Forgotten women of Paleontology: Emily Dix

 

Dr Emily Dix and her assistant Miss Elsie White.

Dr Emily Dix and her assistant Miss Elsie White.

In the 18th and 19th centuries women’s access to science was limited, and science was usually a ‘hobby’ for intelligent wealthy women. It was common for male scientists to have women assistants, often their own wives and daughters. But by the first half of the 20th century, a third of British palaeobotanists working on Carboniferous plants were women. The most notable were  Margaret Benson, Emily Dix, and Marie Stopes.

Emily Dix was born on 21 May 1904 in Penclawdd, in the beautiful area of the Gower Peninsula. At age 18, she gained the Central Welsh Board Higher Certificate in history, botany and geography, with distinctions in both history and botany. In 1925, she graduated with first class honours in Geology at the University College Swansea. After graduation, Emily continued at Swansea to research the geology of the western part of the South Wales Coalfield. Her work was supervised by Arthur E. Trueman, Professor of Geology at Swansea, and a pioneer in developing stratigraphical theory. Trueman realized that the only accurate way to use fossils for correlation was to divide the stratigraphical succession into biozones defined exclusively by the assemblages of species present, independently of the lithology in which they were found. Trueman’s main interest were  non-marine bivalves, so Emily’s early work was on the non-marine bivalves of the South Wales Coalfield.

Emily Dix during the 2nd International Carboniferous Congress in 1935 (From Burek and Cleal, 2005)

Emily Dix during the 2nd International Carboniferous Congress in 1935 (From Burek and Cleal, 2005)

Emily initially studied all aspects of the Late Carboniferous biotas in South Wales, but soon, she realized that plant fossils also had considerable biostratigraphical potential. Although, Paul Bertrand developed macrofloral biozones for the French coalfields in 1914, Emily used stratigraphical range charts for the first time in paleobotany recognising the need to separate biostratigraphy from lithostratigraphy. In 1926 Emily was awarded an MSc based on her Gwendraeth Valley work: ‘The Palaeontology of the Lower Coal Series of Carmarthen and the Correlation of the Coal Measures in the Western Portion of the South Wales Coalfield’.  In 1929 she was elected a fellow of the Geological Society, and a year later she was appointed Lecturer in Palaeontology at Bedford College in London, a position that she held for the rest of her working life. The same year, she attended the International Botanical Congress in Cambridge where she met W. Gothan, P. Bertrand, W. J. Jongmans and A. Renier, leaders in Upper Carboniferous palaeobotany at the time. Five years later, she attended the Second International Carboniferous Congress in Heerlen (The Netherlands) and she delivered papers on Carboniferous biostratigraphy. In 1936, Emily was invited to become the only female on an 11-man discussion group of the British Association for the Advancement of Science on Coal Measures correlation. She was clearly at the international forefront of the field.

Emily Dix in the Auvergne 1936 (seated fourth from right, see white arrow). From Burek and Cleal, 2005.

Emily Dix in the Auvergne 1936 (seated fourth from right, see white arrow). From Burek and Cleal, 2005.

At the start of the World War II, she was evacuated to Cambridge, along with the rest of Bedford College Geology Department. She lost a lot of valuable literature and other records in a London Blitz in May 1941. Fortunately, much of her collection of fossils survived.

At the end of the war, Emily suffered a mental breakdown. She was moved to a mental hospital run by the Quakers in the City of York. That was the end of her scientific career. She died in Swansea on 31 December 1972.

It was not until the late 1970s that her techniques were used again in Britain. Elsewhere in Europe, her approaches were adopted and can be seen in many of the papers presented at the International Carboniferous Congresses held at Heerlen during the 1950s and early 1960s.

References:

Burek, C. V. & Cleal, C. J. (2005) The life and work of Emily Dix (1904-1972). In: Bowden, A. J., Burek, C. V. & Wilding, R (ed.) History of palaeobotany: selected essays. Geological Society of London, Special Publication, 241, 181-196

Burek, C. V. (2005). Emily Dix, palaeobotanist – a promising career cut short. Geology Today, 21(4), 144-145

Climate model simulations at the end of the Cretaceous.

gg_60212w_crater

Artist’s reconstruction of Chicxulub crater 66 million years ago.

About thirty years ago, the discovery of anomalously high abundance of iridium and other platinum group elements in the Cretaceous/Palaeogene (K-Pg) boundary led to the hypothesis that a 10 km asteroid collided with the Earth and caused one of the most devastating events in the history of life. The impact created the 180-kilometre wide Chicxulub crater causing widespread tsunamis along the coastal zones of the surrounding oceans and released an estimated energy equivalent of 100 teratons of TNT and produced high concentrations of dust, soot, and sulfate aerosols in the atmosphere.

To model the climatic effects of the impact, a team of scientist from the Potsdam Institute for Climate Impact Research (PIK), use literature information from geophysical impact modeling indicating that for a 2.9 km thick target region consisting of 30% evaporites and 70% water-saturated carbonates and a dunite projectile with 50% porosity, a velocity of 20 km/s and a diameter between 15 and 20 km, a sulfur mass of 100 Gt is produced. This is about 10,000 times the amount of sulfur released during the 1991 Pinatubo eruption. Additionally, for a sulfur mass of 100 Gt, about 1400 Gt of carbon dioxide are injected into the atmosphere, corresponding to an increase of the atmospheric CO2 concentration by 180 ppm. There could be additional CO2 emissions from ocean outgassing and perturbations of the terrestrial biosphere, adding a total of 360 ppm and 540 ppm of CO2. The main result is a severe and persistent global cooling in the decades after the impact. Global annual mean temperatures over land dropped to -32C in the coldest year and continental temperatures in the tropics reaching a mere -22C. This model is supported by a migration of cool, boreal dinoflagellate species into the subtropic Tethyan realm directly across the K–Pg boundary interval and the ingression of boreal benthic foraminifera into the deeper parts of the Tethys Ocean, interpreted to reflect millennial timescale changes in the ocean circulation after the impact (Vellekoop, 2014).

