whether Pachycephalosaurs a sheep-sized dinosaur dating back 80 to 65 million years ago and found extensively in Canada, the U.S. and China could have butted heads during mating. Pachycephalosaurs are famous for their thick dome shaped heads. The rutting theory emerged are one explaination of Pachycephalosaur's peculiar heads. Now a researcher from University of Alberta has applied finite element analysis (see last week's Komodo dragon post) to simulate collisions amongst three Pachycephalosaur species. A combination of the Pachycephalosaur's thick domes (up to 20 cms) combined with sliding joints in their vertebrae enables nearly-adult Pachycephalosaurs to battle each other with minimal damage - at least in theory.

In the Andes, paleontologists endured thin air, limited water and freezing nights in Chucal, Chile to excavate a new species of armoured mammal. Three feet long and weighing 200 lbs, Parapropalaehoplophorus septentrionalis (try saying that late at night!) is small for glyptodont - an extinct relative of armadillos which could grow to the size of a small car and went extinct around the time humans arrived in the New World. Parapropalaehoplophorus septentrionalis is interesting because its many primitive features. At over 14,000 feet above sea level, Chucal itself is an unusual site. Parapropalaehoplophorus septentrionalis brings the number of new species discovered there up to 18, including armadillos, opossums, rodents, frogs and hoofed animals. 

http://www.vertpaleo.org/news/permalinks/2008/03/08/PRESS-RELEASE---Giant-Fossil-Bats-Out-of-Africa/   http://www.vertpaleo.org/news/permalinks/2008/01/22/PRESS-RELEASE---New-fossil-armored-mammal-from-the-high-peaks-of-Chile/   Image: 1. Reconstruction of Witwati schlosseri, Bonnie Miljour, 2. Pachycephalosaur fossil, www.paleodirect.com 3. Computer simulation of Pachycephalosaur, Chris Kriegner & Tetsuto Miyashita, 4. Reconstruction of Parapropalaehoplophorus septentrionalis , Velizar Simeonovski

Perceiving Patterns of Relationships

Seeing patterns others don't is a skill. Scientists often display this talent for making connections. For example, how do you illuminate the lifestyle of a 37 million year old ancestor of today's elephant when you only have fragments of a skeleton? For that matter, what would lead you to connect our modern pachyderm with an amphibious ancestor? As it turns out, the answer to question A is - you try analysing the isotopes in tooth enamel for evidence of diet and environment, which is only fair. Molecular DNA provided the answer to question B by showing a link between elephants and sea cows and dugongs. Moeritherium and Barytherium lived in the Eocene period. When carbon and oxygen isotopes from their teeth were compared to samples from terrestrial species from the same era, it suggested the animals were semi-aquatic. Pattern complete!

Given 2008 is the Year of the Frog, its appropriate to look back 70 million years to when a giant Madagascan frog dined on insects, lizards and maybe unlucky dinosaur hatchlings! Beelzebufo had a squat body, massive head and yawning mouth and resembled a squashed beach ball. Apart from being seriously gross, Beelzebufo isn't where it should be. Related to South American ceratophyrines, it poses then question of what a South American frog is doing on Madagascar - especially as Madagasgar's current frogs don't look anything like it. Frogs are notoriously poor at crossing large stretches of open water. The pattern suggests Gondwana may have drifted apart later than currently thought with a land link between Madagascar, South America and Antarctica.

http://www.ox.ac.uk/media/news_releases_for_journalists/080414.html   http://www.ucl.ac.uk/news/news-articles/0802/08021803   Image: 1. Moeritherium, Luci Betti-Nash, Stony Brook University, 2. Artist's impression of Beelzubufo

More on the Clovis People

Last week we explored the durability of the theories surrounding the migration of people into North and South America (The Persistence of Belief).  This week, further research was presented by a University of Oregon anthropologist pointing to America being settled by people of Siberian or East Asian origin at least 1,200 hundred tears before the Clovis people hove into view. Ironically enough, the evidence comes from analysis of mitochondrial DNA removed from coprolites (dried out human excrement) found is a series of caves. These finds represent the oldest human DNA yet found in America.

Clovis true believers were further beseiged when anthropologists from Texas A&M published a study fusing archaeological evidence, skeletal remains and molecular genetic studies into current and ancient populations. The study concluded the migration from Alaska started 15,000 years ago.

PS. An amateur archaeologist uncovered 28 flint handaxes in sand and gravel dredged up from the North Sea together with bones and teeth. The axes date back 100,000 years ago to the Paleolithic.

http://pmr.uoregon.edu/science-and-innovation/uo-research-news/research-news-2008/april/researchers-led-by-uo-archaeologist-find-pre-clovis-human-dna   http://tamunews.tamu.edu/archives/article.php?articleid=5920&month=3&year=2008   http://news.wessexarch.co.uk/2008/03/09/evidence-of-ice-age-hunters-found-below-north-sea/   Image: 1. Denis Jenkins in his lab with artifacts found in the Paisley Caves, University of Oregon, 2. Paleolithic Handaxe, Wessex Archaeology, 3. Marine Dredging operation, Wessex Archaeology