Paleontology

I lied about waiting for the X-47B to trap before posting another video. This is damned impressive.

This place is going to be Theropod Central for a bit (until the huge volume of ceratopsians kick in), so here’s an ankylosaur to keep things ticking over. As usual, enthralled though I was with the exhibitions, I didn’t pay that much attention to the various signs or details of some of what I was looking at. As a result I don’t know all the identifications exactly and when it comes to things like these guys, well it’s hardly my best subject either. Happily however, Victoria Arbour has just published a monster paper with Phil Currie on the taxonomy and identity of North American  ankylosaurs and is also furiously blogging about it. So hop on over to her blog and start reading up on them. Handily there’s guides to the various parts of the skulls and rings of armour on the neck too which will really help out here. So while I’m obviously being too lazy to look it up myself, I’ll claim I’m inspiring readers to learn how to do it themselves.

The Pliensbachian–Toarcian (Early Jurassic) extinction, a global multi-phased eventAuthors:1. Andrew H. Caruthers (a)2. Paul L. Smith (a)3. Darren R. Gröcke (b)Affiliations:a. Department of Earth Ocean and Atmospheric Sciences, University of British Columbia, Room 2020 Earth Sciences Building, 2207 Main Mall, Vancouver British Columbia V6T 1Z4, Canadab. Department of Earth Sciences, Durham University, South Road, Durham DH1 3LE, UKAbstract:During the Pliensbachian–Toarcian of Early Jurassic, there is a well-known second order marine extinction that is observable at the species and genus levels. Ammonite diversity data from successions throughout Europe and parts of the Arctic suggest that this extinction may have been multi-phased with diversity declining over six separate intervals. The main-phase of decline begins at the Pliensbachian–Toarcian boundary and extends into the Lower Toarcian, to a level that is correlative with the Tenuicostatum / Serpentinum Zone boundary. To date, only the main-phase of extinction has been demonstrated as being global in extent and affecting multiple taxonomic groups. This multi-phased extinction has been attributed to regional and global controlling mechanisms that are associated with the Volcanic Greenhouse Scenario which links the eruption of the Karoo–Ferrar large igneous province (LIP) to global warming and mass extinction.We compare stratigraphic ranges of ammonite and foraminiferal species in Pliensbachian–Toarcian successions of western North America to the record in Europe and parts of the Arctic in order to test the geographic extent of the multiple phases of extinction. Our results show six intervals of species level decline that correlate with those recognized in Europe: 1) middle of the Lower Pliensbachian (middle Whiteavesi–middle Freboldi Zones), 2) middle of the Upper Pliensbachian (upper Kunae–lower Carlottense Zone), 3) Pliensbachian / Toarcian boundary into the Lower Toarcian (upper Carlottense–middle Kanense Zones), 4) Middle Toarcian (upper Planulata–lower Crassicosta Zones), 5) upper Middle–lower Upper Toarcian (middle Crassicosta–Hillebrandti Zones) and 6) Upper Toarcian (lower Yakounensis Zone).Recognition of this multi-phased event in three separate ocean basins (paleo Pacific, paleo Arctic, and Tethys Oceans), in at least two taxonomic groups, greatly expands the known geographic extent of this multi-phased event and argues for a controlling mechanism that is global in its reach. In relation to the Volcanic Greenhouse Scenario, our study shows that four of the six pulses of extinction occur within the main-phase of Karoo magmatism. The decline in the Early Pliensbachian, previously thought to be separate from this event, occurs within error range of the onset of Karoo magmatism and the decline in the Late Toarcian coincides with the later stages of magmatism. These observations extend the known duration of this multi-phased extinction event to the Early Pliensbachian and support the Volcanic Greenhouse Scenario, specifically the eruption of the Karoo–Ferrar LIP, as a preeminent factor driving the multi-phased extinction of the Pliensbachian–Toarcian.