A time-lapse animation showing severe cooling due to sulfate aerosols from the Chicxulub asteroid impact 66 million years ago (Credit: PKI)

A time-lapse animation showing severe cooling due to sulfate aerosols from the Chicxulub asteroid impact 66 million years ago (Credit: PKI)

References:

Brugger J., G. Feulner, and S. Petri (2016), Baby, it’s cold outside: Climate model simulations of the effects of the asteroid impact at the end of the Cretaceous, Geophys. Res. Lett., 43,  doi:10.1002/2016GL072241.

Alvarez, L. W., W. Alvarez, F. Asaro, and H. V. Michel (1980), Extraterrestrial Cause for the Cretaceous-Tertiary Extinction, Science, 208 (4448), 1095{1108, doi: 10.1126/science.208.4448.1095.

Galeotti, S., H. Brinkhuis, and M. Huber (2004), Records of post Cretaceous-Tertiary boundary millennial-scale cooling from the western Tethys: A smoking gun for the impact-winter hypothesis?, Geology, 32, 529, doi:10.1130/G20439.1

Johan Vellekoop, Appy Sluijs, Jan Smit, Stefan Schouten, Johan W. H. Weijers, Jaap S. Sinningh Damsté, and Henk Brinkhuis, Rapid short-term cooling following the Chicxulub impact at the Cretaceous–Paleogene boundary, PNAS (2014) doi: 10.1073/pnas.1319253111

From Argentina with Love: Top Fossils of 2016

Geographic provenance and speculative reconstruction of the gigantic titanosaurian sauropod dinosaur Notocolossus gonzalezparejasi gen. et sp. nov. (From González Riga  et al., 2016; Credit: Scientific Reports)

Since the discovery of dinosaur remains in the Neuquen basin in 1882, Argentina has gained the title of Land of the Giants. And 2016 has brought us amazing fossil discoveries. From Notocolossus to Gualicho, my fossil pick for this year are:

  • Notocolossus

Notocolossus gonzalezparejasi gen. et sp. nov. from the Upper Cretaceous of Mendoza Province, Argentina is one of the largest known dinosaurs. The name derived from the Greek notos (southern) and the Latin colossus, in reference to the gigantic size and Gondwanan provenance of the new taxon. The species name honours Dr. Jorge González Parejas, who provided legal guidance on the research, protection, and preservation of dinosaur fossils from Mendoza Province. The holotype of Notocolossus (UNCUYO-LD 301) consists of a partial skeleton lacking the skull. It contains an anterior dorsal vertebra, an anterior caudal vertebra, the right humerus (with 1.76 m in length), and the proximal end of the left pubis. The pes of  Notocolossus is comparatively shorter and more mediolaterally symmetrical than those of other titanosaurs, and indeed, most other sauropods. Notocolossus also presents truncated unguals, characteristics otherwise unknown in the Sauropoda.

Cranium of Sarmientosaurus musacchioi in right lateral view. Scale bar = 10 cm. (From Martínez et al., 2016)

Cranium of Sarmientosaurus musacchioi in right lateral view. Scale bar = 10 cm. (From Martínez et al., 2016)

  • Sarmientosaurus

Another remarkable new species of titanosaurian sauropod was Sarmientosaurus musacchioi. The holotypic and only known specimen consists of an articulated, virtually complete skull and part of the cranial and middle cervical series. The new titanosaur comes from the Lower Member of the Upper Cretaceous Bajo Barreal Formation on the Estancia Laguna Palacios near the village of Buen Pasto in south-central Chubut Province, central Patagonia, Argentina. It is the most basal known titanosaur to be represented by a well-preserved skull. Furthermore, the cranial endocast preserves some of the most complete information about the brain and sensory system for any sauropod.

Scapulocoracoid of Viavenator exxoni gen. et sp. nov. MAU-Pv-LI-530. in lateral view. Scale bar: 10 cm

Scapulocoracoid of Viavenator exxoni in lateral view. Scale bar: 10 cm (a, acromion; cf, coracoid foramen; gc, glenoid cavity; pvp, posteroventral process. From Filippi et al., 2016)

  • Viavenator

The holotype of Viavenator exxoni was found in the outcrops of the Bajo de la Carpa Formation (Santonian, Upper Cretaceous), northwestern Patagonia, Argentina. The new taxon belongs to the South American clade of abelisaurid and possesses, among other characteristics, hypertrophied structures in the presacral axial skeleton. The name derives from the latin word ‘Via’ (road) and ‘venator’ (hunter), meaning the hunter of the road; ‘exxoni’ is in recognition of Exxonmobil’s commitment to the preservation of paleontological heritage of the La Invernada area, Rincón de los Sauces, Neuquen, Patagonia Argentina.

Right postorbital (holotype) of Taurovenator violentei gen. et sp. nov. A, lateral view

Right postorbital (holotype) of Taurovenator violentei gen. et sp. nov. A, lateral view. Scale bar: 3 cm (From Motta et al., 2016)

  • Taurovenator.

Taurovenator violantei gen. et sp. nov. was is a medium-sized carcharodontosaurid theropod from the Huincul Formation (Upper Cretaceous) in northwestern Río Negro province, Patagonia, Argentina. The generic name derives from the Latin words “tauro” (Bull) and “venator” (Hunter). The specific name honours Enzo Violante, owner of the farm where the specimen was discovered. Taurovenator is similar in gross morphology to Giganotosaurus, Carcharodontosaurus, and Mapusaurus, but shows two unique features: the presence of a horn-like structure in the orbital brow and the presence of an excavation housed at the posterodorsal surface of the eye socket.

Different appendicular elements of Murusraptor in their original burial positions (From Coria et al., 2016)

Different appendicular elements of Murusraptor in their original burial positions (From Coria et al., 2016)

  • Murusraptor

Murusraptor barrosaensis, from the Upper Cretaceous of Neuquén Province, Argentina, belongs to a Patagonian radiation of megaraptorids together with Aerosteon, Megaraptor and Orkoraptor. Murusraptor, meaning “Wall Raptor”, was discovered in a canyon wall in 2001 during an expedition to Sierra Barrosa in northwestern Patagonia. The holotype specimen includes much of the skull, axial skeleton, pelvis and tibia. The braincase is intact and most of the sutures are still visible, indicating that this was not a fully mature animal. Murusraptor barrosaensis is unique in having anterodorsal process of lacrimal longer than height of preorbital process; sacral ribs hollow and tubelike; short ischia distally flattened and slightly expanded dorsoventrally. Murusraptor also exhibits some characters that are interpreted as convergencies of this taxon with non-tyrannosauroid theropods, including lacrimal with a small pneumatic recess; and a highly pneumatic braincase.

Gualicho shinyae, at the Centro Cultural de la Ciencia.

Gualicho shinyae, at the Centro Cultural de la Ciencia.

  • Gualicho

Gualicho was discovered on a paleontological expedition led by Sebastian Apesteguía in 2007. The name derived from the Gennaken (Northern Tehuelche languaje) watsiltsüm, an old goddess now considered a source of misfortune. The name was chosen to reflect the difficult circumstances surrounding the discovery and study of the specimen. The specific name honors Ms. Akiko Shinya, Chief Fossil Preparator at the Field Museum. The specimen exhibits a new and unusual combination of characters observed in various remotely related clades including ceratosaurs, tyrannosaurids, and megaraptorans. The didactyl manus with a semilunate distal carpal are indicative of derived tetanuran affinities, while the expanded posterior margin of the metatarsal III proximal articulation, are shared with ceratosaurs. The reduced forelimbs with didactyl manus are similar to those of the tyrannosaurids. However, in tyrannosaurids, the carpal elements are reduced and proximodistally flattened, whereas in Gualicho the semilunate and scapholunare carpals retain a more complex shape typical of the carpal elements of most non-coelurosaurian tetanurans. In addition, the manus of Gualicho differs from tyrannosaurids in having a proportionately more robust metacarpal I with a rectangular, rather than triangular, proximal articulation in end view.

 

References:

Bernardo J. González Riga et al. A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot, Scientific Reports (2016). DOI: 10.1038/srep19165

Martínez R.D.F. et al. 2016. A Basal Lithostrotian Titanosaur (Dinosauria: Sauropoda) with a Complete Skull: Implications for the Evolution and Paleobiology of Titanosauria. PLoS ONE 11 (4): e0151661; doi: 10.1371/journal.pone.0151661

Leonardo S. Filippi, Ariel H. Méndez, Rubén D. Juárez Valieri and Alberto C. Garrido (2016). «A new brachyrostran with hypertrophied axial structures reveals an unexpected radiation of latest Cretaceous abelisaurids». Cretaceous Research 61: 209-219. doi:10.1016/j.cretres.2015.12.018

Matías J. Motta, Alexis M. Aranciaga Rolando, Sebastián Rozadilla, Federico E. Agnolín, Nicolás R. Chimento, Federico Brissón Egli, and Fernando E. Novas (2016). «New theropod fauna from the Upper Cretaceous (Huincul Formation) of northwestern Patagonia, Argentina». New Mexico Museum of Natural History and Science Bulletin 71: 231-253

Rodolfo A. Coria, Philip J. Currie. A New Megaraptoran Dinosaur (Dinosauria, Theropoda, Megaraptoridae) from the Late Cretaceous of Patagonia. PLOS ONE, 2016; 11 (7): e0157973 DOI: 10.1371/journal.pone.0157973

Apesteguía S, Smith ND, Juárez Valieri R, Makovicky PJ (2016) An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina. PLoS ONE 11(7): e0157793. doi: 10.1371/journal.pone.0157793

Christmas edition: Geologizing with Dickens, part II.

dickens_by_watkins_1858

Charles Dickens at his desk, by George Herbert Watkins (National Portrait Gallery. From Wikimedia Commons)

Charles Dickens (1812- 1870) revitalized the traditions of Christmas, and to Victorian England, Dickens was Christmas. He had only 31, when began to write A Christmas Carol. The novella tells the story of  Ebenezer Scrooge, a bitter old man who finds salvation through the visits of the three Ghosts of Christmas (Ghost of Christmas Past, Ghost of Christmas Present, and Ghost of Christmas Yet to Come). But Dickens also contributed to the popularity of geology in the nineteenth century. Among his friends were Richard Owen and Sir Roderick Murchison. For Dickens, the ideal science is Geology. In his review of Hunt’s Poetry of Science, he wrote: “Science has gone down into the mines and coal-pits, and before the safety-lamp the Gnomes and Genii of those dark regions have disappeared … Sirens, mermaids, shining cities glittering at the bottom of quiet seas and in deep lakes, exist no longer; but in their place, Science, their destroyer, shows us whole coasts of coral reef constructed by the labours of minute creatures; points to our own chalk cliffs and limestone rocks as made of the dust of myriads of generations of infinitesimal beings that have passed away; reduces the very element of water into its constituent airs, and re-creates it at her pleasure…” (London Examiner, 1848).