A new study shows how complex biochemical transformations may have been possible under conditions that existed when life began on the early Earth.The study shows that RNA is capable of catalyzing electron transfer under conditions similar to those of the early Earth. Because electron transfer, the moving of an electron from one chemical species to another, is involved in many biological processes – including photosynthesis, respiration and the reduction of RNA to DNA – the study's findings suggest that complex biochemical transformations may have been possible when life began.There is considerable evidence that the evolution of life passed through an early stage when RNA played a more central role, before DNA and coded proteins appeared. During that time, more than 3 billion years ago, the environment lacked oxygen but had an abundance of soluble iron."Our study shows that when RNA teams up with iron in an oxygen-free environment, RNA displays the powerful ability to catalyze single electron transfer, a process involved in the most sophisticated biochemistry, yet previously uncharacterized for RNA," said Loren Williams, a professor in the School of Chemistry and Biochemistry at the Georgia Institute of Technology.The results of the study were scheduled to be published online on May 19, 2013, in the journal Nature Chemistry. The study was sponsored by the NASA Astrobiology Institute, which established the Center for Ribosomal Origins and Evolution (Ribo Evo) at Georgia Tech.Free oxygen gas was almost nonexistent in the Earth's atmosphere more than 3 billion years ago. When free oxygen began entering the environment as a product of photosynthesis, it turned the earth's iron to rust, forming massive banded iron formations that are still mined today. The free oxygen produced by advanced organisms caused iron to be toxic, even though it was – and still is – a requirement for life. Williams believes the environmental transition caused a slow shift from the use of iron to magnesium for RNA binding, folding and catalysis.Williams and Georgia Tech School of Chemistry and Biochemistry postdoctoral fellow Chiaolong Hsiao used a standard peroxidase assay to detect electron transfer in solutions of RNA and either the iron ion, Fe2+, or magnesium ion, Mg2+. For 10 different types of RNA, the researchers observed catalysis of single electron transfer in the presence of iron and absence of oxygen. They found that two of the most abundant and ancient types of RNA, the 23S ribosomal RNA and transfer RNA, catalyzed electron transfer more efficiently than other types of RNA. However, none of the RNA and magnesium solutions catalyzed single electron transfer in the oxygen-free environment."Our findings suggest that the catalytic competence of RNA may have been greater in early Earth conditions than in present conditions, and our experiments may have revived a latent function of RNA," added Williams, who is also director of the RiboEvo Center.