In 1846, Dickens visited Naples and climbed the Mount Vesuvius. He described that experience in Pictures from Italy. He wrote: “Stand at the bottom of the great market-place of Pompeii, and look up the silent streets, through the ruined temples of Jupiter and Isis, over the broken houses with their inmost sanctuaries open to the day, away to Mount Vesuvius, bright and snowy in the peaceful distance; and lose all count of time, and heed of other things, in the strange and melancholy sensation of seeing the Destroyed and the Destroyer making this quiet picture in the sun.”

An eruption of Vesuvius circa 1845. Credit: Enrico La Pira.

An eruption of Vesuvius circa 1845. Credit: Enrico La Pira.

Mount Vesuvius is a stratovolcano, consisting of an external truncated cone, the extinct Mt. Somma,  a smaller cone represented by Vesuvius. For this reason, the volcano is also called Somma-Vesuvio. It was formed by the collision of two tectonic plates, the African and the Eurasian. When Mount Vesuvius erupted in 79 AD released deadly cloud of ash and molten rocks, and lasted eight days, burying and destroying the cities of Pompeya, Herculaneum and Stabiae. Vesuvius has the world’s oldest volcano observatory, established in 1845, and Dickens’s own magazine Household Words, frequently ran travel pieces describing the ascent and descent of Vesuvius, alongside trips to Pompei.

The same year, Dickens began to to write Dombey and Son, using his experiences in Italy to describe a violent eruption: “Hot springs and fiery eruptions, the usual attendants upon earthquakes, lent their contributions of confusion to the scene. Boiling water hissed and heaved within dilapidated walls; whence, also, the glare and roar of flames came issuing forth; and mounds of ashes blocked up rights of way, and wholly changed the law and custom of the neighbourhood”. 

Benjamin Waterhouse Hawkins unveiled the first ever sculptures of Iguanodons.

Benjamin Waterhouse Hawkins unveiled the first ever sculptures of Iguanodons.

It was an exciting time full of discoveries and the concept of an ancient Earth became part of the public understanding. The study of the Earth was central to the economic and cultural life of the Victorian Society and Literature influenced the pervasiveness of geological thinking. So when the Crystal Palace was reconstructed at Sydenham in 1854, Dickens and his Household Words were very enthusiastic. Megalosaurus became so popular that is mentioned in his novel Bleak House. In this novel the dinosaurs uncovered by the railway in Dombey and Son move centre stage: “Implacable November weather. As much mud in the streets as if the waters had but newly retired from the face of the earth, and it would not be wonderful to meet a Megalosaurus, forty feet long or so, waddling like an elephantine lizard up Holborn Hill.”  

In Bleak House and Dombey and Son, Dickens encourage reader to perceive the scene of the city as a geological fragment of a much broader spatial and temporal vision. In his last novel Our Mutual Friend (1864–65), Mr Venus, the taxidermist was slightly based on Richard Owen. By the time when Dickens wrote this novel, Owen was the curator of the Hunterian Museum of the Royal College of Surgeons. Our Mutual Friend, also exhibits  traces of the work of Lyell, Jean-Baptiste Lamarck, and Darwin.

References:

A. BUCKLAND, ‘“The Poetry of Science”: Charles Dickens, Geology and Visual and Material Culture in Victorian London’, Victorian Literature and Culture, 35 (2007), 679–94 (p. 680).

A. BUCKLAND. Novel Science: Fiction and the Invention of Nineteenth-Century Geology. Chicago, IL and London: University of Chicago Press, 2013. 400 pp. 9 plts. $45.00. ISBN 978-0-226-07968-4

A brief history of the Climate science

Large rift near the Pine Island Glacier tongue, West Antarctica. Credits: NASA/Nathan Kurtz

Large rift near the Pine Island Glacier tongue, West Antarctica. Credits: NASA/Nathan Kurtz

At the dawn of the Industrial Revolution the world experiences industrial and demographic boom. As a consequence of these substantial events, scientists of the time begin to question whether climate changes over time or not. In the 1760s, the ability to generate an artificial warming of the Earth’s surface was demonstrated by Horace Benedict de Saussure. In 1824, French mathematician Joseph Fourier published a scientific paper titled “Remarques generales sur les Temperatures du globe terrestre et des espaces planetaires” in the journal Annales de Chimie et de Physique, Tome XXVII (pp.136-167), where he presented some ‘general remarks’ on the temperature of the Earth and interplanetary space describing the Earth’s natural “greenhouse effect” without naming it. Terrestrial temperatures was on Fourier’s mind as early as 1807, when he wrote on the unequal heating of the globe. Following Fourier’s work, physicist C.S.M. Pouillet wrote in 1836 a memoir on solar heat, the radiative effects of the atmosphere, and the temperature of space.

Illustration of John Tyndall's setup for measuring the radiant heat absorption of gases (From Wikimedia Commons)

Illustration of John Tyndall’s setup for measuring the radiant heat absorption of gases (From Wikimedia Commons)

In 1861, Irish physicist John Tyndall demonstrated that gases such as methane and carbon dioxide absorbed infrared radiation, and could trap heat within the atmosphere. His interest in radiant heat and its passage through the atmosphere was triggered by his long-standing interest in glaciers and their mass balance. Tyndall’s experimental work suggested the possibility that by altering concentrations of these gases in the atmosphere, human activities could alter the temperature regulation of the planet. In his essay ‘On the Absorption and Radiation of Heat by Gases and Vapours’, Tyndall credited Fourier for the notion that ‘the interception of terrestrial rays [by the atmosphere exercises] the most important influence on climate’. 

In 1896, Svante Arrhenius  was the first to quantify the contribution of carbon dioxide to the greenhouse effect. He used infrared observations of the moon to calculate how much of infrared radiation is captured by CO2 and water vapour in Earth’s atmosphere and formulated his greenhouse law: “Thus if the quantity of carbonic acid increases in geometric progression, the augmentation of the temperature will increase nearly in arithmetic progression.”

Svante August Arrhenius (1859-1927). From Wikimedia Commons

Svante August Arrhenius (1859-1927). From Wikimedia Commons

Almost simultaneously, American geologist Thomas Chamberlin proposed that carbon dioxide fluctuations could cause large variations on Earth’s Climate, including Ice Ages.

By 1930s British engineer Guy Callender proves that temperature of Earth has risen compared to previous century, given records of 147 weather stations across the world. Moreover, he shows that carbon dioxide concentrations has increased at the same time and claims that it is the most plausible reason behind the global warming.

After the World War II, the impact of human activity on the global environment dramatically increased. In 1958, Charles Dave Keeling carries out a long-running experiment in Hawaii and Antarctica and enables unequivocal evidences of increasing carbon dioxide concentration in the atmosphere after four-year-research.

pet vs antropocene

Comparison of the effects of anthropogenic emissions (total of 5000 Pg C over 500 years) and PETM carbon release (3000 Pg C over 6 kyr) on the surface ocean saturation state of calcite. From Zeebe, 2013

In 1972, the United Nations summits the first environment conference in Stockholm and the climate change is determined as the agenda item. Since the conference the importance of this issue increases and public start to deal with the notion of climate change.

The earth’s climate has already reached a tipping point. Glaciers  from the Greenland and Antarctic Ice Sheets are fading away, dumping 260 billion metric tons of water into the ocean every year. The ocean acidification is occurring at a rate faster than at any time in the last 300 million years, and  the patterns of rainfall and drought are changing and undermining food security which have major implications for human health, welfare and social infrastructure.

References:

Hulme, M. (2009), On the origin of ‘the greenhouse effect’: John Tyndall’s 1859 interrogation of nature. Weather, 64: 121–123. doi:10.1002/wea.386

Tyndall J. 1861. On the absorption and radiation of heat by gases and vapours. Philos. Mag. 22: 169–194 and 273–285

Arrhenius, Svante; On the Influence of Carbonic Acid in the Air Upon the Temperature of the Ground. Philosophical Magazine and Journal of Science. 41 (5): 237–276. 1896.

Will Steffen, Wendy Broadgate, Lisa Deutsch, Owen Gaffney, and Cornelia Ludwig. The trajectory of the Anthropocene: The Great Acceleration. The Anthropocene Review, January 16, 2015 DOI: 10.1177/2053019614564785

Smith, B.D., Zeder, M.A., The onset of the Anthropocene. Anthropocene (2013),http://dx.doi.org/10.1016/j.ancene.2013.05.001

 

High variation in postnatal development of Early Dinosaurs.

Cleveland Museum of Natural History Coelophysis block, originally AMNH Block XII collected in 1948 by Colbert and crew

Cleveland Museum of Natural History Coelophysis block, originally AMNH Block XII collected in 1948 (From Wikimedia Commons)

Birds originated from a theropod lineage more than 150 million years ago. Their evolutionary history is one of the most enduring and fascinating debates in paleontology. They are members of the theropod dinosaur subgroup Coelurosauria, a diverse clade that includes tyrannosauroids and dromaeosaurids, among others. Features like “hollow” bones and postcranial skeletal pneumaticity, feathers, a unique forelimb digit formula, endothermy, and rapid growth rate arose in non-avian dinosaurs in a gradual process occurring over tens of millions of years.

In contrast with all other living reptiles, birds grow extremely fast and possess unusually low levels of intraspecific variation during postnatal development, suggesting that this avian style of development must have evolved after its most recent common ancestor with crocodylians but before the origin of Aves. Most studies indicates that the low levels of variation that characterize avian ontogeny were present in close non-avian relatives as well.

Two C. bauri casts mounted at the Denver Museum of Nature and Science (From Wikimedia Commons)

Two C. bauri casts mounted at the Denver Museum of Nature and Science (From Wikimedia Commons)

Compared with birds, the theropod Coelophysis bauri possess a large amount of intraspecific variation. Coelophysis bauri is the type species of the genus Coelophysis, a group of small, slenderly-built, ground-dwelling, bipedal carnivores, that lived approximately 203 million years ago during the latter part of the Triassic Period in what is now the southwestern United States. Using this taxon to interpret development among early dinosaurs, geoscientists Christopher Griffin and Sterling Nesbitt discovered that the earliest dinosaurs had a far higher level of variation in growth patterns between individuals than crocodiles and birds. The presence of scars on the bones left from muscle attachment and marks where bones had fused together helped the researchers assess how mature the animals were compared with their size.

Body size and extinction risk have been found to be related in various vertebrate groups, therefore a high level of variation within a species may be advantageous in an ecologically unstable environment and may have contributed to the early success of dinosaurs relative to many pseudosuchian clades in the latest Triassic and through the End-Triassic Mass Extinction into the Early Jurassic.

References:

Christopher T. Griffin and Sterling J. Nesbitt, Anomalously high variation in postnatal development is ancestral for dinosaurs but lost in birds. PNAS 2016 : 1613813113v1-201613813.