After so many trips back to the '80s and '90s, it's good to return to a book that's properly vintage. Dinosaurs was number 355 in the impressively diverse Little Golden Book series from Golden Press of New York, and was published in 1959. It was a simpler time, when a kids' dinosaur book could be purchased for a mere 25 cents, and palaeoart consisted of lush forests, erupting volcanoes, and giant lizards...all too literally.For you see, while the illustrator William de J. Rutherfoord was clearly an immensely talented individual - just take a gander at the beautifully painted cover art, with its murky, ashen sky and vibrant, surprisingly dynamic dinosaurs - he was a little prone to quite literally applying lizards' heads to dinosaurs' bodies. The cover provides one such illustration, with the noggin of a slightly perturbed-looking small lizard grafted atop the body of a generic sauropod. It looks bizarre to say the least, especially given that the chasing tyrannosaur appears to have the head of, you know, a tyrannosaur. The anatomical mash-up makes the book an entertaining read, though, as you can never quite be sure when a lizard-headed beastie will pop up next.In the tradition of countless dinosaur books before and since, the reader is taken on a (mostly) chronologically ordered trip through the ages, with illustrations of and snippets of text on the various animals to be found at different points in Earth's history. As such, the crocodylomorph Saltoposuchus makes an appearance early on - slightly ill-proportioned, but with lovely skin textures and patterns. For whatever reason, it's depicted standing next to the much later dinosaur Compsognathus, itself sporting a shrunken head and extra lizardy digits; it may be that the illustrator intended the animal to be Procompsognathus, but it ended up mislabelled. Regardless, these are very conventional depictions for the time, which makes what follows all the more baffling...Now, prior to the Dinosaur Renaissance, artists had a habit of interpreting dinosaurs' anatomy somewhat...loosely. Not only were the dinosaurs' obviously mightily muscular limbs reduced to weedy stilts propping up exaggeratedly blobby frames, but features like skulls were often smoothed over or their shapes changed in order to be closer to living reptiles, and in particular lizards like monitors. In this sense, Rutherfoord's approach can be seen as a particularly extreme example of an artistic convention, but...really? An iguana? For Allosaurus? Really!?! As already noted with the cover, what's strangest of all is the lack of consistency - even in the very same illustration, as the wonderfully knobbly Stegosaurus is entirely normal (even rather good) by contemporary standards. On the other hand, images like this wouldn't be so fantastically bizarre if Rutherfoord wasn't so good at painting, well, lizards - it's the realism evident in the iguana head that makes this image all the more amusing.Continuing with the theme, we see here two suspiciously serpentine sauropods - the Diplodocus in particular looks like a snake that's swallowed a decapitated elephant. That said, the vibrant skin patterns - at a time when sauropods were inevitably depicted as dull in every sense - are a very welcome change from the norm, and really help enliven this otherwise quite static (and somewhat familiar-looking) scene. And speaking of the familiar-looking...It's good ol' snorkelling Brachiosaurus again, here described as having the evasive habits of a cartoon ostrich - again, though, the bright-green-with-yellow-stripes look is just fabulous. Darling. I can't help but feel that an opportunity was missed for a rhyme here...There was Brachiosaurus, biggest of all.Massed fifty tons and was forty feet tall!But he couldn't run. He couldn't fight.Instead he went waltzing, all thro' the night.Or, you know. Something like that.Entering the Cretaceous, we encounter the usual suspects, all of which look rather conventional - there's a none-too

Testing the snowball Earth hypothesis for the EdiacaranAuthors:a. Alexei V. Ivanov (a)b. Anatoly M. Mazukabzov (a)c. Arkady M. Stanevich (a)d. Stanislav V. Palesskiy (b)e. Olga A. Kozmenko (b)Affiliations:a. Institute of the Earth's Crust, Siberian Branch, Russian Academy of Sciences, Lermontov Street 128, Irkutsk 664033, Russiab. Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, Academician Koptyug Boulevard 3, Novosibirsk 630090, RussiaAbstract:Ediacaran Siberia was at tropical paleolatitudes when the glacigenic strata of the Goloustnaya Formation (Baikal Group, Siberia) were deposited at sea level. The presence of such deposits (at tropical latitudes) is at the core of the snowball Earth hypothesis, which is generally accepted for the previous Cryogenian glaciations. To test this hypothesis for the Ediacaran Period, we determined concentrations of platinum group elements (PGE) in the transitional unit between glacigenic conglomerates and postglacial cap carbonates of the Goloustnaya Formation. We speculate that if oceans were completely covered by ice during the glaciation, the ice prevented accumulation of PGE-rich cosmic dust and micrometeorites during that period, i.e., the snowball Earth stage. Such particles would have accumulated rapidly on the ocean floor at the ice-melting event, providing a geochemical signal; however, unlike the previous Cryogenian glaciations, this signal is at a background level, and we conclude that either the Ediacaran glaciation did not reach the snowball stage, or it was of very short duration.