Brusatte SL, Lloyd GT, Wang SC, Norell MA (2014) Gradual assembly of avian body plan culminated in rapid rates of evolution across the dinosaur-bird transition. Curr Biol 24(20):2386–2392

Puttick, M. N., Thomas, G. H. and Benton, M. J. (2014), HIGH RATES OF EVOLUTION PRECEDED THE ORIGIN OF BIRDS. Evolution, 68: 1497–1510. doi: 10.1111/evo.12363 A.

A brief introduction to the Early dinosaurs from Argentina.

eoraptor-skeleton

Articulated skeleton of Eoraptor lunensi (From Sereno 2013)

The oldest record of Argentinean dinosaurs comes from the Ischigualasto Formation, NW Argentina, dated from 231.4 Ma to 225.9 Ma. Adolf Stelzner in 1889 published the first data on the geology of Ischigualasto, but it was not until 1911 that Guillermo Bodenbender briefly refers to the fossils of the site. In the early 40′s, Joaquin Frenguelli, initiates a geological survey in the western margin of the basin. Later, in 1943, Angel Cabrera described fragmentary therapsid fossils. However, intensive paleontological study of the Ischigualasto and Chañares Formations, began only in the late 1950s.

The Ischigualasto Formation has 300–700 m of mudstone, sandstone, conglomerate, and basalt, and consists of four lithostratigraphic members which in ascending order include the La Peña Member, the Cancha de Bochas Member, the Valle de la Luna Member, and the Quebrada de la Sal Member. Eight valid species of dinosaurs are known from the Ischigualasto Formation: Pisanosaurus mertii, Herrerasaurus ischigualastensis, Sanjuansaurus gordilloi, Eodromaeus murphi, Eoraptor lunensis, Panphagia protos, and Chromogisaurus novasi.

 

Skull of Herrerasaurus ischigualastensis (Sereno, 2013)

Skull of Herrerasaurus ischigualastensis (Sereno, 2013)

Pisanosaurus mertii is a small specimen, know by an incomplete maxilla and lower jaw fragments bearing teeth, vertebrae, incomplete hind limb, and the impression of the pelvis. Described in 1967 by Rodolfo CasamiquelaPisanosaurus is considered as the oldest known ornithischian.

Herrerasaurus ischigualastensis was described by Osvaldo Reig in 1963. The taxon is one of the best known Triassic dinosaurs and the largest dinosaur of the Ischigualasto Formation. Herrerasaurus was fully bipedal, with strong hind limbs, short thighs and long feet. The skull has a rectangular profile and a transversely narrow snout (Sereno and Novas, 1992). The presence of two sacral vertebrae and lack of brevis fossa made Herrerasaurus, and other herrerasaurids, a controversial group.

Sanjuansaurus gordilloi is similar to Herrerasaurus ischigualastensis, although more gracile and possessing short and straight pubis among other differences (Alcober & Martínez, 2010). It’s known from one specimen that preserves left maxilla, partial axial column, scapulae, left ulna, ungual of manual digit III, partial left ilium and pubis, both femora and tibiae, right fibula, right astragalus and calcaneum, and left metatarsal.

Skull and skeleton of Eodromaeus murphi (PVSJ 560). Scale bar equals 10 cm.

Skull and skeleton of Eodromaeus murphi
(PVSJ 560). Scale bar equals 10 cm.

Eodromaeus murphi is a small species with a total length of about 1.2 metres, known from five specimens. The trunk was long and slender, and forelimbs were shorter than the hindlimbs. The skull is relatively low and lightly built with a relatively spacious antorbital fenestra.  A phylogenetic analysis places Eodromaeus within Theropoda as the sister taxon to Neotheropoda

Eoraptor lunensis is known from eight specimens, including the holotype that preserves most of the skeleton. Eoraptor had a slender body with an estimated weight of about 10 kilograms. The lightly built skull has a slightly enlarged external naris and the premaxilla is observed to have a slender posterolateral process. The long bones of the hind limb have more robust shafts than those of Eodromaeus, although in both genera the tibia remains slightly longer than the femur (Sereno et al., 2013). Initially considered a basal theropod, the sauropodomorph affinity of Eoraptor has been strengthened after the publication of its anatomy in 2013.

Panphagia protos is a small species, known from one partial skeleton including several skull bones, lower jaw, and partial axial skeleton. The specimen is an immature individual with an estimated body length of approximately 1.30 m. It was originally proposed as the most basal sauropodomorph (Martinez and Alcober, 2009)

Chromogisaurus novasi is also similar in size to Eoraptor lunensis. It’s known from a partial skeleton lacking the skull. It includes elements of the front and hind limbs, the pelvis and two caudal vertebrae.

References:

Martín D. EZCURRA & Ricardo N. MARTÍNEZ (2016), Dinosaur precursors and early dinosaurs from Argentina., In book: Historia Evolutiva y Paleobiogeografía de los Vertebrados de América del Sur, Publisher: Contribuciones del MACN, Editors: F. Agnolíin, G.L. Lio, F. Brissón Egli, N.R. Chimento, F. Novas, pp.97-107

Reig, O.A. (1963). “La presencia de dinosaurios saurisquios en los “Estratos de Ischigualasto” (Mesotriásico Superior) de las provincias de San Juan y La Rioja (República Argentina)”. Ameghiniana (in Spanish). 3 (1): 3–20.

Sereno, P.C.; Novas, F.E. (1992). “The complete skull and skeleton of an early dinosaur”. Science. 258 (5085): 1137–1140.

Ricardo N. Martinez; Paul C. Sereno; Oscar A. Alcober; Carina E. Colombi; Paul R. Renne; Isabel P. Montañez; Brian S. Currie (2011). “A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangaea”. Science. 331 (6014): 206–210. doi:10.1126/science.1198467

Martinez RN, Alcober OA (2009) A Basal Sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic, Carnian) and the Early Evolution of Sauropodomorpha. PLoS ONE 4(2): e4397. doi:10.1371/journal.pone.0004397

Ezcurra, M. D. 2010. “A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Argentina: a reassessment of dinosaur origin and phylogeny.” Journal of Systematic Palaeontology 8: 371-425.

 

Dracorex hogwartsia: A fantastic beast and where to find it.

The cover of the book Fantastic Beasts and Where to Find Them.

The cover of the book Fantastic Beasts and Where to Find Them.

It has been nearly 20 years since Harry Potter and The Philosopher’s Stone was released. Written by  J. K. Rowling, the book was the first of a saga about a young wizard, Harry Potter, and his friends Hermione Granger and Ron Weasley, all of whom are students at Hogwarts School of Witchcraft and Wizardry. The original seven books were adapted into an eight-part film series. In 2011, the last part of the saga, Harry Potter and the Deathly Hallows Part 2 debuted in cinemas worldwide. Now, the magic world of Harry Potter is returning to the big screen. “Fantastic Beasts and where to find it” takes place in the Harry Potter Universe almost 80 years before Harry himself enters the scene. The story follows Newt Scamander, a British wizard and magic-zoologist. After being expelled from Hogwarts, Scamander joined to the Ministry of Magic and spent two years in the Office for House-Elf Relocation before being transferred to the Beast Division. Due to his extensive knowledge of magical creatures, Augustus Worme of Obscurus Books commissioned Scamander to write the first edition of “Fantastic Beasts and Where to Find Them”.

Dracorex skeletal reconstruction (Dracorex hogwartsia) is in the permanent collection of The Children’s Museum of Indianapolis.

Skeletal reconstruction of Dracorex hogwartsia in the permanent collection of The Children’s Museum of Indianapolis (From Wikimedia Commons)

Scamander travelled to numerous cities doing research for his book and in 1926 he arrived to New York, a city full of great economic inequality and where wizards were forced to hide. Years later, Scamander worked extensively with the Dragon Research and Restraint Bureau, which led him on expeditions all over the world, collecting information for new editions of Fantastic Beasts. Published in 1927, Fantastic Beasts became an approved textbook at Hogwarts. Among the beasts included in the book are Acromantula, the Basilisk, Manticore and different types of Dragons. Most probably, Scamander would have included Dracorex hogwartsia in a new edition of the book.

Dracorex is known from one nearly complete skull discovered in the Upper Cretaceous Hell Creek Formation of South Dakota and donated to the Children’s Museum of Indianapolis in 2004. It was described by Bob Bakker and Robert Sullivan in 2006. The  name was taken from the Latin words for dragon, draco, and king, rex, and the latinized name for Hogwarts, hogwartsia. 

Dracorex skull (Image credit: The Children’s Museum of Indianapolis)

Dracorex skull (Image credit: The Children’s Museum of Indianapolis)

Dracorex is a dinosaur genus of the family Pachycephalosauridae, a diverse group of small, herbivorous dinosaurs, characterized by short forelimbs, stocky and powerful hind limbs, and a short, thick neck. Their most distinguishing feature was the development of a cranial dome, which is formed by the fusion and thickening of the frontals and parietals, and in some species, peripheral bones of the skull roof. Their remains are known from the Late Cretaceous of North America, Asia, and possibly Europe. The group include Pachycephalosaurus, Stegoceras, Stygimoloch and Prenocephale

Dracorex is similar to Pachycephalosaurus and Stygimoloch, but differs from them in having a flat skull, four-spiked squamosals, enlarged supratemporal fenestrae and a skull covered entirely with dermal ossicles (knobs, rugosities, and spikes). In a paper published in 2009 , it was suggested that “Dracorex” and “Stygimoloch” represent younger ontogenetic stages of Pachycephalosaurus. 

 

References:

Bakker, R. T., Sullivan, R. M., Porter, V., Larson, P. and Saulsbury, S.J. (2006). “Dracorex hogwartsia, n. gen., n. sp., a spiked, flat-headed pachycephalosaurid dinosaur from the Upper Cretaceous Hell Creek Formation of South Dakota.” in Lucas, S. G. and Sullivan, R. M., eds., Late Cretaceous vertebrates from the Western Interior. New Mexico Museum of Natural History and Science Bulletin 35, pp. 331–345. 

Horner J.R. and Goodwin, M.B. (2009). “Extreme cranial ontogeny in the Upper Cretaceous Dinosaur Pachycephalosaurus.” PLoS ONE, 4(10): e7626

Newt Scamander. Fantastic Beasts & Where to Find Them. New York, NY: Arthur A. Levine Books, 2001

A Unique Late Triassic Dinosauromorph Assemblage from Brazil

The skull of Buriolestes shultzi. (Image credit: Cabreira et al., 2016)

The skull of Buriolestes shultzi. (Image credit: Cabreira et al., 2016)

The Santa Maria Formation in southern Brazil, comprises a succession of Middle to Late Triassic sedimentary rocks that have been long renowned for their rich tetrapod fossils including one of the oldest (and the best preserved) associations of dinosaur and dinosaur precursor, respectively represented by new species of Lagerpetidae and Sauropodomorph.