Scientists look at past climates to learn about climate change and the ability to simulate it with computer models. One region that has received a great deal of attention is the Indo-Pacific warm pool, the vast pool of warm water stretching along the equator from Africa to the western Pacific Ocean.In a new study, Pedro DiNezio of the International Pacific Research Center, University of Hawaii at Manoa, and Jessica Tierney of Woods Hole Oceanographic Institution investigated preserved geological clues (called "proxies") of rainfall patterns during the last ice age when the planet was dramatically colder than today. They compared these patterns with computer model simulations in order to find a physical explanation for the patterns inferred from the proxies.Their study, which appears in the May 19, online edition of Nature Geoscience, not only reveals unique patterns of rainfall change over the Indo-Pacific warm pool, but also shows that they were caused by the effect of lowered sea level on the configuration of the Indonesian archipelago."For our research," explains lead-author Pedro DiNezio at the International Pacific Research Center, "we compared the climate of the ice age with our recent warmer climate. We analyzed about 100 proxy records of rainfall and salinity stretching from the tropical western Pacific to the western Indian Ocean and eastern Africa. Rainfall and salinity signals recorded in geological sediments can tell us much about past changes in atmospheric circulation over land and the ocean respectively.""Our comparisons show that, as many scientists expected, much of the Indo-Pacific warm pool was drier during this glacial period compared with today. But, counter to some theories, several regions, such as the western Pacific and the western Indian Ocean, especially eastern Africa, were wetter," adds co-author Jessica Tierney from Woods Hole Oceanographic Institute.In the second step, the scientists matched these rainfall and salinity patterns with simulations from 12 state-of-the-art climate models that are used to also predict future climate change. For this matching they applied a method of categorical data comparison called the 'Cohen's kappa' statistic. Though widely used in the medical field, this method has not yet been used to match geological climate signals with climate model simulations."We were taken aback that only one model out of the 12 showed statistical agreement with the proxy-inferred patterns of the rainfall changes. This model, though, agrees well with both the rainfall and salinity indicators – two entirely independent sets of proxy data covering distinct areas of the tropics," says DiNezio.The model reveals that the dry climate during the glacial period was driven by reduced convection over a region of the warm pool called the Sunda Shelf. Today the shelf is submerged beneath the Gulf of Thailand, but was above sea level during the glacial period, when sea level was about 120 m lower."The exposure of the Sunda Shelf greatly weakened convection over the warm pool, with far-reaching impacts on the large-scale circulation and on rainfall patterns from Africa to the western Pacific and northern Australia," explains DiNezio.

A new study conducted at the University of Bristol and published online today in the Journal of Evolutionary Biology sheds light on how the brain and inner ear developed in dinosaurs.Stephan Lautenschlager from Bristol's School of Earth Sciences, together with Tom Hübner from the Niedersächsische Landesmuseum in Hannover, Germany, picked the brains of 150 million year old dinosaurs.The two palaeontologists studied different fossils of the Jurassic dinosaur Dysalotosaurus lettowvorbecki: a very young (juvenile) individual of approximately three years of age and a fully grown specimen of more than 12 years of age.Stephan Lautenschlager, lead author of the paper, said: "The two different growth stages of Dysalotosaurus provided a unique opportunity to study their brain, and how it developed during the growth of the animal."Using high-resolution CT scanning and 3D computer imaging, it was possible to reconstruct and visualise the brain and inner ear of Dysalotosaurus lettowvorbecki – a small, plant-eating dinosaur, which lived 150 million years ago, in what is now Tanzania.Co-author Tom Hübner said: "Well-preserved fossil material, which can be used to reconstruct the brain anatomy is usually rare. Thus, we were fortunate to have different growth stages available for our study."By looking at the brain and inner ear anatomy, the two researchers found that the brain of Dysalotosaurus underwent considerable changes during growth – most likely as a response to environmental and metabolic requirements. However, important parts responsible for the sense of hearing and cognitive processes were already well developed in the young individual.Stephan Lautenschlager said: "Our study shows that the brain was already well-developed in the young dinosaurs and adapted perfectly to interact with their environment and other individuals."This study has important ramifications for the understanding of how parts of the brain developed in dinosaurs. However, further research into that field is necessary to investigate if the pattern of brain development in individual dinosaurs is also reflected in a large scale trend during the more than 150 million years of dinosaur evolution.

I looked awful that day and they chose to use THAT pic? ugh.