The lagerpetids, a family of basal dinosauromorphs, are represented by a semi-articulated skeleton and a pair of fragmentary femora. As for the dinosaurs, a large articulated individual was preserved, together with smaller and non-duplicated bone elements that indicate the presence of another individual The two articulated specimens are named  Ixalerpeton polesinensis and Buriolestes shultzi.

Ixalerpeton polesinensis helps to define traits of anatomical parts previously unknown for lagerpetids. For example, a skull roof broader than that of most early dinosaurs, an anterior tympanic recess in the braincase, as is typical of Dinosauriforme, although retains traits unknown to that group, such as a large post-temporal fenestra, a postfrontal bone, and a frontal not excavated by the supratemporal fossa.

A: Skeletal reconstruction of Ixalerpeton polesinensis. B: Skull roof. C: Braincase. (Adapted from Cabreira et al., 2016)

A: Skeletal reconstruction of Ixalerpeton polesinensis. B: Skull roof. C: Braincase. Abbreviations: f, frontal; fm, foramen magnum; p, parietal; pof, postfrontal; pp, paroccipital process; so, supraoccipital. (Adapted from Cabreira et al., 2016)

 

Buriolestes shultzi is the earliest member of Sauropodomorpha, although lacks usual sauropodomorph traits such as a reduced skull and an enlarged external naris, and as in all early dinosaurs, the frontal is excavated by the supratemporal fossa. As typical of sauropodomorphs, the humerus is longer than 60% the length of the femur, and the deltopectoral crest extends for more than 40% of its length. The dentary traits are compatible with a faunivorous diet suggesting that early members of the Sauropodomorpha were likely predators.

The fossils, found by a team from the Lutheran University of Brazil, confirms that the co-occurrence between non-dinosaurian Dinosauromorpha and dinosaurs was not restricted to later stages of the Triassic and to the northern parts of Pangaea, suggesting that a rapid replacement was a very unlikely scenario for the initial radiation of dinosaurs.

References:

Cabreira et al., A Unique Late Triassic Dinosauromorph Assemblage Reveals Dinosaur Ancestral Anatomy and Diet, Current Biology (2016), http://dx.doi.org/10.1016/j.cub.2016.09.040

Langer, M.C., Nesbitt, S.J., Bittencourt, J.S., and Irmis, R.B. (2013). Non-dinosaurian Dinosauromorpha. Geol. Soc. Spec. Publ. 379, 157–186.

Halloween special IV: Atlach-Nacha and the Spiders of Leng.

The male, Mongolarachne jurassica, and female, Nephila jurassica, were similar in size. Photo: Kansas University and Paul Selden

The male, Mongolarachne jurassica, and female, Nephila jurassica, were similar in size. Photo: Kansas University and Paul Selden

Clark Ashton Smith (January 13, 1893 – August 14, 1961) was an American poet, sculptor, painter and author of fantasy, horror and science fiction short stories. He was one of the big three of Weird Tales, with Robert E. Howard and H. P. Lovecraft.  His work is marked by an extraordinarily rich and ornate vocabulary, a cosmic perspective and a sardonic humor. Among his numerous contribution to the Cthulhu Mythos is Atlach-Nacha, the spider God, first introduced in “The Seven Geases” (Weird Tales, Vol. 24, No. 4, October 1934). Atlach-Nacha resembles a huge spider with an almost-human face. It dwells within a huge cavern deep beneath Mount Voormithadreth, a mountain in the now vanished kingdom of Hyperborea in the Arctic. The bloated purple spiders of Leng are thought to be its children and servitors.

Dorsal view of a near-complete specimen of Palaeocharinus tuberculatus in Windyfield chert, showing prosoma (Pr), opisthosoma (Op), and the rear three right leg appendages (RL2-4) (scale bar = 1 mm). Image credit: University of Aberdeen

Dorsal view of a near-complete specimen of Palaeocharinus tuberculatus in Windyfield chert, showing prosoma (Pr), opisthosoma (Op), and the rear three right leg appendages (RL2-4) (scale bar = 1 mm). Image credit: University of Aberdeen

From Greek mythology to African folklore, the spider has been used to represent a variety of things, and gained a reputation for causing irrational fear in humans. Among the oldest known land arthropods are Trigonotarbids, an extinct order of terrestrial arachnids related to modern day spiders. The earliest trigonotarbid known in the fossil record is from the Silurian Ludlow Bone Bed. In 1923, Stanley Hirst described five species of trigonotarbids from the Rhynie cherts under the generic names Palaeocharinoides and Palaeocharinus. These are Palaeocharinoides hornei, Palaeocharinus rhyniensis, P. scourfieldi, P.calmani and P. kidstoni.

Spiders (Order Araneae) are massively abundant generalist arthropod predators that are found in nearly every ecosystem on the planet since the Devonian (>380 mya). The oldest true spiders belonged to the Mesothelae. Mongolarachne jurassica, from Daohuogo, Inner Mongolia in China, is the largest known fossil spider. Mongolarachne is remarkable for being larger than its female counterpart, Nephila jurassica, found on the same site in 2011.

 

References:

Garrison, Nicole L.; Rodriguez, Juanita; Agnarsson, Ingi; Coddington, Jonathan A.; Griswold, Charles E.; Hamilton, Christopher A.; Hedin, Marshal; Kocot, Kevin M.; Ledford, Joel M.; Bond, Jason E. (2016). “Spider phylogenomics: untangling the Spider Tree of Life”. PeerJ. 4: e1719. doi:10.7717/peerj.1719

Garwood, Russell J.; Dunlop, Jason (July 2014). “The walking dead: Blender as a tool for paleontologists with a case study on extinct arachnids”. Journal of Paleontology. Paleontological Society. 88 (4): 735–746. doi:10.1666/13-088